Studio Preamp Trouble

The Boogie Board

Help Support The Boogie Board:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Catch

New member
Joined
Jan 2, 2010
Messages
4
Reaction score
0
I've owned a Studio Preamp that I run through a Simul 395 since the early nineties (94 maybe?), and my tone has always been satisfying. However, I have been have trouble with distortion at the edges of my sound on the clean channel for quite some time. I've had two authorized Boogie repair shops take a crack at it. The first worked for a while, while this last fix lasted about a day. I've also had a few bad tubes so I feel as if I'm constantly cracking the top off for some odd problem.

I think the tech replaced caps in both cases. I know that tubes were not an issue in the most recent case. Oh, the first shop also had to replace the reverb tank because it busted.

Has anyone owned a Studio pre or even a Quad and experienced similar problems. The last tech said the recording outputs were pristine and I need the unit fixed for recording during the month of February.

Thanks in advance.
 
When I used to own a studio I think I had the same problem where the clean was getting a little bit distorted the problem ended up being failing LDR's after I replaced a couple the problem went away and it never returned. Hope this helps
 
Thanks! The tech has replaced a few caps and put in a great 12AT7 for the reverb.

Sorry, what's an LDR?
 
Catch said:
Thanks! The tech has replaced a few caps and put in a great 12AT7 for the reverb.

Sorry, what's an LDR?

A LDR is usually a light dependent resistor - like a photo-electric cell. But I wouldn't have thought there would be one of those in an amp! Perhaps it's a load resistor in this case?
 
they are used for switching if one of the lead channel Ldrs starts to fail and leaks it can bleed the lead channel into the clean channel.

000_0010.jpg



I have circled the ldrs in red if you can see it.
 
That's gotta be it, sounds like what's going on because the amount of "bad" distortion in the clean channel must have been changing as I went between low and hogh gain on the dirty channel. Let me know if you're ever in DC, I'll by you a drink.

Thanks!
 
If you turn the lead drive to zero and the distortion goes away in the clean channel the ldrs are definately the problem. The lead channel only uses 2 Ldrs but I cant remember which to,
the middle 2 I think
but I would replace them all if one is starting to fail the others probably are not far away
 
I live in Australia where voltage is 240v and I got my pre from USA which is 120v since I had room inside the unit I decided to fit it there so I didn't have to deal with carring around a step down tranny.

I got the LDRs from RS Components in Australia.
 

Latest posts

Back
Top