Tubes for an Ampeg Tube Combo Amp?

M

Mongoo

New member
My Ampeg Combo Amp is making a hissing noise. It's not really bad, but not good either you know. Close micing it picks it up. I had it in for repair a while ago cause one of the tubes went, and money was tight then so I only had one replaced and he put in a different sized tube (the amp has a bunch of little tubes deep inside it, and then two main tubes towards the back). The guy said it needed a tune up, stating the connector was loose etc.

Anyways, I want to record with it now and suppose I should really have it fixed up with matching tubes and whatever else has to happen to fix the noise issue. I have zero knowledge of the different effects different tubes have on an amp. Should I be considering getting something specific if I have it tuned up or just let him use whatever? Anything you'd recommend, and why, whats it do for the sound? I play alternative'esk music. A lot of Clean to Distortion, back to clean to distortion etc. Like Nirvana but different just the same. You can check out some of the music at http://myspace.com/chrisciccone if that helps you get any ideas.

Thanks for your thoughts
 
I'd want to know which Ampeg amp first off.
Also, something that immediately catches my eye is that the tech put a different type tube in it. I'd want to know which tube. There are Preamp tubes that can be substituted for and sometimes it's useful to do so, but one possibility is that the different tube could be a source of noise. The little tubes are pre amp and possibly 'verb and even a rectifier tube if it's an old one. If it's the little tubes he substituted for ..... then that may be ok although, as I mentioned, it might be the reason for noise. I can't imagine anyone would replace a single power tube (the big ones) with a different type if he weren't replacing both of them so I'm gonna assume we're talking about the preamp tube is what he changed. If it was a power tube, I wouldn't even turn the thing on again without figuring out exactly what he did.
You really need to give a bit more info before anyone's gonna be able to tell you much.
 
Thanks bob, It was one of the big power tubes he replaced. My amps at the practice space, but I'll be able to find out more info by tomorrow. The bad tube was smoking hot before, and I just needed a quick replacement for some shows on the books. He didn't seem to think the different size would be an issue technically speaking, though he thought the sound wouldn't be good. I'll post back with more info later. Thanks again.
 
well, if it was the same type tube but just a different brand which would make it cosmetically different and thus, a different size ..... then it'd work although it's best to replace all power tubes at one time and best of all to have matched tubes..
But if he actually used a tube with a different number .... then ..... EEK! ....... I'm surprised it worked at all and that's a very big deal.
Now, some of the older Ampegs from the 60's and 70's ( I have a bunch) can actually run with several different types of power tubes in them without making any changes. I can use 7027A. 6L6's, ..... ummmm .... 6550's I believe and one other without making any change in the amp although I always use 7027A's.

I can't use EL34's without making a small circuit change.
But I would NEVER combine any of them.

It's fairly important that you make sure he didn't put a different type tube in there.
Also ..... still wondering what model of Ampeg it is.
 
if in fact an output tube was what he replaced then do youself a huge favor and find someone else to do your work.... and tell your freinds as well.... that guy should not be allowed to be in the biz...
 
dementedchord said:
if in fact an output tube was what he replaced then do youself a huge favor and find someone else to do your work.... and tell your freinds as well.... that guy should not be allowed to be in the biz...
Click to expand...
replacing a power tube with a different type tube and even worse, only doing it to one of the tubes would rank right up there in my "dumbest tech" stories!
:D
 
dumbest tech.... well i once went into a church to troubleshoot a system behind a nationally known guy.... we were contracted for the organ ... he was installing a sound system... "all of a sudden" nuthin worked.... he threw up his hands.... i found where his crew had staplegunned the wirring to a floor joist... and shorted the whole thing out....
 
Lt. Bob said:
Now, some of the older Ampegs from the 60's and 70's ( I have a bunch) can actually run with several different types of power tubes in them without making any changes. I can use 7027A. 6L6's, ..... ummmm .... 6550's I believe and one other without making any change in the amp although I always use 7027A's.
Click to expand...

Lt. Bob,

I have an old B-25 myself with what I think are the original tubes or close vintage. Are 7027As that much better to use than 6L6s. Where do you get them? Are they NOS.

Tom
 
Oancient1 said:
Lt. Bob,

I have an old B-25 myself with what I think are the original tubes or close vintage. Are 7027As that much better to use than 6L6s. Where do you get them? Are they NOS.

Tom
Click to expand...
Did the old B-25's take 7027A?
I use them because I sorta feel like having the vintage thing as close as possible to the originals but I've never tried 6L6s to see how much difference there might be. And I have all git amps .... VT-22, VT- 40, V-2 .... etc.
My understanding is that 7027s are basically a very heavy duty 6L6 so there might not be much difference.

They're not that hard to come by and not really expensive. I get all my tubes at http://thetubestore.com/ but I'd bet any good tube supply would have 'em.
 
That's where I got my 7591A's for GS-15R. By the way, I just made a cool mod for it. I put the neg feedback on a switch. It adds quite a bit of "nasty" to it on demand.:D
 
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As a side note, you will eventually find that the Russian tubes sound better thant he Chinese tubes. The Chinese tubes have more edge and harsh bite to them. It's not huge, but you can hear the difference.

There are only 4 places making tubes now, 2 in Russia, 2 in China. So if the tubes are not EHX (Electro-Harmonix and Sovtek are owned by the same parent co), TungSol/Svetlana, Winged C I believe, or Sovtek, then try to avoid them..... my memory is foggy, so correct me if I have the names wrong...
 
Lt. Bob said:
Did the old B-25's take 7027A?
I use them because I sorta feel like having the vintage thing as close as possible to the originals but I've never tried 6L6s to see how much difference there might be. And I have all git amps .... VT-22, VT- 40, V-2 .... etc.
My understanding is that 7027s are basically a very heavy duty 6L6 so there might not be much difference.

They're not that hard to come by and not really expensive. I get all my tubes at http://thetubestore.com/ but I'd bet any good tube supply would have 'em.
Click to expand...

I remember from years back that my B-25 used different tubes than the 6L6s in my Fenders. Haven't looked closde enough to see what is actually installed, but a redrawn B-25 schematic I found on line shows 7027s. According to what I read on line (see link below) 6LCGCs are the same, and the both are designed to handle higher plate voltages.

http://www.triodeel.com/7027.htm

I actually used the B-25 head for guitar for many years, but have been weighing having it recapped and retubed against buying something new in solid state for use as a bass amp. I'll check out the tubestore.

Tom
 
Specs...

Okay, I was able to finally get over to the space and check my amp out. It is an Ampeg VT-60, Tri-Ax Series. The power tubes that were in it before I brought it in were JJ (brand) 6L6 GC's, and the one that was replaced (one on the right side when facing the back of the amp) became a Sovtek 5881WXT 0106.

So, whats that mean? :)
 
They pin out the same but YIKES!!:eek: I'd get a matched pair in there fast and have it biased.
 
well, a 5881 is the same thing as a 6L6 ..... just a different (European I think) designation. It's just a heavy duty 6L6.
But I agree with Track Rat. You need to take care of that.
Even though I'm personally sorta casual about rebiasing, you really do need matching power tubes in there and really, at this point I'd strongly recommend rebiasing.
 
the 5881 is the US Mil spec version of a 6l6... that tech should be the victim of a beatdown... get a matched pair and absolutely rebias... ONLY time rebias is unnecessary is if you're replacing with the same brand AND rated tube...
 
What tubes do you recommend I should use? I want to use this amp for recording soon. Do I need a tech to rebias the amp or is that something I can do? I play with an American stratacaster and plug into a direct box to record the DI plus the amp at the same time. I don't really use effect boxes, but I do use distortion/clean.
 
Variety

The Tube Store has got a good review section on 6l6's

http://thetubestore.com/6l6templeton.html

I took another look at my amp, and it has a diagram with tube models in there corresponding places. It listed the power amps as 6l6gc's. So can I pick from any of the tubes on this page (are they all roughly the same thing after biasing) or do I have to pick from the specific 6l6gc's listed?

Those under 30watts, which I'm guessing I need cause I had two JJ6l6GC's in there before the one went.

<b>Sylvania 6L6GC (used for reference)</b>
<b>JJ 6L6GC</b>
Sovtek 5881WXT
Sovtek 6L6WXT+
<b>S.E.D. 6L6GC ("C" Logo)</b>
<b>TAD 6L6GC-STR</b>
TAD 6L6WGC-STR
<b>Tungsol 6L6GC-STR</b>

What are they talking about when they rate them on microphonics/detail/harmonics? What will matter most when recording in a home studio?

Thanks
 
Hey guys....the customer asked that only 1 tube be replaced because he didn't have the $$ for both. The tech did what he was asked to do. Period. It's not his fault that the customer's request was for less than the best. What are you guys...a bunch of democrats trying to make the customer the "victim" here. What a load of crap. Don't you hate it when a tech tries to pontificate to you about stuff??? Maybe they are correct in their knowledge but I hate it when they get all superior about it. I love ampeg stuff, my favorite amp of all time was a 40 watt 4x10 honey that would kick a marshall's ass. Next fave..a GU-12 with an EV12L.


chazba
 
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