Can some one please tell me how to adjust the trim pots for gain ? And where they are located? I have the first version. I think they are set a little low. It is very quit and I am thinking they have been turned down from the previous owner. The preamp has JJ ecc83s tubes in it that are newer tubes. I owned one of these when they first came out. I remember the preamp having a lot more gain. Thanks
Never mind. I got it figured out.
Hey d1469d, what was the issue ??
The trim pots for the gain were turned down. I turned them up a bit. I just got the preamp last week off eBay. It sounded a little week from what I remembered it being. It came with brand new tubes.JJ ec83s I think. I new it had more gain than what I was getting out of it. With a little research and asjusting, I think I have it just where I want it. This thing kicks ass. I am taking it to band rehersal today. We play a bunch of 80's and some funky blues so I am excited about all the different tones I can get.
Excellent :thumb-up: , there is a post (here somewhere) from MJMP re setting the trim pots but requires a scope. Do you have a MP1 or MP2 ?, they both kick ass, enjoy (IMHO the ADA MP1/2 preamps are the best ever made, the tone cloners are getting better but....I'm sorry, real is better). The JJs are a very good fit for ADA preamps particularly the MP1, I prefer the Mullard re-issues in the MP2
A little late, but these might help:
(http://i1240.photobucket.com/albums/gg481/GuitarBuilder/ADA/ADAMP-1TrimpotLocationsandFunction_zpsad906a12.jpg)
I have the MP 1. It sounded great at rehearsal cranked. Thanks for the photo. I turned the correct ones. That is a relief. I was just going by what I read and by listening to the preamp. I could not really see much in other pictures I seen. Do you guys have yours modified? Mine is very quit even with the trim pots turned up and I have lots of gain. I was told from the original owner no mods were done to it. I am running a noise gate off my Rocktron Replifex which helps.
Cool, glad it's working well (ADA heaven). Seems the MP1 noise mods are popular, particularly with very high gain players so it depends a bit on how you play, the MDRT transformer upgrade is also a very good idea regardless.
Man I just "Tweaked" my T/Pots & HOLY CRAP....What a difference! Especially in my Chorus it sounds I-N-S-A-N-E on the S.S. :banana-trip:
rnolan,
What is the benefit of a MDRT transformer?
Is it worth doing with a stock MP-1?
My sound guys are complaining about noise, so the noise mod is in my near future.
David
What exactly does adjusting the OD2 trimpot do? I know the OD1 trimpot adjusts the amount of signal hitting the first gain stage but other than that I was told never to touch any of the other trimpots...Especially OD2
Quote from: trader144 on July 08, 2014, 06:04:47 PM
rnolan,
What is the benefit of a MDRT transformer?
Is it worth doing with a stock MP-1?
My sound guys are complaining about noise, so the noise mod is in my near future.
David
Hey David, check (http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm). The original transformer was not so great, Machinator designed a new one (well it looks like 2 in one ?) apart from being 240v/115v friendly it helps reduce noise and gives better performance. It's a very worthwhile mod though not cheap (I assume because they are custom made in small numbers). If I still had a MP1 I'd do the noise mods and MDRT
Cheers Richard
Quote from: jarrodthebobo on July 08, 2014, 09:38:13 PM
What exactly does adjusting the OD2 trimpot do? I know the OD1 trimpot adjusts the amount of signal hitting the first gain stage but other than that I was told never to touch any of the other trimpots...Especially OD2
Hey Jarrod, check other threads here (search on OD2 ?), MJMP posted advice re trim pots in a few places. IIRC it adjusts the gain in the OD2 circuit.
Quote from: RandallRG on April 06, 2014, 09:22:57 PM
Man I just "Tweaked" my T/Pots & HOLY CRAP....What a difference! Especially in my Chorus it sounds I-N-S-A-N-E on the S.S. :banana-trip:
Can you please comment more on this?