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Author Topic: new to this board,reviving my old MP1 and have a few questions  (Read 3144 times)

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JeffGT

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Used it back in the day when racks got popular and looking to use it again.  I remember it was a good sounding unit but always wished for:
-a little smoother, less grainy sound (beyond tube swaps, tried those)
-less noise, a little less gain would would be fine as well
not looking to totally transform it, just some (to me) minor improvements.

I found the battery clip mod on here and did that last nite...great idea!

thanks in advance,
jeff
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rnolan

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Hey Jeff, welcome to the depot  :wave: .
Well there's a bunch of things you could do depending on your budget.  As you've done the battery mod I'm assuming you are ok with some soldering  :dunno: .
The noise mod is worth a look.  Basically replacing a bunch of electrolytic capacitors which unfortunately degrade with age so this one is a bit of a no brainer.
Depending on the use the units had, the input jack would have taken the most wear and tare, so worth replacing.  Is it a "top switch" Ver 1 unit ? (where you can change the output from inst level to line level ?) if so then the rear jack mod is worth doing.
The MDRT replacement transformer (available from MJMP here (http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm)) really opens up the unit and helps with noise.
You can change some (or all) the opp amps for better specked versions. There's a post on here somewhere where a member changed all the opp amps and carefully researched each one for the best he could find, he reported it sounded better than new...
My friend MikeB bought a new (stock) tube board from MJMP, so gold plated tube sockets and better/modern components.  Actually Mike has done all the above (except the opp amps) to his Ver 1 MP-1 and it's sounding great  >:D .

To reduce the gain, IIRC there are some trim pots for the OD stages  :dunno: you could tweak.  Or use lower gain tubes (either just one (and V1 would be the go) or both).  Or even use a 12AU7 or 12AT7 in V1 instead of a 12AX7, others have done this.

Apart from that, if you don't already, run it in stereo (makes heaps of difference) with a decent multi Fx unit.

Hope that helps.. ???
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JeffGT

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Thanks very much! Mine is one of the later ones, 2.01 version if that is correct?  I would definitely be interested in installing the new caps... is the 'how to' for that somewhere here on the board?  Would be willing to try the newer transformer as well...makes sense.  Looks like that would be $100 or so give or take.  I'll look for the post on how to adjust the gain trims as well.  Glad I found this place, much obliged!
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rnolan

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Hey Jeff, IIRC the instructions for the noise mod are in the mod section and also PCB layout charts.  To make things easy (and if you are going to pickup a MDRT from MJMP anyway) MJMP will sell you a "kit" with all the parts you need (also save on postage). Just either PM him on here or email him via his site.  He will also help you with the trim pots, MJMP knows these units better than most  :bow:

There are also lots of members who've done the mod (and various other updates) so can help you with tips and tricks etc if you need. Just post and ask  :thumb-up:

With the MP1 versions there are basically 2 main hardware versions ver 1 & 2, the main easily identifiable difference is ver 1 has a slide switch on the lid to change the main outs between inst and line level and ver 2 doesn't. The firmware version (EPROM) is what gets displayed when you boot it (eg 1.38, 2.0, 2.01).  The 2.01 EPROM was the last released by ADA for the MP1 which is the one you have  :thumb-up:
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Iperfungus

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  • Methodical killers do good jobs!

About tubes rolling, if you're looking for less gain, I would suggest a couple of 5751: same as 12AX7/ECC83 with 30% less gain.

If noise is the problem, I'm having good results with TAD 7025 and Ruby Selected JJ ECC83 tubes in my MP-1.

Waiting to send my unit to MJMP for some mods, BTW.
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On the run again!
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