Ceriatone Forum

British Style => JCM 800 2203, 2204, 2550, 2555 => Topic started by: sorbz62 on January 17, 2014, 07:11:18 AM



Title: Potential 2550 owner
Post by: sorbz62 on January 17, 2014, 07:11:18 AM
Hi guys,

I am just about to pull the plug on a used Nik-built 2550 and just wondered a few things:

1.   I already have a JCM900 with the diode clipping - Is this amp a straight through Valve amp with the option to add diode clipping with the switch?

2.   How heavy can the distorted sound go? - I am a classic rocker but just wondered.

3.   How easy is it to bias? I know it has test points on the back but is it justa  case of testing it and adjusting the bias pot? (I have biased my other amps successfully)

Cheers,
Jim


Title: Re: Potential 2550 owner
Post by: wyatt on January 17, 2014, 02:45:44 PM
Hi guys,

I am just about to pull the plug on a used Nik-built 2550 and just wondered a few things:

1.   I already have a JCM900 with the diode clipping - Is this amp a straight through Valve amp with the option to add diode clipping with the switch?

The Lead Channel always uses diodes. The Rhythm Clip switch adds diodes to the Rhythm Channel.

2.   How heavy can the distorted sound go? - I am a classic rocker but just wondered.

I would say about the same as your JCM900. The Jubilee was the stepping stone from the JCM800 to the JCM900.

3.   How easy is it to bias? I know it has test points on the back but is it justa  case of testing it and adjusting the bias pot? (I have biased my other amps successfully)

The bias points make biasing much easier, stick in the multimeter probes and read mV for mA. The caveat is you have to know the actual plate voltage of the amp to calculate dissipation (plate minus cathode). Typically you can measure this once and then treat it as the same in the future.