Dynavox VR70

[Tube mania]

Just to info: This is not my kind of a tube amp...but I like to make things better. Not just better capacitors and resistors..but something that really matters. I consider this one as a good entry level amplifier....specially after my mod. This amplifier was a little dull but not anymore and the owner was very happy.

Both squares 10KHz (both pictures)

Maybe I should ask...which square do you guys like best?

Bad square is the un-modified amplifier.. Good square after mod...

This is how the square looks before modifikation. Roll of -3db15Khz

This is what I achieved. Roll of-3db 70kHz

Remove this capacitor...or make it less. Its there to prevent self-oscillating , but i newer saw any signs of that.

 

[JonSnell Electronic]

That capacitor is there to stabilise the preamp and stop it from taking off at HF or hissing. 70kHZ is not a good idea for an amplifier of this type it should roll off at about 25kHZ. If you want a useless frequency range, use a solid state uncontrolled amplifier.

 

[Tube mania]

I know that and I used to warn about the risk, but many of these amps is now working without the filter. Instead of removing it...the cpacitor could be reduced to half capacity. But still no one have had any problem. I would not bring it here if it hasen't proven safety.

 

[petertub]

I know that and I used to warn about the risk, but many of these amps is now working without the filter. Instead of removing it...the cpacitor could be reduced to half capacity. But still no one have had any problem. I would not bring it here if it hasen't proven safety.

You can also make the phase splitter symmetric by changing the 36k resistor to 33k ( R23 )