Double check my amp mod

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_ej_
Posts: 38
Joined: Thu Aug 22, 2024 6:12 pm

Double check my amp mod

Post by _ej_ »

I just finished up a Mojotone NC3015 build. Amp sounds excellent but after testing everything I know I'll never use the first channel. Brilliant is where its at.

I want to delete the first channel with minimal effort. My plan is to remove the jacks, ground the input to the tube and remove the volume pot. Any issues with this?
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Last edited by _ej_ on Wed Mar 26, 2025 12:32 am, edited 1 time in total.
maxkracht
Posts: 931
Joined: Tue Dec 10, 2019 7:18 pm
Location: Iowa, USA

Re: Double check my amp mod

Post by maxkracht »

Least effort would be to do nothing, the input jacks are already shorting the grid to ground when nothing is plugged into that channel. What you have would also work, but wouldn't improve anything.
_ej_
Posts: 38
Joined: Thu Aug 22, 2024 6:12 pm

Re: Double check my amp mod

Post by _ej_ »

maxkracht wrote: Wed Mar 26, 2025 12:30 am Least effort would be to do nothing, the input jacks are already shorting the grid to ground when nothing is plugged into that channel. What you have would also work, but wouldn't improve anything.
I'm making a custom faceplate so I want to remove the pot and jacks.
maxkracht
Posts: 931
Joined: Tue Dec 10, 2019 7:18 pm
Location: Iowa, USA

Re: Double check my amp mod

Post by maxkracht »

_ej_ wrote: Wed Mar 26, 2025 12:32 am I'm making a custom faceplate so I want to remove the pot and jacks.
Gotcha. You could just remove the plate resistor. Could also think of ways you might want to use the other triode. Switch to add it in parallel, do a cascade thing to add it in series, voice each triode differently and switch between the two. Lots of options that are fairly easy.

Edit: i was being dumb, if you removed the plate resistor, you would want to change the cathode resistor to 820r to keep everything about the same. Grounding the grid is probably what you want if you aren't making any other changes.
_ej_
Posts: 38
Joined: Thu Aug 22, 2024 6:12 pm

Re: Double check my amp mod

Post by _ej_ »

maxkracht wrote: Wed Mar 26, 2025 1:04 am
_ej_ wrote: Wed Mar 26, 2025 12:32 am I'm making a custom faceplate so I want to remove the pot and jacks.
Gotcha. You could just remove the plate resistor. Could also think of ways you might want to use the other triode. Switch to add it in parallel, do a cascade thing to add it in series, voice each triode differently and switch between the two. Lots of options that are fairly easy.

Edit: i was being dumb, if you removed the plate resistor, you would want to change the cathode resistor to 820r to keep everything about the same. Grounding the grid is probably what you want if you aren't making any other changes.
Think I should bother grounding the 47nF cap? right now I have the grid grounded and the pot (and associated wires) removed.

I might try some mods at some point, it's a shame to waste a triode. Right now I just want to get it working as is.
maxkracht
Posts: 931
Joined: Tue Dec 10, 2019 7:18 pm
Location: Iowa, USA

Re: Double check my amp mod

Post by maxkracht »

_ej_ wrote: Wed Mar 26, 2025 2:43 am Think I should bother grounding the 47nF cap?
Can if you want to but shouldn't be necessary
B Ingram
Posts: 137
Joined: Wed Oct 20, 2021 7:40 pm

Re: Double check my amp mod

Post by B Ingram »

_ej_ wrote: Wed Mar 26, 2025 12:02 am I just finished up a Mojotone NC3015 build. Amp sounds excellent but after testing everything I know I'll never use the first channel. Brilliant is where its at.
FWIW, I currently own three 1960s AC30s, and used to have a 4th with a Top Boost channel. I sold the Top Boost amp because that amp/channel got the least use.

I know everyone assumes, "Top Boost is best because more-gain & tone controls," but you never know what you will like until you live with the amp a while.
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