My Legacy crackles - Actually, it snaps and pops, too

[bduersch]

I just picked up a used Legacy combo. I'm pretty stoked about the tone I get out of it, but...

When I first turn the amp on, it crackles and pops quite loudly for a minute or so. During this time, you can hear the guitar coming out through the speakers. After the snapping and crackling stops, the guitar comes out twice as loud. After that, it's usually very well behaved. I was gonna replace all the tubes in it, but I thought I'd run it by y'all before I go spend a small fortune on glowing bits of glass.

I've also noticed that I pick some local radio station through it. Anyone else have this problem?

Killer amp, nonetheless.

--B

[ripl3y]

Can't be any help sorry, but I think the radio station prob is quite common as I've had that happen with many of the amps I've owned

Steve

[bduersch]

Yeah, actually I remember one of my older tube amps having the radio problem. I've been using a Johnson Millennium for so long that I'm used to always having a noise gate in my signal path, so I forgot about the radio bit.

--B

[bill h]

When you first power up the Legacy you should leave it on Standby for *a few minutes to let the tubes warm up. *After that, when you switch off standby, power is slowly applied (over 15-30 seconds or so). *This is supposed to help increase tube life. *This is why initially the volume is low and then increases. *This is normal.

bill

[bduersch]

I usually let the amp warm up on standby for several minutes when I power on. Seems that the crackling occurs during the warm-up period as power is slowly applied.

Does anyone else have the crackling problem?

--B

[rgr]

How old is the amp and how hard has it been used? *If it has been well used you might try replacing the power tubes, it sounds like they may be getting near the end of their life. *"Most" problems with tube amps are, well, tubes, the majority of problems remaining are most likely caps, especially the big filter caps 'cause A) they are big electrolytics and B) they have to contantly deal with very high voltages. *

This is "sort of" a generatlization but I think it's pretty close. *

Hope this helps,
Roger

[Vaibanez]

I agree with the "stanby" solution. I would also replace the power tubes as well. Being that it's used, you really have no idea how hard the amp was ridden. Tubes are pretty cheap and it's a quick remove/replace if you buy the same tubes. Try to get them matched, but I have found this isn't as important as it sounds. If you decide to change the tube type (i.e. 6L6's to EL34's), the amp will need to be re-biased. I don't own a Legacy (yet) so I don't know if they have a bias switch. My Ampeg VT-120 had a bias switch for 3 different tube types. Pretty cool amp. Anyway, do those 2 things and you should have a rockin' amp for a long time to come.

J>

[bduersch]

Thanks for all your help! Today I fired the amp up without the cover on the back, only to notice that one of the power tubes was glowing about 100x brighter than the others. I temporarily replaced it with a spare EL34 I had around the house, and the problem has gone away. Now I just need to pick up a matched set of replacement tubes--I'm currently running a mix of Sovteks and Groove Tubes.

Also, I seem to no longer be getting radio stations through the amp, but that could just be because I can't hear the radio stations because the amp's just so d@#$ loud!

For the record, the Legacy does have a bias switch... it can accept either EL34, 6L6, or 5881's. I highly recommend it. Even though it's been a pain in my butt for the past few days, it's got such great tone that I'm willing to give up the consistency of solid state amps to deal with the occasional flakiness of tubes.

Thanks again!
--B

[kirk]

Brent, I wished you'd contacted me! *Not that I wold have been able to solve your problem, but I wish I knew you were having trouble!

That is a first generation Legacy. *One of the first off the line. *Look at the placement of the Legacy logo on the front and it may even clue you to what I am talking about. *I don't know the life expectancy of tubes in a tube amp, but maybe that was the problem.

I hope that the problem is fixed by replacing the tube and if not, please contact me so we can work this out!

[bduersch]

Kirk--

All is most cool with the amp now! When I unpacked it, there were 6 tubes (4 Sovteks and 2 Groove tubes) packed in with it. I went ahead and put the 4 Sovteks in (thinking I'd have a matched set), but one of the Sovteks was blown. All's working well now, but I'll probably put a matched set of tubes in just to be consistent.

I actually had the amp for several days before it started the funky crackling noise, so I figured I'd give it a few days to see if it would either go away or if I could troubleshoot it. All it took was a replacement tube. Seriously, I love the amp, and hope you're digging the RG570CTAM.

I wondered about the Legacy logo--I remember seeing that the logo was in a differnent place when I saw the amp in the Carvin catalog, but I really didn't dwell on it for long.

Out of curiosity, when you switch the amp from 100w to 50w mode, I think it only uses 2 power tubes, right? Anybody know which 2 of the power tubes it's using (at least I could match those until I get a matched set of 4)? I'm assuming the middle ones, since they glow the brightest, but I'm still becoming reacquainted with the wonders of tubedom.

--B

[kirk]

Bad guy to answer, but I believe that V6 & V7 are the 50w.

Concerning the original question - this is from the Legacy manual:

The 12AX7A preamp tubes V1&2 are the most critical.....V1 most sensitive......try exchanging V1&V2. *Replace these tubes if you have a bad popping or ringing in lead drive channel.....

There may even be a trouble shooting guide for the tubes on the rear panel of the chasis "Tube Replacement Guide."

The CT is doing great, although neglected due to my busy schedule lately!