Audio Note Preamp Circuit a good guess...

[ThorstenL]

Konnichiwa,

On a regular basis people are asking for the transformer coupled linestage in the AN UK Preamp's and DAC's. As far as I can make this out from Schematics and eductaed guesses. I am not 100% on resistor values, if someone would look it up closer we could correct this.

The output Transformer would be similar (but usually not identical) to the Audio Note UK Trans-027 available through the usual sources for AN DIY Parts, Capacitors Black Gate (the PSU decoupling is part of the PSU PCB) and resistors AN Tantalum. The PSU would appear to be LCLC then split between Channels LC/LC and RC/RC (last RC visible in schematic) acounting neatly for 3pcs 100uF+100uF/350V or 500V Black gate Cap's, I'm not 100% on +B either, I'd expect >> 300V.

Okay, feel free to comment.

Sayonara

PS, do not claim that this is EXACTLY the AN M3/6/8 Circuit, it will be close in principle though....

[MaciekP]

You was close!
The AN M3-8 PSU has 6x5 recification with 20H-100uF-20H-100uF-15k-100uF PSU. For a M3 version ELNA Cerafine for the M8 version BLACK GATE WKZ PSU CAPS. The same for Cathode caps. Everywhere tantalum resistors. For M3 output trans is M4 all copper version, for M8 Radiometal C36 permaloy trans with all silver windings. Each channel has it's own PSU. M10 version uses SR48 transformers with 6463 tube /similar to 5687/.

[MaciekP]

one more comment: AN DAC 5 uses the above circuit, but the DAC3, 4 balanced are using different tube and 5:1 output transformer

Maciej

[EsE]

Ok, time to wake up this thread from the deep.
I'm thinking about building an AN dac sometime in the future.
Do you guys have the specs for a good transformer that would fit?
And what MackiekP is writing, is that AN has a choke loaded psu? Just confirming here..

Thanks

[Algar_emi]

Interesting. You have 215V at the double 47K resistors, but what is the HV value before all the CLC filtering, just after the rectifier tube?

What is the heater supply, AC or DC? What type of rectifiers are they using if it is DC?

Thanks...