JCM-800/2204 Build

[Cameron]

I also started a 2204 build earlier in this thread and have tried all of the things Miles suggested along the way, I haven't implemented all of them quite yet but only because I cant decide where to drill the holes for them to live. Even individually the mods bring good things to the table but together.... they make one hell of an amp, downright scary good 800. Gotta give credit where credits due, of the gazillions of 800s out there this combination is very well thought out. Good stuff miles.

heres a pic. be nice its my first build ever.

[IMG:600:800]http://img.photobucket.com/albums/v299/Johnspics/20130819_162828_zps5e600385.jpg[/img]

Nice first build.. John...very cool.

[Reeltarded]

I also started a 2204 build earlier in this thread

Great job, John! It looks very nice and I know it kicks the crap we always wanted to kick right out to the curb!!

Vrrrrrroooooooom and such.

[john l]

Ha ha thanks guys!

Id like it to look as clean the builds I see around here but hey I did the best I could and the next one will be all the better.

Yeah to me the best part about this amp is it despite the everything done, it still sounds like an 800 (which is my favorite amp) just mean as all hell and with some VERY usable options. Really appreciate the help miles I think learned more about what does what from modding it than building the hole amp lol.

One of the things I did that deviates from Miles list is decrease V1bs plate from .022 to .0022 to help keep things tight at volume. Since I suck and only play at dive bars unmiked I found it worth doing YMMV if your typical sounds guy likes low stage volumes you may like the stock .022.

What else is worth giving a go Miles? Anyone else have anything to add?

[Reeltarded]

Everything is worth doing at least once.

[john l]

Everything is worth doing at least once.

Very true sir.

[ampgeek]

Getting there.....slowly but surely!!

Made some quality time over the last couple of days to read through Reel's sage guidance and John I's experiences and to throw it all down on "paper". Thanks once again for sharing all of that mates!!!

All jacks will be isolated Cliff type as opposed to what is shown. Just to lazy to draw those up right now.

I put the standard tone controls on thumbwheels and planted them on a board so that only the Slope control will be on the faceplate.

Whipped up a "universal" clipper board to allow easy insert/swap of all the various elements (diodes, transistors, etc..) that I want to experiment with. Ultimately, 6 positions available from the rotary switch.

Boost and Clip each on a footswitch with manual overide on the back panel. I will be using Ampdoc's power supply (from 6.3V heaters) and relay boards.

Thought it the safest to go with Merlin's cathode follower protection circuit for reduced CF cathode resistor values right from the git-go. That is the tag strip mounted network at V-3. Should also make it easy to play around with bootstrapping later on if desired.

PS filtering per Merlin's guidance which worked very well for me on a recent 18W grunge box. HV CT will be right at the 50+50 uf cap can, up along the ground rail and a single chassis connection at the input jack.

Hoping that the JCM-800 afficianados can take a look and let me know if there are any obvious errors/omissions.

TIA
Dave O.

[Bob S]

Wow Dave - very professional approach - makes me feel like a hack.
I do the other thing.
Line it up in my mind then lay it out in the chassis.
My method doesn't always end well.
I likes the variable slope & rotary switch for transistors/zeners.
We are on parallel paths.
Looks good to me buddy.

[Reeltarded]

AWESOME LAYOUT!! That should be a very cool amp! Good job on that, Dave!

Now, if it only had a quad of recifier tubes.



Only a hack would try such a thing

[ampgeek]

Thanks guys! I hate to admit it...but...sometimes the actual building is anticlimatic.

Seriously though, I seem to always learn new and useable things during the layout/parts spec phase with all of the research and reading that goes along with it. Even though it sometimes feels like all I am doing is making is a drilling template.

One upside is that I know that my faceplates will always fit like a glove

Onward! Time to spend some $ and get this thing cranked out...and up!!

Cheers,
Dave O.

[john l]

Your out of control ampgeek. That things going to rip someones head off

[ampgeek]

Gawd...I sure hope that it rips off a few heads John!

But...then again...you ought to know. I am following in Reel's and your footsteps!!

Rock on,
Dave O.

[john l]

Gawd...I sure hope that it rips off a few heads John!

But...then again...you ought to know. I am following in Reel's and your footsteps!!

Rock on,
Dave O.

Not mine Dave this is Miles' baby. As I said the only way mine deviates is the .002 on V1b to cut off some excess low end. I hope you have as much fun as I did building yours.

Now that mines done I can see all sorts of different ways to make it go any direction one would want. Im still constantly finding rad little surprises all over the dials with it.

Nobody go judging but I was playing through the low gain input (Gasp!) and I found some amazing voxy tones when I clicked over to the 12v Zeners and rolled back on the guitar volume.... Im mean like scary close, I blinked and an hour had gone by lol I got so lost playing. I haven't even turned on the 2204 I was messing with in the beginning of the thread.

[JoeCon]

Dave,

Can you build my next Marshall? Please???

Awesome.....

[ampgeek]

What?!? And deprive you of all of the fun Joe?

Seriously though, I am building this in trade for an early 80's Gibson Explorer from my childhood friend up in Loudon NH.

So...it won't be too far from you after all is said and done. Maybe you can have a mini-amp fest with your Trainwrecks.

And, obvously, I will share layouts and anything else desired with anyone interested in trying one.

Cheers,
Dave O.

[gktamps]

How's the build coming along?