Ceriatone 2550 Presence circuit?

sonofmickel · Post by **sonofmickel** » Mon Jul 27, 2015 11:18 pm

This is for Jubilee aficionados.

The Ceriatone Jubilee 2550-2555 presence circuit is very different from the Marshall version.
How important is this to the sound of the amp?

The differences are
Marshall : Ceriatone
22kl pot : 5kl
.1uf series with 22kl pot : .1uf parallel with 5kl pot(wiper to ground)
4k7 parallel with 22kl pot : no 4k7
10R to ground : no 10R to ground

neikeel · Post by **neikeel** » Tue Jul 28, 2015 1:51 am

sonofmickel wrote:This is for Jubilee aficionados.

The Ceriatone Jubilee 2550-2555 presence circuit is very different from the Marshall version.
How important is this to the sound of the amp?

The differences are
Marshall : Ceriatone
22kl pot : 5kl
.1uf series with 22kl pot : .1uf parallel with 5kl pot(wiper to ground)
4k7 parallel with 22kl pot : no 4k7
10R to ground : no 10R to ground

You just described the traditional plexi Marshall presence circuit in the Ceriatone

sonofmickel · Post by **sonofmickel** » Wed Jul 29, 2015 4:41 am

Exactly neikeel, looks like you know what's going on...the Ceriatone 2550 does not have the Jubilee presence circuit, which is closer to the JCM800 circuit.
So what effect changing the presence circuit to Jubilee/JCM800 would do for the Ceriatone 2550 layout?

neikeel · Post by **neikeel** » Wed Jul 29, 2015 5:35 am

sonofmickel wrote:Exactly neikeel, looks like you know what's going on...the Ceriatone 2550 does not have the Jubilee presence circuit, which is closer to the JCM800 circuit.
So what effect changing the presence circuit to Jubilee/JCM800 would do for the Ceriatone 2550 layout?

Not a lot really IMO, there is not scratch when you turn the pot with the 25k/4k7 combination. It is the 0.68uF cap that can give a bit more bite and perceived gain (same 25k/4k7 combination) there were a couple of variants of the circuit.

sonofmickel · Post by **sonofmickel** » Thu Jul 30, 2015 3:10 pm

Thanks you.
You are correct sir.
I did some more research and the JCM800 presence circuit is designed to stop the "scratching" sound when turning the presence knob.
Both presence circuits work fine.
The Plexi circuit scratches a little when turning the knob and has less parts.

neikeel · Post by **neikeel** » Fri Jul 31, 2015 1:56 am

sonofmickel wrote:Thanks you.
You are correct sir.
I did some more research and the JCM800 presence circuit is designed to stop the "scratching" sound when turning the presence knob on the Plexi circuit.
Both circuits are fine.

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Ceriatone 2550 Presence circuit?

Ceriatone 2550 Presence circuit?

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