Mesa / Boogie M Pulse 12AX7 tube replacement help?

[absentmindeduk]

Hello all!

So I've just absolutley skinted myself as a result of grabbing a bargain on a Mesa Boogie M-Pulse 600 head.

The guy I bought it off has had it for 3 years and never replaced the tubes.
It takes 2x 12AX7's in the preamp stage and the power amp is all mosfet as far as Im aware.

Although tonally it seems OK, I reakon there might be quite a bit of difference if I replace the tubes? Right?

He provided me with 1 spare unused mesa 12AX7 which I'm kind of looking to keep as a spare in case one knackers at a gig.

The stock mesa replacements are available for about £14 a peice.
However, I'm aware that there are a multitude of makes available, is there any real noticable advantage in picking something else?

Has anyone else done similar and have any thoughts?

[Hamster]

The choice of valve can effect the sound, and so you can choose what you want. A Sovtek 12AX7WB is warmer with more gain, while a JJ ECC83S has less gain but a bit more sparkle and imho colours the sound less. I tried both of these in an Eden head as preamp valves and that's what my ears heard.

[absentmindeduk]

[quote name='Hamster' post='771542' date='Mar 11 2010, 01:03 PM']The choice of valve can effect the sound, and so you can choose what you want. A Sovtek 12AX7WB is warmer with more gain, while a JJ ECC83S has less gain but a bit more sparkle and imho colours the sound less. I tried both of these in an Eden head as preamp valves and that's what my ears heard.[/quote]

So would I have to swap them both for a 'matched pair' (if such exists for 12AX7's) or can I swap them individually?

Short of buying like 3-4 different kinds of valve, theres no way I can test them really, which puts me off a little...

[thebassman]

[quote name='absentmindeduk' post='771559' date='Mar 11 2010, 01:15 PM']So would I have to swap them both for a 'matched pair' (if such exists for 12AX7's) or can I swap them individually?

Short of buying like 3-4 different kinds of valve, theres no way I can test them really, which puts me off a little...[/quote]

Have a look on Watford valves, they have lots of valve test reports available, link here [url="http://www.watfordvalves.com/cgi-bin/documents/testreport_2.pdf"]http://www.watfordvalves.com/cgi-bin/docum...estreport_2.pdf[/url].

Not sure how much difference changing the pre-amp valve makes though.
I always go for EH or Harma in my old/ current boogies.
Mesa do pick the best suited valves for there amps from EH or GT and re-brand them.

cheers

thebassman

[Mr. Foxen]

[quote name='absentmindeduk' post='771559' date='Mar 11 2010, 01:15 PM']So would I have to swap them both for a 'matched pair' (if such exists for 12AX7's) or can I swap them individually?

Short of buying like 3-4 different kinds of valve, theres no way I can test them really, which puts me off a little...[/quote]

No need to match. Swapping is fun.

[skankdelvar]

[quote name='Mr. Foxen' post='771581' date='Mar 11 2010, 01:34 PM']No need to match. Swapping is fun.[/quote]
Indeed. "Matching" tends to be reserved for output tubes. And even that's subject to debate, depending on the amp in question.

+1 on the JJ's.

[absentmindeduk]

Thanks a lot guys, that defo helps.

I didn't know that Mesa just re-brand them, I might just go for the stock replacements...

:-)

[Mokl]

JJ's sounded a lot better than stock valves in my Walkabout, if that's any use to you. Also tried EH,Groove Tubes and Ruby Tubes but the JJ's were my favourite.

[The Burpster]

I does make a difference what you put in. I recently swapped mine for the upgrade 12AX7SP Mesa valves and the difference was huge from the std valves. You kinda get what you pay for - or you might get lucky.

You dont need to change them just beacause they havent been changed - you could just be throwing money away. If you want to experiment with the tone then by all means play. Always have a spare set incase one dies (which you'll know about when it happens )
My guitard has had the same set of valves in his g'tar amp for 25 years without so much as a pop!

12AX7s are not the type of valve that needs 'matching' - that is normally (as stated above) output stage valves that work better if they are bias matched.

[thebassman]

[quote name='The Burpster' post='771757' date='Mar 11 2010, 04:02 PM']I does make a difference what you put in. I recently swapped mine for the upgrade 12AX7SP Mesa valves and the difference was huge from the std valves. You kinda get what you pay for - or you might get lucky.

You dont need to change them just beacause they havent been changed - you could just be throwing money away. If you want to experiment with the tone then by all means play. Always have a spare set incase one dies (which you'll know about when it happens )
My guitard has had the same set of valves in his g'tar amp for 25 years without so much as a pop!

12AX7s are not the type of valve that needs 'matching' - that is normally (as stated above) output stage valves that work better if they are bias matched.[/quote]

Hi the burpster

what Mesa amp are you talking about and in what way was the difference Huge?

I only ask as i have just bought my first valve state amp, M6 carbine combo, and was thinking about swapping the pre-amp tube for a 12AX7SP. Where did you get yours from?

cheers

thebassman

[absentmindeduk]

Yea, I did spy the Mesa 12AX7SP valves too...

[The Burpster]

Mine is a walkabout scout 112. Same set up as the M-pulse 600 just smaller MOSFETs. It uses 2x 12AX7s in the preamp stage (same as the M-pulse 600 and Carbine series).

The change was hard to describe, but if I said it makes it richer does that make sense...?

Its sound was a bit clinical (hi-fi) to me before the valve change now it seems deeper, and thicker without feeling muddy or distorted. My gitar'd who is a complete tone freek (tone is everything!) just said "wow" and thought it had a voodoo hex cast upon it.

EVERYTHING else in the chain was the same so its not down to a combination of changes.

The best way I can descirbe is relating it to coffee... do you drink yours black? If so you'll undertsand this.

std= Nescafe

12AX7SP = Columbian ground coffee from a cafetiere.

Oh and I got mine from hotrox nottingham.

[thebassman]

[quote name='The Burpster' post='773437' date='Mar 13 2010, 10:15 AM']Mine is a walkabout scout 112. Same set up as the M-pulse 600 just smaller MOSFETs. It uses 2x 12AX7s in the preamp stage (same as the M-pulse 600 and Carbine series).

The change was hard to describe, but if I said it makes it richer does that make sense...?

Its sound was a bit clinical (hi-fi) to me before the valve change now it seems deeper, and thicker without feeling muddy or distorted. My gitar'd who is a complete tone freek (tone is everything!) just said "wow" and thought it had a voodoo hex cast upon it.

EVERYTHING else in the chain was the same so its not down to a combination of changes.

The best way I can descirbe is relating it to coffee... do you drink yours black? If so you'll undertsand this.

std= Nescafe

12AX7SP = Columbian ground coffee from a cafetiere.

Oh and I got mine from hotrox nottingham.

Thank for the detailed reply.
I didn't even realise my carbine had 2 pre amp valves, I thought it had 1.

I might give them a try, just for an experiment.

Cheers

thebassman[/quote]

[voxpop]

I have just changed my stock 12ax7 on the Genz Shuttle 9. I tried the stock against a Groove tube and NOS Mullard. There were clear inprovements in detail, bass quality and tone with each change. The Mullard was a clesr winner as it is a classic Hifi valve but did cost a heavy £40 from ebay.

I would recommend buying a few and finding the one the suits your budget and ears.

I also tried a JJ and give give them a thumbs up................good clear sound with a clean midrange and OK bass.

Good luck.......its fun.

[SS73]

[quote name='voxpop' post='773530' date='Mar 13 2010, 12:12 PM']I have just changed my stock 12ax7 on the Genz Shuttle 9. I tried the stock against a Groove tube and NOS Mullard. There were clear inprovements in detail, bass quality and tone with each change. The Mullard was a clesr winner as it is a classic Hifi valve but did cost a heavy £40 from ebay.

I would recommend buying a few and finding the one the suits your budget and ears.

I also tried a JJ and give give them a thumbs up................good clear sound with a clean midrange and OK bass.

Good luck.......its fun.[/quote]

Mullard will win every time, no contest, military US tubes are good too, beware of Groove tubes these are just chinese cooking valves, all they do is select them, like matching their power valves in grades, so silk purse etc.

[umph]

[quote name='Mr. Foxen' post='771581' date='Mar 11 2010, 01:34 PM']No need to match. Swapping is fun.[/quote]
getting gain matched triodes can be useful in splitters

[The Burpster]

Thank for the detailed reply.
I didn't even realise my carbine had 2 pre amp valves, I thought it had 1.

I might give them a try, just for an experiment.

Cheers

thebassman


_________________________________________________________________

Bassman, the Carbine series do only have one 12AX7 -

The M-pulse series have 2.!

Bob.

[geoffbyrne]

You might want to have a look at this - follow the link under the pic:

[url="http://forums.musicplayer.com/ubbthreads.php/ubb/showflat/Number/2110479/Searchpage/1/Main/148913/Words/ecc83+/Search/true/Brand_new_tube_TubeTech_Blackb#Post2110479"]http://forums.musicplayer.com/ubbthreads.p...ckb#Post2110479[/url]

I've just been Googling these & it seems that Techtube Valves went bust, so I don't know if they are still being made anywhere.

If you want more headroom & decent tone, you could try a 5751 (70% gain compared to an ECC83) in the V1 and an ECC83 in V2. The ECC83 & the 12AX7's are theoretically the same, but the European-built ECC83's seem to have a mids-bump whereas the 12AX7's are pretty flat.

G.

Edited March 13, 2010 by geoffbyrne

[absentmindeduk]

[quote name='The Burpster' post='773437' date='Mar 13 2010, 10:15 AM']std= Nescafe

12AX7SP = Columbian ground coffee from a cafetiere.[/quote]

:-D
I do drink coffee and black is the way! lol.


[quote name='geoffbyrne' post='773766' date='Mar 13 2010, 05:55 PM']If you want more headroom & decent tone, you could try a 5751 (70% gain compared to an ECC83) in the V1 and an ECC83 in V2. The ECC83 & the 12AX7's are theoretically the same, but the European-built ECC83's seem to have a mids-bump whereas the 12AX7's are pretty flat.

G.[/quote]

I had a look at the link, some of this boggles my head! lol.
Thanks for the info though!

So the general consensus is JJ's are good, 12AX7SP, Mullard's def worth a look...
Prob stay away from groovetubes?

[The Burpster]

Yep sounds good plan.

Be careful of getting 'ripped' with Mullard tho' they havent been made for a long time and all sorts of folks are claiming they NOS.....

The Mesa tubes are selected Russian tubes but TBH I dont really care for 2 reasons. They are sold by Mesa so they come with thier back up, and they sound superb!