ADA MP-1: From Japan with Love

fdesalvo

Member
Messages
436
Oh, looky here! A forum for rack stuff. I have been posting my preamp refurbs in the wrong forum all along.

Here’s a placeholder for my 27th MP-1 refurb. This one is coming in from Japan tomorrow and will include the following:

1. Semi or full electrolytic recap (up to 70 caps) depending on appraisal.
2. Opamp socket install and upgrade. 3-4 depending on appraised condition.
3. LED indicator upgrade
4. Pot and jack deep cleaning and conditioning
5. Solder joint refresh/reball
6. Circuit board chemical wash
7. Tube change
8. Input/Plate load/tonestack resistor upgrade to metal film
9. Battery receptacle install

More pics to come as I dig in and get down to business. Just some parts for the job.

 
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fdesalvo

Member
Messages
436
No, sir. Just a heap of pics on imgur and here on the ol’ gear page. I may put something together though. It’s a pain in the tuchis to have to copy and paste links.
 

fdesalvo

Member
Messages
436
And we are done for the night.

  1. New/upgraded filter caps made to withstand high temps and the rigors of life within a small enclosure
  2. Metal film pate load resistors
  3. LED refresh using clear/contemporary design keeping the traditional color scheme. The MP-1 is missing LED indicators on the Bank/0/1 positions from the factory. The solder pads and components are there, so I added them. Pretty cool.
  4. New Sovtek 12AX7LPS tubes
  5. OD1/2/Chorus trim pots tuned on the scope
  6. Added socket to battery pads + fresh Lion battery
  7. EQ opamp pads received a socket so the next user can experiment. This particular opamp has a nice impact onthe overall tone of the MP-1. New/stock LF347N installed per V1 design (shimmery high end).
  8. Mother and daughter boards chemically washed
  9. Solder joints refreshed
  10. What's left? Maybe nothing! She sounds fantastic!
The previous owner accidentally tightened down the right rack ear while a machine screw was in the rack itself (beneath the opposite hole on that ear), so there's a slight bend present. Hardly perceptible, but Ill see if I can straighten it out. Only real "defect" aside from some very light rack rash.

And now some pics from tonight's fun..



Ah , 1988 vintage. Pre circuit board cleaning.


Old filter caps trying to escape notice behind the newly installed batter/battery socket. None shall pass!


Ye olde LEDs.


New LEDs..


Hard to capture the true look. Very few have seen the first three LEDs lighted here. They don't come installed from the factory.



Carnage


Rest well, soldier. Your job is done.


Original Chinese 12AX7s and filter/bypass caps on the tube board.


New caps. Metal film plate loads installed (little blue dudes).


Cleaned up the old solder/flux from the filter pads and trans ground point. The latter revisions to the MP-1 have this ground moved off the board and onto the chassis. I prefer the original method. In my own amps, I always ground the center tap to the first filter cap's negative end. Ready for the new caps.


New guys in.


LF347N sits in its new socket. A TL074 can be safely swapped in (from the v2) along with several others for differences in tone/background noise. I’ve tried a few. Some offer reduced background noise, but moving away from the LF347N/TL074 really neuters the high-end sheen these are known for. Really takes the hair out of the metal, as it were. I happen to like my metal with a little hair.


Super clean


 
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jaykay73

Member
Messages
754
Beautiful work.

Cleaned up the old solder/flux from the filter pads and trans ground point. The latter revisions to the MP-1 have this ground moved off the board and onto the chassis. I prefer the original method. In my own amps, I always ground the center tap to the first filter cap's negative end.
Is this your method to convert chassis grounding to signal grounding? If so what method do you use to prevent ground loops?

JK
 

fdesalvo

Member
Messages
436
Thanks for posting! Looks amazing :)
Thanks for looking! It’s a labor of love.

Beautiful work.



Is this your method to convert chassis grounding to signal grounding? If so what method do you use to prevent ground loops?

JK
Hey, I just meant on the amps I build. There are folks who like converting these back to grounding at the filter cap and that’s fine. Same with the guys who like grounding near the power cord’s strain relief. Either method is fine and keeps the grounds with higher potential away from the smaller grounds on the other end of the preamp.
 

fdesalvo

Member
Messages
436
A little update. Noting major. Just doing a little refreshing around the input buffer. New caps and metal films. Ran out of bipolar caps (little yellow doods) and certain values of those metal films. Now I wait. To quote a once great man, “...the waiting is the hardest part”. Too soon, man. Too soon.

New caps are black/silver. You can see the one metal film I was able to replace this morning hiding under the brown bit of shielded cable.

 

mrwolf

Member
Messages
276
I think I saw a post that you did a similar thing to a JMP-1 and it looked incredible ??
What sort of cost is this upgrade ?
 

fdesalvo

Member
Messages
436
Thanks!

Yes, I did post the JMP-1 refresh and also a Hafler T-2. I think I have some pics from a recent Sansamp PSA-1 restore, too. I’ve also restored vintage amps and guitars. Anything I can get my grubby hands on. I Def need to put up a website with pics. I’ve forgotten how many projects I’ve had in the last several years.

I charge cost for parts and labor depends on what needs to be done. I do have time to pick up some repairs/refurbs, but I didn’t intend for this thread to turn into that haha. Send me a PM on what’s ailing your MP-1 and we can discuss.
 
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fdesalvo

Member
Messages
436
Send me your tired, your poor, your sick MP-1s. Haha I do work for others as time permits. Best way to contact me is:forgottengearrestorations@gmail.com.

I try to help people help themselves first and if they can’t sort it out or lack the necessary tools or experience, I can jump in to help resolve. A conversation is an easy place to start.

The key thing to keeep in mind is expectations. These old boys contain many obsolete parts, so some repairs require a donor unit, whose parts may be on the way out, as well. I have a couple spare units for such occasions, but it’s only a matter of time until the party ends.
 

fdesalvo

Member
Messages
436
Gah! Just missing ONE resistor and capacitor to finish this job. Well, then there’s tuning the trim pots.

Just finished tweaking the feedback loop around the output and will have the same done for the eq buffer soon. This will help in reducing background hissing. Huge shoutout to Francois for his pioneering efforts in tweaking these two areas.





 

fdesalvo

Member
Messages
436
She’s done. Sounds amazing! I really like the Bur Browns in this circuit and the background hiss has been reduced by ~15% by tweaking the feedback loops around the output and eq. Really pleased with the way this old girl turned out. Let’s close this one out.
 

fdesalvo

Member
Messages
436
Haha my recording desk is packed away. In the middle of a move, so all I can do is tease you mutants. I’ll try to describe it. It’s all MP-1, but it’s a little rounder and clearer. Chewy mids. More gain. Quieter all around. I really love these v1 top-switchers.

If this thing is still around by the time I finish the move, I’ll post up some clips. I’m going to be working on these until the big asteroid comes, so you’ll definitely get to hear how some of these mods translate.
 

fdesalvo

Member
Messages
436
The 3TMs are rad. I’ve been enjoying my preamps through ADA’s speaker cab sim since my recording gear is in boxes. Still not the same, but damn it tickles the itch and sounds fantastic.
 




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