Constant hum or hissing

[aholloway17 33]

I sent my Classic Vacuum Tube in to get some repairs and tubes. The previous owner glued foil to the underside of the cover. Causing the glue to drip onto the tubes causing a little trouble . I also replaced a Carver M-1.0t inverting with a non inverting. Upon reconnecting everything I get either hissing or hum. I have a bluos streamer connected to the sunfire via the aux input. The preamp output feeds the amp from output 1. The sub is connected to the bluos. Any guess as to what could be going on here? 

 

Thanks in advance! 

[jmcipale 228]

My question is why would you swap an inverting with a non-inverting? That could be the cause of your hum/hiss as the polarity of the output signal is inverted.

[BobTFM35 3,415]

Just about anything can be going on.

 

I assume you have alot of confidence in the repair facility. Have you contacted them for some guidance and or suggestions?

 

I would do one of two things. Work my way backwards removing a component and testing to see if the hum or hissing has gone away. Or unhook everything then add an item one at a time. 

 

This is in no particular order, so.....

 

I remember from your previous post you were trying to bi- amp some speakers and at the end you had everything "singing". So things worked then.

 

Something has changed from then to now, is anything new?

 

1. I would plug the bluos into the CD input and then test.

 

2. Next I would remove the sub from the bluos then test.

 

3. I assume the same speakers. What make and model?

 

4. Was the new non inverting amp tested before and worked fine so we can rule it out for now? Still bi-amping?

 

5. Tubes were replaced. Who sourced the tubes? What were they?  Matched sets and tested? Line board and or phono board tubes?

 

6. Any other parts replaced on the preamp

 

7. Any new cables?

 

Just look at one thing at a time and something will pop up.

Edited 3 hours ago by BobTFM35