Mesa M9 mega thread

[Chef]

no it ain't!
enjoy

why DOES this thing sound so damn good? It's just plain WRONG...

 

[Jim Carr]

There is a known issue with the first generation M9's overheating. I sent mine back for the upgrade and it was covered under warranty...

My experience was similar. I bought mine used. I stuck it in a 2 space rack as the original owner's manual OK'd. Thermal shutdown occurred on second use when driving a 4 ohm Epifani 410 UL1 in a loud band.

So off to Mesa, as noted above in this thread. They fixed it under warranty with the latest engineering changes. I also switched to a 3-space rack with a lovely little screen in the empty upper space. It runs cooler with it's two fans, upgraded heat sinks, power transformer upgrade, and slotted cover.

Sadly, I have had minor issues since. At first, I wrote it off to tube microphonics, but now I think there is another problem: There is a slight low freq amplitude distortion of the EQ—which seems to pulsate in a sine pattern on the lowest notes of the E string. Swapping all of the signal chain, including power source, location, string brand, bass, and cab—all except the head—makes no difference. It is the head. I still use it all the time—and it still sounds better than anything else I've had!

Anyone else have this wo-wo-wo-wo low note weirdness?

 

[Crabby]

I would utilize that 5 year warranty Jim and get that taken care of. I recently bought a 4 year old used Powerhouse cab with a defective horn reset switch. My local warranty approved shop got her all fixed up with full coverage for parts and labor from Mesa. They do have a very good warranty.

 

[Jim Carr]

Guess so. Hey, I'm driving out there next week, WOW! I can take my amp right to Mesa!

 

[Chef]

There ya go!
It's been my experience that Mesa really care about making sure their product performs well for you.

 

[Jim Carr]

I'll try to update all Y'all as the road trip (to a friend's wedding), nears Petaluma. My problem is that I will be 4 hours to the south, and will arrive on Friday for the wedding. Looks like I will drive up to Mesa on Monday morning. Anyone have experience dropping off a repair at the "Boogie Factory?" Guess I should call.

 

[Jim Carr]

The Mesa folks (Rich Duvall) asked I bring it in Monday next at 9:30 WITH a cab and an instrument that will produce the problem. Now I need to prepare a demo...

 

[nervous]

Hi Friends, I have a little (probably very stupid) question regarding a Mesa 12AX7 tube. I was ordering a couple small cosmetic replacement parts for my new M9 and because it was all so cheap and they were all so helpful I thought I would add a new tube to the order A) so that I am starting from a like new starting point and B) I can keep the older one handy as a spare. Can't get hurt. However, they were out of stock on the plain old 12AX& but offered me the high grade 12AX7 (ECC 83) or SP12AX7 as I also believe they are called. It came today and I was about to install it but was surprised on opening the box to find that tube has some sort of ' heat-shrink' tube wrapped on it vs. the plain glass I am more used to seeing.

The stupid question is if that sleeve should be removed or if it's on there for a reason? FWIW it's on there like it's meant to stay but I am tube stupid and need and answer ASAP so I can button it up before practice tomorrow.

Thanks all

 

[Chef]

Huh....never seen that, myself.
Not sure what to tell you, other than call them and ask...

post up when you find out?

 

[nervous]

From what I can find that wrap is intended to remain on. Something about reducing microphonics and such.

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"MESA SPAX7 preamp tubes are a super-premium grade substitute for any 12AX7 positions - They are a "Special Requirement Preamp Tube" that possess an even higher standard of overall performance, due to their incredibly low sensitivity to microphonic noise - This is the ultimate preamp tube to use in all critical gain stage positions - It is the absolute best of the best!"

 

[Jim Carr]

Huh....never seen that, myself.
Not sure what to tell you, other than call them and ask...

post up when you find out?

I ordered a plain ol' 12-AX7 from them and it was not wrapped inside its little carton. I think we need a picture, but all I can say is there is no way a tube is going to be happy in a plastic wrapper. After all, vacuum tubes pre-date plastic/shrink wrappery weirdness, NO?

 

[nervous]

After all, vacuum tubes pre-date plastic/shrink wrappery weirdness, NO?

One would certainly think so but they are far smarter than I so until I can get the definitive answer I can't close things up. The only reason it's here is because they didn't have any regular ones available at the time of order.

 

[andrew]

I'm interested to know if this tube makes a noticeable difference to the tone of the amp.

 

[gravesbass]

Those tubes are designed to have the wrapper on it. I have a few of those and don't think it would be advisable to remove the black wrap. It's there for a reason. Mesa ships the M-Series amps with I believe Mesa branded JJ 12AX7 tubes. I would contact them directly and ask. would just install that tube and try it tomorrow. It can't hurt. They are higher grade tubes..... FWIW, I had both my gigging Mesa M9 amps modded with the latest mods and extra fan and they are pretty solid. I play at very loud volumes (x2 M9's w/412 PowerHouse Cabs ) and beat the hell out of them. So far, so good! Just make sure the amp has some room for cooling. I would use a 3 or 4 space rack, not 2 space... They get hot.

 

[nervous]

Another thread of info:

http://www.talkbass.com/forum/f15/mesa-sp12ax7-tube-677248/#post11482634

 

[GRoberts]

JJ12ax7's are great tubes for current manufacture. I use them in hand wired, boutique guitar amps and they sound great.

But it begs the question; should I throw one of my NOS RCA 12AX7's in there? They sound better in every guitar amp I've tried. I wonder if any difference would be heard in the Mesa Carbine? I seem to recall others reporting that changing the tube didn't have much, if any sonic impact versus the stock tube. But maybe I should give it whirl?

 

[Chef]

Sure, give it a shot...

I think Vic and I both rolled tubes thru the M6 at a point, and heard little/no diff.

 

[nervous]

Here's a little up close and personal for those who have not seen the insulator we're talking about:

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[Vic]

I think Vic and I both rolled tubes thru the M6 at a point, and heard little/no diff.

Yeah, I don't think the tube plays as much of a role in this amp as the tubes do in other models.

Here's a little up close and personal for those who have not seen the insulator we're talking about:

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Wow, that's interesting! I don't know if mine is like that. I'll have to check at some point.

 

[tombowlus]

Yeah, I don't think the tube plays as much of a role in this amp as the tubes do in other models.

+1 Same here. While my WalkAbout has proven to be one of my heads that is the most responsive to tube-rolling, the M6 is not as sensitive in this regard.