tubes for a MKIIB

[thesjkexperience]

I am the original owner of a MKIIB, and it has been a very reliable and toneful amp. The amp is 23 years old now and I havent replaced the pre-amp tubes in all that time as Mesa said that if the tube doesnt give you trouble it is ok. The power tubes are about 5 years old but are low mileage (been on an acoustic kick)

The reason I ask is it seem like the amp doesnt have the push in the bass like it used to and single held notes sound a little fizzy, and occasionally ring modulator-ish sound.

In an amp this old could it be the pre-amp tubes, or does it need a cap job? I have also been playing a Victoria tweed deluxe and it has nice bottom and smooth rolled of highs, so my ear could have changed on what I am looking for in an amps tone.

 

[stokes]

A cap job in an amp this old will greatly improve the bass response and tighten up the overall response.I have an old Ampeg Gemini II with Amperex preamp tubes that have been in the amp since it was new back in the '60's and they are still fine.Preamp tube life will vary from amp to amp,so it is possible your preamp tubes are okay.I have no doubt a cap job will improve your tone.I change the caps in my MKIIC+,and all my amps as well every 8-10 years and always see an improvement.

 

[thesjkexperience]

Thanks, the amp has been so reliable I cant remember the last time it was in for a checkup. I did talk to Mesa a number of years ago and they did say if the pre-amp tubes are not microphonic dont change them or there is a possiblility of making things worse. The bass response of the amp is not as deep as I remember when it was new, so I was wondering if the tubes are beginning to show some wear.

What did the cap job cost you?

 

[stokes]

I do my own caps.Dont know what people are charging these days,but if you live in the NYC area,PM me and I'll tell you what I charge.

 

[thesjkexperience]

Thanks, but I am out here in Colorado and NY is just too far to drive for a re-cap

Any hints as to what brand of cap I should request?

 

[edgarallanpoe]

If the amp is 23 year old, it probably has some *killer* tubes. My guess would be Sylvania. While it is possible that you have a bad tube, my guess would be that the problem resides elsewhere. The only real way to determine it is to get the tubes tested. Find an old radio shop. I don't recommend that you take it to a guitar place because I have seen first hand people getting ripped off. They come in with an old Fender or Marshall and are told they have bad tubes, and get ripped off of Mullards or Tung-Sols or ..... Most radio shops really have little use for the tubes we use so they would be less likely to do this. Just my 2 cents.

 

[stokes]

Thanks, but I am out here in Colorado and NY is just too far to drive for a re-cap

Any hints as to what brand of cap I should request?

I use Sprague and F&T's only.