Jennings ac40

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guitarsnguns04
Posts: 286
Joined: Tue Nov 13, 2007 10:49 pm

Jennings ac40

Post by guitarsnguns04 »

Does anyone have any info on the circuit of this one? I heard one the other day and was blown away with its tone. I'm curious as to how it differs from the ac30 any schematics would be greatly appreciated.
Thanks in advance
RevD
Posts: 151
Joined: Sun Nov 19, 2006 9:21 am

Re: Jennings ac40

Post by RevD »

I just found an overview. I went to a place I normally find nearly all the old schematics and it just isn't there (El34world.com). I'm sure somewhere someone has a schematic. Here is the overview:

http://www.guitarplayer.com/article/jennings-ac40/13350

Regards,

Don
guitarsnguns04
Posts: 286
Joined: Tue Nov 13, 2007 10:49 pm

Re: Jennings ac40

Post by guitarsnguns04 »

Thanks don ...that's a start. I saw a few pics...looks like an ac 30 but no choke....I didn't see a rectifier tube either...maybe that's the only difference but I haven't been able to get my hands on one to know for sure. Anyone know anything for sure about this amp,
Thanks again
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Masco
Posts: 251
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Location: Maryland

Re: Jennings ac40

Post by Masco »

I've worked on a couple. How familiar are you w/ 60's JMI AC-30's??
These had tube rectifiers, but here's some differences: Something like a 1k/10W R instead of a choke, slightly different integral top boost layout, but everything still on RS style tagstrips, reversed top panel cutout in case so that control panel is in front of amp instead of rear, PI circuitry is underneath instead of on lower tags on vertical chassis. EL84 sockets are spread apart further since main filter can is elsewhere.
Since JEI was Tom Jennings company, it was very much like the JMI AC-30s, but with some "improvements". It's pretty much an AC-30 w/ slightly different layout, sans choke. Schematics would be practically identical. I'm thinking maybe the Brilliant and Normal channels didn't have a shared cathode in the pre. ? That's about it, very much an AC-30.
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Masco
Posts: 251
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Location: Maryland

Re: Jennings ac40

Post by Masco »

A bit OT, but here was a BBC special on the rise and fall of JMI:
(2 parts)
http://youtu.be/CbrQJHq1xXI
http://youtu.be/wNT7mt-GsCc
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Masco
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Location: Maryland

Re: Jennings ac40

Post by Masco »

Sorry, echo post.
guitarsnguns04
Posts: 286
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Re: Jennings ac40

Post by guitarsnguns04 »

Thanks masco...do you recall any voltage differences between the 30 and the 40?
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