Mesa Boogie Studio Pre Bites Dust

Steve Stallings · Post by **Steve Stallings** » 2 Jan 2003 8:02 am

Just prior to going on New Years Eve, my MBStudio-Pre started making a funny high pitched noise. I smacked it on the side and it stopped and turned off. The fuse was fine.
I quickly took it back stage and opened it up. It looked like it had been dropped or something as the lights didn't line up with the front panel holes. All the tubes were ok.

I reached into and under the main circuit board to line it back up... ZAP!! I touched the caps by mistake and got a real jolt.

I noticed that one of the lines from the reverb tank was off... but I don't think this caused the problem. I don't have the reverb even turned on.

I'm at a loss as to what happened so I guess I'll have to take it into a tech. It is dead as of now.

I played the job using my PV Classic 50-212 which is what I use for guitar. It sounded ok, but not what I'm used to.

------------------
God Bless,
Steve
John 3:16

Bob Hoffnar · Post by **Bob Hoffnar** » 3 Jan 2003 12:37 am

Steve,
I had a beater Furman PQ3 I used as a backup pre amp one time. I got it for $80 and it turned out to sound better to my ear than the boogie studio pre and the vintage alembic pre I was using. If I remember right you use a VHT 2/90/2. You could use just about any gadget with a pre amp in it you have around to bump your signal up and that bad boy power amp will take care of the rest.

Bob

Chuck McGill · Post by **Chuck McGill** » 3 Jan 2003 4:56 am

I just put a rack together with a Mesa Studio
Pre. Is there any history of it being unreliable? I love the sound of the pre using the recording outs direct and fed to me
through ears. No speakers on stage at all.

Steve Stallings · Post by **Steve Stallings** » 4 Jan 2003 3:04 am

yeah... I've got the VHT power amp. Tonight I'm using a Evans stereo pre to drive it. I'm sure it will sound fine. I have not had the time to dig into the MB againg. First, I've got to check the tubes... after all, it looked like it had been dropped. I have never heard that the MB Studio Pre was unreliable.

------------------
God Bless,
Steve Stallings

www.thenightshiftband.net

Fred · Post by **Fred** » 4 Jan 2003 4:36 pm

Steve,

The squeal was probably caused by some form of positive feedback in the circuit. When when you hit it the feedback probably increased to the point that it used up all the headroom so no signal will pass.

This might be caused by the loose reverb wire wether the reverb is used or not. It's more likely that a tube was damaged when the preamp was dropped. Try replacing them one at a time.

Another possibility is that a solder connection cracked or broke or that a trace on the board broke. If you don't have a good tech send it to Mesa for repair.

Try the reverb and the tubes first.

Good luck!

Fre[This message was edited by Fred on 04 January 2003 at 04:38 PM.][This message was edited by Fred on 04 January 2003 at 05:06 PM.]

Ken Fox · Post by **Ken Fox** » 4 Jan 2003 6:11 pm

A microphonic tube will act the same way. I had a batch of Chinese ones in two different Peavy amps (Triumph series), all were making high pitched noises! Replaced them with NOS American tubes and had no more problems. I am now using the JJ/Telsa preamp tubes and have not been dissappointed yet.