Mark IIB at the Tech for a Checkup

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

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

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.

revgsmall said:

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.

Click to expand...

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

Thanks,
Grid

zebpedersen said:

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

Click to expand...

Channel switching relays?

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

Thanks,
Grid

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.

stokes said:

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.

Click to expand...

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

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

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.

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.