JC-120 in need of a lot of love

[bigtone23]

Great work! The amp surely is very happy to be a productive member of ampland again!

That TGP list of JC users is good, but probably still quite short. JCs are defacto clean amps, especially before Peavey nailed their recipe in the late 70s-mid 80s and for those that didn't want the Peavey stigma.

[The_Doc]

It looks and sounds just like a JC-120 should. What a satisfying restoration. Thanks for sharing this story Laurie, I have found it fascinating.

[laurie]

Thanks all! I'm not sure I'd tackle something this big again, but it is nice to be almost finished.

One last note about this specific model. Recall that I said "Repair and reinstall the back panel. The brace on the panel had been cut(?) and the glue wasn't holding what was left very well. I'll make a new brace and glue it in on the weekend."

It turns out that the cut brace is a factory mod. Without the last 100mm (4 in) of the brace removed, it would have fouled on the transformer.

It is clear that the back panels were made, then modified by the factory to fit this model configuration. Adding more weight to the thought that this is a transition model.

[laurie]

In another post I was looking for a darker speaker for this amp.

I couldn't find anything reasonably priced so i decided to adjust the preamp instead - to roll off the highs being sent to the speakers.

After a bit of trial and error I landed on a 6n8 high frequency roll-off capacitor after the signal mixer and before the voltage amplifier.

The highs are tamed and the amp sounds much better.

Just waiting for the corners now and it will be completely done.
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JC-120 finished2b.jpg (243.01 KiB) Viewed 22861 times

[laurie]

One last check of the chorus...

Yellow channel is dry, purple channel is effected.

Amplitudes are equal, purple channel is delayed - you can't see the movement in the still pic, but it is there.

The high frequency taming capacitors described above give a 3dB roll-off point of about 8kHz, taking the icepicks out of the Sammi speakers.
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JC-120 finished4.jpg (181.38 KiB) Viewed 22814 times

[Pepe]

Nice, I bet it sounds really good now. Great to hear that you found a way to avoid buying new speakers.

[laurie]

Nice, I bet it sounds really good now. Great to hear that you found a way to avoid buying new speakers.

Yeah, I was happy with that. It isn't perfect, but it is good enough.

Total cost for the restoration is about CAD$400 for the amp plus parts. Plus between 50 and 100 hours work.

Mrs Laurie said "put a dirt pedal in front of it". I can see why these amps got the reputation - an ML-2 in front with the chorus turned on is a really nice heavy tone.

[Pepe]

Kudos to your wife! Mrs. Pepe is always instantly annoyed whenever I play a dirt pedal at below bedroom volume. And she likes stuff like Linkin Park. I will never get it.

[laurie]

Mrs Pepe likes stuff like Linkin Park.

Nice. Me too

[laurie]

Finished. Corners installed. Footswitch made from a Fender 2 button switch.
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