jcm800 preamp

[darrylportelli]

hey I was thinking about makin a jcm 800 preamp and housing it in a stompbox enclosure and making it in a pedal format do you think this is a good idea?

[chi_boy]

I have a Roland Cube with a JCM800 channel and the thing sounds great. It may be a challenge to replicate that sound. You have a plan?  I think it sounds interesting either way.

[budjb]

http://www.erikhansen.net/?page_id=36

[drewl]

You talkin tubes?
I think rack mount might be better, but a pedal would work.
I built one into a cheapo little ss combo shell and use it to drive some tube power amps i have.

[beatnik]

i am planning to build this too.

founded a good pcb, small enough for pedal housing, it's andyeffect project on a spanish forum

there videos on youtube, several italian mates had made it and been very satisfied!

http://www.youtube.com/watch?v=DvE5xEWNA2I

http://www.youtube.com/watch?v=5ABsJb2-e14

i can give you the files if you are interested.

[doitle]

You should share that PCB you found on here. I might be interested in taking a look into this as well.

[darrylportelli]

Hey guys. beatnik if you have the schem and pcb I would appreciate it a lot. and by the way its on the schem of the jcm800 2203 preamp right not an emulator?? cos I want to build the real preamp. 10x guys for your responses

[SanderNijland]

i am planning to build this too.

founded a good pcb, small enough for pedal housing, it's andyeffect project on a spanish forum

there videos on youtube, several italian mates had made it and been very satisfied!

http://www.youtube.com/watch?v=DvE5xEWNA2I

http://www.youtube.com/watch?v=5ABsJb2-e14

i can give you the files if you are interested.

Any project files you can upload from the tube version? Sound way better than the transistor one!

Thanks.

[rotylee]

is this it in this thread?
http://www.handmades.com.br/index.php?option=com_joomlaboard&Itemid=26&func=view&id=31758&catid=14

[petemoore]

http://img362.imageshack.us/img362/1236/schemjcmsb1.png

[darrylportelli]

Thanks guys. I wisht I had a wider knowledge on tubes but ill manage the schematic by asking around some friends. If ill find the time ill definitly do this and then ill post the pcb. 10x BTW has anybody built this and can confirm it not that im doubting anyone on the forum but i want to be sure its the jcm 800 preamp and not waste my time on anything else 10x

[Ripthorn]

You can find lots of full schems at schematicheaven.  I am going to built a jcm800 pre from those schems in the coming months.

[darrylportelli]

yeah the schematicheaven jcm800 preamp looks preety good remember to take the power stage from the poweramp schematic otherwise nothing would light up!!!!! tonight I have nothing to do so I think Ill stay up designing a pcb since my Ibanez is sick(broken string) lol BTW anybody know why I always have d string breaks??? I always brak the d string !!! and a set of strings only lasts me 2 weeks!!! the string breaks from the saddle and I dont think its the saddle cos I replaced it with a brand new one and the same results. any ways when Im ready with the pcb Ill post it for you my brothers..

[Ripthorn]

For the string breaks I would say check the intonation on it first, then look at the saddle, because it might be just a little sharp.  You could sand or file down just a little bit to reduce the breakage if that is the case.  I'm not familiar with Ibanez bridges and saddles, though.  Let me know how the preamp in a box comes out.  I'm also going to make a little 10W all tube power amp in a separate box to pair with any preamp I decide to make in the future.  Should be fun.

[beatnik]

sorry for the late reply

i don't know how to post a pdf, anyway is the one in the post linked by rotylee

thanks to www.diyers.com.ar forum, this is a great project!

i am planning to use this transformer, hope will minimize hum, and maybe make a dual channel with separate gain and master

http://it.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2239193

[darrylportelli]

yeah ill check the intonation cos to be honest i tune it from every possible aspect but the intonation.....you see with floyds its a pain in the a$$ to tune it, you have to 1) tune,2)check if 12th fret is sharp or flat,3)de tune,4)move saddle,5)retune,6)check again 12th fret,7)re do every step if still sharp or flat,8) pull every dead member of your enemy out of the grave and make them dance with all the swearing. .I think the next pack of strings im gona set the saddle of the d string the whole way towards the pickups and see what happens!!! its gona take some time to make the preamp since im on another pedal project right now but its almost ready so its almost preamp time!!!

[doitle]

Wouldn't the preamp be putting out a pretty large amplitude signal? You couldn't run that into an amp preamp stage or another pedal could you? I'd expect it to clip like mad if not blow up whatever you are sending it to except the input of a power amp.

[Ripthorn]

The preamp will  have a hot signal, but if he puts a master volume out or something he can use it on both power amps and other preamps.  My thought, however, is why stack preamps?

[darrylportelli]

the reason im going to try to run it through my amp is that I have a vintage hohner amp made in the 1960s and it has a non master vol. my idea is to create a rack type unit that can control the volume and give out tube distortion since the amps preamp anly gives it overdrive when its dimed(and believe me its a nice tone when dimed) but I cant always dime the amp because of the f****** neighbours!!! and the amps EQ only has treble and bass, this way Ill be more able to shape the tone using the mids