otl amp.handmade with 12 PL36 tubes per channel .

[Dimitrios0970]

korolyov58 : Thank you for your comments , sorry i can' t post the schematic because i have been working on it a long time , i mean after i disegned it i made many changes and modifications to optain the best results , and maby in the future i will make other modifications and i consider it a little bit secret .

[Dimitrios0970]

To antunkatona : Yes there is an amount of negative feedback to lower the output resistance of the amplifier of course and to lower the total harmonic distrotion . The power supply consist of 3 trafos , 2 big ones , one for each output stage ( for the 12 PL36 - supply and heaters ) and one smaller for the differential stages and drivers of the two channels , and large capacitances and coils to minimize hum .

[antunkatona]

Is there any negative feedback used at all? Can you tell me a bit about power supply? Did you build it as a dual mono all the way?

[korolyov58]

Have you posted the schematic of your final build for this amp? You have done a wonderful job and I myself would love to build one.

[Dimitrios0970]

Hi preludefun , thank you for your comments , the frequency response is huge as you say , the -3db point is at 195 Khz , and the output power is about 28-30 Watt per channel , it's not too much because the output tubes is triode connected , if they are in pentode connection then it would gave about 55 Watt . As for the Cd , i made a tube output stage carefully disigned for low distrotion , and connected it to the output of the TDA1549T ( D/A converter ) with a new and huge power supply .

[preludefan]

@Dimitrios0970 thank you for that!

[preludefan]

amasing system you have there, the frequency range must be huge!, i have couple of questions, how many watts per channel is the output and also, how did you modify your phillips cd player for valves instead of the electronics?

thanks

[Dimitrios0970]

To Takis6c33 : Τακη γεια σου , σε ευχαριστω για τα καλα σου λογια , ειδα οτι εχεις κανει και εσυ πολυ καλη κατασκευη , συγχαρητηρια μπραβο σου .

[takis6c33]

Dimitri mpravo kai apo mena !!! kai o dikos moy OTL einai me topologia futterman kai to [technics variation] edo kai 4 xronia de exei kanena provlima , kai paizei kathe mera toylaxiston 3-4 ores!!!!

[Dimitrios0970]

to MegaMusicheaven : The connection for the PL36 is triode , for circuit simplicity and better sound , but to drive all this PL36 in triode connection , i bias the driver stage harder , this because of large input capacitance and miller effects of the output tubes (12 tubes , 6 PL36 in triode connection per side ) .

[MegaMusicheaven]

Nice Amplifier! it must sound great! The connection for the PL36 is it triode or pentode?

[Dimitrios0970]

I designed and made this amplifier in 2004 ( Jan- May 2004 ) , and till now it's working without any problems , i made many changes only to improve the sound quality . The circuit is Futterman ( Technics variation ) but the first and second stage is differential .