The Boogie Board

Discussion Forum for Mesa Boogie Products
It is currently Tue Dec 18, 2018 3:50 pm

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: 2:90 12ax7's?
PostPosted: Tue Oct 09, 2018 6:26 am 
Offline
Bottle Rocket

Joined: Tue Sep 29, 2009 9:42 am
Posts: 17
Hey all,
I have been away from "TBB" for a while..But as all ...We finally come back
I have one question about the 12AX7's in the 2:90...???

What does anyone suggest?

I hear that we need balanced..and I hear that balanced is a load of BS..

Do the PI need to be balanced?

Will any particular tube make a difference?

I have some new Mullards 12ax7 and 4004 and some Elecro harmonix ...

Any suggestions would be helpful



Thanks

_________________
Frost his bag!


Top
 Profile  
 
 Post subject: Re: 2:90 12ax7's?
PostPosted: Tue Oct 09, 2018 12:08 pm 
Offline
Mark II
User avatar

Joined: Fri Nov 16, 2012 4:55 pm
Posts: 126
Location: East Coast, New Jersey
Not sure how similar the guts of a 2:90 are compared to a 295, but I've thrown in what ever 12ax7s I've had into it.

I picked up a used 295 back in 01' or 02' which didn't have any 12ax7s in it. I had a pair of Mesa branded ones and pair of Groove Tubes and put them in. I didn't even bother to check the socket assignments. The 295 is symmetrical in it's physical layout so I mirrored one side to match the other. It worked and I haven't changed out those tubes since.

I have two 295s and they sound pretty similar. One having all Mesa branded and the other has a mash of Mesa, Groove, Tesla and GE. The all Mesa power amp have the exact same 12ax7 in all four slots.

Like I said, I'm not familiar with the 2:90 but I would think it would accept any 12ax7. I'd really like to hear those Mullards, though. :mrgreen:

_________________

93 97 98 PRS CE24
94 98 G&L Legacy
94 G&L ASAT Special
95 G&L S-500
99 Peavy Wolfgang
11 Gibson LP Studio 60

69 Bandmaster Head
88 Quad Pre
91 & 92 Simul 295
92 DC-5
96 Mark IV Maple/Wicker
98 5150 combo
08 Mark IV Wide


Top
 Profile  
 
 Post subject: Re: 2:90 12ax7's?
PostPosted: Sun Oct 14, 2018 5:38 am 
Offline
Bottle Rocket

Joined: Tue Sep 29, 2009 9:42 am
Posts: 17
jediguitarist wrote:
Not sure how similar the guts of a 2:90 are compared to a 295, but I've thrown in what ever 12ax7s I've had into it.

I picked up a used 295 back in 01' or 02' which didn't have any 12ax7s in it. I had a pair of Mesa branded ones and pair of Groove Tubes and put them in. I didn't even bother to check the socket assignments. The 295 is symmetrical in it's physical layout so I mirrored one side to match the other. It worked and I haven't changed out those tubes since.

I have two 295s and they sound pretty similar. One having all Mesa branded and the other has a mash of Mesa, Groove, Tesla and GE. The all Mesa power amp have the exact same 12ax7 in all four slots.

Like I said, I'm not familiar with the 2:90 but I would think it would accept any 12ax7. I'd really like to hear those Mullards, though. :mrgreen:



Thanks Jedi,
After posting this I did see there was a few questions asking the same thing..

I have only recently purchased it ..And it sounds great.

So what I did was ..

Take it out of it's rack , unscrew the top,
See that they are MESA tubes in there
1 was a 12ax7a ...the other two were 12ax7..
Got scared!
Put them back in ..
Re-screwed and put it back in rack!!!

WEAK!!!!

I know nothing about why one would be an 'A' ...and the others not!

It is IMPOSSIBLE to actually roll these tubes...

I will have another go soon...

Is there a difference???????

_________________
Frost his bag!


Top
 Profile  
 
 Post subject: Re: 2:90 12ax7's?
PostPosted: Sun Oct 14, 2018 5:49 am 
Offline
Bottle Rocket

Joined: Tue Sep 29, 2009 9:42 am
Posts: 17
I actually meant I purchased it second hand..
Is a blue light and has a mixture of GT, Ruby, Svetlana 6L6's in it..

Its a bit noisy..

_________________
Frost his bag!


Top
 Profile  
 
 Post subject: Re: 2:90 12ax7's?
PostPosted: Sun Oct 14, 2018 9:30 am 
Offline
Mark II
User avatar

Joined: Fri Nov 16, 2012 4:55 pm
Posts: 126
Location: East Coast, New Jersey
Most likely, the 12ax7-a is V1
While the other two are for the PI

V1 is located nearest the input jacks on left of the rear panel.
V1a - (left tube) is the Input Stage for Channel A.
V1b - (left tube) is the Input stage for Channel B.
V2 - (center tube) is the Phase Inverter for Channel B.
V3 - (right tube) is the Phase Inverter for Channel A.

I can't really say if it will make an audible difference.

I got this info from this link.
https://mesaboogie.zendesk.com/hc/en-us/articles/224863767-How-are-the-Tubes-arranged-in-a-Simul-Class-2-90-I-vs-II-

You might want to check which version you have, as the Class A and Class AB sections are different in each revision of the power amp.

_________________

93 97 98 PRS CE24
94 98 G&L Legacy
94 G&L ASAT Special
95 G&L S-500
99 Peavy Wolfgang
11 Gibson LP Studio 60

69 Bandmaster Head
88 Quad Pre
91 & 92 Simul 295
92 DC-5
96 Mark IV Maple/Wicker
98 5150 combo
08 Mark IV Wide


Top
 Profile  
 
 Post subject: Re: 2:90 12ax7's?
PostPosted: Fri Oct 19, 2018 7:49 pm 
Offline
Mark II

Joined: Tue Sep 15, 2015 4:49 pm
Posts: 56
Location: Gold Coast, Australia
Hi there,
I’ve got Electro Harmonix in mine at the moment, have tried Mesa Chinese and Russians in it as well as the SPAX7’s. the only thing that really changes a bit is the noise level just slightly. Any 12ax7 can go in any place. 2 volume levels to compensate so it doesn’t really matter about balanced.

_________________
Mesa Dual Rectifier, TriAxis, Recto Recording,
2:90, 2:100, SUS-4 16ru Case,
Flux Five, Throttle Box EQ, 5 Band EQ,
Straight Traditional 4x12 Cabs.
And other stuff!!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group