GHOSTING ON A JTM50 CLONE

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RCGPNY1
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GHOSTING ON A JTM50 CLONE

Post by RCGPNY1 »

I recently found that my JTM50 clone "ghosts" at higher volume settings.
What can I do to minimize this/ Everything being equal, will a amp with
tube recifier ghost more than diodes?
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cbass
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Re: GHOSTING ON A JTM50 CLONE

Post by cbass »

What value filter caps are you using?
Tube recto's can cause more ghosting because of the limit of the maximum capacitance of the first Filter cap.
You might try adding a cap in paralell and see if that stops the ghost.
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Re: GHOSTING ON A JTM50 CLONE

Post by Stevem »

What brand filters do you have, gray cased Illinos brand?
They suck in high current demand / cranked amp uses!
Are you idling the output tubes at more than 65% as that can pull down the power supply voltage and current reserve for no good return in tone.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

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RCGPNY1
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Re: GHOSTING ON A JTM50 CLONE

Post by RCGPNY1 »

The 33uf/33uf is an F&T..the other 2 cans are JJ's but I forget their value.
Id have to remove them to see. I do know one section of one of the cans has no connection. In all the talk I see about this amp, people say it has "minimal filtering"
vibratoking
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Re: GHOSTING ON A JTM50 CLONE

Post by vibratoking »

Sometimes more filtering and sometimes less filtering helps with this. I have some literature about this at home, but I'm at work now. If I can find it, I'll post.
Stevem
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Re: GHOSTING ON A JTM50 CLONE

Post by Stevem »

On all the Marshall's amps I redo for playing use! I install the duel 50 uf cans, jumped for 100 uf, and this is for the first and second filter node.
A good 5ar4 recto can take it,
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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ToneMerc
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Re: GHOSTING ON A JTM50 CLONE

Post by ToneMerc »

RCGPNY1 wrote:I recently found that my JTM50 clone "ghosts" at higher volume settings.
What can I do to minimize this/ Everything being equal, will a amp with
tube recifier ghost more than diodes?
What value choke do you have in it now? If you have the 3H in it now, try a 7 or 10H value.

TM
Firestorm
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Re: GHOSTING ON A JTM50 CLONE

Post by Firestorm »

If this is an accurate reproduction of a late '66/early '67 Marshall, filtering will be quite low; it's part of the sound. '67/'68 100s were even "worse" as the filtering was essentially the same in spite of the power bump. There are stories of frustrated guitarists trying to nail Jimi's sound not realising they were hearing English recordings with 50Hz modulating the signal; impossible to replicate with 60Hz mains. Cone Cry (choose your favorite definition) can accentuate the problem, so maybe try different speakers.

You can certainly experiment with more filtering, but it will change the amp's character.

It has a 5AR4 rectifier? A real Mullard will make a difference.
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Re: GHOSTING ON A JTM50 CLONE

Post by Stevem »

New speakers may need some breaking in in terms of low end output.
Breaking them in and they will output more bass with less amp power
And may take you into the zone where the filtering you have will be good!
It would not be the first time I have seen that change!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
RCGPNY1
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Re: GHOSTING ON A JTM50 CLONE

Post by RCGPNY1 »

Yes the amp has a tube rectifier and the choke is a 20h. The ghosting is definately more prominent thru my Marshall 1982JH cab then my mojo 2x12 Marshall clone cab with G12H30's. I believe both cabs are suitably
broken in.....This was one of the reasons why I got rid of a 100w plexi reissue..it ghosted rather much. THe Marshalls that I owned back in the day..my first was a metal face '72 with the volume control that was more like a switch-either off or full power and just got more overdrive as you turned it up. It had virtually no ghosting! No other Marshall I have owned ( all were '72 or later)ghosted appreciably.
Roe
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Re: GHOSTING ON A JTM50 CLONE

Post by Roe »

check caps and grounding scheme carefully. you may also try a different set of output tubes and to lower the bias somewhat
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Reeltarded
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Re: GHOSTING ON A JTM50 CLONE

Post by Reeltarded »

RCGPNY1 wrote:my first was a metal face '72 with the volume control that was more like a switch-either off or full power and just got more overdrive as you turned it up. It had virtually no ghosting! No other Marshall I have owned ( all were '72 or later)ghosted appreciably.

The 72 had a 5000p brite cap. How loud are you playing your amp to get ghosting?
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Roe
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Re: GHOSTING ON A JTM50 CLONE

Post by Roe »

the 50w shouldn't ghost much at all, even with 32uf on the mains. something appears to be wrong with your amp.
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Reeltarded
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Re: GHOSTING ON A JTM50 CLONE

Post by Reeltarded »

I call tubes as Roe didnearlier, barring a mistake in the wiring. Output tubes can pretend to be the same thing.
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