funny tone caps on this JMP

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funny tone caps on this JMP

Postby boola on Tue Jul 11, 2017 1:58 pm

I saw this amp on ebay

http://www.ebay.co.uk/itm/MARSHALL-JMP- ... Swcj5ZWq1w

The regular mustard tone caps are instead ceramics in parallel. I've never seen this before, has anybody else?
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Re: funny tone caps on this JMP

Postby DrainBamage on Tue Jul 11, 2017 5:06 pm

They look legit to me as well as the 100n coupling cap on the normal channel. Must have been on a .022 shortage at the factory. The Lemco 10k ceramics were seen in 20 watt amps and Trem circuits in the handwired Metal panel years.
I believe one of Neils amps had these ceramic caps in the TS too.

The big question is what do these ceramic caps actually measure? Ive bought a bunch of these Lemcos in the past and you have to weed through a bunch befor you find something that measures right.
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Re: funny tone caps on this JMP

Postby LD50 on Tue Jul 11, 2017 7:29 pm

Yes there are a few like this. Bone stock, wonder how it sounds with those big 0.1s in the other 0.022 spots?
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Re: funny tone caps on this JMP

Postby Ned B on Wed Jul 12, 2017 1:25 am

I had the parallel ceramics equaling .1 in a '73 100w SL in the channel 2 coupling cap position. Channel 1 had the usual .0022 (the lead value). night and day difference between the 2 channels.
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Re: funny tone caps on this JMP

Postby boola on Wed Jul 12, 2017 6:20 pm

LD50 wrote:Yes there are a few like this. Bone stock, wonder how it sounds with those big 0.1s in the other 0.022 spots?


It's gunna either be the best or worst JMP you ever heard! :)
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Re: funny tone caps on this JMP

Postby LD50 on Fri Jul 14, 2017 12:24 am

Just realised I know the seller!!
Lives near me. I bought my 65 JTM45 from him.
Nice guy, has some nice kit, very straight and honest. He was after a new switch (see spares) but I had used all my arrow flat bats up.
This amp is in exceptional condition, although I have not played it (wish I had now knowing how unorthodox the wiring is!)
All bleeding stops.......eventually.
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Re: funny tone caps on this JMP

Postby Ned B on Fri Jul 14, 2017 12:39 am

So that is where my BB box came from?
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Re: funny tone caps on this JMP

Postby LD50 on Fri Jul 14, 2017 6:29 am

Ned B wrote:So that is where my BB box came from?


No, that came from Essex/Suffolk border where it was being used as extension cab.

I bought the fire damaged JTM45 (guy in Hawaii bought the 4x12 that singed with it) and restored it by rebuilding the original pots, switched, jacks and NOS valve sockets - replacing the 1990s spec parts Marshall put in. I posted pics of the OT rebuild here before.

I remember the amazing cleaning job of the cab you posted pics of here before you installed the amp found locally too.
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Re: funny tone caps on this JMP

Postby BIG Dave on Sat Sep 23, 2017 1:57 pm

Never seen gold colored FRACO (red font) caps in the bias circuit in a Marshall.
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