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Author Topic: It’s An Addiction, I’m Sure!  (Read 114 times)

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Moff40

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It’s An Addiction, I’m Sure!
« on: Time Format »

Just scored my 3rd MP-1 from a local person, with another MC-1.  V1/Switch top, 1.38 EPROM, so I’ll be hitting MJMP up.  Everything functions as it should, and the MP’s in pretty clean condition.  Looks stock except for perhaps some parts changed during routine service, the battery mod, and it looks like one of the power caps was changed.  MC-1 has been used a lot.

No real issue, except it has much lower output overall than my other two (and yes, I did make sure it was switched to “line level” output :D).  Any other ideas as to why that might be?

I have to stop buying these things…  :)
« Last Edit: Time Format by Moff40 »
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MarshallJMP

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Re: It’s An Addiction, I’m Sure!
« Reply #1 on: Time Format »

Try switching the topswitch up and down a few times, sometimes these have bad contacts.

BTW is the output low on all 3 voicings?
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Moff40

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Re: It’s An Addiction, I’m Sure!
« Reply #2 on: Time Format »

Yeah, all three voices.  And they all sound fine, just quieter.  Where I could get by on 10:00 on my other MP-1s, I have to set the overall volume in this one to 2:00 or 3:00 to get the same percieved output.  But the headphone output is as stong as the other two, so whatever is “attenuating” the signal appears to be after the headphone out.  I did toggle the top switch quite a bit.  Toward the back is line level, right?  That’s the “louder” of the positions.
« Last Edit: Time Format by Moff40 »
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rnolan

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Re: It’s An Addiction, I’m Sure!
« Reply #3 on: Time Format »

Yes toward the rear panel is Line lv position.  Maybe give the switch a spray with contact cleaner and toggle a few more times (they do gum up).  So the headphone out has it's own pot, I wonder if the main (front) output pot also needs a clean? And is the knob aligned correctly (i.e full off 7 o'clock (ish), same as the other units)?
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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s

MarshallJMP

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Re: It’s An Addiction, I’m Sure!
« Reply #4 on: Time Format »

The only 2 things behind the headphone out are the topswitch and the front vol pot pot and one opamp used as a buffer. Since you have sound the opamp should be fine.
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Moff40

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Re: It’s An Addiction, I’m Sure!
« Reply #5 on: Time Format »

At work right now, but would a wrong-value pot, or one with the wrong taper do it?  Even maxed out, it doesn’t clip my Two-Notes, but the other two will.  I’ll hit the pot and switch with contact cleaner when I get home.
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MarshallJMP

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Re: It’s An Addiction, I’m Sure!
« Reply #6 on: Time Format »

No normally not but check the value to make sure. The taper doesn't matter, it will just give a different feel to it but at max it should be the same.
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Moff40

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Re: It’s An Addiction, I’m Sure!
« Reply #7 on: Time Format »

I was thinking that wide open shouldn’t matter; it should present no resistance.  I’ll check with a meter, and also check to see if an additional or higher-value resistor has been added.
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Moff40

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Re: It’s An Addiction, I’m Sure!
« Reply #8 on: Time Format »

OK.  I hit both the switch and the Ouput Level pot with some contact cleaner, flicked the switch and twisted the knob back and forth multiple times, and no change.  From the markings, the pot is an A50K rather than B50K, so audio rather than linear taper, and measures ~48K front and back fully off, and 1 or two ohms wide open.  Seems within spec.

Is there anyplace where a resistor could have been added or bumped up?
« Last Edit: Time Format by Moff40 »
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MarshallJMP

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Re: It’s An Addiction, I’m Sure!
« Reply #9 on: Time Format »

Have you tried the send output, is there a difference?
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Moff40

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Re: It’s An Addiction, I’m Sure!
« Reply #10 on: Time Format »

OK.  I figured it out.  I tested the output at the FX send, and at the headphone out, all three were the same.  Then I put the pad on my IR loader, attached the regular output, and then pinned all three units with the same preset.  Wide open, they’re identical in output.  The difference has to be the taper of the output pot (LOG instead of LIN).  When I did the first test, I clearly didn’t test properly.  Anyway, it’s probably not urgent for me to replace the pot with a linear for now.  It works right; I just have to turn the knob a little further to the right, and I’ve never been shy about doing that!  :)
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rnolan

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Re: It’s An Addiction, I’m Sure!
« Reply #11 on: Time Format »

Cool, glad you worked it out  :thumb-up: , strange about the pot, must have been replaced at some point  :dunno:
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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s
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