New to me MT-15

[claythomas]

So.....after waiting 9 months for the associate deal (which has now been postponed to December)
I bought a like new MT-15 off Reverb. Great seller,btw.....
Anyhow, I unbox the head, cable it up with my Plethora X5, wireless, Tremonti wah, and Boogie 2x12 Recto Vertical cab.
Put it on half power and flip the standby. Engaging the clean channel I instantly realize the settings are not anywhere like my Dual Rec 3 channel head, which has been my stage head for the last 15 years.
MAN!!! This head is loud!!!
And then I switch channels to the drive side!!! Am I glad my girlfriend wasn't home cuz it was glorius!!!!
I played for 3 hours , adjusting knobs, volumes, and cabs.....(I had a Mesa Recto 4x12 in there, too)
Very happy,needless to say.
But now, I want to retube the amp with new Mesa SP12AX7's and 5881's. Any reason I shouldn't?

 

[bodia]

Nice!

 

[andy474x]

So.....after waiting 9 months for the associate deal (which has now been postponed to December)
I bought a like new MT-15 off Reverb. Great seller,btw.....
Anyhow, I unbox the head, cable it up with my Plethora X5, wireless, Tremonti wah, and Boogie 2x12 Recto Vertical cab.
Put it on half power and flip the standby. Engaging the clean channel I instantly realize the settings are not anywhere like my Dual Rec 3 channel head, which has been my stage head for the last 15 years.
MAN!!! This head is loud!!!
And then I switch channels to the drive side!!! Am I glad my girlfriend wasn't home cuz it was glorius!!!!
I played for 3 hours , adjusting knobs, volumes, and cabs.....(I had a Mesa Recto 4x12 in there, too)
Very happy,needless to say.
But now, I want to retube the amp with new Mesa SP12AX7's and 5881's. Any reason I shouldn't?

No reasons here - not a huge fan of the stock JJ preamp tubes. Happy NGD!

 

[shimmilou]

So.....it was glorius!!!!
I played for 3 hours.......Very happy,needless to say. But now, I want to retube the amp with new Mesa SP12AX7's and 5881's. Any reason I shouldn't?

You described it as “glorious”, why would you feel the need to change anything?

 

[Egads]

^^^^This!^^^^

If you've got the tubes already, cool. If not, play the crap out of it, and enjoy!

 

[Deleted member 5962]

Agreeing with others. Use those tubes, then when they start to fade replace with your preferences. If I love an amp that much when I turn it on, I may only look at the V1 or PI up front, and leave the rest along for at least a while. Heck, they aren't even burned in yet.

 

[claythomas]

I already had the tubes . I'm an ex boyscout and always had spares for my Dual Rec.
I swapped those badboys in and it was even better than stock. I used the SP12AX7's and Green color coded 5881's. Sprayed the sockets with deoxit, wiped the overspray, and fired it up!!
Now I gotta spend more time with the Plethora X5 to get the noise gate where I want it....

 

[BrianC]

I did some tube swapping - makes a small amount of difference, but worth it. There are some threads here on it....

 

[Goran Lorencin]

I did some tube swapping - makes a small amount of difference, but worth it. There are some threads here on it....

Hey Brian, which tubes did you use instead of the stock?

 

[Goran Lorencin]

So.....after waiting 9 months for the associate deal (which has now been postponed to December)
I bought a like new MT-15 off Reverb. Great seller,btw.....
Anyhow, I unbox the head, cable it up with my Plethora X5, wireless, Tremonti wah, and Boogie 2x12 Recto Vertical cab.
Put it on half power and flip the standby. Engaging the clean channel I instantly realize the settings are not anywhere like my Dual Rec 3 channel head, which has been my stage head for the last 15 years.
MAN!!! This head is loud!!!
And then I switch channels to the drive side!!! Am I glad my girlfriend wasn't home cuz it was glorius!!!!
I played for 3 hours , adjusting knobs, volumes, and cabs.....(I had a Mesa Recto 4x12 in there, too)
Very happy,needless to say.
But now, I want to retube the amp with new Mesa SP12AX7's and 5881's. Any reason I shouldn't?

If you feel you need a different nuance of the MT15 sound, just do it (just put in the right tubes) ... you can still put the stock ones back if you don`t like it ... I have also been thinking of replacing one or two preamp tubes, maybe even the power tubes. It would be nice to have a dozen of them to test, so that I could hear the slight differences and choose the ONE, but looks like I˙ll have to go with the gut feeling as don`t want to spend that much money just for testing (do not make money from music).

 

[shimmilou]

How did you set the bias?

 

[Goran Lorencin]

How did you set the bias?

It is now set to around 27mV, am thinking of maybe even going a bit lower as the amp is very powerful. I`m also thinking of swapping a few tubes to see if it makes me smile more.

The biasing process is simple, turn on the amp, let it warm up, put it to full power(15W), take a multimeter/ampmeter, put the probes in the corresponding holes on the back of the amp, set the appropriate sensitivity (or keep turning the knob until you get a reading in the 20-30mV), take a reading and slowly correct with a small screewdriver (there is a hole near the bias ports - it is also mentioned in the manual). There are a few other threads on the forum where biasing is explained. If you need more info, just ask, there are highly intelligent beings on this forum

 

[shimmilou]

I meant what was your set point, thx.

 

[Goran Lorencin]

I meant what was your set point, thx.

It was at around 25.5-26.5 when I first measured it ... then I set it to a bit lower than 30, and then went a yet bit lower. My tubes are 1.5mV apart, which is in the vicinity of or like a matched pair.