My A/B Rig!

fusionbear · Post by **fusionbear** » Sat Dec 20, 2014 2:04 am

My 2204 inspired and JTM 45/100 rig!

Enjoy...

https://www.youtube.com/watch?v=eYKnxe9 ... ilU6OaRURA

Post by **xtian** » Sat Dec 20, 2014 5:29 am

Hey, no heavy lifting! Looks like you're feeling better.

fusionbear · Post by **fusionbear** » Sat Dec 20, 2014 5:49 am

xtian wrote:Hey, no heavy lifting! Looks like you're feeling better.

Lol... Definitely not. The guitar almost acts like my sling. It supports my arm just right...

But, I do have to be careful.... No Pete Townsend windmills for a few months...

Post by **xtian** » Sat Dec 20, 2014 5:32 pm

fusionbear wrote:The guitar almost acts like my sling

Woah! Now, there's a justification. "Sorry, honey, I can't put my guitar down and come to dinner. My injury, you know."

cbass · Post by **cbass** » Sat Dec 20, 2014 5:48 pm

Sounds like you channeled Zappa for a bit .vury nice

john l · Post by **john l** » Sat Dec 20, 2014 11:31 pm

The tones you get out of your stuff at low volume has allways been impressive to me man. Makes me really want to build a JTM45ish thingy next.

fusionbear · Post by **fusionbear** » Sun Dec 21, 2014 6:06 am

john l wrote:The tones you get out of your stuff at low volume has allways been impressive to me man. Makes me really want to build a JTM45ish thingy next.

Thanks John!

Bob S · Post by **Bob S** » Sun Dec 21, 2014 12:51 pm

Great demos Bear!
That's quite the rig you've got there.
Quite a few playing styles - from FZ to Stevie Hillage. Nice.
Man - I've got to learn how to play better.

pdf64 · Post by **pdf64** » Sun Dec 21, 2014 2:22 pm

Nice!
Cool T shirt on the channel intro!

ampmike · Post by **ampmike** » Wed Dec 24, 2014 1:56 pm

Very cool.Great sustain,I could see myself not wanting to put the guitar down when playing your rig!!Really enjoyed the listen bro,Mikey

fusionbear · Post by **fusionbear** » Thu Dec 25, 2014 5:27 am

I got lots of requests on the schematics of the JTM45 influenced amp.

Here you go:

[IMG

789]http://i169.photobucket.com/albums/u223/fusionbear/CustomJTM4580_zpsb75afa5b.jpg[/img]

Feel free to ask any questions. It is a simple amp and, at least to my ears, sounds beautiful....

BTW, note that V1 is wired in parallel...

Littlewyan · Post by **Littlewyan** » Thu Dec 25, 2014 9:36 am

Interesting amp. Its good to see someone experimenting with the Marshall design. One thing I will point out is you could do with 220K resistors across the filter capacitors that are in series, as that will ensure equal voltage drop across them both.

Also to make it bulletproof you could change the bias circuit so the bias doesnt come off the trim pot wiper. At the moment if the wiper lifts then you'll have no bias and the KT88s will melt. If the bias doesnt come off the wiper then if the wiper lifts the KT88s will just be biased really cold.

Mark · Post by **Mark** » Thu Dec 25, 2014 11:22 am

I'm wondering if the KT-88's are biased quite cold in this amp. I'd imagine correct bias would be quite a burden on the power and output transformers.

fusionbear · Post by **fusionbear** » Thu Dec 25, 2014 4:44 pm

Littlewyan wrote:Interesting amp. Its good to see someone experimenting with the Marshall design. One thing I will point out is you could do with 220K resistors across the filter capacitors that are in series, as that will ensure equal voltage drop across them both.

Also to make it bulletproof you could change the bias circuit so the bias doesnt come off the trim pot wiper. At the moment if the wiper lifts then you'll have no bias and the KT88s will melt. If the bias doesnt come off the wiper then if the wiper lifts the KT88s will just be biased really cold.

The 220K's on the filter caps and rewiring the bias circuit is next.

fusionbear · Post by **fusionbear** » Thu Dec 25, 2014 4:48 pm

Mark wrote:I'm wondering if the KT-88's are biased quite cold in this amp. I'd imagine correct bias would be quite a burden on the power and output transformers.

The PT I am using is a P782 Dynaco clone. But, the one I got did not come with the 60V bias tap. They come with that now. The KT88's bias with no problem to 55ma. About 61% dissipation.

When I do the updates, I will post pics... Thanks guys!

[IMG:640:480]http://i169.photobucket.com/albums/u223/fusionbear/JTM%2045%20KT88%20driven%20Igor/IMG_0106_zps6cbadc8f.jpg[/img]

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