Had a similar problem with a Vac Standard Preamp. Problem was bad 100K Ohm plate resistor for the 12au7. Measured good but was breaking down with high voltage.
Diagnosing a spitting/popping channel- need some help!
Did a search here and I think I am on right track, but might need some help here. Getting a sporadic spitting/popping sound sometimes in left front monitor speaker in a 5.1 setup.
I have the following signal chain:
I use the Pioneer HT receiver L/R preamp outputs into the VAC preamp HT bypass inputs for when I use the TV so the Pioneer HT receiver amp sections are out of the chain for the L/R fronts.
Have done the following troubleshooting:
Am I right in assuming it is likely a bad preamp tube in the VAC?
The VAC manual says it has the following two pairs of tubes in the Line stage:
2 x 12AU7 & 2 x 12AX7 (line stage)
Where/how do I start checking tubes?
Am I on right track here?
Thanks.
I have the following signal chain:
- Pioneer HT receiver
- VAC Standard Preamp
- Odyssey Audio Monoblock Extreme amps
- Monitor Speakers are ACI Jaguars and there are dedicated ACI Subwoofers for each channel.
I use the Pioneer HT receiver L/R preamp outputs into the VAC preamp HT bypass inputs for when I use the TV so the Pioneer HT receiver amp sections are out of the chain for the L/R fronts.
Have done the following troubleshooting:
- I switched the preamp out L/R cables and the spitting/popping continued out of the same left front speaker (rather than switch sides).
- I turned off the Pioneer receiver completely and still get the popping.
- I assume that means it is not the Odyssey amp; and not the Pioneer so it must be in the VAC preamp?
Am I right in assuming it is likely a bad preamp tube in the VAC?
The VAC manual says it has the following two pairs of tubes in the Line stage:
2 x 12AU7 & 2 x 12AX7 (line stage)
Where/how do I start checking tubes?
Am I on right track here?
Thanks.
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- 10 posts total
- 10 posts total