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Old 31st August 2004, 08:16 AM   #1
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Default Help with VTL preamp...

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.

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JojoD
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Old 31st August 2004, 08:18 AM   #2
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This is what it looks like...


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Old 31st August 2004, 09:24 AM   #3
EC8010 is offline EC8010  United Kingdom
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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.
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Old 31st August 2004, 04:14 PM   #4
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Quote:
Originally posted by 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 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.

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Old 6th September 2004, 03:08 AM   #5
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EC8010,

Thank you very much! Your right on target!

JojoD818
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Old 6th September 2004, 12:55 PM   #6
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Glad to be of help.
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