2:90 12ax7's?

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Squidz66
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2:90 12ax7's?

Post by Squidz66 » Tue Oct 09, 2018 6:26 am

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
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jediguitarist
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Re: 2:90 12ax7's?

Post by jediguitarist » Tue Oct 09, 2018 12:08 pm

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

Squidz66
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Posts: 17
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Re: 2:90 12ax7's?

Post by Squidz66 » Sun Oct 14, 2018 5:38 am

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!

Squidz66
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Re: 2:90 12ax7's?

Post by Squidz66 » Sun Oct 14, 2018 5:49 am

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..
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jediguitarist
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Re: 2:90 12ax7's?

Post by jediguitarist » Sun Oct 14, 2018 9:30 am

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 ... 0-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

MesaMad1378
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Location: Gold Coast, Australia

Re: 2:90 12ax7's?

Post by MesaMad1378 » Fri Oct 19, 2018 7:49 pm

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!!

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