SVT-CL tube pop and flash

ChasFL · #1 03-22-2010, 03:34 PM

I bought a brand new Ampeg SVT-CL amp last summer. I've been playing it through an Ampeg 810e cab with a Modulus Genesis 5-string. I was playing gigs about 3 times a month. It always worked and sounded great, no problems, just what you'd expect for such a rig. I used a spare amp rig for rehearsals so the SVT-CL amp didn’t have that many hours on it. Then I had about a 2 month break.

When I went to gig again recently, I let the amp warm up for 20 minutes just like I always did. Then when I flipped it off standby, it popped very loud and no sound. Tried it again and got the same thing. I looked behind the amp and tried it again and one of the tubes flashed very bright when it popped again. I had to use my spare amp for the gig.

I took the amp to an authorized Ampeg dealer and he said a small piece of filament fell out of the tube that flashed and that's what caused the flash and the loss of connectivity. He was able to replace the one tube and it has been fine ever since.

Is this a common or known problem with a relatively new SVT-CL amps? Someone told me that this is a common problem of last year’s model and that there was a recall on them. Has anyone had this happen to them or know about this recall?

Thanks.

Bassmec · #2 03-22-2010, 04:02 PM

This is nothing to do with ampeg, it is however to do with lots of new production tubes used by many amplifier manufacturers today.

DanRJBrasil · #3 03-22-2010, 04:03 PM

as you post it wasn't a amp prob but just a bad tube and that happens

ChasFL · #4 03-22-2010, 04:21 PM

Thanks, that's what the repairman said also, that that just happens sometimes with tubes, that it wasn't a real biggie. I was glad cost-wise that he said that since there was so little hours on the amp and tubes that it would be OK to replace just the one bad tube instead of the whole set. I thought I had heard that tubes had to be replaced in at least pairs, if not better to always replace the whole set of 6.

derridiandrift · #5 03-22-2010, 04:28 PM

It's not necessary to match tubes. I most certainly improves performance if you do match tubes.

One tube can be replaced as long as it is matched to the other 5 tubes or at least matched to the tube that it's mated to. If your repair guy is even halfway competent he'll already know this and likely do this without even mentioning it to you. If you're not sure, ask him.

JimmyM · #6 03-22-2010, 04:33 PM

Quote:

Originally Posted by ChasFL

Thanks, that's what the repairman said also, that that just happens sometimes with tubes, that it wasn't a real biggie. I was glad cost-wise that he said that since there was so little hours on the amp and tubes that it would be OK to replace just the one bad tube instead of the whole set. I thought I had heard that tubes had to be replaced in at least pairs, if not better to always replace the whole set of 6.

absolute crap and nonsense. any tech who says to replace all 6 is ripping you off. first off, they work in triplets, not pairs. second, if one in a triplet set goes bad, then you should try to find a match and replace just the one instead of replacing 3. if that's impossible, then yes, get the triplet set, but replacing an entire sextet for one tube is ridiculous and a ripoff.

ChasFL · #7 03-22-2010, 04:42 PM

Thanks Jimmy, as he is an authorized Ampeg Repairman, I took it that he knew what he was doing. The amp certainly sounded as good as new after he replaced the tube and he guaranteed it, he said to bring it back if I had any problem with it at no charge. I was just surprised that with so little use on the amp, that something breaking on it would have happened so soon, but I guess that's the give and take working with an all tube amp, that you sacrifice a little hardware stability if you want to get that warm tube sound. Thanks for the Tube-101 also.

JimmyM · #8 03-22-2010, 04:47 PM

you really shouldn't have to, chas, but with today's tubes it is a little tougher than it used to be. however, tubes aren't nearly as delicate as some think they are, and once you get a working set, you should expect them all to last a good few years at least. i've got some power tubes here with close to 40 years on them.

ChasFL · #9 03-22-2010, 05:40 PM

Quote:

Originally Posted by JimmyM

you really shouldn't have to, chas, but with today's tubes it is a little tougher than it used to be. however, tubes aren't nearly as delicate as some think they are, and once you get a working set, you should expect them all to last a good few years at least. i've got some power tubes here with close to 40 years on them.

Yeah, I thought maybe because I had to transport the amp on its side a few times rather than on its feet in my SUV due to room restriction with my 810 cab (until I discovered I could set my cab on its side and then I had a lot more room to work with) I thought I might have jostled the tubes, but the Ampeg repairman said that probably didn't do anything, due to a spring support around each tube and that it was probably just a random thing that sometimes happens even to new tubes, that sometimes they just give out for any number of reasons.

ChasFL · #10 04-07-2010, 07:12 AM

Quote:

Originally Posted by JimmyM

you really shouldn't have to, chas, but with today's tubes it is a little tougher than it used to be. however, tubes aren't nearly as delicate as some think they are, and once you get a working set, you should expect them all to last a good few years at least. i've got some power tubes here with close to 40 years on them.

Hey Jimmy,
I was just taking a finer look behind my amp and noticed that the tech had replaced that burnt tube with a "Ruby" tube, not a same brand tube that came stock with my Ampeg CL amp.

Any feedback on Ruby tubes, or the consequences on replacing a tube with something other than the SVT-CL stock tube? The tech said if anything goes wrong with it, he'd replace it for free and didn't mention a time limit. It has played fine since, and sounds good, but then I didn't get a chance to compare it side-by-side either.

I was just wondering what your take was on that. Thanks.

okcrum · #11 04-07-2010, 09:43 AM

Chinese tubes in general are not as well made or reliable as European or US types. I've seen 20% broken filaments on new Chinese power tubes before ever plugging them in. Ruby is actually Shuguang Electron Group Co., who also make Shuguang, Valve Art, TAD, Sophia Electric, and Taylor Tubes brand names.

I'd feel better about an Electro Harmonix/Tung Sol/Sovtek/Mullard/Genalex - they're all made by New Sensor in Russia.

ChasFL · #12 04-07-2010, 09:48 AM

Thanks Chuck. Well, it was one of the SVT-CL stock tubes that broke a filament to begin with, so as long as I have the guarantee, I'll ride it out and if it happens to the Ruby tube, I'll ask him to replace it with something other than a Chinese tube. I guess I was also wondering what the sound difference might be, as in is it that noticeable if it had been replaced with one of the stock tubes.

JimmyM · #13 04-07-2010, 12:17 PM

as long as the tube's measurements match enough to be considered matching, you can stick 6 completely different types of 6550 in there and be fine. he probably used a ruby because that's what he had on hand. not a biggie.

ChasFL · #14 04-08-2010, 08:36 AM

Thanks Jimmy. I just played it again for a gig last night and it seems to work and sound great. I'll just roll with it then. The one change I'm making now is I'm using the -15db input on the amp rather than the 0db that I used before as I'm playing a Modulus Genesis bass with what seems a pretty hot active Bartolini NTMB preamp. I'm not sure if that had anything to do with it burning the filament in the tube before, but it seems more manageable now and less hum using the -15db input.

ajunea3 · #15 04-08-2010, 08:50 AM

I doubt the -15dB pad has anything to do with the tube going bad. Plugging into the -15db jack is equivalent to plugging into the 0 dB jack and turning down the gain knob a bit. All that really affects is the amount of tube saturation you're getting in the preamp.

I don't know what really causes power tubes to go bad. Heck, just last night at practice I plugged in my SVT-CL and went to turn it off of stand-by, when I heard a loud hum followed by a pop noise. I looked into the back of the amp and noticed that one of my power tubes more closely resembled a lava lamp than a power tube. Luckily I had a few spare tubes on hand. I took the bad one out and popped in a new one.

I have Sovtek tubes, which usually come with a number between 40 and 50 written on the front of the tube. I assume this number represents the impedence or voltage or some electrical value. The bad tube was labeled 40, so I replaced her with another "40" tube, assuming that they were very closely matched. Turned the amp on and everything was gravy.

The moral of my story: it may be a good idea to just buy some spare power tubes and keep them with you at all times.

ChasFL · #16 04-08-2010, 09:04 AM

Thanks, yeah I'm going to get some spares to keep on hand.

Even Dino at Ampeg said that he recommends to use the 0db jack whether using an Active PU or not. I tried both jacks last night and it seemed that with the -15db, I had more varience to play with in the volume control when I brought it up, meaning more of a gradual incline rather than a quick jump, and less hum than with the 0db.

MAMMOTHvolume · #17 04-08-2010, 09:10 AM

Quote:

Originally Posted by okcrum

Chinese tubes in general are not as well made or reliable as European or US types. I've seen 20% broken filaments on new Chinese power tubes before ever plugging them in. Ruby is actually Shuguang Electron Group Co., who also make Shuguang, Valve Art, TAD, Sophia Electric, and Taylor Tubes brand names.

I'd feel better about an Electro Harmonix/Tung Sol/Sovtek/Mullard/Genalex - they're all made by New Sensor in Russia.

in my experience shuguang valves have been much more reliable than newer russian ones.

JimmyM · #18 04-08-2010, 10:24 AM

Quote:

Originally Posted by MAMMOTHvolume

in my experience shuguang valves have been much more reliable than newer russian ones.

really? how come my experience with rubys has been so bad then? is this a newfound standard of excellence they're trying to cop?

johnk_10 · #19 04-08-2010, 10:46 AM

Shuguang (aka Valve Art) tubes have been very reliable for me too. i also think that they are not only built alot most robust than the russian tubes, but also sound better in my amps that i've installed them.

ChasFL · #20 04-08-2010, 11:17 AM

Well I'll let you know if I have problems with this one. I know you mentioned Jimmy that "you can stick 6 completely different types of 6550 in there and be fine." but is there that much of a detectable sound difference from the original stock SVT-CL tubes, or is it just the amp itself that's producing its distinct CL sound.