Modding an Kustom KGA16R guitar amp

darscuzlo

New member
I thought I'd share this because these things are a dime a dozen and IMO a lot of bang for the buck.
I've had mine for over 12 years and although I have other, bigger tube amps this is the one I grab to bring to an open mic or impromptu jam at a cookout.
It's small and light and (for me) disposable.

However, the gain channel doesn't sound that good and I found the spring reverb to be not to my liking.
Why not mod it? I emailed support about schematics at Kustom and was pleasantly surprised to get a reply within 15 minutes EST with a .PDF attached!

I'm not an electronics expert, but I've done enough DIY etc. to get by. pedal mods, guitar wiring etc etc.

The gain circuit appears to be nothing more than a diode clipper a la tube screamer and the like. There are two pairs of diodes in series in the circuit for symmetrical clipping.
One could do all of the usual tricks there I assume (asymmetrical, LED, germanium).
I did a simple smoothie cap mod to tame the buzz of the overdrive (for the KGA16) I soldered a 47nf cap across each diode pair (D8, D9) and (D10, D11).
I played around with different values until I settled on the 47nf.

This gave me a smoother fatter sounding overdrive. I use VERY little drive in my playing. If I crank it however I now get more of that Clapton "woman tone" thing than the previous buzz saw tone pre-mod.

Next: I replaced the 1K resistor at R22 with a 100K in the reverb circuit. Near as I can tell this is where the "dwell" control is if the amp had one. Increasing this value cut down the signal to the OP AMP driving the reverb tank removing all of the "boing" that I found annoying and giving me more of the dark hall type of reverb I desired.

Anyway, now I have more of the tone that I want without having to drag extra pedals. Just plug and play!

I hope anyone with a Kustom 10 or 16 finds this info useful.

cheers.
 
Kustom kga16 schematic.

I thought I'd share this because these things are a dime a dozen and IMO a lot of bang for the buck.
I've had mine for over 12 years and although I have other, bigger tube amps this is the one I grab to bring to an open mic or impromptu jam at a cookout.
It's small and light and (for me) disposable.

However, the gain channel doesn't sound that good and I found the spring reverb to be not to my liking.
Why not mod it? I emailed support about schematics at Kustom and was pleasantly surprised to get a reply within 15 minutes EST with a .PDF attached!

I'm not an electronics expert, but I've done enough DIY etc. to get by. pedal mods, guitar wiring etc etc.

The gain circuit appears to be nothing more than a diode clipper a la tube screamer and the like. There are two pairs of diodes in series in the circuit for symmetrical clipping.
One could do all of the usual tricks there I assume (asymmetrical, LED, germanium).
I did a simple smoothie cap mod to tame the buzz of the overdrive (for the KGA16) I soldered a 47nf cap across each diode pair (D8, D9) and (D10, D11).
I played around with different values until I settled on the 47nf.

This gave me a smoother fatter sounding overdrive. I use VERY little drive in my playing. If I crank it however I now get more of that Clapton "woman tone" thing than the previous buzz saw tone pre-mod.

Next: I replaced the 1K resistor at R22 with a 100K in the reverb circuit. Near as I can tell this is where the "dwell" control is if the amp had one. Increasing this value cut down the signal to the OP AMP driving the reverb tank removing all of the "boing" that I found annoying and giving me more of the dark hall type of reverb I desired.

Anyway, now I have more of the tone that I want without having to drag extra pedals. Just plug and play!

I hope anyone with a Kustom 10 or 16 finds this info useful.

cheers.

Hello, so you have the schematic for the KGA16 amp in .pdf? Would you please email it to me? Thanks a lot.

lentzell@yahoo.es
 
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