Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: timmyjoe on March 08, 2023, 08:35:36 pm
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I'm wanting to have the master volume on the front of a JTM 45 build. I'm not liking the option of putting on the back of the amp or replacing one of the inputs. Would like to keep all 4 inputs for jumper. (By the way I'm doing this build instead of doing a 59 bassman that I thought I was going to do.) Here are some ideas I've had on how to make this happen. And some problems.
1. Buy a bigger amp chassis? The normal layout of this amp is 17" wide. I thought it would be easy to get an 18" or 19". But no go I'm not finding anything in that size. Or have I just missed the obvious retailer?
2. Move the Power and Standby switch to the back of the amp. The only think that worries me with doing this is that it would put the master volume or presence control closer to the power transformer. Maybe just using shielded wiring would make this OK. Any thoughts?
3. Maybe I get a taller chassis for the JTM and stagger or stack the controls? This would make the wire runs a little longer, so not ideal?
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Just a thought... You could jumper the two channels internally. Like this...
http://sluckeyamps.com/november/november.pdf
Or use a dual concentric pot for the two volume controls. This would free up a hole for the MV.
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Thanks Sluckey. I'll check out both options! Good to know that I can use the dual concentric pot on the volumes. Wasn't sure if that could cause a problem or not.
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oooh. I really like the November build input. My guess is that it kind of works like pickup blend pots.
This would help the amp face to look really clean. For me the amp look is 1/2 the fun. Would like it to look as good as it sounds.
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I'm assuming the unmarked hole next the standby is for a pilot light. Maybe the MV will fit there and possibly drill a new pilot light hole on the other side of the power switch?
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I took out the standby switch and put my MV in its place. Works perfect.
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Joel, is it really OK to bypass the standby switch? I haven't read up on what they really do.
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Joel, is it really OK to bypass the standby switch? I haven't read up on what they really do.
It’s not just ok; for a JTM45 and similar hot switching standby arrangements, it’s beneficial to get rid of them. Or at least, never use them.
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Unless you need to plug 3 or 4 different things into the amp, 2 input sockets can do everything you need. See https://music-electronics-forum.com/forum/amplification/guitar-amps/31380-4-hole-functionality-from-2-holes-almost
The front panel space that’s freed up can be used for an additional control
(https://i.ibb.co/6ggnZdv/E75-A73-FD-FE8-D-45-D5-8-EE2-F375-A466428-D.jpg)
I used a Modulus JCM800 faceplate, used a brown felt tip pen to get rid of the original engraved lettering, and handwrote the control functions with an edding 780 white pen :laugh:
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Joel, is it really OK to bypass the standby switch? I haven't read up on what they really do.
My research, for my intended use, lead me to the view that the vast majority of standby switch implementations are either not required or actually harmful to the amp. I suggest you research this topic for yourself and decide based on how you intend to use you amp.