another 7pro down....

[nubs]

turned amp on this afternoon, and it made a sound like i was plugging in the instrument cable with the amp on, then i guess i would call it a little "pop". out put level is very very weak. if i turn the compression up at all i pretty much loose all out put, and the thresh light comes on.....i am no tech head at all. anyone know what this could be? i have a authorized ampeg tech to take it to, but wont be able to get it looked at for a couple days at least in Wisconsin we are supposed to be in for a Snowmageddon the next couple days...i am bummin'! any input would be cool..

[hdracer]

About all you can do is get it to your tech and rent a amp.
Or you could go to GC and buy a amp and return it when yours gets back from being repaired.
If your live with that.....

[JimmyM]

Did you try replacing the tube yet?

[nubs]

Originally Posted by JimmyM

Did you try replacing the tube yet?

no, you feel it may be the preamp tube?

[nubs]

Originally Posted by JimmyM

Did you try replacing the tube yet?

can an electrical dummy do something that complex, remember i dont know nothin!

[will33]

Originally Posted by nubs

no, you feel it may be the preamp tube?

It's certainly worth a shot. As well as running a patch cord from effects send to return.

Go another amp of any kind? See if you can get a good sound either out of the pre or into the power, again using the effects loops.

[JimmyM]

An electrical dummy can easily replace the tube. Unbolt the lid, open it up, pop the old tube out, po the new one in, replace lid. Try Will's idea first, though...it's free.

[will33]

Originally Posted by nubs

can an electrical dummy do something that complex, remember i dont know nothin!

If you can both operate a screwdriver and change a lighbulb.....you can do it!

[nubs]

so i should try and run a patch cord from return to send? and if this gives me a proper signal then its the preamp tube? am i understanding this correctly, i dont have another amp here now, but i do have one i can get from the rehearsal joint. thanks for the help guys

[JimmyM]

Originally Posted by nubs

so i should try and run a patch cord from return to send? and if this gives me a proper signal then its the preamp tube?

Correct, except there's a chance it's the preamp tube, not a for-sure thing. But in a hybrid, the second thing behind corrosion in the effects loop that you should suspect is the tube. 12ax7a, in case you don't know the tube number.

[nubs]

okay tried it, and it doesnt improve on anything.

[Downunderwonder]

The patch cord thing is to check out the condition of the loop jacks, some amps put the loop out of play when nothing is plugged in but get corroded, so you get noise or nothing.

If it cleans up with something in the loop then it isn't the tube! If the noise is still there then it is more likely it could be the tube,

[nubs]

no, i have some output i would say about 25% of its actually power. patching the effects loop, everything pretty much is the same.

[will33]

If the patch cord makes it work again, it means those jacks need to be cleaned. If it doesn't, then try a new tube, they're onoy $10-$15. Preamp tubes usually last for years or decades, but, quality/consistency nowdays isn't what it was back when militaries depended on them and it's possible you have a bad one.

If neither of those help anything, it's probably tech time.

[nubs]

again thanks, i guess its time to try a tube, the patch cord and effects loop had no noticable improvement.

[JimmyM]

Don't know if you have any tubes laying around, but if you don't, I have to recommend trying a different brand besides JJ. I know Ampeg puts them in there as stock tubes, but I've yet to ever buy a JJ that lasted me longer than a few months. I had one that lasted a year. Other than that one, they have all gone belly up for me within a few months, and I just bought a set of JJ 6L6's for my Super Reverb that were microphonic out of the box.

[nubs]

any suggestions then sovtek, groove tube, mullard, mesa boogie thanks in advance

[B-string]

EH, Shuguang , TAD, Tung Sol, Ruby, Peavey re-brands, Fender re-brands, Genalex are some others.

[JimmyM]

A NOS Mullard sounded really hot in Johnk's 7 Pro, but I don't think you need to spend $100 on good tone I prefer the decent not too expensive NOS tubes like RCA, Sylvania, etc., but I've also had pretty good luck with Sovteks. And I know they're rebrands but I've never gotten a bad Groove Tube. They apparently have some sort of weeding out process that actually works.

[nubs]

so as long as the number is 12ax7a, i should be good to go? i see allot of tubes with the 12ax7 number but with different letters at the end, C, r, S, WA just double checking.....do i have to find the 12ax7a's?? sure as heck dont wanna buy the wrong stuff...