GroupDIY

General Discussions => The Lab => Topic started by: on July 22, 2004, 09:27:38 AM

Title: Helios thread
Post by: on July 22, 2004, 09:27:38 AM
rather than hijacking another thread I thought I would put some Helios stuff here..

Good quote on the resissues:
"With a c.1973 desk built for Eric Clapton as his reference, Arnold set about replicating Helios modules carefully including all the faults of the original to begin with. In the course of his research he found that the original desks' 20dB pad used a centre-tap from the Lustraphone input transformer. These sounded better than later Helios desks, which used Beyer transformers with resistors rather than a centre- tap for the pad. Arnold approached Sowter to copy the Lustraphone transformers. "

Reissues again..
"As Helios equalisers use some exotic bits from Switzerland and France, the lead time on some components can vary between six and ten weeks."


I am sorry but this (from Dan Alexanders site) wins hands down on looks

(http://www.danalexanderaudio.com/danspics/redconsole.jpg)
Title: Helios thread
Post by: sismofyt on July 22, 2004, 09:33:49 AM
I have like 50 Helios pics, do you want 'em here?

Helios are my pets. I L_O_V_E the looks of that gear!

Btw, it's hard to talk about a specific Helios 'sound' or trannietype, ect, because nearly every desk was a one of a kind job. They're all different.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 09:47:57 AM
Helios galore can be seen at www.sismofyt.net/lab_helios.htm

Heavy drooling is to be expected :green:
Title: Helios thread
Post by: sismofyt on July 22, 2004, 09:51:44 AM
GET IT!

Or at least book a day or two. Bring camera :cool:
Title: Helios thread
Post by: on July 22, 2004, 09:51:44 AM
mmmhhh - Helios....

Schematics all here...

http://www.vintageking.com/Library-Schematics.cfm

original
http://www.vintageking.com/images/schem_V69-1973-1-Var-1.jpg
http://www.vintageking.com/images/schem_V69-1973-2-Var-1.jpg

reissue
http://www.vintageking.com/images/schem_V69-2003-A3-Var-1.jpg
http://www.vintageking.com/images/schem_V69-2003-2-Var-1.jpg
http://www.vintageking.com/images/schem_V69-2003-1-Var-1.jpg

This is what they look like racked...
http://www.vintageking.com/data/4_space_helios_rack_loaded_front.jpg


self oscillating at high gain (+60db) with the eq on
weird phase reverse circuit, line in and line out NOT balanced
NOT +4 actually . 775
Discret electronics with transformer balanced input & output.
Mic/Line Input Transformer Preamplifier with stepped gain.
Stepped frequency/gain HF EQ,
Stepped frequency MID EQ.
Stepped frequency LOW EQ.
HighPass Filter.
Phase-switch.
Phantom Power.
Metering on rack version.

i am going to print all this of...
Title: Helios thread
Post by: sismofyt on July 22, 2004, 09:52:22 AM
Sorry bad link, works now!

Helios today: www.helios-electronics.com/index.htm

Another Helios company: www.helios-audio.com/index.htm
Title: Helios thread
Post by: on July 22, 2004, 09:53:23 AM
Quote from: "sismofyt"
Helios galore can be seen at www.sismofyt.net/lab_helios.htm

Heavy drooling is to be expected :green:

OMFG!!!!
Title: Helios thread
Post by: sismofyt on July 22, 2004, 10:03:39 AM
I doubt they're using that Helios today, but why don't you try to track it down? Does the TV company still exist today?

Helios is just beyond cool. May Swettenham R.I.P :cry:
Title: Helios thread
Post by: on July 22, 2004, 10:08:57 AM
More schms (from Dans site again)
Pinout
http://www.danalexanderaudio.com/OutboardPic/HeliosPinout.jpg

Input module schematic
http://www.danalexanderaudio.com/OutboardPic/HeliosInputSchematic.jpg

EQ pinout
http://www.danalexanderaudio.com/OutboardPic/HeliosEQ.jpg


Channel Schematic
http://www.danalexanderaudio.com/OutboardPic/HeliosChannelSchem.jpg
Title: Helios thread
Post by: sismofyt on July 22, 2004, 10:10:36 AM
Paul Weller (The Jam, Style Council - godfather of britpop) made a REALLY cool album called 'Heliocentric', recorded at Heliocentric on a custom/modernized Helios (the last pic on my site). Check it out, some smashing songs on that album :grin:

www.paulweller.com/newSite.html

www.heliocentric.co.uk is not working though :roll:

(http://friends.s5.net/mazzini/glasbeneocene/images/weller.jpg)
Title: Helios thread
Post by: on July 22, 2004, 10:20:22 AM
the current issue of SoS has an interview with Keanes producer - they layed some tracks down there....
Heliocentric has the hybrid Island/Alvin Lee console and is now owned by Chris Difford (from Squeeze) and Elvis Costello
there is a piccie here of the outside of the studio
http://www.soundonsound.com/sos/aug04/images/keane8.l.jpg?session=87aaf722d7c9a28b94f35626529e6c27
But if you are not an SoS subscriber you won;t be able to see it!
Title: Helios thread
Post by: sismofyt on July 22, 2004, 10:23:08 AM
What's your subscribtion # ?.. hehe.. :cool:  :green:
Title: Helios thread
Post by: sismofyt on July 22, 2004, 10:24:34 AM
Oh, I can see the pic.. that's just a fukkin' house. Could be anything really. I'm no fan of SOS, so I'll just wait 4 years until it's online :roll:
Title: Helios thread
Post by: on July 22, 2004, 10:40:43 AM
News just in from Sowter

> I notice that you make the reissue Helios transformer based ont he
> lustraphone
>
> Which model number is it?
>
> regards
> Simon
>
The type number is 8666 but this is not listed on our site.

You can view the size on our Pro Packages button. The
transformer is size E and is available in styles f and e.

The price is UKP 33.20 each ex-works.

Carriage and VAT (if applicable) is charged extra.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 10:45:08 AM
OHHHHHHHHHHH!

So who's gonna pony up a GroupDIY Helios clone?  :green:

Me, I'd never clone anything.. never... ever... eh... oh... mm'kay :razz:
Title: Helios thread
Post by: sismofyt on July 22, 2004, 11:04:09 AM
Some random thoughts/observations:

Okay, looking at the reissue schematic; I wonder if it's correct. I mean why would they put that online? I don't understand why there's a 36V zener diode parrallel with a cap in the ampcards when the they running +24V?

It's really hard to read  :cry: I'd think that making amp cards and hardwire the eq caps would be the way to go. Original Helios style. And there's that inductor...

Not a smart way to do phase reverse. I'd leave that part/amp out.

Rafafredd, you got that fancy sim app. Could you run the amp through it?

The schematic at Dan's site is -24V stuff.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 11:15:35 AM
The preamp alone sans EQ would not be that hard to make with that new Sowter trannie. And not very expensive either.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 11:23:36 AM
Is there any ninja tricks to make the schematic more readable :?
Title: Helios thread
Post by: dmlandrum on July 22, 2004, 11:45:34 AM
Does this help?

http://studioconsul.net/techtalk/misc/HeliosInputSchematic.gif

I played around with it for a bit. I'm sure it could be better, though.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 11:48:30 AM
No, that's for another Helios at Dan alexander's site. I think the complete schematic at Dan's site is too full of mods and errors. One inductor do have it's value written though. It's running -24V and may use germaniums (allthough I don't think so)

I think the schematic at Vintage King is where we should put our money..
Title: Helios thread
Post by: dmlandrum on July 22, 2004, 11:49:46 AM
Okay, which schematic do you need cleaned up? I'll give it a shot. I just guessed based upon your posts which you were looking at.
Title: Helios thread
Post by: on July 22, 2004, 11:57:05 AM
I find them all very readable (after the "make it big icon" appears in the bottom right )- but I haven't a clue what I need to look at...
Title: Helios thread
Post by: sismofyt on July 22, 2004, 11:58:04 AM
There are three schematics.

This is the original 69 Helios:

www.vintageking.com/images/schem_V69-1973-1-Var-1.jpg

www.vintageking.com/images/schem_V69-1973-2-Var-1.jpg

It would be great if you could clean this :thumb:

This is the reissue, which doesn't look like the original 69. The two buffers aren't there and the amp cards are different. I wonder why :?

www.vintageking.com/images/schem_V69-2003-A3-Var-1.jpg
www.vintageking.com/images/schem_V69-2003-2-Var-1.jpg
www.vintageking.com/images/schem_V69-2003-1-Var-1.jpg

I think these are the ones we should try to clone. Maybe. I'm not sure. What do thers think? Maybe Sowter can make those two inductors? (One is multitapped). Would be swell if you can clean those as well.

This is the old one from Dan Alexander's site:

www.danalexanderaudio.com/OutboardPic/HeliosInputSchematic.jpg

www.danalexanderaudio.com/OutboardPic/HeliosChannelSchem.jpg

Hmm, that appears to be the same as the original 69 :? But running at -24V :shock: Hmm, me confused.

Hell, clean 'em all if you can :grin:
Title: Helios thread
Post by: dmlandrum on July 22, 2004, 12:00:11 PM
It'll take some time, but I'll go for it. I'll post here when I'm done.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 12:02:16 PM
It's the reissue that's mostly unreadable, but I think we should not make that one. Yes, I said the opposite before. I'm typing, looking, thinking all at once. Real time simofyt :grin:

Ok. The old 69 and the Dan Alexander is the same.
Title: Re: Helios thread
Post by: SSLtech on July 22, 2004, 12:07:07 PM
Quote from: "uk03878"
I am sorry but this (from Dan Alexanders site) wins hands down on looks

That's 10CC's old Helios. It was made a custom red to go in Strawberry Studios in Stockport. I worked on it a few times... it had at least one cigarette lighter (12V, out of a car) in it!

That was an awesome board, and at the time, Strawberry was an awesome studio! -unfortunately, it ran downhill in the 1980's, and by 1990 it was a pit, with a useless Quad-eight/Otari/Westrex/Mitsubishi console/machine package. Otari was making cold-sounding junk and badging it as QUad-Eight in those days...

Lotta history in that board... check out this thread on GM's forum:
http://recforums.prosoundweb.com/index.php/mv/msg/1178/0/16/2172/?SQ=f6a6568ae8a257298e84bf24f9af3bfa

Keith
Title: Helios thread
Post by: sismofyt on July 22, 2004, 12:10:28 PM
Looks like it's all -24V stuff.

Ahh, the multitapped inductor, only has one tap. And I think it's 220mH & 680mH.

Still need to figure out the L1, #L3857
Title: Helios thread
Post by: NewYorkDave on July 22, 2004, 12:18:44 PM
Quote from: "sismofyt"
I don't understand why there's a 36V zener diode parrallel with a cap in the ampcards when the they running +24V


Overvoltage protection ("crowbar")?
Title: Helios thread
Post by: dmlandrum on July 22, 2004, 12:18:48 PM
http://studioconsul.net/techtalk/helios/schem_V69-1973-1-Var-1.png
http://studioconsul.net/techtalk/helios/schem_V69-1973-2-Var-1.png

The others look hopeless. I couldn't do anything to make the component values readable. Maybe someone else has some tricks.
Title: Helios thread
Post by: sismofyt on July 22, 2004, 12:21:22 PM
Yes, I thought of that Dave, but is that really neccesary? Doens't he trust his PSU? Depending on the fuse/PSU, the zener might blow instead. I think it's a bad idea. Edit: It's current limited through a resistor.

Consul, I think we can make it without better schematics. I was concerned about the 69 reissue, but I think that's not the one to clone.

I'll try to figure out what value that inductor may have tonite or tommorrow. Perhaps NYCDave will give a hand?
Title: Helios thread
Post by: soundguy on July 22, 2004, 02:27:00 PM
I guess this seems like a good time to bring this up-

A friend of mine has an Island Studios helios limiter, taken from a console.  He uses this thing on pretty much everything he does and Id bet most of the guys here reading this have heard his records.  Ive been playing phone tag for weeks with him, but hope to see him soon to photograph the insides of that box.  Kind of exciting, I always thought that the Island boards just had repackaged AD&R compex limiters in them, I have seen at least one helios board that must have been licensed from AD&R.  According to my friend, its not a compex, it definitely doesnt sound like mine.  Ive never heard a compressor do what that thing does.  Stay tuned, hopefully in the next few weeks I'll have more info on this one, kind of exciting.  

dave
Title: Helios thread
Post by: Mark Burnley on July 22, 2004, 02:35:55 PM
Dave,

I'm all ears (literally!  :grin: ), that sounds amazing- I've been looking for internal shots of that for a long time.

Great stuff.

 :thumb:

Mark
Title: Helios thread
Post by: dmlandrum on July 22, 2004, 02:44:03 PM
All I know is, seeing those pictures of the old Helios consoles is making me want to build all of my gear as one large console again, instead of inidividual rackmount pieces.

I'm with sysmofit on this one. I'm not fond of rackmounting. Now I just need to figure out how to fit a G9 into a different style of case.

Those extruded Hammond cases look good.
Title: Helios thread
Post by: Bear on July 22, 2004, 04:43:34 PM
Quote from: "sismofyt"
The preamp alone sans EQ would not be that hard to make with that new Sowter trannie. And not very expensive either.


Damn, you know I'm starting to think I need to win the lottery to keep up with building gear, much less buying it.  Still, I want to be the coolest home studio on my block, so I think I must.  

Bear

[So anyone have the inductor spec's?]
Title: Helios thread
Post by: on July 23, 2004, 04:07:19 AM
Quote from: "Consul"
All I know is, seeing those pictures of the old Helios consoles is making me want to build all of my gear as one large console again, instead of inidividual rackmount pieces.

I'm with sysmofit on this one. I'm not fond of rackmounting. Now I just need to figure out how to fit a G9 into a different style of case.

Those extruded Hammond cases look good.

That's exactly what I am thinking...
Using a 3 unit card frame case as a base for vertical modules based on Eurocards - and going to two panels wide for those which need more space.
Bolting the case into a desk
Maybe three layers....
Top layer - mic pres
Second layer - limiters, compressors
Third Layer - Faders
Title: Helios thread
Post by: ijr on July 23, 2004, 05:53:41 AM
(edit: post deleted)
Title: Helios thread
Post by: sismofyt on July 23, 2004, 06:42:33 AM
I think we can figure out the missing inductor values allright. I'm gathering information about the 69 module. I'll have something by this weekend. Don't put to much into my posts on this thread, it was just loud rambling :green:

I've also found some transistor subs. It be cool if we could do a sim on the amps. The two amps seem to be the same with different gain arrangement.

I wonder why the re-issue is so different from the original :?:

I'm also wondering where the famous 1dB @ 100Hz bump is hidding. Probably in the trannie? I don't think it's that important anyway. The EQ is all passive and could be used with any 20dB gain makeup. The input Lustraphone trannie is important though. I hope Sowter made a good copy. I would have no way to check, as I don't know anyone who has an original Helios. Jules @ Gearslutz have some and I'll bet he'd do a shootout as his place if any brits make a clone :razz:  :thumb:

Dave, that's great! That is kinda exiting!

It be cool to do a real Helios look, so if anyone wanna do the layout, it be tres bien :grin: I'll redraw the amp schemaitcs and do a pcb layout.

Stay tuned!

I know what you're saying Consul. Afterall the reason we use outboard is because the console (pardon the pun!) sucks.

uk, I don't think these 69 Helios modules will fit in a modular scheme as they're running -24V. I don't know of any comp that uses that. It will be interesting to see just what is inside that comp Dave mentioned :cool:
Title: Helios thread
Post by: on July 23, 2004, 06:45:05 AM
Quote from: "sismofyt"

uk, I don't think these 69 Helios modules will fit in a modular scheme as they're running -24V. I don't know of any comp that uses that. It will be interesting to see just what is inside that comp Dave mentioned :cool:

I was planning on having multiple PSUs in the back of the rack
And Audio going to a patchbay....
Title: Helios thread
Post by: on July 23, 2004, 06:50:34 AM
From the Helios history...
"In 1994 I loaned him a Type 78 to clone, while I continued to maintain and support those that were still in use throughout the world, later he returned my Type 78,  complete with drawings for the first prototype, in the meantime I had contacted various respected Engineers/Producers,  they felt that the best sounding Mic/EQ was the ones that he first built using a Lustraphone Input Transformer which utilised the Centre Tap as a 20dB pad, this was the main Type 69 Mic/Pre plus Passive EQ, although not as versatile as the Type 78 they all felt the Type 69 was without doubt the best sounding.

April 1997,  I approached Dick to clone the Type 69, but he stressed that due to unforeseen circumstances he had not had time to complete the type 78, and also to find  the finance and the time involved to work on both Types was impossible, we agreed that I should clone the Type 69,  3 months later, we sent Dick a Type 69,  he agreed that it was such a perfect clone, it had even inherited the problems of the  original.

i.e.  1 Db 100 Hz boost,  with its EQ switched out,   the unit ran at . 775 as opposed to today?s standard of plus 4dB, it also oscillated when on full Mic Gain,  but the sound was identical.

We solved these inherited problems one at a time, by making comparison checks with the originals at each stage of the modifications."

I put the emphasis in bold - it looks like they got rid of all the "problems" i.e. the EQ boost, .775 level
Title: Helios thread
Post by: sismofyt on July 23, 2004, 06:55:43 AM
No, I don't think they got rid of the eq bump. I think they did what they could to be sure it stayed there.

This is the George Shilling review:

A brief history lesson: the late Dick Swettenham was a maintenance engineer at Olympic Studios in its late 1960's heyday. In the early 1970's he built a rather wonderful desk for Olympic and subsequently a number of Olympic clients' private studios. When Island Records wanted Swettenham to build a desk for Basing Street Studios legend has it that his Olympic employers were none too happy, so he left and went into business with the Helios name. As time went by, gear fanatic and music producer Tony Arnold started to buy old Helios consoles and acquired seven of them for export to the US. With a c.1973 desk built for Eric Clapton as his reference, Arnold set about replicating Helios modules carefully including all the faults of the original to begin with. In the course of his research he found that the original desks' 20dB pad used a centre-tap from the Lustraphone input transformer. These sounded better than later Helios desks, which used Beyer transformers with resistors rather than a centre- tap for the pad. Arnold approached Sowter to copy the Lustraphone transformers. He then built a console for Elvis Costello and Chris Difford's Helioscentric Studios and put in 20 original Helios modules and 18 new modules. Over a period of over two years incremental modifications to correct problems with the original modules were carried out on the new ones. Each time these were carefully compared to the originals to make sure none of the modifications had any detrimental effects. Cyril Jones of Raindirk helped with some aspects of problem solving. Having acquired the Helios name, Arnold set about perfecting the EQ1 modules we now have here.

The originals' unreliability was always a bugbear for Arnold, so the new units are built to military specifications by CLI who amongst other things makes tyre-warmers for Formula One racing teams. The front panels are dipped in paint and the discrete circuitry is bulletproof. Modules from subsequent production runs will feature phantom power (which is already included in the rack version).

The lunchbox comprises a flight case with two vertically mounted Input/EQ modules alongside a panel with 6 bantam sockets for mic and line inputs and outputs - very convenient if you encounter bantam patchbays, a nuisance when you occasionally don't - and an IEC mains socket. There are no LEDs or lights anywhere. And with everything on the front, there is no need to open the back of the box.

The Input section features a three-position toggle switch for mic/padded mic/line input and a stepped control for gain.

I had a couple of the original modules in a lunchbox for comparison: the old ones sometimes sounded slightly smoother. This is probably due to the new ones' extended high-frequency response, which if audible, is not necessarily preferable to my ears. But any difference is extremely subtle. One vast improvement over the originals is in the build quality and reliability - crackly knobs are understandable on something almost 30 years old, but the originals were notoriously unreliable.

The stepped gain fixed 10kHz high frequency band is gentle and open, wonderfully enhancing clarity without introducing harshness. It goes in 2dB steps from -10dB to +10dB, although I have an inkling which way it will generally be turned. The Mid band comprises a selection of eight switched frequencies from 0.7 to 6kHz. A toggle switches boost or cut, with an uncalibrated pot giving a roughly 10dB range. Gain for the Low frequency band is also controlled by uncalibrated rotary pot giving a maximum boost of approximately 10dB at 30, 80, 120 or 240dB. These are 'boost only' frequencies. The frequency selector becomes an attenuation switch below zero, with cuts in 3dB steps down to -15dB at a fixed 75Hz shelf. I thought I might miss the ability to cut low-mid frequencies, being something of a fan of subtractive EQ, but with the Helios, boosting always sounds so good that I quickly adapted to this way of working. One Helios aficionado I spoke to testified to the glory of "F'BAAF" (Full Boost At All Frequencies) on the Helios desk he had used! On the low frequency gain pot there is a click at the off-extreme. The originals had a low-frequency boost of 1dB even when the EQ was bypassed. For purists this has been retained, but the click position gives you the option of switching it off. A high-pass filter gives 15dB/Octave cut at 40 or 80Hz, which is bypassed if the EQ is bypassed. A proper phase switch circuit is incorporated, the original design for this being something of a bodge.

By modern standards the features and control are limited. But here the sound is everything. You know you're in heaven when just about any setting sounds good, not just one compromise setting, which can be the case with many desk EQs. I recorded and processed all sorts of sources and the Helios always imparted a wonderful openness and clarity. If I were to own just one input module the EQ1 would certainly be near the top of the list.

A giant from a previous era returns in style, and in a portable package to take wherever you go.

 

Copyright ©2000 George Shilling
Title: Helios thread
Post by: sismofyt on July 23, 2004, 06:56:43 AM
So, it seems they're using the same Sowter as well... interesting :cool:
Title: Helios thread
Post by: sismofyt on July 23, 2004, 08:55:32 AM
I think this is the layout to go for:

(http://www.sismofyt.net/Helios_31.jpg)

Looking at the module from top to bottom, we got:

Top left switch:

1 - LINE

2 - MIC

3 - MIC -20dB (this is done on the split secondary winding. Wicked)

Top right rotary switch:

1 - GAIN 20dB

2 - GAIN 30dB

3 - GAIN 40dB

4 - GAIN 50dB

5 - GAIN 60dB

6 - GAIN 70dB

Left rotary switch:

10kHz shelf(?) in 2dB steps, +/- 10dB

Right pot:

MID GAIN. BOOST/THROUGH is selected with the TOOGLE switch under the pot. PK=PEAK & TR=THROUGH=DIP

Left rotary switch:

MID FREQ SELECTOR

1 - 700Hz

2 - 1kHz

3 - 1,4kHz

4 - 2kHz

5 - 2,8kHz

6 - 3,5kHz

7 - 4,5kHz

8 - 6kHz

Right pot:

BASS BOOST ONLY, 10dB

Left bottom rotary switch:

BASS FREQ SELECTOR

1 - 400Hz

2 - 250Hz

3 - 120Hz

4 - 60Hz

5 - 0 (zero action)

6 - -3dB CUT/SHELF at 75Hz

7 - -6dB CUT/SHELF at 75Hz

8 - -9dB CUT/SHELF at 75Hz

9 - -12dB CUT/SHELF at 75Hz

10 - -15dB CUT/SHELF at 75Hz

And lastly and EQ CUT TOOGLE switch.

It seems the re-issues have a 40/80Hz HP filter as well.
Title: Helios thread
Post by: on July 23, 2004, 09:32:51 AM
I am talking to Brian Sowter about the inductors and whether they make them for the reissue
He replies saying that we can have them made - awaiting a reply about whether they actually make the reissue ones

Sent an email of to Tony Arnold (current owner of Helios)  asking if has any idea what the values for the first inductor are....
Why not - what have I got to loose..

(on an unrelated not - more old UK type console info
This one from Sound Techniques Studios - set up and created by Geoff Frost - pictures here..

http://www.soundtechniques.co.uk/history.htm

As used by Pink Floyd, Nick Drake, Fairport Convention, Incredible String Band etc....

Got an email from him when I asked for some pictures - so he is still around and contactable) - in fact I have sent him an email asking for old schematics or if he is available for questions about the "old stuff"

 I might be a newbie in the world of DIY - but my job is a management consultant and I can get some stuff done... just know how to ask nicely !!
Title: Helios thread
Post by: sismofyt on July 23, 2004, 09:42:01 AM
There seems to be a bit of difference in the 10kHz section on the two schematics. The one at Vintage King have -3, 0, +4 steps and the one at Dan Alexander's have -4, 0, +4 steps. The pic of the module above and the re-issue have -5, 0, +5 steps.

Helios 69 at Dan Alexander:

www.danalexanderaudio.com/OutboardPic/HeliosChannelSchem.jpg

Helios 69 at Vintage King:

www.vintageking.com/images/schem_V69-1973-1-Var-1.jpg

The switches:

S1A - LF db CUT at 75Hz

S1B - LF FREQ BOOST SELECTOR

S2 - PREAMP GAIN

S3 - HI BOOST/CUT at 10kHz

S4 - MID FREQ SELECTOR

S5 - MID BOOST/THROUGH=DIP SELECTOR

S6 - EQ IN/OUT

RV1 - LF BOOST GAIN

RV2 - MID GAIN
Title: Helios thread
Post by: on July 23, 2004, 09:44:07 AM
PK Peak
TR Trough
(http://www.vintageking.com/data/Helios%20Type%2069%20Vertical(5).jpg)
Title: Helios thread
Post by: sismofyt on July 23, 2004, 09:45:01 AM
uk, that's just super great! :thumb:  :grin:

I thought about contacting the fellow myself at SoundTechniques, 'cause I just luv my Drake records. There's also was a bit of fuzz about it at TapeOp. I'm curious about that beatifull console he made.

If either Sowter or Tony Arnold will spill the beans about those inductors it would be really nice.
Title: Helios thread
Post by: sismofyt on July 23, 2004, 09:46:46 AM
TR=Through=Dip. Never heard that Through term used before :?
Title: Helios thread
Post by: on July 23, 2004, 10:00:08 AM
Quote from: "sismofyt"
TR=Through! Right, the MID EQ is (also) a boost only type.

No it is Trough - as in the opposite of Peak.
I can't quite get my head around EQing a trough?
Title: Helios thread
Post by: on July 23, 2004, 10:26:21 AM
Got it...

The Mid range dial  only goes positive

For the switch however
In the Peak position it boosts the Mid range
In the Trough position it cuts the Mid range
(another word for trough is dip! - the penny finally dropped!!!)
Title: Helios thread
Post by: sismofyt on July 23, 2004, 10:33:28 AM
Yes, it's easier to see if you break into small portions. I'm redrawing the mid section so I can figure out the inductor :?

The amps:

The schematics both have +24V and -24V written, but I'm positive that it's a negative voltage we need. The 2N3707 NPN can be sub'ed with a BC184L and the 2N4058 PNP with a BC212L. Both common and cheap.
Title: Helios thread
Post by: Bear on July 23, 2004, 11:09:14 AM
I nominate the project "Apollo 11".  Yes, I know that unlike Helios, Apollo is technically not a sun god, wheras Sol would be.  But the mission was the right year.

Bear
Title: Helios thread
Post by: dmlandrum on July 23, 2004, 11:26:12 AM
Quote from: "sismofyt"
I know what you're saying Consul. Afterall the reason we use outboard is because the console (pardon the pun!) sucks.


Really, I just like having all the knobs and controls available to me all at once. It makes the workflow easier. I know that's funny coming from a long-time computer user and programmer, but ergonomics is ergonomics.

I have plenty of time to think out the design and implementation of what I have in mind. It should be pretty darn cool.  :thumb:
Title: Helios thread
Post by: on July 23, 2004, 01:06:39 PM
More info....

Via fletcher in an old web posting...
" the Olympic desk that I used to have ran on -24vdc, not +24vdc"

"The Olympic "pre Helios" desks employed germanium transistors... the later versions didn't.  
There were lots of different versions of Helios stuff... some of it better sounding than others."

And an interesting post from the same newsgroup
"Yes.  With PNP transistors, it's somewhat easier to design circuit using
negative rails, especially if you are used to working with tubes or NPN
transistors.  
When germaniums were new, the PNP products were generally a lot better than the NPNs so there is a whole generation of stuff out there
designed for use with negative supply rails.  I
t's not hard to work on once you wrap your head around the idea that everything is reversed."

That's what I like - reasoning behind why they choose that design.

Later versions fo the desk ran at +36 and bi-polar 24.
Title: Helios thread
Post by: sismofyt on July 23, 2004, 01:22:11 PM
Yes, I've searched hign'n'low too and found that info. The amps aren't a problem. We'll just go -24V and use BC184s & 2N212s..

I've been frying my brain and calculator with that eq circuit..  :shock:  :? In the LF BOOST part, as far as I can see it's basicly a capacitor in series with that inductor in series with that 50kOhm pot. Which all are in parrallel with the 22kOhm R17. So the inductor could be calculated like this:

1/(6,28 x ('squareroot symbol' LxC)) = Frequency

I get 10,5 Henry.. :shock:  :cry:  :?  :?:  :?:

Which is probably not right, allthough looking at the modules, there's does seem to be a big ironcore inductor.

My floor is filled with papers now and I'd like to post a simplified EQ circuit. I got no scanner, so anyone know of a free app to draw a schematic?
Title: Helios thread
Post by: soundguy on July 23, 2004, 09:40:42 PM
It would be best to build this with silicon transistors, I would be pretty suprised if the new re-issues use germanium transistors...

I would like to know what desk was at olympic in 1969 and if the same desk was there in 1975 for the physical graffiti mixes.

this would be pretty monumental to get off the ground, hell of a lot better than dropping trow and paying $7K (???) for the lunchbox...

dave
Title: Helios thread
Post by: CJ on July 23, 2004, 10:01:14 PM
Drop Trow!
sOUNDS LIKE THE gREASE mAN!

Physical Graffittii?

Why would you want to duplicate that piece o crap?
They should have made that a 1 album set.
Depressing. The begining of the end.
I guess Kashmir is cool.

I mean is it any wonder why Bonham drank himself to death?

Hey Bonzo, we got a new song!
It's called Hot Dog!
It goes like this:
1...2...3..... puke!
Poor guy. :twisted:

Jason Bonham is cool if you ever get a chance.
Like Zeplin in your living room, those small clubs that is.
 :sam:
Title: Helios thread
Post by: soundguy on July 24, 2004, 01:19:50 AM
gee chris, shouldnt post when you are drunk..

If you dont like the sound of physical graffiti you wont have to bother taking all that time to make yourself a helios EQ.  good thing for you, saves you lots of work.



 :sam:  :sam:  :sam:

dave
Title: Helios thread
Post by: CJ on July 24, 2004, 01:24:31 AM
totally straight now.
i guess I was just going thru crappy times when that came out.
the "sumer of love" days were long gone, the viet nam war was still winding down, i dropped out of college, split up with my girlfriend, didn't have a job, depressed, parents were pissed at me, i was alone in a strange town with no money and no friends, managed to survive somehow, experience i still fall back on today. toughen you right up.
then that album came out.
seemed like everything was on the decline, including zeplin.
it's funny how we equate music with the times, ehh?

 :cry:
Black Dog was the last really killer zep song, IMHO. :guinness:


Be cool, soundguy, or you won't get the secret password!
 :wink:
Title: Helios thread
Post by: sismofyt on July 24, 2004, 07:07:49 AM
I don't care what those albums sound like. I wanna DIY a Helios because THEY'RE FUKKIN' COOL! :razz:  :green:

It's not gonna be germanium amps. They just run on a negative rail because they use PNPs at the input. It should be possible to 'flip it' and make it run +24V with NPNs instead, but I don't see the point. There's no need to be afriad of a little negative voltage :cool:

The two amps are identical and pretty low tech. Since the EQ is totally passive you could use whatever you wanted.

I _think_ (because I have never heard or used that Helios) the sound is in that Lustraphone input trannie and the EQ schematic. So, if Sowter makes a decent sub and we can get the 'right sounding' inductors, I'd say we're very much in the ballpark. Sure, the amps are a part as well (and the PSU :green: ) but not a major player. Again, that's just what _I_ think. There's so much urban myth, that I could be totally off my rocker :shock:  :?  :cry:

I would have no way to check though, 'cause there aint no 69 Helios in my neighbourghood.

That famous 1dB @ 100Hz bump is probably due to the input trannie, or what? It's supposely still there with the EQ in bypass. I don't think the amps are boosting half a dB each. Anyway, I don't think it's that important... or is it. What do you guys think?

Also, I think the one to clone is the original 69 not that reissue. That looks quite different, new hi/lo-pass filters, totally different amps, two active buffers and more taps on the midrage inductor. And much less mojo/coolness factor, imo :cool:

Soooo.. anyone wanna help out with those EQ values  :wink:
Title: Helios thread
Post by: ytrehalf on July 25, 2004, 12:49:10 PM
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23793&item=3738435738&rd=1

I sure hope no one pays this price. The listing has some info worth checking out though.

Soundguy, I'm pretty sure this is the compressor model that was in that Calrec console at Vintage king.
Title: Helios thread
Post by: soundguy on July 25, 2004, 01:18:33 PM
yeah, those arent the ones my friend has, totally different.  hopefully I can get my hands on them this week or the next.

dave
Title: Helios thread
Post by: on July 29, 2004, 10:47:25 AM
helios eq up on ebay
it's one of the ones that run on 36v
I have got the seller to send me extremely detailed photos of the insides
(which I can't host - but they are being emailed to  sismofyt  right now)
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:00:00 PM
I read that in a review. I thought it was in that George Shilling review I posted some pages back, but  couldn't find it. Maybe it's in one of my ol' Studio Sound mag, I'll look it up.

If you're looking for metal can trannies, you're probably thinking BC109c, nice onces too.

I'll upload the pics uk send me in a few minutes.

I'm sorry I don't have much time for this project right now, but I'm currently in bed with 'cause I'm sick :cry: I also have a sh*tload of owrk to do... :sad:
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:06:58 PM
(http://www.sismofyt.net/36_3.jpg)

(http://www.sismofyt.net/ae_3.jpg)

(http://www.sismofyt.net/b0_3.jpg)
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:13:45 PM
Sorry for the big pics!

(http://www.sismofyt.net/b0_4.JPG)

(http://www.sismofyt.net/b0_5.JPG)
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:19:02 PM
Doh, it was in the George Shilling review, I even highlighted the 1dB part in red :oops:

I'm only guessing it's the Lustraphone trannie doing it, unless the amps have half a dB bump each. The bump is still there with the eq switched out.
Title: Helios thread
Post by: CJ on August 12, 2004, 09:30:46 PM
I think Tr15 is mounted backwards.

 :wink:
Any boards available yet?
 :guinness:
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:35:01 PM
Ha! We're not clonning that one. Mr. Swettenham made more different Helios desk/eqs than I can keep track on. I don't think they're all _that_ cool. The 69 is the one to DIY.

I'm still fukkin' with that eq, but now I got one of them fancy sim apps, so I may do some progress, when I get up on my legs again...
Title: Helios thread
Post by: sismofyt on August 12, 2004, 09:37:08 PM
I don't see any inductors and isn't that TO-5 an opamp?
Title: Helios thread
Post by: Joechris on August 13, 2004, 11:15:02 AM
It seems to me that every helios shematics is different. Here is the hi eq section from a helios desk that once lived in norway.
(http://studio.pogostick.net/hishelf.jpeg)
jo
Title: Helios thread
Post by: sismofyt on August 13, 2004, 11:20:07 AM
Yes, that's what I think too. Helios wasn't a Neve like company, they did one offs to various studios. Some alike some not. Some not so good, some really neat. I don't see anything unique in the Helios schematics though. But the consoles look FUKKING COOL

A totally irrational reason for DIying I guess :grin:
Title: Helios thread
Post by: Joechris on August 13, 2004, 11:37:06 AM
No nothing unique, but the others I have seen the shematics off have less steps. The "arctic" also had balaced line input, with a pad infront of the mic trafo.
jo
Title: Helios thread
Post by: CJ on August 13, 2004, 07:08:31 PM
Butta, that third link needs adjusting.
And the Stancor line to line looks very good at the bottom end, but rolls off quickly after 20 k hertz, which might explain why you like it.
Nice mellow top end with no peaks.
cj
haven't tried the Thordarson yet.

Just the name Helios is enuff to diy!
 :guinness:
Besides, the Olympics are on in Greece!
Title: Helios thread
Post by: soundguy on August 14, 2004, 01:29:45 AM
man oh man oh man, tonight has been one for the books...

Got an ear full from the horses mouth- was able to sit down for one drink with Mr. John Paul Jones this evening, the conversation was pretty focused on dick swettenham and helios consoles.  Apparently after clearing the cobwebs, the helios that was in the stones truck had the "69" black eq's in it which inside the truck sounded slightly different than the big silver wrap around console at Olympic which inspired them to book the truck in the first place. REALLY interesting conversation and my god is he just the nicest most HUMBLE dude I think I may have ever met in my life.  Oh, I saw him play too, he got better...  FRIGHTENING...  Hats off to JPJ, its so f**king rewarding when your heroes turn out to be ten million percent more than you ever imagined they could possibly be.

I guess you know you are a geek when you can get the answer to any question you've ever had about your favorite band EVER and you talk about helios consoles...  That one is for you guys...

dave
Title: Mmmm Helios
Post by: JustinS on August 14, 2004, 03:22:29 AM
I am a newbie DIY'er (building my first 1176 at the mo - much thanks to the lab and group DIY) and am very much into building some Helios pres / EQ's for 1. cause the Nick Drake stuff recorded at Island sounds fab and 2. just cause its a little different than Neve / API stuff...

Anyway looking at the small collection of Helios info I have dl'ed from the Net...  1. Correct me if I am wrong, on the readable schematics there are 2 cards labelled (obviously) card 1 and card 2... Are these both the same cards - the Helios line amp???  If so, it makes the thing not too scary ... a trannie or 2, 2 line ams, and a passive eq... nice!! 2. Is there a relatively easily obtainable alternative to the Lustraphone trannie on the input?
Title: Helios thread
Post by: bluebird on August 14, 2004, 04:39:58 AM
Holy smokes Dave :shock:

Thats incredible. I think I would just flub up anything I was trying to ask if presented with a situation like that.

you've touched something special there...
Title: Mental note
Post by: JustinS on August 14, 2004, 09:51:35 PM
Mental note to self,

Fully read all previous posts before posting... Sowter makes the Trannies...  :oops:

Justin.
Title: Helios thread
Post by: SSLtech on August 14, 2004, 10:31:54 PM
Hmmmm...

This is the old console that Iremember working on at Strawberry:
http://www.danalexanderaudio.com/danspics/redconsole.jpg

...and it appears to be the same console as this one:
http://www.sismofyt.net/Helios_36.jpg
Title: Helios thread
Post by: Bauman on August 15, 2004, 08:57:44 AM
uhmm... tant caps all around. But they are bad right?  :wink:
Title: Helios thread
Post by: Bauman on August 15, 2004, 06:28:38 PM
Hey butta!

I told that cos I really like tants...  :cool:
I'm using them on my hamptones... great stuff.

btw, I love the look of those Helios consoles!!!
I'm in this diy!!!
Title: Helios thread
Post by: CJ on August 16, 2004, 05:56:48 PM
Soundguy, how in the hell did you get hooked up with JPJ?
Title: Helios thread
Post by: soundguy on August 16, 2004, 06:10:05 PM
He played a gig in town, bumed into him walking out the door (good timing) and had a drink, pretty casual.  Perhaps it was refreshing for the guy to try to remember some esoteric detail about an old console compared to the questions he must be hit with everynight...

dave
Title: Helios thread
Post by: on August 24, 2004, 07:45:09 AM
Piccie of the innards of the EQ modules from reconrding consoles.net

http://www.4sync.com/rc/picdisplay.asp?itemkey=1010
Title: Helios thread
Post by: JustinS on August 24, 2004, 07:57:43 AM
Wow, Neve internals sure put that to shame!!  But there's, something in the sound of those Helios for sure...

Justin.
Title: Helios thread
Post by: on September 01, 2004, 08:57:01 AM
From a friend of mine....
BTW the schamtic he is talking about is the dan alexander one with the missing value for the inductor...

I quote

"
I've just had a long, very long, chat with a friend of mine about this. I was on the phone to him when I spotted your question. He was a senior tech at Olympic and one of the people who designed, built, modified and looked after the original Helios (and other) console(s) at the studios. He's a bit tied up at the moment but he'll have a look at the circuit diagram later and come back with some info. He did say "if it's the drawing off that american site, it's bollocks, that's not the original Helios design its some bastardised ripoff". He didn't expand on that but he's never a man to mince words  

He told me that the *only* completely original Helios EQ modules are in the UK and there are only about 4 of them. He has a couple and one of the other ex-Olympic techs has the others. (Apparently the original Helios console currently for sale in the US for rather a lot of money had a number of it's sections, including the EQs modified during it's life at Olympic.)

For anyone thinking of trying to copying them, two of the orignal EQs are currently with Raindirk (Cyril Jones was also involved in the early consoles at Olympic, and later supplied some Raindirks there) and Cyril has disassembled the units down to taking apart the inductors and other parts to enable him to produce a proper copy that'll be "as close as it can get; and miles better than the bollocks other people are passing off as real Helios bits". There are some Helios "recreations" around at the moment but these apparently are not as close as they could be.

I'll post more when I find it out.

Incidentally, if you're looking for a nice old console and have about £7.5K to spend, there's a Raindirk Series 3 on eBay at the moment. We also talked about this as the seller says it's ex-Olympic in "Richmond". Since Olympic were never in Richmond I was a bit confused but my friend was able to confirm that it was one he worked on quite extensively from Olympic Studio 2 in Barnes! He described it "as a very nice little console and if you want a really simple recording console with a nice short signal path you could do a lot worse - not worth the price though. Might be a bit noisy but it's full of 5532s so if you want to make it quieter it'd be easy"
Title: Helios thread
Post by: Tekay on September 01, 2004, 10:51:26 AM
Since Sowter is making the input tx (8666) maybe they're making the inductor too? Has anyone asked Brian about that?
Title: Helios thread
Post by: on September 01, 2004, 11:38:59 AM
Quote from: "Tekay"
Since Sowter is making the input tx (8666) maybe they're making the inductor too? Has anyone asked Brian about that?

Yes I have asked the question and no is the answer
Title: Helios thread
Post by: kpeek on September 01, 2004, 01:07:27 PM
I have some decent pictures of what I believe are amp cards from a Helios preamp/eq. I did not see anyone post these pics yet.


They have OLYMPIC SOUND STUDIOS M.M.C. 1 printed on them.

I do not have any way to post them. Maybe I can email them to someone and they can post them.

Maybe this can help with the components.[/img]
Title: Helios thread
Post by: smilinfu on September 02, 2004, 03:54:09 PM
I don't use it but there is photobucket which is free, or email them to me at smilinfu"at"earthlink.net and I'll pop them up tonight.
Title: Helios thread
Post by: CJ on September 02, 2004, 04:50:32 PM
This is all I got and you have probably seen it already but what the heck:

http://vacuumbrain.com/The_Lab/TA/Helios/helios-filter.jpg

http://vacuumbrain.com/The_Lab/TA/Helios/helios-frontend.jpg
Title: Helios thread
Post by: kpeek on September 02, 2004, 09:05:50 PM
I emailed the pics to buttachunk.

I am pretty sure these are from the Helios that was originally built for Olympic.

I had inquired about cloning these some time ago. some info is under the rec.audio.pro newsgroup under the heading "helios discrete" or something like that. Thats where I first inquired about the Helios design. Thats also where Fletcher had brought up the germanium transistor thing. The problem is in obtaining  germanium NPN transistors. Germanium PNP are used in a lot in DIY guitar fuzz boxes. See smallbear electronics.

Anyway, the 2N3707 is available by the assload from Mouser. And the 2N4058 can be replaced with the NTE234 for $1.25 each from Mouser. Or you could possibly find a suitable germanium replacement for the 2N4058 and maybe, just maybe for the 2N3707 if your heart desires.

Specs for the 2N3707:
Hfe min 100  max 400
Specs for the NTE234
Hfe   min 350  max 700
Title: Helios thread
Post by: soundguy on September 02, 2004, 09:13:57 PM
I have a big handful of toshiba germanium pnp's that arent too leaky to use in a fuzz box, hfe's around 130, if they are any use on this project...

dave
Title: Helios thread
Post by: sismofyt on September 03, 2004, 05:30:15 PM
I've been behind this project due to an operation. I'll read up and get back. I haven't had any time to do any practical experiements though, sorry.

uk, any luck sourcing that inductor at Sowter?
Title: Helios thread
Post by: Tekay on September 04, 2004, 12:22:56 PM
The inductors in the new Helios units (modular) looks exactly like the Neve inductors, maybe Carnhill is the source?
Title: Helios thread
Post by: on September 06, 2004, 04:19:01 AM
Sowter doesn't have the inductors but read on...
Passed onto me from somebody who definately knows what they are talking about on Helios' - inc;uding the original Veroboard prototypes....
D'oh! I just typed out a long post, then managed to crash my pc and lost it all!

Anyway - in short, from a phone chat I had this afternoon:

The inductor value is 12H (12 Henrys) and it's the bass control so it's a good idea to get a good one. For such a high value you'll probably need to go with a ferrite cored unit. (The originals were ferrite cored.) The original inductors were hand made and the ones used in the first full production modules were produced by a company that no longer exists. As far as my friend knows, Sowter made some of these for fitting in the modern copies sold by Vintage King in the US (for rather a lot of money!) and they might be able to help you out with them.

Ther might be some more info on this as the question prompted some rummaging in the "junk" cupboard which yielded one of the two original-original prototypes of these units, made on veroboard! My friend describes it as the Mk 0 design that never went into production whereas the Mk1 production unit is the Mk2 design. The two Mk0 design/Mk1 production units that my friend has are what's with Raindirk and there shoufl be commercially available copies available very soon - at a price.

A few further comments to pass on about the circuit and Helios console in general:

What goes before and after the EQ circuit is critical in getting it to sound right.
If you build any of this Helios stuff you need to use germanium transistors and get the right transformers as without these you have no hope of getting it to sound right.
The original console was noisy, had "crosstalk like you wouldn't believe, way up into RF", had little headroom and ran very low levels internally.
The famed sound of the console and EQ came from these problems and the fact that they lead to the circuits distorting very easily. Distortion in the EQ, and most of the other circuits, is "badly asymmetrical" and the settling time from saturation to full recovery after removal of the signal is "about a weekend"! The engineers using the console frequently (almost routinely) drove it into (and kept it in) distortion by keeping the gain high and the fader low to get a warm sound and use the natural compression of the circuit saturation.


OK, I thought I'd left a bit out so I was just checking what I wrote and that fourth paragraph is gibberish! I got my Mk0/Mk1/Mk2 mixed up. I wrote it off the notes I made during the phone call but somewhere it all went wrong. It seemed so lucid at the time! I've called and checked this morning that what I now have makes sense. So here's a new version, now that I'm awake and with coffee ! There's a bit added that I forgot yesterday too.


Quote:
--------------------------------------------------------------------------------

Me, in my last post above:
Ther might be some more info on this as the question prompted some rummaging in the "junk" cupboard which yielded one of the two original-original prototypes of these units, made on veroboard! My friend describes it as the Mk 0 design that never went into production whereas the Mk1 production unit is the Mk2 design. The two Mk0 design/Mk1 production units that my friend has are what's with Raindirk and there shoufl be commercially available copies available very soon - at a price.



--------------------------------------------------------------------------------



This makes no sense; it should've read:

There might be some more info coming later on this as the question prompted some rummaging in the "junk" cupboard which yielded one of two original-original prototypes of these units, made on veroboard! My friend describes it as the Mk0 design that sounded best but never went into production; the Mk1 production unit is apparently a small revision of this design. The two production units that my friend has are what's with Raindirk and there should be a commercially available modern version very soon - but at a price." He's also got a couple of the further slightly modified EQs from the console in Olympic Studio 2. These he describes as "technically a bit better; much more stable; almost identical to the first production units but not quite as warm sounding - not enough distortion".
Title: Helios thread
Post by: sismofyt on September 06, 2004, 07:27:00 AM
Nice work uk! :thumb:

I did try out a breadboard version with that 10H inductor I mentioned earlier. I use a big ass choke, it did work, but I didn't finish it up before I went to the hospital :roll:

I'll try a 12H then..
Title: Helios thread
Post by: on September 06, 2004, 07:48:52 AM
Here is the stuff that Raindirk are going to put out
http://www.lntech.nildram.co.uk/helios.html
I quote:
"EQ capacitors are either polystyrene or polyester. Rotary switches are Elma types - just as the originals."
(http://www.lntech.nildram.co.uk/Resources/heliospassiveeqmi.gif)
(http://www.lntech.nildram.co.uk/Resources/item4a.gif)
Title: Helios thread
Post by: sismofyt on September 06, 2004, 09:31:28 AM
Yeah well, I don't care about the pissing match. Every Helios mfg seems to say that the competitors product is inferior and not 'real Helios'. Hmm, where have we heard this before? Neve, Vintech, BA, Aurora, whatever...

It's just advertising bullsh*t. The vast majority of the buyers have never heard an original Helios module anyway :roll:

Looking at original Helios modules, they look kinda messy, with cheap standard components. Also, Swettenham made so many different modules, that the sound is all over the place (I guess, I haven't listened to the lot). No module is gonna make me sound like Rolling Stones anyway :green:

Everybody uses Elma switchec and 'polystyrene & polyester caps' could mean anything. From junk to NASA/audiophool parts. Me thinks they're standard Philips stuff or whatever.

I mostly concerned about how the Sowter replacement will sound compared to the Lustraphone and that inductor as well. At 10/12H with an iron core it certainly will have it's effect on the sound. The actual amps will be the easiest part to recreate. All components are standard and exact types can be had today. Hope the schematics indeed are true to the originals :?

The distortion part is interesting too. The overload characteristics of an amp/product is one of the first thing I check out. It's very telling about the sound quality in general :wink:
Title: Helios thread
Post by: Bear on September 06, 2004, 01:43:28 PM
So the amps are no problem?  Are there commonly available Germaniums of the right type?  Is it best to do like the original with the negative supply?

Bear
Title: Helios thread
Post by: NewYorkDave on September 06, 2004, 01:56:38 PM
Isn't it a shame when no-talent a**holes buy up the nice consoles? That's almost as bad as Lenny Kravitz buying an Abbey Road REDD  :wink:
Title: Helios thread
Post by: JustinS on September 06, 2004, 05:53:01 PM
Hey Butta, love to see the copper side... which transistors did you end up using??
Title: Helios thread
Post by: cuelist on September 07, 2004, 12:31:00 AM
Quote from: "uk03878"
The original console was noisy, had "crosstalk like you wouldn't believe, way up into RF", had little headroom and ran very low levels internally....     Distortion in the EQ, and most of the other circuits, is "badly asymmetrical" and the settling time from saturation to full recovery after removal of the signal is "about a weekend"!


Does this sound like Mr Swettenham new what he was doing??
Title: Helios thread
Post by: soundguy on September 07, 2004, 01:34:28 AM
Quote from: "cuelist"
Does this sound like Mr Swettenham new what he was doing??


well, at the risk of sounding argumentative, Led Zeppelin 1, 4, houses of the holy, snippets of physical grafitti, Rolling Stones Beggars Banquet, Deep Purple Machine Head, Free Fire and Water and *countless* others all pretty much sound like Mr. Swettenham either knew what he was doing or had the most holy f**king accidental discovery EVER.  

I use circuits to make records.  I could honestly give a rats ass about what these circuits look like on a scope or a distortion analyzer.  Records are meant to be listened to, not looked at.  That sounds really arrogant, but if it sounds good I really could care what the white lab coat has to say about it.  I have a console for film production dialogue mixing that has the most useless specs for music recording, cross talk is just ABSURDLY high for music, but the console was designed for dialogue (not kick drums) and lots of compromises were made based around the specific use of the design, so for what we use it for, dialogue, it is heralded as one of the best mixers ever built for our industry, but to look at the crosstalk specs for music, for instance, its really laughable.  At the end of the day, the dialogue tracks sound amazing on it, so thats all that matters.

Not trying to be an ass, just dropping some perspective, I'll take the worst specs on paper that sound like a helios any day of the week...

dave
Title: Helios thread
Post by: JustinS on September 07, 2004, 06:13:47 AM
Hey Butta,

What's your take on this with your electro bypass at C5??

Quote

There does seem to be a drawback with this approach, however. Even though you are by-passing the HF around the ele cap, the slower, phase-shifted HF is still going to come through the ele?s. So, even though the sound is a little clearer, it is still prone to some high-end ?smear?. This is probably why some respected designers just use electrolytics or tantalums and leave the film cap off altogether.

Flatpicker


Justin
Title: Helios thread
Post by: kpeek on September 07, 2004, 08:10:59 AM
I don't know if these would work for the inductor:

Hammond 193B,  12H, 100ma, 155 ohms, 600VDC

Enclosed, 4-hole mounted chokes. Tolerance of 15% on both inductance & resistance. Inductances measured at rated D.C. current. Minimum 8" long leads. Units will exhibit less inductance at slightly higher currents or more at lower currents. Perfect for high voltage power supply filtering, case matches power transformers & tube audio output transformers.


They are easliy sourced for about $25US.


These are normally for power supplies so I don't know how they would sound. It maybe easier for Sowter to make a 12H inductor.
Title: Helios thread
Post by: on September 07, 2004, 09:07:01 AM
Email from Sowter

"Hello Simon

We make 12H EQ inductors using a gapped M6 core.
The price and size would be the same as our type 9810 which is 10H.

"

And guess what - here is the info for the 9810..

"9810 Neve T1295 EQ Inductor
A 10H inductor tapped at 7.0, 3.0, and 1.3H. DC resistance 739/619/405/267 ohms approx. Mumetal can with colour coded leads.


  £34.08 "

Somebody mentioned a Neve inductor earlier in the thread...
Title: Helios thread
Post by: Tekay on September 07, 2004, 10:15:12 AM
That was me!
The inductors in the new upright moduls looks very much like Neve inductors! May be Carnhill is the sourse?
Title: Helios thread
Post by: Bear on September 17, 2004, 04:24:57 PM
In the interest of being cheap, what poor-boy input transformers look technically adequate to substitute?  Obviously I wouldn't expect a total reproduction in performance, but the cheaper I can do most of the channels, the easier it is to afford to build a small console.

Bear
Title: Helios thread
Post by: Kev on September 17, 2004, 05:55:26 PM
Tekay ,

are you deep in prototyping this project or are you just following the thread with interest  .... like me ?
if you are me, drop me an email
Title: Helios thread
Post by: Tekay on September 19, 2004, 09:08:24 AM
Kev ! for now I'm only following the project! No time for prototyping right now! But I will take a closer look at a modul soon!
Title: Helios thread
Post by: on October 19, 2004, 06:32:40 AM
bump!!!!!
Anybody got a status on what's happening with the protoypes......
Title: guess I'm a little late to the party . . .
Post by: strangeandbouncy on November 29, 2004, 08:48:52 PM
Dear All,

   I am the lucky owner of several Helios bits that are in daily use. i own three channels of turquoise passive channels from the MCA desk. These are my favorite posession in the whole wide world.  Beyer mic tx's. The hump in the bass eq is nothing to do with input tx. since it is there on the line input too( no tx). I also have two simpler channels that allegedly were fx rtns from the strawberry desk, but they are black in colour. Also beyer tx, and fixed mf(boost only at 1k4 or 2k8 and wierd bass at @200hz - also wicked mic pre's. i also had the great pleasure in owning two Black active 3b eq's with Sowter 3374 mic transformers - still available btw. These were the best pre's i have ever used, but only slightly better than the beyer ones. - PERIOD! eq was also cool, but not as cool as Passive ones. I also had one red channel from 10cc desk - totally cool with switchable HF frequencies. I also had two compressors from MCA desk. They had A+D boards, but difffernt ratios/controls. Couldn't get them working, and they are long lost.
      I have never seen a lustraphone one, but my ex-boss Roger Quested, of monitor fame, was Glyn Johns Tape-op at Olympic back in 1967. Imagine! his first session was The Stones-Jumping Jack Flash! for Top of the Pops( they had to re-record in those days because of Musicians Union, followed by Led Zep One as his first Album!!!!!!!!
   i used to use the Ramport/TownhouseIII late Helios in the past. it was in shocking condition, but ROCKED! I loved it and started my love of Class A gear here at his desk.
   www.larking.com have a cool 20:8:16 of the same vintage(1979?) for sale from a Finnish Film co. only £25K!!!!! and yes, I would, if I had that kind of money . . .

    If I can be of any assistance to anyone - inductor values etc, please let me know.

  i have a few schematics too. passive eq, output driver card . . .

    BTW, what do the colour codings meen on the pre-amo card transistors? do they need to be matched or what?

    Big Love to ALL . . . .

        Andy P

ps Helios is my favorite secret weapon in da studio . . . . Spread the word . . .
Title: Helios thread
Post by: MikoKensington on November 29, 2004, 10:40:23 PM
I've been intrigued by the voodoo of Helios.  I was thinking about this thread the other day.
Title: Helios thread
Post by: soundguy on November 30, 2004, 12:57:01 AM
here's the real voodoo about helios and something Ive talked about alot with friends:  is it that the consoles are amazing OR is it that the bands that more or less defined the history of modern rock made their records on them?  The Led Zeppelin helios records are my favorite, I doubt thats any coincidence though...

dave
Title: Helios thread
Post by: CJ on November 30, 2004, 04:04:05 PM
Or was it the smack?
Jimmy was strung out during the whole second album.
I like it when they toured with Jeff Beck and Bonham came out and tossed Jeff's drummer's kit  off the stage before they came on.
 :razz:
Title: Helios thread
Post by: soundguy on November 30, 2004, 07:34:25 PM
the second album was recorded in 1969...

the misinformation surrounding led zeppelin is pretty intense.

I only say this having heard it from the horses mouth.

dave
Title: Helios thread
Post by: fum on December 02, 2004, 01:11:32 PM
These records would have come out great no matter where they were recorded ( I think they would have found a place that had what they needed regardless).  I shudder to think how many times I've spun these records.

One thing I do wonder is what kind of reverb they were using back then? Was it all just large plate reverbs, or....

When did Lexicon really emerge on the market?  When did EMT hit?

I guess this is all in tangent to this thread, but what they hey...  :?

ju
Title: Led zep rev
Post by: strangeandbouncy on December 02, 2004, 01:37:48 PM
Sounds like 2 seperate mono EMT plates on "stairway to heaven to me", one left and one right. Whenever I am at a studio with two plates, this is my fav set-up. Slightly different rt's. Much better stereo than a single stereo plate, which is much muddier.
Title: Helios thread
Post by: CJ on December 02, 2004, 02:03:58 PM
Led Zep 1 recorded after 24 hours of rehearsal.
I used to have this underground fort in my back yard when I was a kid. Plywood walls with day-glo artwork, a mescalito poster, concrete floor with carpet, stereo with spaekers built into the wall and two albums. Lee Michaels fourth, you know, the one with Frosty's hand solo, and Zep 1 complete with dayglo spiral painted on the center label. It was the favorite hangout in the neighborhood with kids jumping over the fence to huff down at all hours. When ever I got a phone call, mom would unplug the extension cord in the garage a couple of tiimes to signal me. One time these friends of mine she hated were down there. She put a garden hose down the trap door and let er rip!
  :razz:
Title: Helios thread
Post by: chrissugar on December 02, 2004, 03:56:03 PM
Hi Andy [strangeandbouncy]

Please can you upload somewhere the schematics you have?
Thanks.

chrissugar
Title: Helios thread
Post by: soundguy on December 02, 2004, 04:11:33 PM
The first record was recorded after a short tour the band did to settle old yardbirds obligations that jimmy page was still contracted for.  Also served as a good source of revenue.  The band was indeed together for a short time, but they had slightly more than 24 hours rehearsel.  Legend has it that the whole thing was done in 36 hours, which I can believe.  What most people discount or dont realize about Led Zeppelin 1 is that it was a completely independant record.  Jimmy Page financed the record (or most likely Jimmy Page and Peter Grant) and finished it entirely on their own at which point they went out to solicit a record deal.  Atlantic didnt scoop them up and throw them in a studio, the first recording atlantic was involved with, unless I have my history totally wrong (which is possible, I wasnt there) was the second record which was recorded at a myriad of studios in NY, LA and London while the band was on tour.  Led Zeppelin did indeed sound great no matter what they did, LZ2 is a great example of that, tracked by different engineers through different consoles in a few different studios.  What I would really like to know, the stuff recorded in London was almost certainly CCIR (whole lotta love, what is, thank you, living loving maid) while the US stuff (lemon, heartbreaker, ramble, moby dick, bring it on home) was probably NAB.  Im too young to know but my guess is that it probably wasnt too common for US studios to have CCIR eq's on their decks, but its just a guess.  The only commonality outside of the band was the fact that it was all mixed in the same studio in NY by eddie kramer (blech).  Thats quite a lot of variables for one record, which when you listen to it sounds a little disjointed but most of the people that listen to it would never notice.  argh, rambling.

dave
Title: Helios thread
Post by: CJ on December 02, 2004, 04:26:25 PM
Makes you wonder how a band like the eagles can take years to put out a piece of crap like the long run, and these guys just get in and get out. I guess talent has something to do with it.
Title: Helios thread
Post by: soundguy on December 02, 2004, 04:29:28 PM
haha, did it take them 10 years to make that album?

Presence was I think a 10 day or 2 week record, they got bumped out of the studio by the stones who had a prior booking.  Thats a lot of record (mixed) for two weeks of work!  I bet JPJ is still bummed by his flubs on that record, theres a bad one in achilles.

dave
Title: Helios thread
Post by: CJ on December 02, 2004, 04:33:58 PM
I think he liked to leave the mistakes in,thats what i read in a Guitar Player interview at least. Like on Physical Grafetti when that plane was flying overhead and he told the engineer to "leave it".
Title: Helios thread
Post by: soundguy on December 02, 2004, 04:36:14 PM
that is edited on from another take...

dave
Title: Helios thread
Post by: CJ on December 02, 2004, 04:53:36 PM
or that screw up on 1 during I can't quit you.
Title: Helios thread
Post by: kvintus on December 13, 2004, 07:59:24 AM
Bump...

Some inspiration for you guys working on this project. Good close-ups of some PS2 modules.

http://www.larking.com/Used%20Console%20Pages/helios.htm

But I guess you've seen this one already...
/A
Title: Helios thread
Post by: on March 02, 2005, 12:05:00 PM
Bump.....
State of the Union...

Strangeandbouncy come on down....
Buttachunk - whats happening?
Title: Helios thread
Post by: strangeandbouncy on March 02, 2005, 05:02:19 PM
Guys,

   I am so very sorry not to have posted any schemo's etc, but I have to give the lame-assed excuse that I am too darn busy right now - flooded flat/builders/other leaseholders/LVT-(Leasehold Valuation Tribunal)/V.V.V. busy at work. . . . . plus I don't have a scanner . . . .

    . . . . Please watch this space . . . .


     Andy P
Title: Helios thread
Post by: on April 18, 2005, 10:51:41 AM
Piccies at Larkings list for the internals of a rack mounted Helios
http://www.larking.com/Small%20Pics/Helios%20eq%20pcb's.jpg
http://www.larking.com/Small%20Pics/Helios%202X2%20eq.jpg

Quote
2 x 2 channel 4 band sweep EQ units available. Low bass 40Hz - 700 Hz Low Mid 500 Hz - 5 kHz High Mid 700 Hz 0 7 kHz Top end 7 kHz - 17 kHz All + or - 14db. Virtually discrete - one op amp in each band apart from that it is Transistors all the way.
Title: Helios thread
Post by: FMS56 on December 10, 2005, 10:39:25 PM
hello! I've been following this post for a while now, and wanted to know if anyone has found out the values of the inductors in the '69? All i found was:
L1 value tap 1) common; 2) 19.7 mH; 3) 37mH ; 4) 345mH. ????
And a 12H for L2 ?

Has anyone confirmed this? Many thanks in advance

Cheers!
Title: Helios thread
Post by: Bauman on February 15, 2006, 12:13:10 PM
BUMP!

If we are going to make some pcb for this we need to sort the inductor details!!  :green:

Fabio
Title: Helios thread
Post by: on February 15, 2006, 12:24:52 PM
ok...
Andy P - did you get a chance to talk to Cyril about this?
Title: Helios thread
Post by: Bauman on February 15, 2006, 12:31:15 PM
Andy come on man!!  :green:
Title: Helios thread
Post by: strangeandbouncy on February 15, 2006, 01:46:33 PM
If i had an inductance meter, i could measure mine!

   Anyone in the london area with an inductance meter?
Title: Helios thread
Post by: strangeandbouncy on February 15, 2006, 01:48:11 PM
I was only going to talk to Cyril about mix-amp hook-up, and some spares for my channels . . .
Title: Helios thread
Post by: mik on February 15, 2006, 02:43:50 PM
Quote from: "FMS56"
hello! I've been following this post for a while now, and wanted to know if anyone has found out the values of the inductors in the '69? All i found was:
L1 value tap 1) common; 2) 19.7 mH; 3) 37mH ; 4) 345mH. ????
And a 12H for L2 ?

Has anyone confirmed this? Many thanks in advance

Cheers!

yes, I do confirm the value for L1, I've wrote on paper this volue wen I've got a pair.
can't confirm L2 Value, gere of mine wasn't able to mesure it.
M.
Title: Helios Thread
Post by: Arny on April 23, 2006, 05:17:46 PM
Dear All,
   Every one seems to think that the Inductors are made by Sowter, I am afraid that is not the case, they are hand made by ourselves to a special specification.
   
 Good Luck"
Tony

Tony Arnold (Director)
www.helios-electronics.com.
Title: Helios thread
Post by: Joechris on April 23, 2006, 06:48:12 PM
Hi Arny
Good to see you here.
I hope you will pop by more often, now that you have found this place.
Lots of great information in one place.
Do you still got that D30 mic I got you (clue)
Title: Helios thread
Post by: on April 24, 2006, 04:51:29 AM
Welcome Tony
More info from Cyril Jones

http://www.groupdiy.com/index.php?topic=14184&highlight=cyril+jones
Title: Helios thread
Post by: hejsan on April 25, 2006, 06:40:42 PM
Hey, I wan't VU's like these:
http://www.helios-electronics.com/More_Pics/more_pics.html

Where do I get them??

 :sam: hejsan
Title: Helios thread
Post by: Viitalahde on April 25, 2006, 06:45:43 PM
Those are actually Sifams, they have a "retro" looking version.
Title: Helios thread
Post by: hejsan on April 25, 2006, 07:04:41 PM
Dang!... then I'll have to start selling out my organs..

prepare for some blood in the black market, will beat russian mob prices for kidney, liver, cornea, no API, NEVE!!!
Title: Helios thread
Post by: Tekay on April 26, 2006, 02:10:18 AM
The Sifam meters are AL20SQ, Canford Audio use to stock them!
Title: Helios thread
Post by: hejsan on April 26, 2006, 10:17:44 PM
Thanks for the tip tekay, they're not as expensive as the other sifam stuff people have been discussing :thumb:

Does canford ship abroad?

hejsan
Title: Helios thread
Post by: on April 28, 2006, 04:17:26 AM
(http://www.helios-electronics.com/AUT_4616.JPG)
I see grayhill switches (I think I have sintech a load of these - ex-military surplus - from RAF cockpits)
Single gang Elma
Home made inductor?
BC box caps
Title: Helios thread
Post by: ozzy on May 25, 2006, 04:51:35 PM
Can anyone please explain to me what the "Card 1" and "Card 2" is which you see on the schematic diagram that you can download on vintag king. is card 2 the line amp which you can also download of the site. if so, what is card 1 and where can i find the diagramm for it.
Title: Helios thread
Post by: ruffrecords on November 12, 2006, 07:22:28 AM
Hey everyone, what is the current status of this project? Seems to be a bit quiet since May?

I have made a few notes looking through this thread.

1. Several references to -20dB  mic input achieved by the Lustraphone transformer secondary centre tap.  Maybe I am just pedantic but it is not a centre tap. This is a 1:10 transformer and the -20dB setting is achieved by a 1:1 tap. Maybe this is FUD put out by those who would prefer we don't make our own clone?

2. -24V supply. This is probably a holdover from the original germanium designs. Even today it is well known that PNP transistors are less noisy than NPNs, so the original design would most likely have used a PNP as the first transistor. The various currently available schematics show an NPN as the first transistor which is probably the easiest way of updating the circuit to silicon without doing a complete redesign.

3. I have managed to simulate the amps and the EQ using switcherCAD. I can post swCAD files if anyone is interested.  There is no sign of the fabled bump in the simulations I have done. Also the EQ gives the right bass boost frequencies with an inductor value of 10H.

4. Some people have noted the older cards sound 'smoother'. The 150pF at the card input seems to be the cause of this making the 20KHz response drop by 1.6dB. Reissues may use a different value; 50pF reduces this drop to 0.3dB

5. Asymmetric distortion is also mentioned as one of the well liked features. This appears to be due to the way the output is biassed. Generaly you aim to get the biggest possible output swing so you arrange the bias so the output collector is half way between the emitter and supply voltages. On the Helios 69 this is not the case; it is biassed somewhat lower than this which means the bottom of the waveform clips first. This produces lots of nice second harmonic (read musical) distortion. At first I thought there was an error in the schematic becuase if you swap the positions of the 680K and 820K bias resistors the output collector voltage is much more central. This produces symmetric distortion with loads of 3rd (read yukky) harmonic distortion. I don't know if Dick did this deliberately or accidentally but it certainly ties in with the reported 'sound'.

6. The simulations show a rather poor LF response of -2.1dB at 20Hz mainly caused by the 125uF gain capacitor. Raising this to 470uF brings the 20Hz response to -0.6dB.

7. Sowter now do their own version of the Lustraphone transformer type number 7490 with the 1:1 tap.

That's it for now. Just waiting for the parts to arrive before I start building a prototype.

Cheers

Ian
Title: Helios thread
Post by: Wonderlandaudio on November 15, 2006, 03:08:01 PM
I have Tony Arnold´s ones in case you need any help.
I think the Sowter is the 8666x.
Title: Helios thread
Post by: Wonderlandaudio on November 15, 2006, 03:15:05 PM
I use mine with a B283 and Lo1166 as output stage. And took Tony´s transistor based phase reverse switch, which changes gain as well.
Card 1 and card 2 in the schematics are the same.
Title: Helios thread
Post by: ruffrecords on November 15, 2006, 04:05:33 PM
Quote from: "Wonderlandaudio"
I have Tony Arnold´s ones in case you need any help.

That is interesting. It would be nice to know what silicon they use and whether the input transistor is a PNP or NPN. Also what value cap do they use in series with the first stage gain switch. The original circuits show 125uF but this gives poor LF response at max gain. 470uF would cure this. Lastly the HF perfomance is affected by the 150pF across the input of each 'card' in the original circuits. It would be interesting to know if they have changed these values.
Quote
I think the Sowter is the 8666x.

I read somewhere that the Sowter 8666X is a custom design that is exclusive to Tony Arnold. Sowter cannot and will not sell it to you. Their own design of the lustraphone is the 7490.

Ian
Title: Helios thread
Post by: Wonderlandaudio on November 15, 2006, 04:26:21 PM
Check the archive. The 8666 is also 200:20K with the 1:1 tap at the secondary. Suspicious...
Title: Helios thread
Post by: Wonderlandaudio on November 15, 2006, 05:32:59 PM
220uF. Still 150pF.2TX214c,bc184c,bc184c, ip to op.[/b]
Title: Helios thread
Post by: ruffrecords on November 16, 2006, 03:06:53 AM
Quote from: "Wonderlandaudio"
220uF. Still 150pF.2TX214c,bc184c,bc184c, ip to op.[/b]

That is good. I see they are using a PNP input. Should that be a ZTX214C rather than 2TX214C??? I had already bought BC184s for the two NPNs. I'll check out 220uF on the simulation and see what it does to the LF response.

Ian
Title: Helios thread
Post by: Wonderlandaudio on November 16, 2006, 03:11:19 AM
It IS ZTX214c. It was dark. Sorry
Title: Helios thread
Post by: on November 16, 2006, 08:12:28 AM
Quote from: "Wonderlandaudio"
It IS ZTX214c. It was dark. Sorry

That would be the amp I just sold a thousand of to various members of this forum
BTW - check my look see on the original Helios amps on this thread
http://www.groupdiy.com/index.php?topic=16647&highlight=helios

Cyril then starts pulling out old modules
A module from the FIRST Helios desk ever made
I spotted - Colvin Pots - the turret board with BIG mustard caps
Then - Veroboard/Stripboard
Lustraphone transformers and the inductor

Then he pulls out the module from the SECOND ever Helios desk
Now this one is quite different inside - two little RadioSpares (RS Components) Interstage transformer right behind the panel
Title: Helios thread
Post by: Wonderlandaudio on November 16, 2006, 08:18:03 AM
I had the chance to meet Cyryl in Spain. We bought a Symphony and he came himself to help with the installation. Really nice man. An open book
Title: Helios thread
Post by: CJ on November 16, 2006, 02:19:37 PM
Can someone send me one of those laundramat transformers or
whatever they are called? (chops a lickin!)  :razz:
Title: Helios thread
Post by: Wonderlandaudio on November 16, 2006, 02:40:50 PM
Lustraphones???? Man, I´ve seen rare things but never a Lustraphone.... Sorry. I have Decca transformers, EMI´s,... but not Lustraphones.
Title: Helios thread
Post by: ruffrecords on November 16, 2006, 02:47:38 PM
Quote from: "uk03878"
That would be the amp I just sold a thousand of to various members of this forum]

What amp would that be then? Can you post a link?

Ian
Title: Helios thread
Post by: on November 17, 2006, 07:37:10 AM
amp as in ZTX214
Title: Helios thread
Post by: ruffrecords on November 18, 2006, 02:26:29 PM
Quote from: "uk03878"
amp as in ZTX214

Oh, I see, you mean the transistor itself. Do you have any left?

Ian
Title: Helios thread
Post by: ask on December 03, 2006, 11:46:48 AM
bump  :roll:
Just wondering, and hoping for a successfull DIY "Helium"
Title: Helios thread
Post by: ask on December 03, 2006, 02:55:13 PM
Am I right in tkinking that the line in goes straight to the amp, bypassing the tranny?
Title: Helios thread
Post by: ruffrecords on December 03, 2006, 05:13:55 PM
Quote from: "ask"
Am I right in tkinking that the line in goes straight to the amp, bypassing the tranny?

Generally yes, and certainly in the 69. I think as a rule Helios consoles just had transformers at the mic input and the main outputs. Inserts were generally unbalanced.

Ian
Title: Helios thread
Post by: Wonderlandaudio on December 03, 2006, 07:26:47 PM
In those days,Line input actually meant MIX mode, so those line ins were actually tape returns. Xformers were in groups of 8 inside the console.

Anyway, talking about vintage Helios consoles means no rule applies. Not 2 consoles are the same, not even close.
Title: Helios thread
Post by: enthalpystudios on December 03, 2006, 09:11:49 PM
had the wonderful experience of tracking some guitar thorugh a space eho, silvertone tube combo, rca ribbon, into a helio micpre/eq module the other day.

sounded phenomenal.  i think we'll have to use that helios module again, and again, and again, and then use something else so it doesnt all sound like helios.

or maybe not.
Title: Helios thread
Post by: ruffrecords on December 04, 2006, 05:52:34 AM
Quote from: "Wonderlandaudio"
In those days,Line input actually meant MIX mode, so those line ins were actually tape returns. Xformers were in groups of 8 inside the console.

Interesting snippet. Do I take this to mean they did use transformers on line inputs but they were simply remote from the module?  What transformer did they use?

Ian
Title: Helios thread
Post by: on December 04, 2006, 07:26:24 AM
here's what I saw inside two Helios modules
http://www.groupdiy.com/index.php?topic=193030&highlight=interstage#193030
"A module from the FIRST Helios desk ever made
I spotted - Colvin Pots - the turret board with BIG mustard caps
Then - Veroboard/Stripboard
Lustraphone transformers and the inductor

Then he pulls out the module from the SECOND ever Helios desk
Now this one is quite different inside - two little RadioSpares (RS Components) Interstage transformer right behind the panel
"
Title: Helios thread
Post by: enthalpystudios on December 05, 2006, 05:46:37 PM
quote from psw:

 
Quote
If you have Helios EQ's with Beyers, you are missing half of the sound, run to the phone and call Steve Firlotte at Inward Connections and get some of his Lustraphone modeled transformers.


perhaps these are still available...  anyone know?  sowter 7490 also looks good, not sure which would be more.... lustraphoney

or if his transformers are the mic in with 1:1 tap, or if they are for eq's, line out or something.

it would be awesome to see this materialize however!
Title: Helios thread
Post by: on December 06, 2006, 07:11:50 AM
Lustraphones just happened to be what was on the shelf at the time these were built
They werent chosen specially
Title: Helios thread
Post by: Wonderlandaudio on December 06, 2006, 08:54:38 AM
Quote from: "uk03878"
Lustraphones just happened to be what was on the shelf at the time these were built
They werent chosen specially


MarinAir was chosen because the factory was close to Neve´s. Painton quadrant faders in EMI TG consoles were leftovers from the REDD consoles... the 2nd inductor in the 1073 midrange eq was a leftover used in lopass filters... I´ve noticed that all the things, or at least most of the things we love from old gear are either design errors, technical limitations of the time or mostly casualties...
Title: Helios thread
Post by: enthalpystudios on December 06, 2006, 09:23:03 AM
yeah, so it needs to be exactly the same thing right?  ;]

j/k...  but seriously, i'd imagine that the sowter 7490 is a good solid transformer with the correct taps.

and thats about all you'd want out of a transformer i guess, in any case, is a well built transformer with the correct taps.

man, re reading this thread, a lot has been done!  i wonder how much those elmas are.  also wonder if there are any others that will fit.  although i'm all up for going quality, even the elmas cost my right nut
Title: Helios thread
Post by: ruffrecords on December 06, 2006, 06:30:36 PM
Quote from: "enthalpystudios"
 i wonder how much those elmas are.  also wonder if there are any others that will fit.  although i'm all up for going quality, even the elmas cost my right nut

I am currently investigating alternatives form Lorlin that are significantly cheaper. The only real downside seems to be they are rated for only 10,000 operations instead of 25,000 that the Elmas do. For DIY projects 10K should be more than sufficient and the prices are roughly in the same ratio too.

Ian
Title: Helios thread
Post by: enthalpystudios on December 06, 2006, 11:41:55 PM
cool man!

are they the size of the lorlins i'm used to?  or smaller lorlins hopefully.....
Title: Helios thread
Post by: Wonderlandaudio on December 07, 2006, 12:39:28 PM
The difficult parts to clone the Helios would be basically both inductors, which I don´t know who made them or who makes the substitutes now. Definitely neither  Sowter nor Carnhill. At the end of the day a rotary switch is a rotary switch, mechanically diying at 10000 op´s or 25000 will be dusty and scratchy earlier almost for sure.
And would be of help a correct schematic. Some of them out there aren´t. as  some people have noticed yet.
Title: Helios thread
Post by: ruffrecords on December 07, 2006, 03:57:48 PM
Quote from: "enthalpystudios"
cool man!

are they the size of the lorlins i'm used to?  or smaller lorlins hopefully.....

Depends what you are used to. They have a PCB mounting model type PT. The most expensive switch to make is the 2 pole 10 way for the bass EQ control in the Hellios 69. Using the PT series you need a base 1 pole 12way switch, a 1pole 12 way wafer and a pair of spacers from the PT series, which totals about 7GBP before tax (from RadioSpares). These switches are about 32mm high

Lorlin also do an RA series, which according to their website 'A precision range of wafer switches for high quality instrumentation, the dual wiping contacts for each terminal ensure reliable low resistance contact. RA wafers can be stacked to provide numerous switching configuration'. These are a more conventional hard wired type of wafer switch and I expected them to be a lot more expensive. However, I have a preliminary quote from them for a two pole 10 way of 6.68GBP ex works but there is a minimum order quantity of 100 - way to much for me alone but a possibility for a group buy.

For the single pole switches, for the gain, treble and mid controls, Lorlin do a very small (TO5 sized) MT series which is less than 10mm in dia. RadioSpares are due to stock a limited range of these starting some time this month so I don't yet have prices.. The only downside of these parts so far is that their rated life is only 5000.

Lastly, for prototyping purposes I am messing around with some switch kits from RadioSpares (Part no 352-187) which are made by NSF in the UK. These have a really long rear shaft so I am going to try spacing wafers by the length of the capacitors on the bass control and wiring the caps between them. That way I can build a switch bass switch assembly which has just three flying leads. Building the bass switch this way does cost nearly 18GBP though. I'm thinking of a similar construction techniques for the single pole switches in the prototype which would then cost about 11GBP.

Ian
Title: Helios thread
Post by: ruffrecords on December 07, 2006, 04:12:39 PM
Quote from: "Wonderlandaudio"
The difficult parts to clone the Helios would be basically both inductors, which I don´t know who made them or who makes the substitutes now. Definitely neither  Sowter nor Carnhill.

Sowter make any inductor you specify for the one off price of their standard ones (about 40GBP) but that is a little expensive IMHO. I have purchased some core and former kits from RadioSpares and plan to wind my own for a prototype. The bigger of the two (10H or 12H depending on who you believe) is going to be hardest to make - might be best to find someone who can make a batch for a reasonable price.
 
Quote
At the end of the day a rotary switch is a rotary switch, mechanically diying at 10000 op´s or 25000 will be dusty and scratchy earlier almost for sure.

The main difference seems to be in contact material. The 10,000 life ones use silver whilst the 25000 ones use gold over silver. You also need to be careful how you define life. Most manufacturers define it as when the contact resistance reaches 10 times its initial value but even then it is only about 100 milliohms which is not going to affect circuit operation. The other thing to remember is that life is very dependent on the contact current and published life expectancy figures generaly assume currents of the order of tens of milliamps. Again, the currents in the Helios pre will be much lower so switch life should increase significantly.

Ian
Title: Helios thread
Post by: Wonderlandaudio on December 07, 2006, 05:14:08 PM
IMHO 40 quid for an inductor is far more than a little expensive...
Title: Helios thread
Post by: enthalpystudios on December 07, 2006, 10:26:09 PM
especially for one of those little tiny inductors.

buyt regarding the switches, those are the lorlins i'm used to...  but i'm kind of going for small here, to fit a more or less standard sized module, so it may be elmas or grayhills for me, unless i can find a reasonable alternative..  i do have a bunch of small, 1/8" shaft, grayhill 2x12's that could work there however.

i plan on getting some frontpanel layout work done soon here, and will probably have them engraved locally, i'll post my findings if anything turns out.
Title: Helios thread
Post by: ruffrecords on December 08, 2006, 04:53:11 AM
Quote from: "Wonderlandaudio"
IMHO 40 quid for an inductor is far more than a little expensive...

Depends. You pay that much for an input transformer and the materials cost is much the same. The big inductor in the Helios is 10H which is one hell of a lot of wire. However, I do agree it should be possible to obtain good quality inductors more cheaply.

Ian
Title: Helios thread
Post by: ruffrecords on December 08, 2006, 04:57:32 AM
Quote from: "enthalpystudios"
especially for one of those little tiny inductors.

I wouldn't call them tiny. 10H is large by anyone's standards and it might well be a good idea to find a group buy source for this. The other inductor is a few hundred milliHenries so it should be practical to wind them ourselves.

Ian
Title: Helios thread
Post by: lotus on January 22, 2007, 01:14:35 PM
BUMP
Title: Helios thread
Post by: enthalpystudios on January 22, 2007, 05:52:45 PM
well, if i can be of any help, i have a lustraphone version mic/eq module here that i'm racking up for a buddy of mine...  a very lucky buddy of mine ;]

its got the back to back turretboards right behind the switches, and the lustraphone next to it.  behind those there are two 8way (i believe, not sure off hand) edge connectors on top one another, and two plug in cards, one is a 'line amp' and one is something else......

anyway, if this is something close to the modules that we're talking about working with, and if anyone is into the idea of original circuit layouts, one thing i could certainly do to help is run them on the scanner, or certainly doublecheck anything.  most parts look original, but an iron has definitely been in here and melted a little blue plastic off an elma.
Title: Helios thread
Post by: on January 23, 2007, 08:38:11 AM
Quote from: "enthalpystudios"
well, if i can be of any help, i have a lustraphone version mic/eq module here that i'm racking up for a buddy of mine...  a very lucky buddy of mine ;]

its got the back to back turretboards right behind the switches, and the lustraphone next to it.  behind those there are two 8way (i believe, not sure off hand) edge connectors on top one another, and two plug in cards, one is a 'line amp' and one is something else......

anyway, if this is something close to the modules that we're talking about working with, and if anyone is into the idea of original circuit layouts, one thing i could certainly do to help is run them on the scanner, or certainly doublecheck anything.  most parts look original, but an iron has definitely been in here and melted a little blue plastic off an elma.

I know exactly what you are talking about because I have seen that module (see this post http://www.groupdiy.com/index.php?topic=193030&highlight=interstage#193030)
Call Cyril and ask him.. (nicely)
Title: Helios thread
Post by: enthalpystudios on January 23, 2007, 09:17:13 AM
well i guess what i'm trying to say is that with the sowter (close enough for me) transformers, it would be a lot of fun to think up a clever way to make these diy-able...

i have only a couple hand drawn schematics, and i have to double check, but i'm not exactly sure which model this one is, or if its anything like the one people here are interested in building, but i'd certainly be happy to double check things to help with component identification and schematic interpretation and what not.  anyway, i feel like it could be a fun little project....  i was also thinking about boards, and think that the layout of this module and others like it is quite a neat layout...   from my measurements, and again, i'm not sure if something like this is possible or just better left to offboard elmas, but i wonder if a doublesided board could use pc mount grayhills alternating on either side of the board.  makes it easier to do the LF freq switch as well.

i really need to start with a simple pcb layout and just start trying to do it rather than talk up ideas that i'm not actually working on....

anyway, i'm not sure what the best way to proceed would be.  Also, I suppose that with offboard switches, those who might want to just make a rackmount unit could do so rather than going with little modules.

also, i don't see an output transformer on this one, unless i'm totally mistaken, i just have a small iron core inductor, a large, black encased inductor, and the large lustraphone.

did these have output transformers, or was that left up to different places down the signal chain?
Title: Helios thread
Post by: ruffrecords on January 23, 2007, 11:35:48 AM
Quote from: "enthalpystudios"
i have only a couple hand drawn schematics, and i have to double check, but i'm not exactly sure which model this one is, or if its anything like the one people here are interested in building, but i'd certainly be happy to double check things to help with component identification and schematic interpretation and what not.

That would be cool. I would really like to see some close up pics of this.
Quote
did these have output transformers, or was that left up to different places down the signal chain?

No they didn't, as you correctly surmise, they were further down the chain - basically at the final output - Helios inserts were unbalanced.

Ian
Title: Helios thread
Post by: enthalpystudios on January 23, 2007, 06:14:53 PM
excellent...  good to know about the output transformers.  i also like, in general, the idea that not everything has to be balanced.  these days its always balanced this, balanced that, but for most peoples setups, who cares.  i have all kinds of unbalanced stuff that has no real troubles.

anyway, do let me know whatever you need, and my roommate has an excellent camera that i can use when hes around, so no problems.
Title: Helios thread
Post by: Lindell on June 13, 2007, 05:19:20 AM
Found some pix:

(http://i2.photobucket.com/albums/y32/tobbelito/helios.jpg)

(http://i2.photobucket.com/albums/y32/tobbelito/helios2.jpg)

(http://i2.photobucket.com/albums/y32/tobbelito/helios3.jpg)
Title: Helios thread
Post by: Wonderlandaudio on June 13, 2007, 09:37:52 AM
The Clapton´s console original ( click to enlarge )

(http://i119.photobucket.com/albums/o130/wonderlandaudio/th_HELIOSCLAPTON.jpg) (http://i119.photobucket.com/albums/o130/wonderlandaudio/HELIOSCLAPTON.jpg)
Title: Helios thread
Post by: CJ on June 13, 2007, 01:00:02 PM
the coil is in thaty silver can, middle bottom?
Title: Helios thread
Post by: Sonic Screwdriver on June 13, 2007, 04:35:29 PM
Quote from: "CJ"
the coil is in thaty silver can, middle bottom?


That is the input transformer I would guess? The EQ coils being located vertically and to the right

Thanks for posting the pics BTW

regards

David
Title: Helios thread
Post by: mrcalrec on June 26, 2007, 11:43:41 PM
Do not buy anything from Wonderlandaudio - Pedro Rodriguez.  I think he is a scam artist.  I bought a Neve 2254A from him through Ebay and paid through paypal on May 23rd - $2000 US.  I have not heard a peep since.  He was very responsive prior to the sale.  One he received my money - nothing.  I have sent at least 50 emails - no response.  I know other who have been ripped off as well.
Title: Helios thread
Post by: rotheu on August 26, 2007, 05:14:58 PM
Hi everybody,

Just built helios 69 prototype, but having some problems. It has strange frequency responce.The famous 100Hz bump is not  bell shaped. It's a low shelf which starts at about 110-120Hz and at the end of the spectrum I get 6dB of boost (20Hz). It's happening in the amp, not the filter. Right now i have only the filter and gain make up amp. I can imagine another amp on the input will give double boost. Also the headroom is low. I get some crazy distortion(sounds great though :twisted: ). I reversed transistors and caps polarity and used +24 PSU. Any ideas? Thanks.
Title: Helios thread
Post by: khstudio on August 27, 2007, 01:09:02 AM
Quote from: "mrcalrec"
Do not buy anything from Wonderlandaudio - Pedro Rodriguez.  I think he is a scam artist.  I bought a Neve 2254A from him through Ebay and paid through paypal on May 23rd - $2000 US.  I have not heard a peep since.  He was very responsive prior to the sale.  One he received my money - nothing.  I have sent at least 50 emails - no response.  I know other who have been ripped off as well.


That sucks :mad:

I don't want to get involved here but I've heard bad things about that guy for a LONG time.

The MODERATOR of this forum should be notified to keep an eye on things. :wink:
This is a forum of trust.
Title: Helios thread
Post by: rotheu on September 02, 2007, 07:49:35 PM
Is there any way to make the through cut of the mid section in the filter wider. More of a regular dip instead of notch? I tried adding resistance but it doesn't make it wider, just cuts less. The Q stays almost the same. Thanks.
Title: Helios thread
Post by: rotheu on September 02, 2007, 07:52:40 PM
BTW , fixed the problem I was having before with the amp.
Title: Helios thread
Post by: lotus on September 03, 2007, 10:30:21 PM
so how does it sound?   what input transformer did you use?  have you implemented a output transformer?
Title: Helios thread
Post by: rotheu on September 12, 2007, 12:56:38 AM
[so how does it sound? what input transformer did you use? have you implemented a output transformer?]

The micpre sounds really good. Didn't do real life tests yet, just some speach and run few prerecorded tracks through it. Sounds very open, natural and punchy. I've used Jensen 10KB-D  10K/600 step-down line input xformer reversed, 1/4, which gives about 12dB of gain (instead of 20dB with the original 1/10). I also added direct coupled  two transistor output driver and Edcor WSM 600/600 xformer. Still messing with EQ. Tried using small audio transformers from mouser suggested by NewYorkDave as inductors. Inductance values are good, but the problem is self-resonance. When used in low boost circuit, along with boosting the lows it is boosting high shelf by the same amount and I endup having a wide Q dip at around 1K. Same with highs. Edcor WSM 10K/10K works great for low boost though, unfortunatly it's 5 times more expensive ( I'm planning on building 16 channel mixer with this modules).[/quote]
Title: Helios thread
Post by: rotheu on September 12, 2007, 01:00:01 AM
Quote
so how does it sound? what input transformer did you use? have you implemented a output transformer?


The micpre sounds really good. Didn't do real life tests yet, just some speach and run few prerecorded tracks through it. Sounds very open, natural and punchy. I've used Jensen 10KB-D  10K/600 step-down line input xformer reversed, 1/4, which gives about 12dB of gain (instead of 20dB with the original 1/10). I also added direct coupled  two transistor output driver and Edcor WSM 600/600 xformer. Still messing with EQ. Tried using small audio transformers from mouser suggested by NewYorkDave as inductors. Inductance values are good, but the problem is self-resonance. When used in low boost circuit, along with boosting the lows it is boosting high shelf by the same amount and I endup having a wide Q dip at around 1K. Same with highs. Edcor WSM 10K/10K works great for low boost though, unfortunatly it's 5 times more expensive ( I'm planning on building 16 channel mixer with this modules).[/quote]
Title: Helios thread
Post by: lotus on September 29, 2007, 07:26:36 PM
Just wondering if you've had a chance to further test your helios? Also are you still running it at +24?
Title: Helios thread
Post by: CJ on October 01, 2007, 01:41:33 PM
rotheu, i am working on those inductors right now, gettting them to work without resonance in the audio band, piece of cake, literally...
Or did I mean pie....yes..make that pie.
Apple pie. With a thin crust, topped with maple syrup and ice cream.
4 twenty kind o treat.
Title: Helios thread
Post by: khstudio on October 01, 2007, 02:37:08 PM
I just want to thank everyone for their efforts on this :thumb:

I'm definitely in on this one if you guys can get it going :green:

This also might sound dumb... but the only reference I have to even coming close to hearing a HELIOS is the UAD EQ plugin. It is by far my favorite EQ plug for several things. I know it's not "real" but if it even resembles how the originals works then... :green:

The shape of the mids, the low shelf/ bump & the high shelf are ALL KILLER :!:
Title: Helios thread
Post by: rotheu on February 28, 2008, 12:22:38 AM
Quote
rotheu, i am working on those inductors right now, getting them to work without resonance in the audio band, piece of cake, literally...
Or did I mean pie....yes..make that pie.
Apple pie. With a thin crust, topped with maple syrup and ice cream.
4 twenty kind o treat.


Hi CJ. I didn't visit the forum for long  time, just saw your post. Did you get anywhere trying to get them to work? What's the idea behind it? Thanks a lot.

rotheu
Title: Re: Helios thread
Post by: Whoops on October 16, 2011, 11:05:17 PM
A long time went by now,
But how did your projects go?

Any more results since the prototyping stage?

Does anyone still have the schematics?
all the links are dead now and I would really love to study this project and prototype a unit.

Thanks
Title: Re: Helios thread
Post by: Whoops on October 14, 2012, 10:22:22 PM
Bump
Title: Re: Helios thread
Post by: CJ on October 18, 2012, 05:56:46 AM
i might have the inductor specs laying around,

Title: Re: Helios thread
Post by: bruno2000 on October 18, 2012, 09:06:34 AM
I'm interested in the info as well.  Thanks!
Best,
Bruno2000
Title: Re: Helios thread
Post by: Whoops on October 21, 2012, 05:24:01 PM
i might have the inductor specs laying around,

That would be really cool, thanks
Title: Re: Helios thread
Post by: Whoops on October 21, 2012, 05:25:52 PM
The links for the schematics in the first page of this thread are all dead now unfortunately

Does anyone still have the Helios modules schematics?

Thanks
Title: Re: Helios thread
Post by: ruffrecords on October 22, 2012, 06:46:26 AM
There are a few still online here for example:

http://www.danalexanderaudio.com/recorder.html (http://www.danalexanderaudio.com/recorder.html)

Cheers

Ian
Title: Re: Helios thread
Post by: bruno2000 on October 22, 2012, 01:45:42 PM
There are a few still online here for example:

http://www.danalexanderaudio.com/recorder.html (http://www.danalexanderaudio.com/recorder.html)

Cheers

Ian

Thanks!
Best,
Bruno2000
Title: Re: Helios thread
Post by: Whoops on October 22, 2012, 02:54:32 PM
There are a few still online here for example:

http://www.danalexanderaudio.com/recorder.html (http://www.danalexanderaudio.com/recorder.html)

Cheers

Ian

Thanks Ian,
But it seems that the input module schematic for the Mic Pre is not correct. Or at least it's not the most common version of the Helios 69 Mic Pre
Title: Re: Helios thread
Post by: kpearsall on October 22, 2012, 07:03:22 PM

Would this help?  ;D

I've never seen this anywhere else before. I found it listed in the photos of a channel strip in an Ebay auction. If anyone has a problem with me posting this let me know I'll take it down.

This is the best one I've ever seen though. Enjoy :)
Title: Re: Helios thread
Post by: Whoops on October 22, 2012, 09:17:39 PM

Would this help?  ;D

I've never seen this anywhere else before. I found it listed in the photos of a channel strip in an Ebay auction. If anyone has a problem with me posting this let me know I'll take it down.

This is the best one I've ever seen though. Enjoy :)

Thanks really good actually,
it's clean and it has the schematics for the full module.
Thanks

I think that the circuit probably differs between different schematics, the transistor arrangement at least seems different.
Title: Re: Helios thread
Post by: kpearsall on October 22, 2012, 09:46:31 PM
If anyone's curious, that was from the musikladen console. Made my day when I found it and it had the HPF section with line amp in there :)
Title: Re: Helios thread
Post by: Strat96 on December 29, 2012, 09:36:02 PM
If anyone's curious, that was from the musikladen console. Made my day when I found it and it had the HPF section with line amp in there :)

Yes it is.  There are actually three different versions of that schematic.  The main difference is which amp cards are being used, and also the extra filter switch.
Title: Re: Helios thread
Post by: gemini86 on December 30, 2012, 04:57:32 AM
There was a -24V version of the line amp (15C1) and then later, a +24V version (2128)

If you look at these two moduels, the schematic is the same, although note that the 2128 schematic is incorrect, as the PNP and NPN transistors should be swapped (it should read 2n4058, then 2n3707, 2n3707).

Title: Re: Helios thread
Post by: nickvivid on March 18, 2013, 03:47:42 PM
Hey guys I just got in a 500 series helios type 69 module. Anyone who is interested in working on a project based on this, pm me.
Title: Re: Helios thread
Post by: Brian Roth on February 01, 2014, 01:14:43 AM
I've read through this thread several times, trying to determine the values of the inductors.  From the schematics, there are two different midrange versions, one with a single tap, and another with two taps.  I gleaned a bit of info, but have a few questions.

I did see what were apparently the values for the two tap version:  19.7 mH/37 mH/345 mH.  Can anyone verify that, and does anyone know the DC resistances?

I couldn't find any info regarding the midrange inductor with just a single tap.

The LF inductor is apparently 10H, but I never saw any DC resistance info.

Or maybe I just got lost in the thread   LOL!

Thanks.

Bri

Title: Re: Helios thread
Post by: ruffrecords on February 01, 2014, 06:41:02 AM
I am in touch with one of the original designers of the Helios circuits. He told me that the 10H inductor did not have a spec as we would think of it today. The first units were made from a bunch of inductors purchased from a surplus store in the Edgeware Road.

Cheers

Ian
Title: Re: Helios thread
Post by: ruffrecords on March 10, 2014, 09:27:51 AM
I got some more info and a pic from my ex-Helios contact today. The bass inductor was made by Parmeko (see attached pic). it looks to be some kind of choke or plate load as it is specified as 4H at 22.5mA dc current but he measured it with no dc flowing and its inductance was 9.97 H which is very close to the 10H I use in my design. He said the dc resistance was 573 ohms.

Cheers

Ian
Title: Re: Helios thread
Post by: Strat96 on January 13, 2015, 06:54:28 PM
Hi everyone. Hopefully it's not too late to join the conversation, but I can confirm that 10H and 12H were used in different versions of the Helios. There isn't a 'Holy Grail' recipe for the exact sound, because the company used what was available at the time and modified the design throughout the 10 years these were made. Certain combinations did sound "better" than others of course, but any gear lover would be happy with any of the Helios modules.

The schematic kpearsall posted is actually from my book. I purchased the Musicland Helios a few years ago, and have been working to restore it (a major undertaking). There are three EQ designs: v1 is Lustraphone Transformer w/ 10H Bass and 220mH/680mH mid; v2 is a Lustraphone  Transformer w/ 10H Bass 115mH/180mH/360mH/680mH; v3 is a Beyer w/ 12H Bass and the same mid from v2.

**Note the inductors are calculated based on the capacitors and freq in the schematics, as the inductor values never are listed.  12H works for all capacitors in v3, except the 60Hz boost would be in actual use an 80Hz boost based on the capacitor used. In other posts from people who know about the equipment, there is mention that 12H and 10H were both used for Helios. From the math anything from 12-16H would be in an acceptable range to work on v3 since nothing ever exactly lines up to the exact boost/cut frequency on a Helios.
Title: Re: Helios thread
Post by: ruffrecords on January 14, 2015, 05:11:00 AM
Thanks for the additional info Strat69. It is always good to hear first hand information. I am sure my ex Helios man would help you with your restoration. PM me with your email and I'll introduce you if you want.

Cheers

Ian
Title: Re: Helios thread
Post by: warpie on January 14, 2015, 07:08:42 AM
I have some free time and I was thinking of breadboarding the preamp to hear how it sounds.
I only have a spare Lundahl ll1538 mic tx (1:5) though.

I think the original had 1:10 tx. Do I need to change any resistors in order to get the thing working with the ll1538?

PS. I'm referring to this (http://groupdiy.com/index.php?topic=1222.msg636182#msg636182) schematic which i believe is the right one?
Title: Re: Helios thread
Post by: ForthMonkey on January 19, 2015, 03:32:36 PM
Any info about Sowter 7490? There is no datasheet on website. I need to know pins and mounthing hole.
Title: Re: Helios thread
Post by: Whoops on January 19, 2015, 04:37:02 PM
Just to let everyone know that there are Lustraphone clone transformers available from 2 different sources.
Those were cloned by analyzing and  dismantling original Lustraphone transformers.

In my opinion the lustraphone clones are the best option for an Helios project.

Sowter makes great transformers, and Im sure the sowter transformer is high quality, although the lustraphones were very much part of the sound of this circuit, and they have a behavior that was not Sowter's intention to emulate. The Sowter transformer is overall better speced what might not be not desirable.
just my 2 cents

Title: Re: Helios thread
Post by: Whoops on January 19, 2015, 06:10:47 PM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0
Title: Re: Helios thread
Post by: ForthMonkey on January 20, 2015, 06:36:05 AM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0

Lots of info but nothing about transformer.Sowter 7490 is clone of Lustraphone M10.Needed datasheet.
Title: Re: Helios thread
Post by: Whoops on January 20, 2015, 08:21:12 AM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0

Lots of info but nothing about transformer.Sowter 7490 is clone of Lustraphone M10.Needed datasheet.

You're wrong.
Sowter 7490 is not a Lustraphone Clone, its a replacement transformer.
Title: Re: Helios thread
Post by: ForthMonkey on January 20, 2015, 08:39:10 AM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0

Lots of info but nothing about transformer.Sowter 7490 is clone of Lustraphone M10.Needed datasheet.

You're wrong.
Sowter 7490 is not a Lustraphone Clone, its a replacement transformer.

Yeah,you're right.My bad...It's a replacement transformer.But still there is no info about Sowter 7490 or Lustraphone M10.How to wiring?

I have no Lustraphone M10.So i have to find info about 7490.

Title: Re: Helios thread
Post by: Whoops on January 20, 2015, 11:20:33 AM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0

Lots of info but nothing about transformer.Sowter 7490 is clone of Lustraphone M10.Needed datasheet.

You're wrong.
Sowter 7490 is not a Lustraphone Clone, its a replacement transformer.

Yeah,you're right.My bad...It's a replacement transformer.But still there is no info about Sowter 7490 or Lustraphone M10.How to wiring?

I have no Lustraphone M10.So i have to find info about 7490.

First of All,
when someone posts rare and difficult to find Technical Documents what you should say is "Thanks",
instead of coming here complaining.

Those documents were collected by me after 4 years of research, and Im sharing them with everyone, so I can help the community as the community helps me.

If you are looking for info about a Sowter product you shouldn't search for it in a Helios Technical Docs page, as there was never any Helios module with Sowter transformers, you should search instead in a Sowter Technical Docs thread, or even more clever contact Sowter directly.

If there is no Sowter Tech Docs thread, maybe you should get the information you need yourself and create a thread and post that information sharing it with everyone.




Title: Re: Helios thread
Post by: ForthMonkey on January 20, 2015, 11:45:45 AM
Helios Schematics and documents, here:

http://groupdiy.com/index.php?topic=58393.0

Lots of info but nothing about transformer.Sowter 7490 is clone of Lustraphone M10.Needed datasheet.

You're wrong.
Sowter 7490 is not a Lustraphone Clone, its a replacement transformer.

Yeah,you're right.My bad...It's a replacement transformer.But still there is no info about Sowter 7490 or Lustraphone M10.How to wiring?

I have no Lustraphone M10.So i have to find info about 7490.

First of All,
when someone posts rare and difficult to find Technical Documents what you should say is "Thanks",
instead of coming here complaining.

Those documents were collected by me after 4 years of research, and Im sharing them with everyone, so I can help the community as the community helps me.

If you are looking for info about a Sowter product you shouldn't search for it in a Helios Technical Docs page, as there was never any Helios module with Sowter transformers, you should search instead in a Sowter Technical Docs thread, or even more clever contact Sowter directly.

If there is no Sowter Tech Docs thread, maybe you should get the information you need yourself and create a thread and post that information sharing it with everyone.

Sorry...

I've sent email to Sowter.If i get any info,i will share.

Thank you for all.
Title: Re: Helios thread
Post by: ForthMonkey on January 20, 2015, 03:48:30 PM
I've found color code for Sowter 7490.

http://www.sowter.co.uk/colours/7490.pdf (http://www.sowter.co.uk/colours/7490.pdf)
Title: Re: Helios thread
Post by: Whoops on March 19, 2015, 04:27:32 PM
My Lustraphone Clone transformers arrived today.

They are manufactured by Cyril Jones from Raindirk

He went to great lengths to be able to produce a Lustraphone clone, they look great.
Will test them soon in an Helios type Mic amp



Title: Re: Helios thread
Post by: Whoops on March 19, 2015, 04:30:55 PM
more pics
Title: Re: Helios thread
Post by: J0hanne5 on December 15, 2016, 07:58:36 AM
I bought eight preamp modules and 15 eq modules those are pulled out from a Helios console owned by the Finnish TV channel called MTV3  http://www.helios-electronics.com/Mainos_TV_Finland.JPG
I started to reverse engineer the pre and found already an input, an output and a voltage pins so I can test the preamp (it will happen in next weekend).  However, any info about Helios modules is welcome!

My plan is to build a side car with 8 pre and eqs. The rest of the eqs I will put in rack enclosures.
Title: Re: Helios thread
Post by: Whoops on December 15, 2016, 08:01:57 AM
I bought eight preamp modules and 15 eq modules those are pulled out from a Helios console owned by the Finnish TV channel called MTV3  http://www.helios-electronics.com/Mainos_TV_Finland.JPG
I started to reverse engineer the pre and found already an input, an output and a voltage pins so I can test the preamp (it will happen in next weekend).  However, any info about Helios modules is welcome!

My plan is to build a side car with 8 pre and eqs. The rest of the eqs I will put in rack enclosures.

Nice Buy,
were the modules expensive?

What are the card numbers inside?
Title: Re: Helios thread
Post by: J0hanne5 on December 15, 2016, 08:39:21 AM
Nice Buy,
were the modules expensive?

What are the card numbers inside?

Thanks! No, they were not :) I paid 500 euro from all of those.
I will post new info soon. Here is some pics https://drive.google.com/open?id=0B53QfYJWE3UVUUczOFo4bGxfSm8 The pre is fully discrete but the eq has one IC and there is no inductors.
The seller said that he might know a guy who has the rest of the modules and maybe the original manual!

Does someone know what is the type of those connectors? Maybe I should just replace them with connectors those are easier to find.
Title: Re: Helios thread
Post by: Whoops on December 15, 2016, 08:49:28 AM
Well if you know a source for more modules and dont want them all for yourself please let me know, I would buy a few.

Thanks
Title: Re: Helios thread
Post by: Whoops on December 15, 2016, 08:52:59 AM
Those look like Lustraphone transformers, nice.

I can't see what cards are fitted on the mic amplifier. Can you take some pictures of the cards at the top?
Title: Re: Helios thread
Post by: J0hanne5 on December 15, 2016, 10:12:40 AM
Well if you know a source for more modules and dont want them all for yourself please let me know, I would buy a few.

Thanks

I am not sure if the modules are for sale but a copy of the manual would be nice...


Those look like Lustraphone transformers, nice.

I can't see what cards are fitted on the mic amplifier. Can you take some pictures of the cards at the top?

There is no any text on the trannies and Lustraphones are new to me so I cannot say anything about them.
I can try to measure them also if it reveals something.

I will take more and better pics soon!

Edit. Pics of the PCBs added https://drive.google.com/drive/folders/0B53QfYJWE3UVUUczOFo4bGxfSm8

"line amp" is a line amp for sure and "5252" seems to be a level meter circuit which drives an LED.  "5349" is the first PCB in the signal path and "5054" has two identical circuits on it.
Title: Re: Helios thread
Post by: Whoops on December 15, 2016, 01:03:43 PM
I searched my Helios docs,
I don't find any info, pics, or schematics of the 5359, 5054.

I have the schematics for the 22113 that are posted in this thread.

As for the Lustraphone transformers those are the most regarded transformers that Helios used.
you can see this pictures of the original Lustraphone transformer

(http://i1124.photobucket.com/albums/l579/ilcaccillo/Helios%20MMC1.jpg)


(http://i1124.photobucket.com/albums/l579/ilcaccillo/Heliossilver2.jpg)
Title: Re: Helios thread
Post by: skidmorebay on March 06, 2017, 12:03:17 PM
I've put together a mostly point-to-point version of the Helios eq, based on Ruff Record's schematic. Make up gain is via CAPI-Gear's 2-stage booster board, basically one 2520 as a receiver and another as a booster amp. Since I took the photo I've installed 990's in place of the GAR2520's. There's a Cinemag CMOB-2S, 1:1 transformer on the output.

Has anyone found that the lowest frequencies of the mid range boost have a very broad Q? I noticed that in RuffRecord's documentation also, but it seems a bit exaggerated in mine.

Title: Re: Helios thread
Post by: skidmorebay on March 06, 2017, 12:06:12 PM
Here's a cheapo screenshot (iphone photo...) of the mid range curves:

Title: Re: Helios thread
Post by: ruffrecords on March 07, 2017, 11:00:26 AM
Just because they look broader at lower frequencies does not necessarily mean the Q is lower. The frequency scale is logarithmic  so the low frequencies spread out s lot more. Try measuring the Q from the curves.

Cheers

Ian
Title: Re: Helios thread
Post by: Squeaky on June 10, 2019, 10:41:32 PM
I know there has been some interest about Helios consoles and output transformers and whether they were ever used or not (interest in the very least from me). There are currently some Sowter output transformers for sale and the sales blurbs include some interesting photos and comments. The transformers were apparently used in a small Helios console (special order in 1976). Furthermore, these same (or similar?) type of Sowter transformers were also apparently used in a couple of large format recording consoles.
Title: Re: Helios thread
Post by: Whoops on June 11, 2019, 09:05:44 AM
There are currently some Sowter output transformers for sale and the sales blurbs include some interesting photos and comments. The transformers were apparently used in a small Helios console (special order in 1976). Furthermore, these same (or similar?) type of Sowter transformers were also apparently used in a couple of large format recording consoles.

Do you have links?

I have yet to see any Helios schematic, or photo with an output transformer.
Even if there's a particular model that had output transformers the original ones would not be Sowter for sure.

Title: Re: Helios thread
Post by: ruffrecords on June 11, 2019, 10:46:36 AM
Do you have links?

I have yet to see any Helios schematic, or photo with an output transformer.
Even if there's a particular model that had output transformers the original ones would not be Sowter for sure.

I have definitely seen photos of Helios consoles showing output transformers but I agree they are unlikely to have been Sowter ones.

Cheers

Ian
Title: Re: Helios thread
Post by: ruffrecords on June 11, 2019, 11:03:58 AM
Check out this video at 1:05

https://www.youtube.com/watch?v=k28PCcB2rG4 (https://www.youtube.com/watch?v=k28PCcB2rG4)

Cheers

Ian
Title: Re: Helios thread
Post by: Squeaky on June 11, 2019, 03:34:55 PM
https://www.ebay.com.au/itm/Helios-Sowter-3865-transformers-LOT-of-seven-6-1/264302853643?hash=item3d89ad7e0b:g:2MQAAOSwwRBc0rAx

https://reverb.com/nz/item/22309576-7-x-sowter-3865-transformers-from-helios-broadcast-mixer-plug-play-6-pack-2ru-panel-1-spare-unit
Title: Re: Helios thread
Post by: Squeaky on June 11, 2019, 03:38:32 PM
Apart from the 3865 the other model mentioned is the 4231.

https://reverb.com/item/21802872-9-x-talent-studio-helios-sowter-transformers-1-boxed-8-unmounted-split-sales-at-150-piece-ok
Title: Re: Helios thread
Post by: ruffrecords on June 11, 2019, 04:59:51 PM
There is a serious amount of hype surrounding  those ads and the prices are ridiculous when you consider you can get a brand new Carnhill for £25.

Cheers

Ian
Title: Re: Helios thread
Post by: Rob Flinn on June 11, 2019, 05:38:08 PM
Why don't you email Brian Sowter and ask him if those model numbers were made for Helios ?
Title: Re: Helios thread
Post by: Squeaky on June 12, 2019, 04:12:10 AM
From my perspective, I was mainly interested in the information (if it were true) that accompanied the advertisements. Gleaning becomes a pass-time.
Title: Re: Helios thread
Post by: Whoops on June 13, 2019, 08:34:36 PM
Thank you so much for the video Ian, and thank Squeaky for the links.

I really don't think any of those transformers have anything to do with Helios or Helios consoles.
Those were probably post-installation transformers that clients asked to be installed to have balanced outputs.

All of those are externally mounted, and don't feel like they were part of any original console.
Neither were any of them made for Helios specifically. They are balancing transformers that a contractor "Benum" ordered for their custom installation.

Some clients, like broadcast companies felt the need for Balanced outputs and they would contract a  post-installation of balancing output transformers, that would be mounted on the patchbay, the back of the console or wherever it was practical.

I never seen an Helios Schematic with an output transformer, neither I have ever seen an Helios console picture with factory installed output transformers.
Maybe there is, but I still have to see one

Title: Re: Helios thread
Post by: snigglepit on October 07, 2019, 03:46:27 AM
Hi,

I'm wondering if anyone might be able to help out with information about some modules from an old radio console.  The forum software won't let me attach a photo, but there are some pix here:

www.themorningpeople.com/helios/

They're being restored and racked at the moment but I am struggling to piece together their history because they were not part of a Helios console. They were actually built into a mixer by Tweed Audio that was installed at Capital Radio in London. What seems to have happened is that Helios were in the middle of a big job for Capital when they went out of business, and after this happened, the Capital engineers went to the Helios factory and took away a lot of parts, presumably including these modules.

I've talked to Cyril Jones and a couple of ex-Helios engineers and none of them has a clear memory of these modules, even though they are unusual. Were they originally intended for Capital, or for some other job? Why do they have a compressor built in when no other Helios channels do? Does anyone have any schematics that might be relevant to these? They are the later style with active rather than inductor-based EQ, and the compressor uses a dBx 202 VCA.
Title: Re: Helios thread
Post by: Winston O'Boogie on October 07, 2019, 08:56:53 AM
When Dave Amels was helping restore and modify Lenny Kravitz's Helios desk and external modules, he added a push-pull transistor buffer to the outputs so a transformer and lower load could be driven comfortably.
On pretty much all the Helios amp stages I've seen, I think this is necessary.
Title: Re: Helios thread
Post by: Winston O'Boogie on October 07, 2019, 09:06:41 AM
Neat looking modules and story Snigglepit 👍

I think the issue may be the pics are a bit too large to upload, gives us more resolution to zoom in though so thanks 😊
Title: Re: Helios thread
Post by: Whoops on October 07, 2019, 11:54:47 PM
he added a push-pull transistor buffer to the outputs so a transformer and lower load could be driven comfortably.
On pretty much all the Helios amp stages I've seen, I think this is necessary.

Do you have idea of what circuit was that?
Any schematic available for that circuit?

thank you so much
Title: Re: Helios thread
Post by: Winston O'Boogie on October 08, 2019, 09:24:41 AM
Do you have idea of what circuit was that?
Any schematic available for that circuit?

thank you so much


I went looking and found the info in an old email.   I was incorrect in remembering it being push-pull, it's an emitter follower with a constant current source.   Anyway, I think this was made public by Dave Amels over 10 years ago so I'm hoping it's OK to post here.

PDF is attached to this and pertinent info written by Dave is:

"These were for the silvers which ran on -24V.  The schematic shows two which
were both on a pcb.  You can rearrange the circuit for +24V if needed.  The
output transformer is a Cinemag CMOQ-3L wired for a 1:2 stepup."
Title: Re: Helios thread
Post by: Winston O'Boogie on October 08, 2019, 11:30:19 AM
Internal pic of  Manor mobile or Strawberry desk module, not sure which, it's been a long time:
Title: Re: Helios thread
Post by: Winston O'Boogie on October 08, 2019, 11:32:16 AM
Likewise, it's a Manor or Strawberry, probably whichever the other pic isn't.
Title: Re: Helios thread
Post by: Winston O'Boogie on October 08, 2019, 11:34:47 AM
No idea!
Title: Re: Helios thread
Post by: Winston O'Boogie on October 08, 2019, 11:36:54 AM
Has this particular drawing of the 69 been posted?
Title: Re: Helios thread
Post by: Squeaky on October 08, 2019, 03:17:09 PM
Thanks for posting the photos and schematic John, they are all appreciated.

I have never seen the version 3 schematic you posted (there is version 2 schematic available that is drawn in the same style). Interesting to see that the 22113 makeup following the eq employs the same sort of filter and bypass attenuation configuration (27k and 5k1) as modules that use the 2128 as the eq makeup. Rightly or wrongly, I did the same with my diy versions. The 22113 is running on 24V (early example of use?). I have seen a snapshot of the 22113 part of that version 3 schematic somewhere.

The module in the first photo has the high level line amp (22113) with an extra HPF buffer transistor (8 transistor) on the board. Looks like a little Beyer input tranfo?

The second has the high line level amp without the the filter buffer (seven transistor) but with an output transformer?  I presume the output transformer was a mod and not original? I wonder if it was a step-up or 1:1? Looks like there is a Carnhill inductor added as well (on its side). Also looks like it might be using a little Beyer transformer?

The boards on the third photo do not look like original Helios boards at all, at least not like I have seen in photos. However, unlike yourself and others, I have no first hand experience. Everything else looks as it should. Looks like a  three transistor amp with the filter buffer (makes 4 transistors) and looks like a Lustraphone transformer. This one reminds me of the version 2 (Musicland) channel module. Unfortunately, the makeup amp is obscured.

Cool.
Title: Re: Helios thread
Post by: Whoops on October 08, 2019, 05:03:22 PM

I went looking and found the info in an old email.   I was incorrect in remembering it being push-pull, it's an emitter follower with a constant current source.   Anyway, I think this was made public by Dave Amels over 10 years ago so I'm hoping it's OK to post here.

PDF is attached to this and pertinent info written by Dave is:

"These were for the silvers which ran on -24V.  The schematic shows two which
were both on a pcb.  You can rearrange the circuit for +24V if needed.  The
output transformer is a Cinemag CMOQ-3L wired for a 1:2 stepup."


Thank you so much for the schematic and info Winston, I will try that circuit out.
Some fellow members were using the 22113  circuit after the mic pre to be able to drive a transformer, but it seems maybe too much circuit just for that.
This simple 4 transistor buffer from Dave Amels seems elegant and simple enough.

Byt the way, do you know what output transformers were used on the Kravitz's console?

Thank you
Title: Re: Helios thread
Post by: Winston O'Boogie on October 09, 2019, 08:37:08 AM
This simple 4 transistor buffer from Dave Amels seems elegant and simple enough.

Byt the way, do you know what output transformers were used on the Kravitz's console?

The buffer is even simpler than it looks, the schematic shows buffers for 2 channels since it was laid out in pairs on a PCB.
It's a simple class A emitter follower with the other transistor as a  constant current source.  There's a healthy amount of quiescent current - 100mA - and a heatsink will be required for both transistors.
As for transformers used in the modded Kravitz modules, Dave indicates they used Cinemag CMOQ-3L strapped as 1:2.

Remember, this was for the older silver Helios modules which ran on negative 24v so, for other schemes running on a positive rail, you'll need to switch polarities.




Title: Re: Helios thread
Post by: Winston O'Boogie on October 09, 2019, 08:47:14 AM
Thanks for posting the photos and schematic John, they are all appreciated...

Hey, thanks for the analysis of the modules, you know your Helios that's for sure 👍

I'm pretty certain the amp card in the last picture is original as the owner of it is a big collector of Helios and originality would be VERY important to him.
I think it just looks different because it's an older module, an earlier iteration of the amp.
Title: Re: Helios thread
Post by: Winston O'Boogie on October 12, 2019, 11:12:03 AM
Some fellow members were using the 22113  circuit after the mic pre to be able to drive a transformer, but it seems maybe too much circuit just for that.

I missed this part of your reply, sorry  :o
Yes I think you're right regarding the 22113.  If the card was run on 36V like some desks were, then the headroom is "just about" OK for pro levels in my opinion.  But running on 24V, we need help via other means to get headroom up.
Having a beefy class A follower driving a 1:2 step-up gives us around 6dB extra output before the amp clips.
Even if you're running on 36V, I don't think it hurts to have an output able to source enough current to the outside world.

By the way, thank you for your uploads to the Helios docs section, I'm late to the party and only just saw them.
Cheers 👍
Title: Re: Helios thread
Post by: Whoops on October 12, 2019, 07:07:28 PM
By the way, thank you for your uploads to the Helios docs section, I'm late to the party and only just saw them.
Cheers 👍

Thank you also for your knowledge Winston
Title: Re: Helios thread
Post by: rooster on November 06, 2019, 08:11:48 AM
I am in touch with one of the original designers of the Helios circuits. He told me that the 10H inductor did not have a spec as we would think of it today. The first units were made from a bunch of inductors purchased from a surplus store in the Edgeware Road.

Cheers

Ian
Maybe you can me help out.
I got from a customer 2 Helios 69 for repair. One is working well now. The second shows no output. Up to the input section the signal is there. Any ideas to help me out with this issue????
Title: Re: Helios thread
Post by: ruffrecords on November 06, 2019, 01:30:21 PM
Maybe you can me help out.
I got from a customer 2 Helios 69 for repair. One is working well now. The second shows no output. Up to the input section the signal is there. Any ideas to help me out with this issue????
Divide and conquer is the best approach. Check for output from the mic pre stage. If that is OK then check for output in wiper of bass cut switch - if this is not working then no signal gets to the rest of the EQ.

Next check for lower level signal at EQ output (across the 5K1 resistor (should be about 14dB down). If it is there then check output of HPF then the output stage.

You do need a schematic to trouble shoot these but there are many variants so they are not always accurate.

Cheers

Ian
Title: Re: Helios thread
Post by: Whoops on November 07, 2019, 07:56:43 PM
Maybe you can me help out.
I got from a customer 2 Helios 69 for repair. One is working well now. The second shows no output. Up to the input section the signal is there. Any ideas to help me out with this issue????

Post some pics of the modules and circuit board, then we can know which circuit you have and help out with the proper schematic.

Like Ian said there's a few variants of the 69