Help with VTL preamp...

[JojoD818]

Hi,

I have a VTL Integrator linestage/preamp and when connected to an amp, the speakers (woofers) moves forward and back in a random fashion. I have checked the heater supply ad found it to be ok. It is supplied ith a solid state rectifier giving an output voltage of 280V and uses 2 pieces of 12Au7. Any ideas on what I should check, obviously i'm out of ideas.

Thanks,
JojoD

 

[JojoD818]

This is what it looks like...

 

[EC8010]

If its accompanied by a tearing sort of noise, then I'd point the finger at those 12AU7. If it's a slow pumping at about 1Hz that happens in phase between channels, then I'd suspect a motorboating power supply and electrolytic capacitors that have failed.

 

[JojoD818]

If its accompanied by a tearing sort of noise, then I'd point the finger at those 12AU7. If it's a slow pumping at about 1Hz that happens in phase between channels, then I'd suspect a motroboating power supply and electrolytic capacitors that have failed.

Yes yes yes! That's it! It's like 1Hz that happens exactly the same on both channels. So it's really in the psu. I forgot to include that I have already replced the tubes but still have that 1Hz pumping in and out.

Ok, so I will try and connect a separate known good power supply and see if it disappears.

Thanks!

 

[JojoD818]

EC8010,

Thank you very much! Your right on target!

JojoD818

 

[EC8010]

Glad to be of help.