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Author Topic: MP-1 volume drop  (Read 5273 times)

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mp1addict

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MP-1 volume drop
« on: Time Format »

I bought an MP-1 off eBay and I've had it for a year now. I've gigged with it, it's withstood ridiculous Chicago weather changes and I haven't had any problems with it until now. I have my MP-1 going to into a Crown x1000 power amp into an Avatar 4x12 with Celestion Hot 100's and just this morning when I was playing at medium volumes I noticed 15 minutes into playing my volume dropped and it sounded like the MP-1 was "dying", I could still hear my guitar and the distortion but just really quietly. Is this a simple matter of swapping tubes or could this be something serious? I'm not familiar with soldering and to be honest I've never opened the unit because I've never had a problem until now.
« Last Edit: Time Format by mp1addict »
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Rig: >Ibanez RG570FM(w/DiMarzio's)>ADA MP-1(fx loop:TC Electronic HOF mini>MXR 9-band EQ>ISP Decimator)> ADA GCS-2

rnolan

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Re: MP-1 volume drop
« Reply #1 on: Time Format »

Bummer, my Mp1 or Mp2 never let me down this way (thank god over 30 years), could be tubes, unlilkely it's the MP1, they are very robust pre-mps but who knows, sh#t happens. What  is the rest of your rig ??  Sounds like it's further down the chain...
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Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few

mp1addict

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Re: MP-1 volume drop
« Reply #2 on: Time Format »

Ibanez RG 570FM going into a ISP decimator into the front input jack of the MP-1. I also have an MXR 6-band eq pedal going into the fx loop of the MP-1. I also noticed when I wiggle the chord going from output A to my power amp the wrong way I get signal loss but the units been doing that since I've bought it and the sound the signal makes when its lost isn't the same as I described above.
« Last Edit: Time Format by mp1addict »
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Rig: >Ibanez RG570FM(w/DiMarzio's)>ADA MP-1(fx loop:TC Electronic HOF mini>MXR 9-band EQ>ISP Decimator)> ADA GCS-2

rnolan

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Re: MP-1 volume drop
« Reply #3 on: Time Format »

Time to simplify the patching and trouble shoot each bit.  Maybe start with just guitar <> MP1, un-patch the loop (the MP1 loop is serial so that could stop the signal getting through properly if there are lead issues or MXR issues) try output B to power amp with good known patch lead.  Check if the headphone out is working (plug in some headphones).  It's probably time for some new tubes, they are easy to change but I'd try all the above first.  Are you running in mono ? or stereo ?  We need to work out if it's an issue in the MP1 but it may be as simple as a patch lead.  If you have low signal with just guitar <> MP1 <> headphones the next thing I'd try is taking off the lid (easy, bunch of small philips head screws, careful don't loose them or over tighten when you put the lid back on  ;) ), then clean all the pots and jack sockets with some decent contact cleaner (I use CRC CO Contact Cleaner), you can clean all the jack sockets without taking off the lid, give them all a decent spray.  This is all worth doing from time to time regardless.  To clean the pots, use the little plastic tube that the contact cleaner has and spray into the pot where the connections go in (should be a small gap) while turning it full up down a few times (this will clean any residual carbon etc from the pots sweeping contacts).  ADA recommended a tube change every 2 years.  In practice the tubes tend to last much longer depending on usage and climate.  If the tubes just have red 12AX7A on them and no brand they are probably the original Chinese tubes and are as old as the unit.
(I also noticed when I wiggle the chord going from output A to my power amp the wrong way I get signal loss) this shouldn't happen and is probably either the patch lead or the jack socket(s) needs a clean.  Also, given how cold it can get in Chicago, you need to let the tubes cool down (~15 mins or more) before going outside or they will die faster (and could fail).  Let me know how you get on.
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Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few

mp1addict

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Re: MP-1 volume drop
« Reply #4 on: Time Format »

Thank you for all of you help and support, my MP-1 is up and running and sounding as sexy as ever. I took out the tubes(they were not the original Chinese ones, I actually couldn't even read the brand) and replaced them with JJ's. I also upgraded and downsized my rig. Thanks again!  :thumb-up:  :banana-guitar:
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Rig: >Ibanez RG570FM(w/DiMarzio's)>ADA MP-1(fx loop:TC Electronic HOF mini>MXR 9-band EQ>ISP Decimator)> ADA GCS-2

rnolan

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Re: MP-1 volume drop
« Reply #5 on: Time Format »

No worries, good to hear it's all working now  :whoohoo!:
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Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few
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