Been looking on some layouts, now I see in the instructions for the 2203 a 1000Pf ceramic disc cap on the pre-amp pot, does this function as a bright cap or is it also functioning as snubber cab to prevent oscilation? In the ceriatone layout I see a 100Pf ceramic disc cap on V1, this should be a snubber cap but it's missing on the Metroamp.
Advise please.
Thanks,
Dennis.
Function of 1000Pf ceramic disc cap on pre-amp pot?
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- wildebassman
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Function of 1000Pf ceramic disc cap on pre-amp pot?
Amps: JTM 45, JTM 50, under construction: JCM 2204. CAB: 2x12" G12H 30 55Hz. Heritage.
- demonufo
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Re: Function of 1000Pf ceramic disc cap on pre-amp pot?
The cap on the pre-amp vol is the bright cap, and unless you use that amp real loud all the time, you might want to consider leaving it off.
Choice is yours, and tone is subjective an' all that.
The cap on V1 socket is to prevent oscillation, and if the lead dress is good, you shouldn't need it.
Especially if you use shielded cables to feed V1. Shielded cables should be grounded at one end only, preferably not at V1, but at the ground buss on the pots.
This might give you an idea of what is going on. The lead on the left of V1 is actually going to the preamp vol pot (goes underneath pot and upwards) and is grounded at the buss between the pre-amp pot and the master vol.
The lead on the right of V1 is going to the jacks. I actually re-did this with the 68K resistor connected at the V1 end of the lead as opposed to the input jack end, as that way round is less likely to induce nasty signals on the lead.
There is a lot of gain effectively on these two leads (which get amplified through the whole circuit) so using shielded cable here can be a good idea.
But not essential.
After all, this is just how I did it. There better/different/cleaner/tidier ways I'm sure, but I like how it turned out just fine.
Choice is yours, and tone is subjective an' all that.
The cap on V1 socket is to prevent oscillation, and if the lead dress is good, you shouldn't need it.
Especially if you use shielded cables to feed V1. Shielded cables should be grounded at one end only, preferably not at V1, but at the ground buss on the pots.
This might give you an idea of what is going on. The lead on the left of V1 is actually going to the preamp vol pot (goes underneath pot and upwards) and is grounded at the buss between the pre-amp pot and the master vol.
The lead on the right of V1 is going to the jacks. I actually re-did this with the 68K resistor connected at the V1 end of the lead as opposed to the input jack end, as that way round is less likely to induce nasty signals on the lead.
There is a lot of gain effectively on these two leads (which get amplified through the whole circuit) so using shielded cable here can be a good idea.
But not essential.
After all, this is just how I did it. There better/different/cleaner/tidier ways I'm sure, but I like how it turned out just fine.
So I like purple, okay!!!!!!
83.7% of all statistics are made up on the spot!
83.7% of all statistics are made up on the spot!
- wildebassman
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- Location: Suburbia Amsterdam Netherlands
Re: Function of 1000Pf ceramic disc cap on pre-amp pot?
This is exactly the last info needed, thanks a lot mate!
Cheers,
Dennis.
Cheers,
Dennis.
Amps: JTM 45, JTM 50, under construction: JCM 2204. CAB: 2x12" G12H 30 55Hz. Heritage.