Audio Innovations S200 Schematic request

[Audiojunky13]

Dear Oracle,
I have an Audio Innovations set, 1x S200 Preamplifier MM model, and 2x 200 MK2 power amps.
I want to install the MC section and upgrade the preamplifier.

I need the schematic for the preamp, does anyone out there have one or know where I can get one?
I already have the power amp schematic.
Thank you

 

[euro21]

If I remember correctly it was the original AI 200MM schematic.

 

[Audiojunky13]

Hi Euro21,
Thank you for the schematic but it seems that it does not agree with what I have on the bench. I notice that my amp has 4x 0.47uF caps and your schematic only 1? I have attached a picture of my amp for clarity. If you have any other leads or schematics that would be great.
best
Steve

 

[euro21]

It was more than a decade ago ... but now I use 220nF as "first" capacitors.

There I also wrote some information:

Audio Innovations Series 200 Phono Stage

The "MC" stage is unusable.
I tried it, but even with low noise 5751 tube it's only a hiss producer.

I use E.A.R. Paravicini MC3 transformer for my Supex 900 pickup.

 

[Audiojunky13]

Thanks again Euro21.
I have read the thread you directed me to....very interesting list of mods. I want to try a few, so do you have any details? Like;

AI200 tweaked:
- HEXFRED diodes in both power supply (high voltage, heater);
- CRC snubbers in both power supply; Have you values and positions?
- 5 H choke in HV supply (C-L-C); Have you values and positions?
- BlackGate supply capacitors; Which ones are these?
- NOS Sylvania (3 mica) 5751 tubes in first positions;
- NOS Tungsram ECC82 tube;
- LED (green) bias in first and second tubes cathodes; How does one do this?
- AuriCap coupling capacitors (0.22, 0.47);
- direct phono input, Cardas RCA, silver coax; How?
- Vishay S102K phono input resistors;

 

[euro21]

CRC snubbers in both power supply

It was the early "Quasimodo", like this:
TJERET FILE: Snubberized power supply (Quasimodo)

5 H choke in HV supply (C-L-C)

There is a resistor between first and second HV capacitor. Change it to choke with appropriate DCR (if I remember correctly it was larger than power transformer).

BlackGate supply capacitors

I tried to change six 47uF 400V capacitors to BG VK ones (it was a pricey game), but later remove its, and change all to Rubicons.

LED (green) bias in first and second tubes cathodes

I killed R//C in cathodes, and exchange its to old 5mm green LEDs.

direct phono input

I inserted Cardas RCA sockets in the rear side "MC" holes as direct phono input.

There is a (input) ribbon cable in the front of the main panel.
I killed it, and connected directly to pins the input shielded cable from RCA.

 

[Audiojunky13]

Euro21,
That is great....

Have you a diagram for your LED mod, I do not understand how this works or where it fits in the schematic? Do you mean; replace the 220u cap // 3k3 R and 220u//3k6 R in the schematic with green LEDs? If so, do you not need a resistor to limit the LED current?

 

[Alex M]

Guy Sergeant, one of the Audio Innovations founders, posts regularly on the Pink Fish Media audio forum (audio | pink fish media) under the moniker Puresound. He is very forthcoming with advice and information on all of the AI products.

Alex

 

[Audiojunky13]

Thanks Alex,
I have been in touch with Guy and he sent me the schematics.
Now the fun can commence.