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Unconventional low voltage tube amplifier

post #1 of 4
Thread Starter 

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.

 

chitarra.bmp

 

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.


 

Version 2:

 

valvol30.jpg

(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).


- Protototype 1:

 

p1030811.jpg

 

- Prototype 2: MP3 Tube Stereo Amplifier

 

p1030818.jpg

 


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

 

p1030718.jpg

 

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

 


Edited by pilovis - 3/6/12 at 9:08am
post #2 of 4

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.

post #3 of 4

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

post #4 of 4

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?       


Edited by havazli - 3/27/14 at 4:32am
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