More Mesa Boogie problems

[Psycho Bass Guy]

Is that how this amp works? two 8 ohm speakers get plugged into the 4 ohm slots?

Yes

If you are running 1 (8)ohm cab obviously it gets plugged in 8. I would say you plug both of your 8 ohm cabs in 8 slots and the amp makes it a 4ohm load automatically.

No. Mesa really screwed up here, IMO, by putting two jacks for each output tap because it is misleading.

 

[GeneralElectric]

They aren't "blown." I'll almost guarantee that they will work fine in another amp.

I have a Fender Deluxe Reverb and an old B15. Not sure off hand but I'm pretty positive my Fender uses a few 12AX7s. The only reason why I'm not sure, is that its still running its original tubes.

I'll swap them out and test them when its a reasonable hour, since its almost 3am here.

 

[adam precision]

GE, glad you took my advice and your amp works. Don't worry about the comment:

"Right, but if the previous owner set the bias for the previous JJ tubes, the bias will be off. I'd take it to a tech, let them know you put Mesa tubes back in".

Preamp tubes don't need biasing.

If its easy/cheap to take it to a tech do it. Its always good to have your tube amp looked over once in a while even when there's nothing wrong with it.

But in my opinion you just got dodgy tubes from the shop. Send them back.

Mass manufactured tubes are like cheap light bulbs, the most likely time they will fail is when you first put them in.

I've been playin vintage valve amp for years (most of my amps are older than me!). I've got a hiwatt that still has all the original 1970's 'mullard' tubes and sound amazing. Why can't they make tubes like that anymore?

This is my first time in this forum so hello everyone and be careful with valve amps even if you think know what your doing!

 

[Bassmec]

Yes. Tubes are meant to glow a "healthy" orange. If it is blue, it is a faulty tube(s).


I'm no tube expert, but I'm sure someone else can back me up on this?

This Means Every EL34 I have Fitted in the last 38 Years as an amp tech
was faulty!.
Goodbye Cruel World!

 

[quickervicar]

This Means Every EL34 I have Fitted in the last 38 Years as an amp tech
was faulty!.
Goodbye Cruel World!

Yup. Time to turn in your soldering iron.

 

[daysleeper]

It's irresponsible to suggest an end user replace tubes as first course of action.

Preamp tubes should last a really long time. There is no reason to change them just to change them. You should only change them if they fail or if you seek different gain values (i.e., sounds).

Power tubes wear much faster, but still they're good for thousands of hours, and you will know when they're dead.

There is one thing that Boogie does not publish: They use two 12AX7s, one is Russian and the other is Chinese. These two tubes have different gain values. As a result, one or the other may work better in each of the preamp positions.

If you call Boogie, they will gladly tell you whether your amp is sensitive to this issue, and if so, how they set it up when it goes out to the dealer.

 

[GeneralElectric]

Well I put those two 12AX7s into my Deluxe Reverb and I got the same blaring feedback, so at a much lower volume. I'm guessing that its because this amp isn't that loud to begin with...

 

[Psycho Bass Guy]

Get your Mesa checked out. It's possible that something in it has fried those preamp tubes, and it's only matter of time before it does it to the new ones, too. The only other thing to check: are there any cracks in the glass? I had some Mullard 12DW7's that had split their envelopes and gassed that caused that in one of my SVT's.

 

[BurningSkies]

The bad news is that most likely you didn't have to change out those tubes, therefore spent about 300 bucks without needing it.

Having owned that particular Mesa 400+ in the past I can tell you that it had tube ring from the beginning. Only noticeable if you play at low practice volume. I switched out the Mesa tubes it came with because I didn't really like them that much. I thought the JJ tubes sounded much better and lively. I don't believe the Mesa tubes needed to be changed either.

When I sold the amp to the intermediate owner (who you bought it from), it came to him with the JJ tubes installed, plus 22 6L6 tubes (the full set of previous Mesas plus the original set from 1997, minus 2 tubes that I gave to a guitarist in an emergency gig situation). The JJ set was sent (complete with preamp tubes) from Bob & Eurotubes, and supposedly were picked to match the amp's spec. As I wanted clean and low, that's what we worked towards.

I don't believe that any of the tubes were bad out of any of the sets. Sometimes we switch them for other reasons!

Anyway, back to the tube ring. Vibration based and completely harmless. It rang like that the entire time I had the amp and the guy before me also commented upon it. It is disconcerting the first time or two you get it, but otherwise...

The amp has a 100% clean service record. Never a problem, never a repair. I can't say that it suffered from noise or any other defect. I used the amp on stage the whole time I had it (almost 2 years, IIRC) and also used it for rehearsals. No manhandling, drops, etc. I drove 6+ hours each direction to pick it up when I bought it so it wouldn't be shipped, and I did the same when I sold it.

I never 'cranked' the amp...I play in reggae bands and while I would be room filling loud I never needed to push the amp and I worked to avoid distortion at all times. I always ran the fan at high, and also had a second clip fan that fit into the back of the rack as I didn't think there was enough ventilation without it to keep the sound clean.

I had a few issues that made me sell it, none based on the amp's performance. They basically amounted to the fact that I knob tweaked it way too much while playing, I didn't really dig the DI on it and I had a hard time moving the amp/rack by myself (especially into my second floor flat at 3am after a show!). Oh, and it hardly fit in the back of my car!