Mark IIB at the Tech for a Checkup

[DC3 Gridlock]

Bought this amp a few months ago and love it.

Checking filter caps, tubes, and swapping out the two outer EL34's (Simul-Class model) with two 6L6's.

Hoping this smooths out the overdrive tone a bit and I just prefer the tone of 6L6's over EL34's.

Any other items that I should ask the tech to check out?

Thanks,
Grid

 

[zebpedersen]

Check the switching relays. When I had a IIB they made my life miserable.

 

[revgsmall]

You may want to double check else where here on the Board but I did read that Simul Class has a higher tube failure with four 6L6's in it, versus the two EL-34s on the outer sockets.

 

[DC3 Gridlock]

You may want to double check else where here on the Board but I did read that Simul Class has a higher tube failure with four 6L6's in it, versus the two EL-34s on the outer sockets.

I've read the same but I contacted Mesa and they stated no issues. Probably need to stay with Mesa branded tubes.

Thanks,
Grid

 

[DC3 Gridlock]

Check the switching relays. When I had a IIB they made my life miserable.

Channel switching relays?

I'll mention this to the tech when he calls.

Thanks,
Grid

 

[stokes]

If it has the original filters,a re-cap will be necessary.If you want to "smooth" out the distortion,a NOS 5751 in V1 and/or V3 will go a long way to that end.If you have the money NOS 6L6's are nice too.When using 4 6L6's one pair will be very cold,the bias supply can be tweaked to get them closer.A general cleaning will be all else thats needed,should include socket re-tension.If the switching works,I wouldnt be too concerned,all he's going to do is try them,if they work,they are good.

 

[DC3 Gridlock]

If it has the original filters,a re-cap will be necessary.If you want to "smooth" out the distortion,a NOS 5751 in V1 and/or V3 will go a long way to that end.If you have the money NOS 6L6's are nice too.When using 4 6L6's one pair will be very cold,the bias supply can be tweaked to get them closer.A general cleaning will be all else thats needed,should include socket re-tension.If the switching works,I wouldnt be too concerned,all he's going to do is try them,if they work,they are good.

Thanks great advice. I will definitely look into changing V1 abd V3.

 

[DC3 Gridlock]

Picking up amp this weekend. Can't wait to hear it running all 6L6's.

 

[DC3 Gridlock]

Got my amp back from the tech that took well over a month to do the job but I amp pretty happy with the work.

Changed out the two outer EL34's (Simul Class) and the inner 6L6's with a new quad of Mesa branded 6L6's, filter cap changes, a few preamp tubes, a general checkup, and a new blue indicator lamp.

Sounds great with the quad of 6L6's, the clean is even better and the overdrive seems smoother though I have not really had a chance to ring out the amp since bringing it home.

The reverb is even more pronounced.

 

[DC3 Gridlock]

Got the amp back. Sounds great with the four 6L6's in the Simul-Class amp.

Kind of surprised not more interest in the results of this change.