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Temp "Time Format" issue Fix in Discussions

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Author Topic: Not 1 but 2 mp1s for sale >SOLD<  (Read 9556 times)

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MarshallJMP

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Re: Not 1 but 2 mp1s for sale
« Reply #15 on: Time Format »

 ;D
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rnolan

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Re: Not 1 but 2 mp1s for sale
« Reply #16 on: Time Format »

Hey Harley, well not in a hurry (LoL), hey it's late and I didn't even notice (good PU MJMP  ^-^ ).
Hey MJMP, many thanks  :thumb-up: .
Well picked the MP1s up today, crap the rack is deeep... Great rack, custom built but it's like a deep rack and a short rack depth joined together, step down tranny bolted to the rack bottom..  I haven't had a chance to fire them up yet, got sidetracked being back in my home town and I have nothing to plug them into here (5 hours from where I live, considered a short drive here (~500kms  :facepalm: )).  Apparently the 73 Marshall is good to go with new caps (hum fixed  :thumb-up: though he said presence is noisy, IIRC it always was), by the time I get home he should have replaced one of the big white resistor thingys (attached to speaker output jacks) which he said was working but a bit how's your father physically. I'd like to get one of the inputs to be a power amp in (ala MJMPs set up), also considering a master vol  :dunno: mod, (before phase spliter after phase spliter  :dunno: , after seems to make sense but slightly more complex ?). Maybe leave it alone and just do the power amp in on one jack ?.  Mean time I'll just try MP1 into it (as MJMP suggested  >:D and bridge the 2 inputs (the lead input is so toppy in that amp so I always bridged the lead/bass inputs)).
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MarshallJMP

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Re: Not 1 but 2 mp1s for sale
« Reply #17 on: Time Format »

The presence knob on those old Marshalls (and some Fender) are always scratchy,it's a design thing and happends due to the dc voltage on the pot.So changing the pot doesn't help.You could alter the presence circuit a bit if it really bothers you. Also replacing those caps is a very good idea.I had a few of these in for repair where one of those caps shorted out and took out the power transformer because people have the tendency to always replace the fuses with a fuse with a high rating.Usually after getting the repair bill they use the correct values  ;)

I would not do a master vol mod on it. BTW what white resistor on the output jacks? You mean the screen grid resistors on the tube sockets?
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rnolan

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Re: Not 1 but 2 mp1s for sale
« Reply #18 on: Time Format »

Hey MJMP, no it doesn't bother me, once the presence is set I just leave it.  I thought he said the resistor was connected to the output jacks ? but it's obviously a bit worse for wear (it's one of those big rectangular ceramic white resistor thingys, and they do tend to be around valve sockets from what I've seen/remember), albeit still working, hey that amp has bounced around to so many gigs so will be good to get it back to par.  I'll forget about the master vol and FX loop ideas (thanks for that advice), though I'd still like to do the poweramp in from one jack (that would be useful with MP1). I still have my Tom Schultz power soak so I can be in the same room as it when it's cranked up  >:D although if I use MP1 in front that won't be such an issue.
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MarshallJMP

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Re: Not 1 but 2 mp1s for sale
« Reply #19 on: Time Format »

Converting one input so it's connected to the power amp is quite easy.And you can use the original jack.
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rnolan

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Re: Not 1 but 2 mp1s for sale
« Reply #20 on: Time Format »

That's the plan, so does it connect just before the phase spliter tube ??  seems to make sense.
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MarshallJMP

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Re: Not 1 but 2 mp1s for sale
« Reply #21 on: Time Format »

Yes that's it, you disconnect the wire going from the taper of the treble pot, disconected the input you want to use.Then take a (shielded) wire to go from the taper of the treble pot to switch of the input,then a wire going from the input to the phase splitter and you're good to go.This way when you plug something in, the preamp will be disconnected and you go streight into the poweramp (phasesplitter), if you disconnect it the amp will run like normal, but only on the other 3 inputs.
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rnolan

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Re: Not 1 but 2 mp1s for sale
« Reply #22 on: Time Format »

Cool thanks MJMP.
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rnolan

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Re: Not 1 but 2 mp1s for sale >SOLD<
« Reply #23 on: Time Format »

Hey MJMP, been talking this through with my tech dude, do you wire the input to the cap before the phase spliter ? or after the cap ?  He managed to cream my output tubes  :facepalm: , the amp rolled on the bench apparently and bent/busted the pins.  Oh well it gets a new pair of Mullard EL34s (seems a good choice as it's such a toppy amp), Looking forward to trying it with the MP1 direct into power amp  >:D .  I'd been thinking to put an ADA APP1 with a MP1 Channel in the APP1 loop in front of the Marshall and see how that sounds also. May be a good way to make an old Marshall a bit more versatile  :dunno: . Though need to include some delay and reverb somehow, maybe also in the APP1 loop ?
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MarshallJMP

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Re: Not 1 but 2 mp1s for sale >SOLD<
« Reply #24 on: Time Format »

Before the cap!!
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rnolan

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Re: Not 1 but 2 mp1s for sale >SOLD<
« Reply #25 on: Time Format »

Cool, that's what we figured but just wanted to check  :thumb-up: .
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