I want to build a JCM-800 -w- FX loop

[Just Mike]

Does anybody make kits for these?

[hamfist]

Just put a completely passive loop inbetween the output of the master volume and the 0.022uF coupling cap before the PI .... that always works a treat for me - with line level equipment.

This would be a on a 2203/2204 build BTW.

[Just Mike]

Which kit would you recommend?

[hamfist]

Originally Posted by Just Mike

Which kit would you recommend?

I haven't tried any kits to be honest. I tend to buy an old amp and convert it. I live in the UK so old Selmers, Carlsbros etc are easily found, just asking to be modded or converted to something else. I suspect old Fenders might be the thing to start with in the USA.

[Diablo]

Originally Posted by hamfist

I haven't tried any kits to be honest. I tend to buy an old amp and convert it. I live in the UK so old Selmers, Carlsbros etc are easily found, just asking to be modded or converted to something else. I suspect old Fenders might be the thing to start with in the USA.

Mod an old Fender?....

Much cheaper to buy a brand new kit.

[Normybaby]

I never built any of these amp Kits but I've heard a lot of good things about them

http://www.ceriatone.com/productSubP...CM800_2204.htm

[magneto69]

soldano slo is pretty much the same as the jcm 800 2205 . there are boards , schematics and a forum for this one.
there you have your 800 with fx loop.

you can always change or re-arrange the faceplate.

i am in the process of building one.

[Slobrain]

The SLO and the JCM800 are not really alike, the SLO is a bit more medium advanced build and is much higher gain and channel switching. The JCM800 is a single channel amp with a lower gain but when you put tube screamer in front it has a much smoother gain and more pleasing to the ear.

I have built both and I have to say the JCM800 was an awesome sounding amp. Its limited by being one channel but look what Zakke Wylde can do with that rig.

A 50 watt version is all you would need unless you want your ears to bleed...

The SLO is grittier in the hi gain and sounds good but the FX loop isn't a very good design using two cathode followers. The SLO could be a better amp if someone with electronics engineering skills would take the time to tweak it. The clean channel is also out of phase with the hi gain channel too.

You probably should go to youtube and listen to both amps before you decide what to build.

Cheers

[wizard333]

Actually the 2205 is a very high gain channel switching amp.

You are thinking of a 2203 or 2204. Not at all the same thing.

I haven't looked at the schems for a SLO so no idea if they are at all similar in design, but I can tell you, some Soldanos, like the Hot Rod 50 which is SLO derived, sound a WHOLE LOT like a 2205.

[Enzo]

That is the problem when you call an amp a JCM800 instead of a model number.

[Robert M. Martinelli]

Yeah, Enzo!
OTOH I must say that the Marshall model numbering system is hard to grasp, at least for me....
This said....
When the first JCM800s came out in 1980, they were single channel amps with adjustable gain, while some years later, dual-channel JCM800s were issued (with a SS channel switching circuit). To a Marshall purist, the first JCM800 models are the last "true" Marshalls....I'm more tolerant, and I'd say that the 2x12 50W split channel combo (model 4212, combo version of the model 2205 head) is the best sounding JCM800 amp, despite its SS-based channel switching circuitry. If I was to build a JCM800 clone, this would be my amp of choice.

JM2CW

Cheers

Bob

[wizard333]

The 4210, 4212, 2205, 2210, all shared the same pre-amp, which is the two-channel IC channel switching circuit.

It actually assumed that form in 1984. The 2205 was available before that, looks the same on the outside, same model number and same controls, but pre-mid 84 it was a completely different circuit using individual transistors for the channel switching and having the tone controls on the gain channel early in the gain staging (sounded pretty bad).

I agree that the 84 and on 4210/4212/2205/2210 design was the best and most versatile of the bunch. Some people bitch that there were clipping diodes in them, but only because they read on the net somewhere that clipping diodes make things sound bad, whereas its bad circuit design (ala JCM900) that make a circuit sound bad. The 800s sounded killer.

[Robert M. Martinelli]

Hi,
I liked the 50W ( 2205-4210-4212 ) more than the 100W because to make the 100 W "roar" at its best you had to bring it to "ear-bleeding" levels, while the 50W were indeed killer sounding and more usable IMHO, as you could add some "output stage" distortion to the one coming from the preamp without scaring the neighborhood away. The 4212 was better than the 4210 because of the "voicing" effect of the 2X12 arrangement.

As to the "clipping diodes" issue, I leave such crappy issues to purists, if it sounds good, it sounds good-period. BTW it quite amazes me how some of the more convinced purists, ( i.e. the nit-pickers or hair-splitters that turn away in contempt when they see a single SS diode or a single BJT inside a tube amp ), often put, without any hesitation, small boxes full of various SS devices ( diodes, ICs, BJTs, FETs ) between their guitars and their "all tube" amp's input.

Cheers

Bob

[wizard333]

it quite amazes me how some of the more convinced purists, ( i.e. the nit-pickers or hair-splitters that turn away in contempt when they see a single SS diode or a single BJT inside a tube amp ), often put, without any hesitation, small boxes full of various SS devices ( diodes, ICs, BJTs, FETs ) between their guitars and their "all tube" amp's input

Seems like I've heard that somewhere before.......Oh yeah it was from ME on a different thread lol. Totally agree.

The difference between 50 and 100 watts in terms of volume before power clipping is only about 3db; both will easily send the neighbors running to the phone to call the cops.

Even 15 watts, which is less than 3db quieter than a 50 watt, will do the same.

I've been toying with converting one of those 800s to dual 6V6s with a diffent OT for that reason.

[Guitarist]

I agree with Hamfist, these are practically "predesigned" to accomodate an effects loop. And having compared and heard an added tube buffer--->EFFECTS--->recovery stage, I much prefer the stock easy-wire method. Sure it works best with +4 dB reverbs/eqs. Also these usually have a send level which makes an added tube-recovery redundant - and a tone killer.

Insert in a Lexicon MX200 and an old Rane EQ and Løøk øut!

[thehoj]

Originally Posted by hamfist

Just put a completely passive loop inbetween the output of the master volume and the 0.022uF coupling cap before the PI .... that always works a treat for me - with line level equipment.

This would be a on a 2203/2204 build BTW.

Does it make more sense to have it just before or after the master volume using the 2204 design..?

Also, this is the effects loop I was thinking of implementing in my particular build.. With the send and return level pots.
https://taweber.powweb.com/store/el_schem.jpg
Is this a good design to go with? I have an extra preamp tube to do something with (in my particular build) so I figured this makes sense.