1176 in 51x/500 format: FEELER. Goto page 5 for pre-orders.

[drumgod52]

put me down for 2 with grayhills etc.
Would like to have a good matching pair.

 

[AP carrier]

I'd be sure in for one. PCB, metalwork and hard bits, if your selling this way.

Thanks,
Andrew

 

[joe-electro]

I hope this isn't a stupid question or one that's been answered before, but I just had to ask. The original 1176 circuitry is essentally single-ended class A (or partially class AB, starting with Rev F) design with a +30V rail for the audio amplifier and a -10V rail for the FET control voltage. Are you somehow converting the +/-16 from the 500 rack's power supply to these voltages or is your circuit primarily a bipolar design?  If it's the latter, isn't it a bit of a stretch to call it an 1176?

Thanks,

Joe

 

[Igor]

Long one
Smoked whole pipe filled with great Virginia when typed

I hope this isn't a stupid question or one that's been answered before, but I just had to ask. The original 1176 circuitry is essentally single-ended class A (or partially class AB, starting with Rev F) design with a +30V rail for the audio amplifier and a -10V rail for the FET control voltage.

I don't pretend to be final instance, but yes, there are about 300 original 1176's in the world,
which have both input and output stage running in class A. The rest using class AB output stage
and most of "original" 1176 using IC balancing circuit at the input. It is statistic

-10V deliver from -16V rail, there's LM337 regulator on board, dedicated for this purpose.

51X F76 has same gain reduction circuit, same gain structure, as 1176 rev.F;
it can be built with input transformer and 600 Ohm T-pad, or input IC+pot;
F76 has at least 5 options for output transformer, 2 options for input transformer,
tens of options for amplifiers.... etc.
"Original" amps, from rev.F and later, can be used here and they running OK
on +24V.
"Original" 1176 amps can be used only in case your rack has +/-24V, i.e. it is 51X.
"Input" (first) amplifier in my version has additional output current source (load)
to get more output swing from single +24V than "original" do at +30.
Input amp can run BTW without current source, if somebody feel it closer to "original".
Please refer to schematic:
http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/IN_AMP.png
Q101, R101, R102, D1, D2
R17 lowered a bit btw. So....yes, it is "original", more or less.

I recommend kinda 2520 or Forssell DOA at output stage for more headroom
and "sound"

IMHO: sound of 1176 does not come from amplifiers itself only.

Most part of sound is FET distortion and distortion of output transformer.
You know very well FET compressor built on same principle with kinda digital control, transformerless
and chip-based, received excellent reviews. It is...more or less conclusive evidence of above theory

Now, without pretending to be closed on "original"1176.
Imagine compressor based on 1176 principle, same compression and distortion coming from FET.
Now, let it run with API output stage! I mean 2520 discrete op-amp and 2503 output trafo.
It has more funny coloration IMHO. Or, use here Forssell FET op-amp and Lundhall trafo.
This way, we can run output stage on +/-16 V (it is 2V more headroom than "original")
and even more if we use 51X rack with +/-24V!  

Are you somehow converting the +/-15 from the 500 rack's power supply to these voltages or is your circuit primarily a bipolar design?  

I used "bipolar" design. +/-16 is more then single 30.
"Original" amps can run at single +24V. I'd use input "original" stage on single +24 and not
original Forssell FET opamp running on +/-24, have a fun of "original" compression
and more headroom, call it F76 and very happy with this.
As well, OPA604 adapter board can go for "input" (gain reduction) amp on +/-16V.
For those who want to learn how it works, it is good point to try different amps etc,
and it can be way easier build compared to 1176 clones.

If it's the latter, isn't it a bit of a stretch to call it an 1176?

Up to you

I have a friend who know one thing: ORIGINAL N*VE. He selling kinda 1272's.
Now, the fun is, when 1166 trunny's disappeared, he started to use choke+class AB trunny.
At this point, his pre's are not original, but, he told me choke+class B trunny sound better than 1166.
Very important argument. At the moment it was impossible to buy 10468's, he
started to use round line inputs connected with half of windings. It sounded of course better,
real improvement to original design. But, he call these pre's "original as possible".
This brought as real "bit of a stretch" example.

I am not pretending to clone 1:1 existing circuit. It is illegal

Wanna 1176-buy old, rev.A...E, neither clone nor reissue.
It always raise customer's rating of studio.

From the other side. I built discrete, full-format console for TanTan Studios.
(Google: tan tan studios Israel).
IMHO it is great console, fully discrete except EQ filters (OPA2604),
loaded with best possible trunnies etc etc.
One-toggle to change passive or active main summing bus, passive relay-based monitor controller.....
Aran have to stock a pair of SSL6000 channels for this so-called customer rating as well as U87..
Not many people BTW know what is ELA-M251

F76 built to be great sounding FET compressor with more options,
same compression character and possibility to be faster/slower/darker/whatever
up my or your taste when you build it, as me/you like it for the studio where F76 will work.

 

[joe-electro]

Thanks for the clarifications!

Joe

 

[gemini86]

Igor, I may have missed it earlier, are you offering the original amps in a footprint that will work in the f76?

 

[Ryake]

You're the man Igor! Using the 2520 and 2503 Api stuff for the output stage sounds very interesting  ;D

 

[Igor]

are you offering the original amps in a footprint that will work in the f76?

Yes, they laid out in DOA format and coming with set of pcb's, as well as other set of amps...

 

[haima]

as usual - you are a machine igor!  ;D

i'm interested in a pair when they are ready, with any hard to get/matched parts... grayhills etc.

thanks mate!

 

[damnyankee]

Igor,

All I can say is WOW! 

Your work is first class and you are a true electronics artisan!

DY

 

[drumgod52]

Are these almost ready?

 

[AudioGimmer]

Hey drumgod52, slow down.

It's like fine wine, you can't rush these things.....


AG

 

[Igor]

Haha! This weekend, btw, we enjoyed in good company with friends
with 2 bottles of Chateau Golan 2003, kinda barbecue
("Shishlik" in rum+lemon+sweet chili marinade, my invention), and,
of course, there was some Rock-four locally made cheese.
I hope F76 will have same good sound! Still no news, last version proto PCB's
are on the way....the rest is stuffing, checking, studio test again,
time-frame for release....mid'September-first half of October.

 

[haima]

good news igor!

 

[desun]

Any more news on this Igor? I know you've been a busy guy, but this one looks fantastic!

 

[bugfight]

mmmm sounds great, in for 2 partial kits

 

[babyhead]

Chateau Golan?  <3 Israel.

BTW, Santa Isreal.

 

[kepeb]

Any more news on this Igor?

yer, still watching patiently

 

[drumgod52]

No updates since September 1st....any news Igor?
Thanks,
Steve

 

[haima]

igor's been a bit under the weather - working too hard i think! but i think he's getting back on this project soon.

check his white market thread, he posted there recently with an update.