Unconventional low voltage tube amplifier

[pilovis]

This is my personal project: Low Cost 2+2 W tube stereo Amplifier @ 60Vcc
 
This amplifier uses two tubes per channel: PL504 (EL504) and ECC82.

The performances are very good in spite of such a low unconventional supply voltage.
 
The output Audio Transformer is 800/8 ohm impedance, but if you accept a little bit lower bandwidth (low frequency cut < 100 Hz ), you can use line transformer 220/24 Vac (not less than 35W to avoid dc saturation).
 
Note: in all my prototypes I used line transformers as output transformers.
 

 
The above schematics is for one channel, uses two triodes preamp (common cathode and cathode follower).
The supply voltage of 60Vcc is achieved using a diode voltage doubler and a 15+15Vac Line transformer.

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Version 2:
 

(stereo) version with just one triode preamp per channel and without the diode voltage doubler (transformer @ 48Vac).
In this version I used EL504 (6.3 V filament) instead of PL504 (27 V filament).

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- Protototype 1:
 

 
- Prototype 2: MP3 Tube Stereo Amplifier
 

 

-Prototype 3: Stereo Amp with line transformers used as output transformers
 

 
- Test: Stereo Amp with line transformers used as output transformers
 

 

[nikongod]

Neat project! 
 
Have you considered a push-pull output stage to reduce the offset current & saturation in the transformers? Parafeed is pretty fun too
 
Also, if you have not tried them out Edcor makes some very affordable GAPPED transformers for SET tube amps. Totally worth a look if you want to stay with series-feed SE.

 

[trimer1]

The magic eye looks amazing o.o I may consider it for my next project

 

[havazli]

Hi,great and cheap amplifer.I guess you're quite experinced.So let me ask you a question:
What if I heat in such way a PCL86 (13.3v) and ecc83 (6,3)?
Roughly I mean this:
____________           -------I
I                                                 I
I                                                 I
I                          PCL86 -13,3v
I____________                      I
I                           I                     I
I       ECC83 - 6,3v                   I
I____________I       --------I   
 
May I?  Thanks in advance?