New Project - single ended JCM800

Fri Jun 17, 2011 11:19 am

Yesterday I got my final shipment of parts to start a retro-fit of my single-ended amp. The amp was originally built for me by a guy starting out as an amp builder...it was his take on a single-ended plexi. I tweaked it a few times, then last year decided to overhaul it with a Blackface preamp. While I'm pretty happy with it in its current form, I've been intrigued by this design of a single-ended JCM800, and recently realized that this is a fairly inexpensive way to scratch my itch and see if it's "all that" or not.

I found the project on the Single-Ended Forum. It's intended as a retro-fit for an Epi Valve Jr...http://www.guitaramplifierpcbs.com sells the PCB board, and provides a parts list and build manual. I'm using it to retro-fit my amp, so there will be some adaptations. But for the most part, I'm just pulling out the current eyelet board and replacing it with this PCB, utilizing my existing chassis and transformers. I am adding an additional preamp tube, but the chassis is already punched for it, which is nice! If I'm really happy with the end product, I will buy the chassis, transformers, etc, to complete the build. Then I'll put the Blackface board back into this amp.

Last night I spent most of the evening getting my head around the adaptations I need to make, but I did get the filter caps, bypass caps and coupling caps soldered, as well as the rectifying diodes. I'm excited!

Re: New Project - single ended JCM800

Fri Jul 01, 2011 1:37 am

I'm new here and have not even had a chance to post an intro but would like to know how your Blackface preamp sounded with the EL-84? Obviously it was not the sound you wanted or were looking for but did the BF preamp along with the single ended EL84 at least get some convincing classic US tone?
I have read that it is not so much the power amp that gives an amp it's sound (although it does add to it) but it is more the preamp that effects the sound.
Also I am very interested in how this JCM800 is gonna sound. I hope you will post some sound clips.