cr_XD Posted February 29, 2004 Report Share Posted February 29, 2004 got this nasty problem with my marshall jcm 800 4210, it´s the dual channel version and i really hate it not being clean on the clean channel, i mean, if i turn the volume louder than one it starts to distort and i ain´t no electronic guru, but neither got the money yet to take it to the shop. i wanted to know, maybe it's the preamp valve's that are driving the output stages too hard, or is it just preamp distortion, i would swear it's a different distortion than in the boost channel... so bad ear :DB) anyway, can anybody help me with this, i want a clean channel Quote Link to comment Share on other sites More sharing options...
ansil Posted February 29, 2004 Report Share Posted February 29, 2004 is tehre a push pull switch tehre or a push on push off button to od the clean channel most marshalls have this function... Quote Link to comment Share on other sites More sharing options...
cr_XD Posted February 29, 2004 Author Report Share Posted February 29, 2004 no there isn't, i found the schematics if you wanna have a look (doesn't say much to me ) preamp poweramp edit: no, these are not, these are 2210 and i own 4210 ouch Quote Link to comment Share on other sites More sharing options...
lovekraft Posted February 29, 2004 Report Share Posted February 29, 2004 Here's your schematic: JCM800 4210 Combo With single coils, the clean channel isn't bad at moderate volumes, but this is a Marshall - you're never gonna get Fender clean out of it. Get rid of those diodes in the gain channel and you've got a great classic amp. Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 29, 2004 Report Share Posted February 29, 2004 yeah the jcm800 is not a clean amp...it is a high gain amp...most metal guys frpom the 80s and 90s consider it the ultimate amp though Quote Link to comment Share on other sites More sharing options...
rob Posted February 29, 2004 Report Share Posted February 29, 2004 I Know that the JMC800 doesn't have a clean channel as such, but the normal channel should remain almost clean until about 5 on the normal channels vol. Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 29, 2004 Report Share Posted February 29, 2004 I Know that the JMC800 doesn't have a clean channel as such, but the normal channel should remain almost clean until about 5 on the normal channels vol. depends...amps can be "hot rodded" so to speak with higher gain tubes and such...maybe this one has been modded if it was mine i would love the extra gain....but that is just me Quote Link to comment Share on other sites More sharing options...
Little Bit Posted March 1, 2004 Report Share Posted March 1, 2004 Post pulled by author. Quote Link to comment Share on other sites More sharing options...
ansil Posted March 1, 2004 Report Share Posted March 1, 2004 looking at the scheme replace the capacitor on what is it the cathode. end... lol i never learned the terms i just know how it works. anyway replace the .1cap with like at least a 1mfd if it isn mislabeled and already a 1mfd then change it to a 10uf or so.. this will help with the freq shaping which since bass freq use more energy therefore you will have to use the gain to to drive a broader freq range. you can raise the 1k upt to 2.7k and even decrease the 100k to around 75k. and thiss will help. Quote Link to comment Share on other sites More sharing options...
ansil Posted March 1, 2004 Report Share Posted March 1, 2004 also for a more throaty distortion remove one of the 4007 diodes Quote Link to comment Share on other sites More sharing options...
lovekraft Posted March 2, 2004 Report Share Posted March 2, 2004 also for a more throaty distortion remove one of the 4007 diodes Or, if you want a tube amplifier sound, get rid of all four of the infernal things! Quote Link to comment Share on other sites More sharing options...
cr_XD Posted March 2, 2004 Author Report Share Posted March 2, 2004 really thanks for all the input. just talked with the guy at the shop and told me more or less the same, i really don't dare to do it myself for the time being, so i will take it to him and ask to make it sound thicker and bassier and to get the diodes out for a try xD just a question to see if i have understood anything from all the schematics i've looked at: is it that diode configuration meant to make a distortion, cos it reminds me of the distortion pedals? Quote Link to comment Share on other sites More sharing options...
ansil Posted March 2, 2004 Report Share Posted March 2, 2004 also for a more throaty distortion remove one of the 4007 diodes Or, if you want a tube amplifier sound, get rid of all four of the infernal things! very true.. but one of the things that gives it that sound is the diodes. it doesnt' sound the same wihtout them... not better or worse just different.. of course i think most people (not all) have a hard time distiguishing between tubes and ss. i know of one circuit.. that would blow your gourd but i donbt' hvae it on the computer only on paper. i foudn a rough version of it on the net. it uses a mosfet and a jfet to act like a tube.. and all at highvoltages. i gutted a dead 12ax7 and plugged it into my marshall i had at the time. and everyone wanted to know what i had done to make it scream and sound so creamy.. i laughed i told them i retubed it.. which in a sense i did... lol Quote Link to comment Share on other sites More sharing options...
lovekraft Posted March 2, 2004 Report Share Posted March 2, 2004 ...is it that diode configuration meant to make a distortion, cos it reminds me of the distortion pedals? Yup, it's a fuzzbox - so much for "classic tube distortion", huh? You'd be surprised at the list of highly-regarded "tube" amps that have SS diode clippers in them (Mesa V-Twin, for instance). Quote Link to comment Share on other sites More sharing options...
lovekraft Posted March 2, 2004 Report Share Posted March 2, 2004 very true.. but one of the things that gives it that sound is the diodes. it doesnt' sound the same wihtout them... not better or worse just different.. Yeah, hard clipping has become really popular, particularly with metal players, but you can get that with a stompbox. If you want a tube saturation sound, get rid of the 1N4007's - the preamp gain stages may need tweaking a bit if it's not crunchy enough for you. of course i think most people (not all) have a hard time distiguishing between tubes and ss. i know of one circuit.. that would blow your gourd but i donbt' hvae it on the computer only on paper. i foudn a rough version of it on the net. it uses a mosfet and a jfet to act like a tube.. and all at highvoltages. i gutted a dead 12ax7 and plugged it into my marshall i had at the time. and everyone wanted to know what i had done to make it scream and sound so creamy.. i laughed i told them i retubed it.. Ansil, if you've found a MOSFET circuit that actually sounds like a 12AX7, you need to go into production - and don't forget us little folks when you're rich and famous! Quote Link to comment Share on other sites More sharing options...
ansil Posted March 3, 2004 Report Share Posted March 3, 2004 its mosfet and a jfet. it required heavy tweaking from a bsic circuit i found on the net.. right now i am trying to find out the source it came form on the net so i dont get copyright infringment problems.. and such... i believe the theory behind it was that the mosfet was working as a voltage divider/ regulator. but i could be wrong.. i built a low gain version of it for a stompbox and then slowly worked up the high gain version.. till one day i just handed one of them to a friend at the local music store and tld him to plug it into his marshall.. still a little hotter than a normal tube stage Quote Link to comment Share on other sites More sharing options...
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