Triaxis with TX4 vs TX5

[SigiZ58]

Hello,

I have bought just a(nother) used Triaxis

The Triaxis I had already is one with the TX4 Board, no PHAT Mode
The second I got now has the TX5 board.
I am running through a 2:ninety

Honestly speaking - I am so disappointed with the model with TX5 board, but I am unsure about the reason.
The new one has a compete much more darker sound in all modes. It is like a blanket over the speakers - very dark sound. The clean sound also seems to distort a bit. The seller told me, the Amp came from Mesa Boogie Switzerland and was setup fine. I start to believe this isn't well done.
Would I have not the direct compare to the other one, I would not think the Triaxis is a great preamp.....

But I heard already, the never versions would sound different, but I thought this was focused on LD1.

Any Ideas ? Did I get a piece of Crap or does the newer ones (TX5) really sound so bad (dark and exaggerated mids) on all modes compared to those (mine) with the TX4 board ?

Can it be mine is only bad calibrated ? Of course I changed already the tubes, but they seem all to be new and it did not make any difference (I use always MESA Tubes)

Can I sell it without having bad feeling that it might be defective ?

Thank you

 

[Old BF Shred]

I have heard many times that the pre- PHAT mod w/ TX4 (rectifier) board units are more desirable. I have one and it hardly sounds like the TX5 unit you describe.
Your earlier triaxis, I suspect, sounds more lively and seems to be the one most folks want.

I would not have thought the difference is as great as you describe, and am also wondering if it needs some attention, service-wise. Hopefully others with an experience similar to yours will chime in and let you know what to expect.

I do know that the ribbon cables in some of the earlier triaxis units can and may go bad. I know as I had to replace almost all of them in mine. With a bad ribbon, it will sound lifeless (at least to my ears).

The good news is, if that is all that's wrong, the cables are not too expensive and fairly easy to replace.
Perhaps call Mesa and get their opinion on this. Seems to me, IIRC, I have read that the PHAT mod can be reversed.

Best of luck!

 

[crane]

Have you tried to swap all tubes from a TA to the other ? Mesa branded tubes have changed producer many times, and if the TX5 has the JJ relabelled tubes it could really be dark for sure.

 

[SigiZ58]

Hi,

many thanks for you input.

I swapped the tubes, but there is - maybe unbelievable . almost no difference in sound.

I test most with preset 4, Ry1. Still it is, as if the treble is set all ways down. I can get a bit more highs by set presence and treble to 10, while reducing bass and middle to allmost zero. And still it seems lifeless. Also it sounds a bit distorted to my ears, even it should not in RH1 with gain set to 5 (SC Pickups)

I think the idea to check the ribbons is good. The Amp was opened and checked by me already. It is clean and you see it got a service not long ago - looks almost like new inside..... Also you get no change in sound when moving wires or make soft ticks to suspicious places. It even does not hum like my old Triaxis....

The TX5 is the the board (>T8296) with the LD1 "Classic Boogie Lead" , not the Rectifier with PHAT Mode and so can not be reversed because this would need a different mainboard and a TX4 instead TX5 board.

I think I will check the ribbons and hope to get also further input.

Thank you all very much

 

[Jackie]

AFAIK the only tonal change that should happen is in the LD1 Red mode, not other channels as well. I have a non-fat TriAxis and it doesn't sound dark at all.

I think you may have a dud.

 

[JMMP]

Everything the OP is describing is how I would have described my tx5 rev triaxis in comparison to my quad. Although played through an IR, a lot of it seemed to go away.

 

[jeff5]

There technically should be no change to the other channels regardless of what board is in there for Lead 1 Red. I have the TX4 no fat (had it removed) and it is not a dark amp at all. Either it's a tube issue, or something is wrong with it. You should definitely give Mesa a call. They are really helpful.

 

[SigiZ58]

I have to thank everyone for these helpful inputs.

Think I have resolved the issue now.

When I opened the Triaxis, my eyes were caught by a strange element. It was a piece wraped in black isolator, conncted to the +/- 15V. A LDR near the input was opened and this element had been put between.

As the Amp was checked by a service I thought at first this would be part of the new series. But a strange feeling made me unwrap this piece. What I found was an obvious hand-made small pcb with a few resistors and a TL72. After thinking for a moment, i decided to remove this pcb, had only to close the legs of the LDR again.

Yep - now the sound is nearly the same as with my other unit. I cannot understand, how and why someone could add such a piece of crap in the input stage of an Amp like the Triaxis. A dark "mod" ? Better use the 2:ninety.....

Thank you again

 

[Old BF Shred]

Awesome!
Love it when the solution costs nothing but a little time!
Good troubleshooting! :wink:

 

[stephanovitch]

Hi SigiZ58,

are you able to post pictures of the guts of your Triaxis please?
I search the value of a big white square resistor since many months.

Stef

 

[SigiZ58]

Hi Stef,

you mean pictures of the TX5 board ? Or can you describe which resistor at which position, then I can help you of course

 

[stephanovitch]

After many searches of information about TX5 board, nothing!
It will be the first pics of this PCB!

 

[stephanovitch]

Hi SigiZ,

have you had time to take pictures?

Stef

 

[SigiZ58]

Here we go!

The TX5 board
It is single-sided one layer, so no backside shot necessary

 

[stephanovitch]

Many changes had been made :shock: !

 

[steve_k]

Maybe it has had the presence mod done to it?

Check C6, next to the IC4 Op Amp in the middle of the main board. If it is a .01uf, it has been modded to be darker. The stock cap is 10uf.

 

[SigiZ58]

Thank you for your input, Steve_k

I found the problem already, as I described some posts earlier.

 

[Demon Of The Fall]

Thank you for your input, Steve_k

I found the problem already, as I described some posts earlier.

Hi all, now you found the problem, how different are LD1 Red mode in the two units ? could you upload a sound test comparison ?

Thanks in advance
DZ