Ampeg SVT 4 Pro no line out signal - Tubes?

[my07bass]

Okay, I hooked up my amp to our drummer's PA and got sound through the PA as I should. It was connected through a Monster mic cable.

I took the amp home and connected it to my PA and no signal. When I turn the line out volume up and down I do hear the hiss get louder and quieter through the PA.

Ive got both buttons on the back set to mono. I'm using channel "A" wet, all as before. I've also tried the buttons in various positions.

As a side note, I've got several Livewire mic cables but none of them would click into place on the back of the amp. When I went to my drummer's house his Monster cable clicked right in. I went to GC and tried a Monster cable on one of their SVT 4Pro amps but it wouldn't click. I ended up buying a Mogami cable that clicked in, which is what I'm using at home.

My amp is about 2 years old. How do I know when it's time to replace the tubes? Could this be the problem?

Thanks in advance for any of your input.

 

[RickenBoogie]

Doesn't sound like a tube problem at all, more like either your cable, or your mixer. Could be anything, though, you need to isolate the problem by going through everything, one connection at a time.

 

[my07bass]

I guess I could take it back to my drummer's house and hook it up there again... Seems strange though, same mixer as mine and everything....
Except the cable.. Does it need a special cable other than a mic cable?

 

[my07bass]

I've switched some cables around. I used one of my Livewires that doesn't click in. I'm able to get a signal if I wiggle the cable and push in a bit hard. However, as I slightly move the cable I get a lot of hum and hiss. I put the Mogami cable back in and got sound through channel "B" (dry) side. I got signal but a very bad hum. Looking inside the sockets (balanced socket back of amp) the 3 pins look dirty (a brown kinda scaly coating). Could this be the issue with the no signal and/ bad hum? Any ideas how to clean the pins?

 

[megadan]

If it worked perfectly at the drummers house (no hum, hiss, or intermittent) it's probably the cable, not the amp.

But a quick wipe with a damp cloth is probably the quickest way to clean the jacks. Or a special expensive spray, but....

 

[my07bass]

For those of you interested, and those who replied (thanks), here's what's happened.

My Ampeg was plugged into a different outlet than my PA. I plugged the PA and the Ampeg into the same outlet and the hiss/hum is gone. For some reason the sound from the Ampeg is now coming through the PA.

Is it possible the other outlet is so dirty (frequency wise) that it blocked the signal and created the hiss/hum? Dunno, but it works now.

 

[RickenBoogie]

No, it created a ground loop. Each outlet on a seperate circuit. Best to use one outlet in this case.

 

[Jerrold Tiers]

The 4 PRO has transformer isolated DI output, so grounds should not matter.

probably the mixer has a "pin one problem", meaning that the shield and signal circuitry are connected inside the mixer, in a way that shield currents affect the signal. That's common these days with plastic XLR jacks.

You can cut the shield at one end so it isn't connected to the shell of the cable and that may help. Not an ideal solution, the problem is actually inside the mixer (if that is the issue).