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Mesa Boogie Bass 400+ tubes question

#21
I remember 20+ years ago when I was playing the same Mesa amp as my main gigging amp, and I brought it to an amp tech for service. The bill to get it serviced and re-tubed just killed me. I could not believe it was that expensive. BUT... it also reminded me how dang good that amp sounds when it's running properly! IMHO, there's nothing like it. Nothing.
 
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#22
I have a 400+ with adjustable bias mod, money well spent. Frees you up to buy tubes from any reputable store. I like: Tube Depot and the Tube Store.
Sometimes they run sales during the Holiday Seasons, great time to retube your beast!
 
#23
Even if you could run your 400+ with less tubes (and you can't!) on a good day, it struggles to produce even 360 watts. So, what are you aiming for?

Buy a Fender Champ (tube amp) @ 6 watts and run it for bass?
 
#24
This brings up an interesting point that I see fairly often.

Folks who complain about how expensive and disposable class D amps are compared to tube amps. In fact, the most expensive repair to any class D amp that I have designed over my entire career is less than the cost of a proper service and retube of any 300 watt all tube bass amp out there.

Just to put things into perspective.
 
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#27
agedhorse said:
Just to put things into perspective.
Click to expand...

I love the practicality and simplicity of D class amps. I bought D-800, I liked it but switched it for M-2000, which I like more. For me, it's all about the sound. D-800 sounded a bit more "modern", closer to my Carbine M9 I would say. I like it, but I prefer the "older" Mesa sound. To my ears, 400+ and M-2000 are still the best of them all. That's why I'm very interested in TT-800.
 
#29
diegom said:
Since we have @agedhorse participating in this thread, I've been dying to ask this question directly! How does the new TT-800 REALLY compare to a 400+? At first glance, the TT doesn't have the 7-band EQ, but it has a mid freq... What else?
Click to expand...
It compares pretty closely in the important ways, but it's not identical. I addressed shortcomings with the original tone stack (a byproduct of being more guitar oriented), added the sweep HPF, made the deep and bright functions more useful and improved the smoothness in the range of all of the controls.

Then there's the increased headroom from greater power, a more controlled handling of under-damped cabinets, control of power amp symmetry under heavy loads, universal 115/230V power supply, pre and post DI's, and a lot more etc.

The goal was to take the 400+ concept forward about 30 years.
 
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#32
Vintage tube bases can be reglued. There are a lot of internet suggestions as to how to accomplish this out there, not all are wise.

Warning: The process is not for the faint of heart. First try it on a tube that you can afford to loose.

A good way to start is to reuse the existing dried glue of a vintage tube. If the adhesive is alcohol based, it can be reconstituted by applying isopropyl alcohol (pharmacy in better times) around the top of the base. This can soften the dried glue. Once softened, the tube needs to be clamped in an upside down position, I use elastics for clamping. It is important to wait at least 24 hours for the solvent to fully evaporate before the tube is used.

The formulation for the glue that RCA used on their tubes. It produces about a 200 pound batch.

  • coarse marble flour, 170 lb
  • orange flake shellac, 19-1/2 lb
  • Durite phenolic resin LR275-2, 7-1/2 lb
  • medium-color (grade G) rosin, 3-1/4 lb
  • denatured alcohol, 9 liters
  • Malachite green aniline dye, 10 grams

The formulation was alcohol based and that's why the existing dried glue can be softened with alcohol.

It is important to note that an old tube should never be removed from its socket by pulling on the glass envelope. This can break the seal between the base and the glass envelope. Hold the base and gently rock it back and forth while applying pressure away from the tube socket. Reverse the procedure when installing a tube, only holding it at the base.

Here is an alternative:

TUBE BASE GLUE. DATA SHEET

Note the importance of letting the tube dry upside down so that the adhesive doesn’t run onto the pins.
 
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#33
Something here isn't adding up.
1st, he wants to low power his 400+ so he can have the sound this amp makes "by far", I think he said. Well if you run an amp at half or 3/4 power, it would change the dynamics of the sound dramatically- so that theory stinks just on principal.

2nd,- he can't afford to re-tube "ATM" but is willing to risk an expensive amp (repair wise), that he loves, but is considering a new TT800? ***?

And 3rd, he has 6 Mesa amps now- including a M-2000. So why is there even a question? You can't use a spare amp?, or sell one till the funds are available (which is in the $200-250 range, BTW).

EminentArcticIraniangroundjay-mobile.jpg
 
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#34
Removing tubes will change the impedance that the power supply sees. This may affect performance in an audible way.

The Mesa 400+ is a conservative design in terms of power tube service life. They should last a long time. That’s a plus.
 
#35
Note that denatured alcohol is generally not isopropyl alcohol. It's usually ethyl and/or methyl alcohol and may have other components added to make it bitter (and more toxic).
 
#37
Rockbobmel said:
Something here isn't adding up.
1st, he wants to low power his 400+ so he can have the sound this amp makes "by far", I think he said. Well if you run an amp at half or 3/4 power, it would change the dynamics of the sound dramatically- so that theory stinks just on principal.

2nd,- he can't afford to re-tube "ATM" but is willing to risk an expensive amp (repair wise), that he loves, but is considering a new TT800? ***?

And 3rd, he has 6 Mesa amps now- including a M-2000. So why is there even a question? You can't use a spare amp?, or sell one till the funds are available (which is in the $200-250 range, BTW).

View attachment 3883100
Click to expand...

1 - Are you stupid or what? What stinks? It was a question. And I got an answer. So I won't do it. I was looking for a temporary solution so I can play with my 400+ a bit before I can afford to retube it.

2 - I can't afford to retube it AT THE MOMENT (because of a certain situation). I also can't afford TT-800 at the moment. Otherwise, I'd already had it obviously. I'm considering adding it to my collection sometime in the future. I'll buy it for sure, if I'll like it enough, I'll keep it. I'm not willing to risk anything with my 400+. That's why I asked this question.

3 - I can use another amp, and I do. And it's not a "spare" amp that I'm using. M2000 is my main amp that I've been playing for more that 20 years now. Actually I got two M2000's. I got another M2000 for backup just recently. So technically 400+ is my "spare" amp, but I'd still like to play it from time to time. I enjoy playing all amps in my collection, and I'm not selling any of them, just because I need to retube one. You're just looking at this from a different perspective. You're not collecting amps.
 
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#39
Rockbobmel said:
Gee, thanks for pointing that out. I guess I must be. I was just wondering why you would want to drive your car on just 2 tires when you love the way it drives on 4....
Click to expand...
Oh, the metaphors again. I can't AFFORD to drive 4 wheel car atm ok? What is your problem? I've read on multiple forums that this can be done with this amp, so I asked here, just to be sure. It turned out that this is not recommended, so I won't do it. It will have to wait. So what is your problem again? What stinks? Am I testifying in court? Why do you call BS? What exactly is BS here? There's not a pinch of BS in my words. This topic is over.
 
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