[hobiesound]

oh yeah on the dan alexander schematic it says L2= 680mH with a 220mH Tap. That one more or less works.

greetings,

thomas

[Igor]

Carenhill can be good option. The .pdf file have detailed pinout for most inductors, but does not have the exact pinout for VTB9048.
I guess, for low frequency inductor we will need good shielding (it may pick up some inductive noise and 50/60Hz hum).
For example, RM10 core can fit inside A262CAN, which can be used with nickel EI24 core as well.
Pinout for both Carnhill and RM10 inductors can be done on PCB.
As Keith pointed, we don't want any mess with manufacturers, etc, so it should be bit different then commercial product.

[MikoKensington]

Is the idea of mic/line/DI switching on the table? 

[tommypiper]

Is the idea of mic/line/DI switching on the table?  

I second that.  I hope so.  An EQ's utility is only fully utilized if you can use it both during tracking (with mic input) and mixing or downstream from another mic pre (line input).  Having a DI input also, would increase the utility!

Carenhill can be good option. The .pdf file have detailed pinout for most inductors, but does not have the exact pinout for VTB9048.

Igor, the VTB9048 is a good choice, as it's also used in the Neeve 1081.  The pinout info should be easy to find because of that, if not directly from Carnhill.  Just look at a 1081 schemo.  The Neeve and other part numbers are: vt22675, L1, IN2012.  (All are the same part = VTB9048.)

8 pin package (5 connected), core material not specified
Shielded can

Mid-Hi :  L1, (VTB9048) inductance taps at   767mH,  504mH,   296mH, 205mH
            resistance at taps      105R,       57R,       46R,   24R

Mid-Lo : L2, (VTB9047) inductance taps at 5.11H,   3.56H, 2.06H, 1.43H
            resistance at taps  1036R,    804R,  611R,   500R

Source : Carnhill part # VTB9048, VTB9047 measured resistance, inductance specification.

[Biasrocks]

Is the idea of mic/line/DI switching on the table?  

I second that.  I hope so.  An EQ's utility is only fully utilized if you can use it both during tracking (with mic input) and mixing or downstream from another mic pre (line input).  Having a DI input also, would increase the utility!

Third.

Mark

[Igor]

OK. Pad before input transformer gives us "line" option.
Active buffer before input transformer for DI. When jack inserted, relay takes care of this.
Insert after micpre, right before the EQ will give us "only EQ" option.

Insert can be done with relay and active line receiver/driver....
This complicates a bit and requires +/- audio power supply instead of single + or - 24V
(depending on how old the Hel**s model is...)
Just a thought. Older Hel**s modules were using -24V supply. We need +24V for makeup stage (second half of BA283).
So, why not use +/-24V power supply and power from here switchable insert's balancing driver/receiver?
This way we have (if insert is "on") balanced micpre out and balanced input into EQ.
When insert is off, relay takes care of insert and sound does not passing thru balanced driver/receiver.

Carenhills can be easy sourced, but I will try to fit here standard RM10 inductors for folks
who want to save some money and wound inductors by themselves.

Regarding the Elma switch. The easy and cheap solution is next.
One Lorlin takes care of low cut, second takes care of low boost.
We can have even more settings with single 12-pos switches which is allways wellcome (more OPTIONZZ!!!!)
With use of dual on-on-on toggle, we can apply boost, cut, or both-oops, new feature!!!
For those who can't find on-on-on dual toggle, with use of dual on-on toggle (on same pcb) there will be boost or cut only option.

So, than, the thing will be not exactly original Hel**s, BUT this is what we want.

Ahemmmm....Thoughts?? Oppinions?

[Joechris]

From wikipedia: "The best known story involving Helios is that of his son Phaëton, who attempted to drive his father's chariot but lost control and set the earth on fire."
Maby PHAETON could be a cool name for this project 
j

[Igor]

What-so-ever. Ideas about naming the busstard are wellcome as well as ideas about functionality/desigh.

[phishman13]

I 4th the inclusion of the mic pre section.

And 2nd the name Phaeton. That sounds bad ass. Especially as this could be considered offspring of h*lios. And from the way things are shaping up, it will set audio on FIRE!

[Joechris]

ok,ideas about functionality/design..The switch between bass cut/boost/both is unnessesery because if you use two 12 steps all those options can be obtained just by using the rotarys. (placing the low cut infront)
12 possisions seems a bit overkill for cut, since its just a 6 db slope anyway. You would´n  hear much differece beetween the steps, unless you take the range all the way up to something like 500hz. But the boost would be nice since its a peak thing, and with a multitap like the vtb9043, a lot of different curves and frq could be obtained. Out of normal range is of cause a good thing.
j

[Igor]

@joechris: yes, when lo cut is shorted, it is OK.
Ahemm...Phaeton....FIRE??? My DOB is 8th Dec, and I am almost 33.
FFFFFIIIIIRRRRREEEEE!!!!!!!!!!!!!!!!!!!!

[Igor]

Next: why can't we use the rest of LF inductor's peaking values for different freq's?
All I actually needed from lo-cut circuit is...50 or 120, 2nd order, bit peaking=always prefereable,
in any circuit, in studio or PA across.. some small arreas at this world.
No more, it is...maybe just my bad taste.
But......MAYBE.... 11 positions for lowcut from "off" to 500 can be usefull?
VTB9043 gives us a lot of midrange options as well to increase lo-range switch to some fun positionZZZ...

[desol]

Is the idea of mic/line/DI switching on the table?  

I second that.  I hope so.  An EQ's utility is only fully utilized if you can use it both during tracking (with mic input) and mixing or downstream from another mic pre (line input).  Having a DI input also, would increase the utility!

Third.

Mark

Well, that's cool i guess. I have 16 nice preamps, don't need anymore, don't want anymore, don't need to spend $100 per input transformer(which i would rather put into other parts for the eq), that will never sound like the original transformer anyway, etc. I think it's a waste of money, most everyont has tons of pre's...and what about 51x? If we go that way, will everything fit?

[audiovisceral]

2 Phaetons please. I also would appreciate a line/DI/mic function. To be honest I don't even need more pres but as long as the eq can still be used independently I think this should be great. Looking forward to it.  Good choice.

[desol]

From wikipedia: "The best known story involving Helios is that of his son Phaëton, who attempted to drive his father's chariot but lost control and set the earth on fire."
Maby PHAETON could be a cool name for this project 
j

Phaeton...curiously similiar to Photon?? Who knows..

[hitchhiker]

I agree with Keith, Why find trouble? it's a current product.
 Besides, much of the great vibe of this fella may likely have be the amps/console/transformers themselves. And sadly that's not a well covered subject.  Why not look at the passive eq design and go from there? Get the inductors, Q's freq'"s etc. Go for neve, helios amps or whatever? And yes a new name too.
cheers, Lance

[MikoKensington]

I'm all for the preamp.  Sowter makes a Lustraphone-style 1:10.  That appears to be what the current Type 69 is employing.  I think the input transformer and preamp are part of the magic.  The new and originals are unbalanced out.  So there's some savings there.

There are plenty of EQ only projects around here, between the 5003, two 1084's, Pultecs, Calrec 1549, S800, W492 and the NYD Passive.  So you want EQ only, build one of those and let us have our preamp! 

[tommypiper]

I'm all for the preamp.  Sowter makes a Lustraphone-style 1:10.  That appears to be what the current Type 69 is employing.  I think the input transformer and preamp are part of the magic.  The new and originals are unbalanced out.  So there's some savings there.

I second Miko.  Yes, there's lots of pres out there.  This is a pre AND an EQ!  We don't see those that often.  And as Miko points out, maybe we can have an optional unbalanced out that doesn't require output iron.  However, if Igor puts in the Neeve 283 output, those Carnhill and other output iron options are not expensive.  Cinemag has some.  And Miko, weren't you doing a group buy of some other Neeve outs that were inexpensive?  In any case, even the 283 circuit has an unbalanced out built in, for those who wish to avoid output iron.  (I personally always favor using output iron!)

I'm not a fan of the 500 or 51x series module sizes.  Too small. 

[Igor]

Ok...Where can I find PCB footprint for Sowter Lustraphone-style 1:10?

[Kingston]

http://www.sowter.co.uk/vintage-audio-transformers.php

model 7490

http://www.sowter.co.uk/mech.php

"eE" Mumetal,
Mumetal can
Threaded boss

In other words, it doesn't have a PCB layout, but mounts in a hole with a bolt (M10 I think) and you solder the wires.

créer son PE1A

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69. Not Helios/Phaeton. Pics/schematics/building support thread.

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