Helios thread
« Reply #40 on: July 23, 2004, 06:56:43 AM »
So, it seems they're using the same Sowter as well... interesting :cool:


Helios thread
« Reply #41 on: July 23, 2004, 08:55:32 AM »
I think this is the layout to go for:

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:


1 - 700Hz

2 - 1kHz

3 - 1,4kHz

4 - 2kHz

5 - 2,8kHz

6 - 3,5kHz

7 - 4,5kHz

8 - 6kHz

Right pot:


Left bottom rotary switch:


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.

Helios thread
« Reply #42 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..

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 !!


Helios thread
« Reply #43 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:

Helios 69 at Vintage King:

The switches:

S1A - LF db CUT at 75Hz



S3 - HI BOOST/CUT at 10kHz






Helios thread
« Reply #44 on: July 23, 2004, 09:44:07 AM »
PK Peak
TR Trough


Helios thread
« Reply #45 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.


Helios thread
« Reply #46 on: July 23, 2004, 09:46:46 AM »
TR=Through=Dip. Never heard that Through term used before :?

Helios thread
« Reply #47 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?

Helios thread
« Reply #48 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!!!)


Helios thread
« Reply #49 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.


Helios thread
« Reply #50 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.



Helios thread
« Reply #51 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:
Darren Landrum

Be comforted that in the face of all aridity and disillusionment
And despite the changing fortunes of time,
There is always a big future in computer maintenance.

Helios thread
« Reply #52 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
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.


Helios thread
« Reply #53 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?


Helios thread
« Reply #54 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...


chips are good with dip...


Helios thread
« Reply #55 on: July 23, 2004, 10:01:14 PM »
Drop Trow!

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.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page:
Guitar Amps:


Helios thread
« Reply #56 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:


chips are good with dip...


Helios thread
« Reply #57 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?

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

Be cool, soundguy, or you won't get the secret password!
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page:
Guitar Amps:


Helios thread
« Reply #58 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:


Helios thread
« Reply #59 on: July 25, 2004, 12:49:10 PM »

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.


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