Subway Blues "FFFFFT FFFFFT FFFFFT"

[velorush]

I think the Subway Blues is having filter cap issues. When I take it off Standby I get a faint "FFFFFT FFFFFT FFFFFT" sound at about two FFFFFTs per second. At first I thought it was just the chili I had for lunch, but no, it's the amp.

Can anyone confirm my suspicions or offer a different diagnosis?

[carfish7]

Man, I hate to hear that. Sorry it is giving you issues. First thing I'd do is get a new 12ax7 and substitute first V1, then on down the line to ensure that it isn't a tube issue on the front end. Could be the power tubes too I guess. I could send you a few known good 12ax7's if you'd like, since I'm the one that sold you that POS in the first place................

With Boogies, that's always the first avenue to pursue - the tubes. As far as filter caps go, I recall the originals in my late 80's MKIIC+ being perfect 20 + years on, but one never knows really. If it doesn't get used for long stretches of time I suppose they could begin to lose their integrity.

I hope it is easily resolved.

[velorush]

An excellent idea! Come to think of it, the only amp I've ever had with confirmed filter cap issues had a rhythmic noise, but it was "motor boating" (more "bub bub bub bub bub bub" than "ffffft ffffft ffffft").

Thanks for the offer of tubes, but I've got a box of assorted tubes here behind the desk. I'll give the swap a try. This 'anti-Mesa' is the only Mesa I've ever owned, so the tube tip is much appreciated.

As for "POS," I still maintain this is the best all-around amp ever! It is my Princeton Reverb only with an effects loop, direct out and much more effective tone stack (blasphemy, perhaps, but it's that good!). Even with this issue, it still sounds great (the noise is not as loud as the guitar signal, but I'm afraid if I let it go it's going to get louder).

Thanks!

[Ting Ho Dung]

My Mesa did something similar but it was quite loud. It turned out to be V1 or V2, don't remember which. Also one of those tubes may have a rubber ring around it. I don't remember which but the schematics are easy to find online. Mesa tubes are Sovtek but they grade the Power tubes. So I'd buy Mesa / Sovtek power tubes since there is no bias adjustment. As you know you can throw in any preamp tube you want. Just watch for the one with the rubber ring. That one needs to stay in its position IIRC. But you can swap it out with anything 12xx7 to see if it silences your farts and then get a replacement with the ring.

[velorush]

No rings in this amp - four 12AX7's (two preamp tubes, reverb driver and a phase inverter) and and a couple of EL84's for power.

Could you have run into a EF86, maybe? Those get that sort of thing regularly due to their susceptibility to vibration. No way to confuse those because they don't pin out like the octal 12A*7 variety.

Thanks!

I'm guessing it's in the preamp section, but I do have a spare set of EL84's around (somewhere) if it gets to that.

[carfish7]

The "special" spax7 has a rubber sleeve on it from the factory. They are supposedly extra low-noise. And extra $$$.

[velorush]

The "special" spax7 has a rubber sleeve on it from the factory. They are supposedly extra low-noise. And extra $$$.

Apologies to Thorn: obviously you were right and I had no idea what I was talking about there! Never heard of the spax7, but then again, this is my only Mesa (well, in the early '90's I experimented with a Carvin X-100... but I didn't inhale!).

Okay, so I pulled V1 and replaced it with a Fender GT that I'd pulled out of something... the FFFFFT FFFFFT FFFFFT was gone, but it was replaced by terrible microphonic noise. Guess that's why it got pulled out of whatever it was it got pulled out of! To the trash with it!

Then I reached back into the tube box and what did I find? Chris, do you remember that angry GT 12AX7 you had in V1 when I bought it? Ahhhhh! Glorious! Put it back in V1 and no more FFFFFT FFFFFT FFFFFT, just beautiful beautiful sound!

I've still got a small microphonic noise coming when I hit a note from E to F, mainly on the A string (this is different entirely from the original noise). The "eraser test" didn't identify the culprit, but it's there. Not too annoying. You know, the amp's what, twenty years old? I should probably retube the whole thing! Four pre's and a couple of EL84's. Pretty cheap and easy, especially with no need for biasing.

Ended up with an hour-long diversion on a busy Saturday. The Senior sounds too great through this thing! Step on the Red Snapper and why would I need anything else? Grabbed the Strat - what a Strat amp! It's just all there! Beautiful.

Okay, back to work. Too much more to do today!

Thanks for all the help. Much easier to pull a tube than to mess with filter caps!

[carfish7]

Nice! Glad to hear it was an easy sort.

Now I want one again. I have the Heartbreaker, and while it does some mighty fine things, that little beast was all the amp I should have ever needed. Much easier to carry, too. I guess "Nigel" is close enough (my Laney LC15R 1x10 combo with a sweet Dr Z speaker), but I will now be keeping my eyes peeled for a SB with the 1/2 power jack. I bet running Nige and a SB in a stereo setup would rule.

[velorush]

I run the SB and the Reeves Custom 12PS in stereo. The Reeves has a 12" speaker in a larger cab, so they compliment each other nicely, especially with the reverb up on the Subway. Makes Madison Square Bedroom sound like a nice concert hall... well, a concert hall with really crappy playing.

[Ting Ho Dung]

The "special" spax7 has a rubber sleeve on it from the factory. They are supposedly extra low-noise. And extra $$$.

Apologies to Thorn: obviously you were right and I had no idea what I was talking about there! Never heard of the spax7, but then again, this is my only Mesa (well, in the early '90's I experimented with a Carvin X-100... but I didn't inhale!).

Okay, so I pulled V1 and replaced it with a Fender GT that I'd pulled out of something... the FFFFFT FFFFFT FFFFFT was gone, but it was replaced by terrible microphonic noise. Guess that's why it got pulled out of whatever it was it got pulled out of! To the trash with it!

Then I reached back into the tube box and what did I find? Chris, do you remember that angry GT 12AX7 you had in V1 when I bought it? Ahhhhh! Glorious! Put it back in V1 and no more FFFFFT FFFFFT FFFFFT, just beautiful beautiful sound!

I've still got a small microphonic noise coming when I hit a note from E to F, mainly on the A string (this is different entirely from the original noise). The "eraser test" didn't identify the culprit, but it's there. Not too annoying. You know, the amp's what, twenty years old? I should probably retube the whole thing! Four pre's and a couple of EL84's. Pretty cheap and easy, especially with no need for biasing.

Ended up with an hour-long diversion on a busy Saturday. The Senior sounds too great through this thing! Step on the Red Snapper and why would I need anything else? Grabbed the Strat - what a Strat amp! It's just all there! Beautiful.

Okay, back to work. Too much more to do today!

Thanks for all the help. Much easier to pull a tube than to mess with filter caps!

I believe I may have removed mine or changed positions as it was noisy / microphonic.

[Caddie]

The "special" spax7 has a rubber sleeve on it from the factory. They are supposedly extra low-noise. And extra $$$.

I've still got a small microphonic noise coming when I hit a note from E to F, mainly on the A string (this is different entirely from the original noise). The "eraser test" didn't identify the culprit, but it's there. Not too annoying. You know, the amp's what, twenty years old? I should probably retube the whole thing! Four pre's and a couple of EL84's. Pretty cheap and easy, especially with no need for biasing.

Ended up with an hour-long diversion on a busy Saturday. The Senior sounds too great through this thing! Step on the Red Snapper and why would I need anything else? Grabbed the Strat - what a Strat amp! It's just all there! Beautiful.

Okay, back to work. Too much more to do today!

Thanks for all the help. Much easier to pull a tube than to mess with filter caps!

i had that problem. Very simple solution, The Keith Richards Mod. Remove the fat E string, tune to open A. Sling it low so you gotta strum from your elbow, gets ya that railroad train feel.

Cheers!

caddie