JTM45/100 info

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BoogieEngineer
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JTM45/100 info

Post by BoogieEngineer » Sat Jun 30, 2012 4:45 pm

Hope the majority of you guys are still active here and could help me with my future JTM45/100 build.

I am sourcing the components at the moment and I was wondering about the cap in the middle of the preamp board. I've seen both George and Germino use 33uf caps for power filtering but I'm not sure what value I should get for the one in the preamp. In the Dickinson layout it's a dual 32/32uf but I'm going for the standard version here. So what should it be?

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neikeel
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Re: JTM45/100 info

Post by neikeel » Sun Jul 01, 2012 9:10 am

The stock cap is 16uF although 15uF is the modern equivalent.

IIRC my Metro 45/100 has a BC 22uF @ 450v on the board.

Very happy with that spec although I am hoping to make a Dickinson 7026 copy (when I get time :roll: ) with the dual 32 and the extra dropping resistor.
Neil

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Re: JTM45/100 info

Post by BoogieEngineer » Sun Jul 01, 2012 12:58 pm

neikeel wrote:The stock cap is 16uF although 15uF is the modern equivalent.

IIRC my Metro 45/100 has a BC 22uF @ 450v on the board.

Very happy with that spec although I am hoping to make a Dickinson 7026 copy (when I get time :roll: ) with the dual 32 and the extra dropping resistor.
Thanks Neil! I've got a few options: TAD 16uf or Rifa or BC 22uf. Might as well get all of them to swap in and out at some point.

Also, as for the snubber cap, does it affect the tone at all? I've read that George recommends a Sozo .1uf in there but seen Germino's that've got a Cornell Dubilier .047uf there.

And for the ceramic caps, are the Silve Mica's as good as the NOS's? And what kind of fuse (amp and fast/slow?) should I get?

Thanks!

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neikeel
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Re: JTM45/100 info

Post by neikeel » Sun Jul 01, 2012 5:25 pm

I use the RS flat brown coloured silver micas or Lemco silver micas but my supply is about out (enough to finish the projects I have lined up).
Next option are the ceramic disc types which are fine in fact some prefer the slight graininess they offer, the red tubular Lemco silver micas are the same.
Always use SLO-BLO fuses of correct rating.
I use 1000v rated 0.05uF RS snubbers or similar, no effect on tone just there for smoothing out the diodes. If you use the silver top hat diodes or modern UF type (1000v @ 3A) you probably do not need a snubber at all.
Neil

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Re: JTM45/100 info

Post by BoogieEngineer » Sun Jul 01, 2012 6:42 pm

neikeel wrote:I use the RS flat brown coloured silver micas or Lemco silver micas but my supply is about out (enough to finish the projects I have lined up).
Next option are the ceramic disc types which are fine in fact some prefer the slight graininess they offer, the red tubular Lemco silver micas are the same.
Always use SLO-BLO fuses of correct rating.
I use 1000v rated 0.05uF RS snubbers or similar, no effect on tone just there for smoothing out the diodes. If you use the silver top hat diodes or modern UF type (1000v @ 3A) you probably do not need a snubber at all.
Thanks buddy. Would you elaborate more on the fuse? So both internal and external fuses should be slo-blo? What amp rating am I shooting for? I guess I'll be using the US 110V all the time.

Also can I use the 1-ohm 2W Carbon Film resistors for the power tubes sockets?

Thanks!

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Re: JTM45/100 info

Post by BoogieEngineer » Mon Jul 02, 2012 10:16 pm

Still need advice for both fuses. What type and rating should I get to use 110V from the wall?

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