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Author Topic: New MP-1 owner. Need help!  (Read 12131 times)

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aramism

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New MP-1 owner. Need help!
« on: Time Format »

Hi all.

First off nice to be here, it's cool to see a forum dedicated to just one amp!  :metal:

I just got my first MP-1, but have used them way in the past and at times during recording. It's worth noting I am a music producer that plays guitar and I have a collection of different amps and guitars for different situations. This is only for studio use, no live. So not too long ago I decided to get an MP-1. Anyway, I found a pretty good deal on craig's list and the guy gave it for very cheap but did tell me that he had not played it in years. So I got it anyway and it's not terrible or dead or messed up (actually cosmetically it looks brand new) but it has some issues and I was wondering how to address them. One more thing to note is that I'm not interested in any any distortion mods. I primarily got this for it's ability to do a shimmering and bright 80's clean.

So here are the problems:

1) It's way noisy. I put in fresh tubes, and will try the mesa SPAX7 for lower noise, but it's just a bit noisy, even in clean modes, ESPECIALLY with the chorus.
2) The input jack is messed up and only works when you pull the cable up. I guess that is an easy fix, just need to order a new jack and install it, right?
3) Sometimes when I go into edit mode, the LED flashing "bleeds" into the audio and I hear the "siren" type noise which is in sync with the lights.
4) I have to work extra hard to get it "clean". It's kind of gainy, not sure if that is just how it is. I have to get all 3 gain controls at or slightly under 3 for it to clean up, otherwise, even with single coils, it breaks up very easily. And I've tried with multiple power amps and cabs.
5) When I go into the voicing mode anytime I switch ss, tube clean or tube dist, the sound goes away period, and I need to go back into the presets and change the preset then the sound comes back. It seems to be ok going from tube dist to tube clean, but the ss kills the signal.

So these are the main things. I was hoping someone could help me in figuring out the cause of some issues and perhaps suggestions some upgrades which will not alter the tone much and make it be cleaner and easier to get nice clean tones out of it with minimal noise.


Thanks

PS - I attached some pics
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aramism

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Re: New MP-1 owner. Need help!
« Reply #1 on: Time Format »

can't attach for some reason so I uploaded to drop box


https://www.dropbox.com/sc/1yqcb5660guz3vt/AAB7a-DUCvk3wvLtixtiPcEQa






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rnolan

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Re: New MP-1 owner. Need help!
« Reply #2 on: Time Format »

Hey aramism, welcome to the depot, nice to have you here  :wave: . We'll do our best to help with your issues.  Some I can address now, some of them other members will be more help (e.g. the LED/siren issue, MJMP will hopefully be able to assist, it's not one I've come across before, and also may be an indication of why some of the other issues are happening ??).

Well it's no quite just 1 amp LoL although true say there's quite a bit on the MP1 preamp. I migrated to the newer MP2 when it came out years ago.  We also get into all the other ADA gear (MB1 (bass preamp), MP1 Classic (between the MP1 and MP2), power amps, FX, cabs). But also all the other bibs and bobs various here use in their respective rigs and of course a fair bit of chat about guitars/basses.

The Boogie SPAX7s work well in MP1 but are very high gain. For what you are chasing (more clean stuff) you may want to consider other low noise 12AX7s that have a little less gain (have a read through some of the posts in the Tube discussion area for ideas). Unfortunately, while the ADA preamps lasted well for many years they are getting older and noisier (capacitors wear out over time and some other bits). There's a few MP1 noise mods which help, how are you with a soldering iron ? A good resource for mods and spares is MJMPs site (http://www.marshalljmpmodshop.net/index.htm) and he's also very good "under the hood".

OK so I can see from the pics you have the first MP1 version (vers 1) as yours has the instrument/line level switch (slide switch accessed on the top cover). This switches the A/B main outputs for inst/line level (and generally need a clean by this age with decent contact cleaner). I had the same unit initially, it's now owned by a friend (MikeB) and he's going through the refurbish process currently (so can also help no doubt). For recording you probably should switch it to line level (but depends on your recording inputs (obviously)). Also big tip, run it in stereo, sounds heaps better. MP1 were designed to plug into a poweramp (or guitar amp input (hence inst level switch)) and cabs. So direct into desk/record the patches are very toppy (for 12" speakers). Most here use a cabinet simulator for direct recording (or mike up the cabs). Plenty on that topic here.

IIRC the front input jacks are no longer available (and they mount to the pcb so not a simple swap like a "regular" guitar jack). The rear input on the V1s is line level so you could plug guitar into desk channel and use Aux send to feed it, if so use a monitor send (pre fader). Most here don't like the line level input and just want it the same as the front (for rear unit patching access in their rigs).  MJMP has a mod which changes front jack to more normal non pcb mount style and replaces rear jack which is mounted on pcb and turns rear jack into inst level. This mod is a little bit tricky/fiddly depending on your experience with solder/desolder/pcb work (removing (desolder) and replacing the old jacks). But the instructions are easy to follow. MikeB and I (well mostly Mike) did this on his MP1 recently, took our time, all worked well.

They are a very gainy unit   >:D but you should be able to clean it up, also you could try turning the guitar vol(s) down. Lately I've been turning my JP Les Paul vols down to 2.5 - 3 with my MP2 (which have way more gain than stock MP1 BTW). I suspect though there may be some other issues at play ?? not to worry, I'm sure we'll work it out. Obviously for clean tones you wouldn't normally use the distorted tube voice (changes eq in tube circuit and adds gain). SS and clean tube voices should be able to do what you are after. The SS switching issue is interesting, others will know more than me about why that may be happening. BTW have you got the manual for it (http://adadepot.com/index.php?topic=111.0), and if your EPROM isn't v2.01 (the last available upgrade) then grab one from MJMP and change that out (that's a very easy upgrade). The version is written on the sticker on top of it (EPROM located toward front of unit on transformer end) but also displays on power up.

If it were me I'd be doing (or getting done by decent tech) all the mod/upgrades that Mike has/is done/doing (and he's chosen to keep it stock sound, as is also your desire):
EPROM upgrade
Rear jack mod (replaces front as well so fixes that (BTW Mike had exactly the same issue with front jack)
MP1  noise mod (the one you need depends on if you upgrade the transformer with MDRT which also helps from noise perspective and highly recommended for performance).
MDRT ( Machinator Developed Replacement Transformer) very worthwhile doing but depends on your budget, not essential however (depending on your perspective (i.e. to me it's a no brainer/must do)
New tube board, MJMP can make you one that has modern/better components but is stock sound (rather than the gain mod versions)
Battery mod (this will dump all the non factory patches as it keeps the ram alive), from pics, you have original battery, it will die soon, you can do the battery mod or just buy a CR2032 that has the connectors attached/on it (they have them in electronics/hobby shops) which should last another 20 ish years, if you don't change the battery soon, you risk loosing all your custom patches, so write them down, you can also save them to PC and reload (but also write them down just in case).
New Vol pot
Replace all the rear jacks and pots (not essential but good idea).

You can go further and replace all the opp amps (that you can get modern new ones of). There's a post where one our members did this, bigger job to do and he did allot of research to get the best opp amps he could but he said the difference was astounding.

So this should bring it up to about as good as you can and stay stock sound wise.

And hopefully we can benefit from your production expertise/experience in the recording area, the more ideas the better  :thumb-up:

Cheers Richard

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MikeB

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Re: New MP-1 owner. Need help!
« Reply #3 on: Time Format »

I can't add to much to what Richard has already said except i can say that when you switch one voicing to another the master volume gets reset to zero.  I guess this was prevent enormous sudden gain increases when switching to higher OD voices. The other preset values should stay the same.
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aramism

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Re: New MP-1 owner. Need help!
« Reply #4 on: Time Format »

Wow thanks for the reply.

Several things

1) I will check the master volume reset thing, maybe that's what it is! I hope so.
2) Regarding outputs and inputs: I am never going to use this straight "to tape". I have a whole bunch of different amps, power amps, cabinets, etc. and will be constantly experimenting with running it in stereo with a stereo power amp, or mono into the return of another head and different speaker/cabinet combos also. As I said, I am using this purely in a recording studio so I am looking forward to years of experimentation.
3) I am ok with soldering but ultimately will have either a trusty local tech or my friend who is extremely good with this stuff do it. I'm just kind of doing the research to figure out what I need.
4) Can you point me to a good thread about pre-amp tube suggestions? Or make suggestions? I did spend hours trying to find it and it was somewhere on here I heard about the mesa spax7. I have many mesa amps and am aware of the high-gain nature of their 12ax7s but I just heard that the spax7 is so low noise that it would help quiet down the mp1. If there is a better low-gain but extremely low-noise preamp tube out there I'm all ears, because as I said, aside from just personal satisfaction and just jamming out to some nice distortion tones ala nuno, the primary goal of this amp professionally speaking is to attain a nice chimey and bright (not shrill) 80's clean guitar tone sometimes with it's own chorus, or with something like a tri-chorus. So really a tube that is low-gain and better for cleans would work great due to the fact that as you said, this preamp has a tone of gain.
5) Mods: I don't mind mods, but I don't want to change or upgrade the tone, I want to keep it as original as possible. My main goal is to just quiet down the unit and make it function good. I'm not looking to do anything that alters the tone much.

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aramism

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Re: New MP-1 owner. Need help!
« Reply #5 on: Time Format »

Oh and thanks for the link to the marshalljmp site. That place looks great!!
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MarshallJMP

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Re: New MP-1 owner. Need help!
« Reply #6 on: Time Format »

Maybe if you're looking for clean sounds only,you could lower the OD1 and OD2 trimpots (this lower the gain and noise).Start with the OD1.
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aramism

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Re: New MP-1 owner. Need help!
« Reply #7 on: Time Format »

Ok will try but even when I dial in a clean sound, it gets noisy. And when the chorus is on it's even more, not to mention the weird LED sound.
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MarshallJMP

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Re: New MP-1 owner. Need help!
« Reply #8 on: Time Format »

Is it noise or hum (or both)?

The led sound,do you also get on clean sounds?
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aramism

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Re: New MP-1 owner. Need help!
« Reply #9 on: Time Format »

Both noise and hum. Obviously the distortion channels it is much louder but it's there with clean as well. I've tried several different guitars. Modern humbuckers take it better but still much noisier than any other amp I own and I have some other vintage stuff dating back to the 60s and 70s.

The LED noise kind of went away, then again it was intermittent anyway, so if it comes back I will document it.

Here is the video of the noise:https://db.tt/U6v33PiT

Also, I suspect some general maintenance work needs to be done I found a couple of these bad boys: https://db.tt/qIUIjrmu
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rnolan

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Re: New MP-1 owner. Need help!
« Reply #10 on: Time Format »

That cap doesn't look happy  :facepalm: and I agree some general maintenance is a good idea, but while you have it being serviced do as much of what I posted as you can, none of those mods are designed to change the tone/gain etc just make it as quiet as you can due to various parts aging (caps harden internally over time etc.). This is basically what MikeB is doing, trying to bring it into the now.
The noise hum will be reduced by the input jack mod I suspect and the smallest MP1 noise mod will also help (if you don't go MDRT), hey it all will help incrementally.

Tubes is a very subjective area. The boogie tubes are just re badged and highly tested tubes from others, mostly JJs which are quite 2 dimensional but great gain and distortion (and best feedback I've heard so far). Personally, I like the new sensor Mullard reissues (long plates), very 3d tubes and IMO would suite what you want. You can also put in 2 different tubes (many here do) for various reasons. IIRC Mike has a Mullard short plate in V1 and a spAX7 in V2 which works for him. I think SC runs a NOS Mullard and a TAD reissue ?, the TADs are probably the closest to the original tubes (no brand Chinese bottles). All these tubes are low noise (lots of posts here http://adadepot.com/index.php?board=38.0) but all sound quite different. Also MJMPs advice re trim pots will/can make a big difference to the gain in the V1 and V2 circuits and lower gain = less noise.
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MarshallJMP

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Re: New MP-1 owner. Need help!
« Reply #11 on: Time Format »

What happends if you turn down the guitar volume pot,does the noise go away (or is it less)?
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aramism

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Re: New MP-1 owner. Need help!
« Reply #12 on: Time Format »

That cap doesn't look happy  :facepalm: and I agree some general maintenance is a good idea, but while you have it being serviced do as much of what I posted as you can, none of those mods are designed to change the tone/gain etc just make it as quiet as you can due to various parts aging (caps harden internally over time etc.). This is basically what MikeB is doing, trying to bring it into the now.
The noise hum will be reduced by the input jack mod I suspect and the smallest MP1 noise mod will also help (if you don't go MDRT), hey it all will help incrementally.

Tubes is a very subjective area. The boogie tubes are just re badged and highly tested tubes from others, mostly JJs which are quite 2 dimensional but great gain and distortion (and best feedback I've heard so far). Personally, I like the new sensor Mullard reissues (long plates), very 3d tubes and IMO would suite what you want. You can also put in 2 different tubes (many here do) for various reasons. IIRC Mike has a Mullard short plate in V1 and a spAX7 in V2 which works for him. I think SC runs a NOS Mullard and a TAD reissue ?, the TADs are probably the closest to the original tubes (no brand Chinese bottles). All these tubes are low noise (lots of posts here http://adadepot.com/index.php?board=38.0) but all sound quite different. Also MJMPs advice re trim pots will/can make a big difference to the gain in the V1 and V2 circuits and lower gain = less noise.


Aren't the spax7 specially made for lower noise than traditional 12ax7's? In other words, I don't mind other brands, particularly mullard, but the spax7 has a different design from what I understand to be extra low noise.

Also, what is the input jack mod? Did I miss that? The way it is now is super annoying.


Regarding guitar volume: I will test that tonight.
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MarshallJMP

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Re: New MP-1 owner. Need help!
« Reply #13 on: Time Format »

The rear jack mod replaces the front and rear input jack so both inputs are instrument level input.
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rnolan

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Re: New MP-1 owner. Need help!
« Reply #14 on: Time Format »

Also the rear jack mod replaces the front jack with a standard style jack rather than the original PCB mounted jack which are now hard to come by (check out the pic http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm). The rear jack is PCB mounted and is a direct replacement. If you can source the correct PCB mount front jack (it's different from the rear PCB mount jack) you can just change that and leave the rear jack as a line level in.  I don't know where you can buy a correct replacement for the front PCB mount jack though so the rear jack mod makes it all too easy and gives you inst level on the rear jack (which the later MP1s and MP2s use).

With boogie tubes it's mostly marketing, The boogie branded (they don't make or design tubes) spax7s are just specifically selected (when boogie test them (they test them for a range of things, also gain, microphonics etc)) to be the lowest noise of the already low noise batch of JJs they buy (or whatever, they don't always use JJs). The difference between a STR SPAX7 - A and a STR-12 AX7-A (apart from low noise test results (and price)) is the SPA has a rubber(ish) collar around part of the tube (so you can't see that they are exactly the same (very short plate) design inside, it looks cool  O0 and would help a little to reduce microphonics).
Each tube is slightly different, the reason you'd buy a boogie "branded" tube rather than a JJ is they have a very strenuous testing regime (they throw any back that don't pass). Groove tube do much the same thing and re-brand the tubes made by others (as does Ruby etc).  All the decent tube sellers (e.g. Dougs Tubes) also do similar testing and only offer up the good ones so if you bought a JJ from them it will typically be just as good (but heaps cheaper, boogie tubes are very expensive, usually more than double the price (well here in OZ)).  The New Sensor Mullards are a reissue of the original super low noise (for HiFi) Mullard tubes and they are a different design, hence more 3D (particularly the long plates, they also do a short plate version).  Typically short plate designs are a little less microphonic than long plates (so if you are playing at ear bleeding levels >120db it may help a little). JJ do short and long plates also.  All the tubes I mentioned previously are super low noise, high gain and low microphonics.  At this end of town (where we only want the best of the batch) the main differentiation is the sound. They all sound different so you need to pick a tube that suits your needs/style.  E.g. if you are going super high gain (in say MP1 3TM), JJs are tried and true (spax7 are a good fit here but will cost double the JJ price for no particular benefit/difference as long as you get well tested JJs). Have a read through the All Things Tube (http://adadepot.com/index.php?board=38.0) posts, this is a very subjective area and there is good discussion on what and why various members like different tubes.  Also some attached/posted articles regarding tubes that are well worth a read.

BTW SPAX7s wont solve your noise issues (if that's what you are thinking (won't hurt though)). Hey they are great tubes, but I'm looking at a > $50 dud right now that pretty much failed from the get go in Mikes MP1. If your not chasing a super high gain distorted sound there are better tube choices at more reasonable prices.
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