Help with adding a second input jack and gain stage.

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RCP1
Posts: 3
Joined: Wed Dec 09, 2020 9:12 pm

Help with adding a second input jack and gain stage.

Post by RCP1 »

Hi all. This is my first post and I'm very happy to be a member.
I've converted over 60 old PA's/Hi-Fi's into all different styles of guitar amps but after a lot of searching I'm unable to find an answer to my current problem.
Currently on my bench I have an old Bell Hi-Fi with two GC's and/three 12A*7's. Currently all of the valves are wired up except for V1 (12A*7) to be a Fender Bassman AB763 style head.

What I plan to do is use one 12AX7 as the driver along with a Long Tail Pair PI for the lo gain jack.
This leaves me with a spare 12A*7 which I'd like to use 1/2 of for a higher gain channel but I simply don't know how to wire the jack to the new gain stage valve and on to the volume control (I have room for two volume controls).

Although I've converted about 5 or 6 PA's to JCM800 2204 heads using Cliff jacks I prefer to use Switchcraft/Fender style jacks because I have a hard time understanding Cliff jacks on a schematic.
Perhaps I could get some help with Cliff jacks as well. They usually show 3 dots on a schematic but I don't know which lug is which on a Cliff jack. I had to pull the chassis on my old Marshall JCM800 2204 to see how the Cliff jacks were wired

So, back to my original issue. Can anybody please help me out with a schematic of Hi and Low inputs with the Hi input wiring 1/2 of the first 12A*7 (or any single triode) to the vol control and then on to V2 pre amp valve? A verbal description of where to run the wires from the Hi jack to the 1/2 gain stage would be helpful as well. I'm not using a cold clipper as the cover of this amp wont allow for the taller EL34's and I'm not too fond of the JCM800 2204 sound with valves.
Thanks so much in advance.
Rob.
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Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Help with adding a second input jack and gain stage.

Post by Phil_S »

Cliff jacks. Easy.
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T Wilcox
Posts: 365
Joined: Fri Feb 11, 2011 1:52 pm
Location: Sacramento, CA

Re: Help with adding a second input jack and gain stage.

Post by T Wilcox »

http://www.ceriatone.com/ceriatone/wp-c ... 23-Aug.jpg

Unless i'm missing something seems you would want to wire the cliff jacks jcm800 style to add a 2nd input jack with added gain stage
RCP1
Posts: 3
Joined: Wed Dec 09, 2020 9:12 pm

Re: Help with adding a second input jack and gain stage.

Post by RCP1 »

T Wilcox wrote: Tue Dec 15, 2020 11:39 pm http://www.ceriatone.com/ceriatone/wp-c ... 23-Aug.jpg

Unless i'm missing something seems you would want to wire the cliff jcm800 style to add a 2nd input with added stage
Thanks T Wilcox. As I mentioned in my original post I have a difficult time with Cliff but I did find a diagram on line https://i.postimg.cc/RFLJKpMQ/CLIFF--W- ... MBERED.jpg that explains the numbering of the lugs but I still dont know how to read the Cliff lugs on a schematic.
Also, the Ceriatone 2203 layout looks different than the Ceriatone 2204 layout that I tried using.

Can someone please help me transpose the Cliff lug numbers (see above url) to the connection/solder dots on a JCM800 2204 schematic https://mhuss.com/MyJCM/JCM800_2204.gif or layout ? I prefer to work off schematics but layouts are fine too.
Please see attached pic/links.
Thanks for the reply's. You guys are great!
sluckey
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Location: Mobile, AL
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Re: Help with adding a second input jack and gain stage.

Post by sluckey »

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RCP1
Posts: 3
Joined: Wed Dec 09, 2020 9:12 pm

Re: Help with adding a second input jack and gain stage.

Post by RCP1 »

THANK YOU very much Steve! I'll give it a shot. :D :D :D :D :D :D :D :D :D :D :D
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