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croccodillo 14th September 2005 08:45 AM

YOur opinion, please
 
I found this schematic on the net, in an Italian site:

Schematic

I'd like to know your opinion about it: is this a good schematic, how should it sound?
It s rated for 8W output.

Ciao,
Giovanni

plovati 14th September 2005 03:10 PM

This is an Nuova Elettronica project, originary designed for an EL34. There are several mistakes in the tube polarization. EL34 is overdisippating and ECC82 is working at too low voltage.

Power transormer runs very hot. Output transformers are of good quality but only for frequencies greater than 50-60Hz.
The OPT trnnies are good for a 6080 single ended, limited to 2,5W.

I tried a 6V6 pentode output with cathode feedback driven by a 6AU6, with the same trannies and the sound is pleasant, power output 4,5W, clean.

For a EL34 single ended, much better the Audiophile EL34 (serach in this forum) by jean Michel LeClerc (If I remember correct).

amperex 14th September 2005 03:40 PM

Amp design is like a game of chess
 
Choosing a design for high performace is like a game of chess. You pick high performance parts and place them in the proper position & best operating parameters. Why spend money & time & end up with less than great performance.

If one knows better sounding tube families, do not use an inferior tube. Same with capacitors, power supply design, rectifier, etc.

I never had poor performance from a direct coupled preamp/driver design. I also like a 6P5GT to a 6SN7 or 6J5GT. I had best luck with Tung-Sol or Sylvania. I was also pleased with a RCA metal 6J5, but not other metal 6J5s- go figure. I also like 6V6GT triode connected when a true triode tube is not an option. I suspect without much experience a KT88 may sound good triode connected per what others have stated. I also believe the inexpensive Wing C 6550 with the rectangle hole (not all round holes) in the plate is a reasonable quality tube.

I prefer oil caps or polypropylene caps over any electrolytic cap. A minimal quality coupling cap is AuriCap unless one likes distortion from say a Sprague 715P orange drop or simular low quality capacitor. Best are reported to be the Russian teflon design.

If using a SS rectifier, use UF4007 for lower noise operation. I also prefer choke input filter in a LCLC configuration to the power tube(s) with an additional LC to the preamp tubes. If I have to use a capacitor input, use CLC to the power tube & another RC or LC to the preamp tubes.

Use a high quality audio transformer. I understand Hammond has improved some of their SE designs.

My 2 cents.


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