Members bleedblack Posted December 11, 2005 Members Share Posted December 11, 2005 Does anyone know of any mods that can be made to a jcm 2205 head. I have read about removing the bright cap from the input to reduce some treble harshness, but does the 2205 have one, or is this only the 2203/2204 models........this I ask, because i can't be bothered to take it apart to look right now!! Link to comment Share on other sites More sharing options...
Members axe2 2001 Posted December 18, 2005 Members Share Posted December 18, 2005 Thats somthing i'd like to know too. I saw a one that had the diode clipping stuff bypassed or removed. Mine is down right now and she's goin in for service so I was wondering the same thing. So , bump Link to comment Share on other sites More sharing options...
Members JimAnsell Posted December 18, 2005 Members Share Posted December 18, 2005 Originally posted by bleedblack Does anyone know of any mods that can be made to a jcm 2205 head. I have read about removing the bright cap from the input to reduce some treble harshness, but does the 2205 have one, or is this only the 2203/2204 models........this I ask, because i can't be bothered to take it apart to look right now!! the bright cap thing is only on the 2203/2204's Link to comment Share on other sites More sharing options...
Members igge Posted December 18, 2005 Members Share Posted December 18, 2005 The 2205 is a two channel amp so a bit more complex to mod than the 2203. It also depends on how old it is. The early models had post PI master volume, the later pre PI master volume. That's one of the things to try out. Link to comment Share on other sites More sharing options...
Members Voodoo Amps Posted December 18, 2005 Members Share Posted December 18, 2005 I have read about removing the bright cap from the input to reduce some treble harshness, but does the 2205 have one, or is this only the 2203/2204 models........this I ask, because i can't be bothered to take it apart to look right now!! You may want to look at the schematics for those two amps. I only mention this as they are designed completely different from one another so the 2204/2203 mods will not apply to a 2205/2210 (just giving you a heads-up). If the amp has not been recapped I would recommend having it recapped as that will help to restore some bottom end, which will more than likely off set the top end you are hearing. Naturally tubes will make a difference as well as biasing, etc. Thats somthing i'd like to know too. I saw a one that had the diode clipping stuff bypassed or removed. Mine is down right now and she's goin in for service so I was wondering the same thing. So , bump You can of course remove the diode clipping from the preamp circuit but you will loose gain as a result. Hope it helps - Happy holidaysTrace Link to comment Share on other sites More sharing options...
Members jaybird Posted December 18, 2005 Members Share Posted December 18, 2005 Do some searches, there are few mods that you can do yourself that are posted. I found some a couple years ago when I had a 2205. Never did them, except adding a simple bright cap to the "clean" channel, which helped IMO. Of course Trace can mod that amp for you. Jeff Seal does those amps too. Link to comment Share on other sites More sharing options...
Members axe2 2001 Posted December 18, 2005 Members Share Posted December 18, 2005 Originally posted by Voodoo Amps I have read about removing the bright cap from the input to reduce some treble harshness, but does the 2205 have one, or is this only the 2203/2204 models........this I ask, because i can't be bothered to take it apart to look right now!!You may want to look at the schematics for those two amps. I only mention this as they are designed completely different from one another so the 2204/2203 mods will not apply to a 2205/2210 (just giving you a heads-up). If the amp has not been recapped I would recommend having it recapped as that will help to restore some bottom end, which will more than likely off set the top end you are hearing. Naturally tubes will make a difference as well as biasing, etc. Thats somthing i'd like to know too. I saw a one that had the diode clipping stuff bypassed or removed. Mine is down right now and she's goin in for service so I was wondering the same thing. So , bumpYou can of course remove the diode clipping from the preamp circuit but you will loose gain as a result. Hope it helps - Happy holidaysTrace hi trace, thats what I saw, I actually sent you an email about possibly workin on my amp . So removing that would result in less gain, meaning it would be more like a 2203 or 2204? I only ask because if it's not somthing thats commonly done , would I be just as well to find a different model? I'm finding that I like working with the normal channel cranked up anyhow with less pre-gain and more power tube crunch. I don't use the reverb but I do like the FX loop. Your advice is appriciated, Rob Link to comment Share on other sites More sharing options...
Members Voodoo Amps Posted December 19, 2005 Members Share Posted December 19, 2005 hi trace, thats what I saw, I actually sent you an email about possibly workin on my amp . So removing that would result in less gain, meaning it would be more like a 2203 or 2204? Perhaps I read your initial post wrong and if so please forgive me (I logged 74 hours last week) as I was under the impression you wanted to mod the amp yourself. What I was trying to impress upon you is that the typical free-net-mods that pertain to the 2204/2203 would not pertain to the 2205/2210 models (just trying to say you some time and frustration is all--ha, ha). I only ask because if it's not somthing thats commonly done , would I be just as well to find a different model? Over all it depends on what type of tones you are going for so I do not want to recommend selling the amp you have in the event that it may work for you over all. I would like to make sure I understand what you are going for sonically before I recommend or suggest something for you (hope that makes sense, I'm still waiting for the morning coffee to brew--ha, ha) I'm finding that I like working with the normal channel cranked up anyhow with less pre-gain and more power tube crunch. I don't use the reverb but I do like the FX loop. Your advice is appriciated, Rob Lately more and more this seems to be very common. Through a very similar requests we modified a 2205/2210 for some customers. We disconnected the reverb circuit, hooked up an additional two gain stages (his was an 83 so it was a bit different from yours) but we kept the effects loop circuitry intact so he could still use the loop. It actually sounded very good when all was said and done but it was very extensive. Naturally this is all based on preamp gain (high gain) if it sounds like something you are interested in we can review the schematics and see what needs to happen to make this apply to your amp. Aside from that (brain is working a little slow right now--ha, ha) we do have a Standard as well as Deluxe Mod for the 2205/2210 that does increase the gain. It's not a super high gain mod but it does sound really good. We have also designed a very killer mod for the JCM900's as well (adds 2 more gain stages with more bottom end on tap). Time for some coffee (ha, ha) -- Happy holidays!! Trace Link to comment Share on other sites More sharing options...
Members Hi-Gain Posted December 19, 2005 Members Share Posted December 19, 2005 Originally posted by bleedblack Does anyone know of any mods that can be made to a jcm 2205 head. I have read about removing the bright cap from the input to reduce some treble harshness, but does the 2205 have one, or is this only the 2203/2204 models........this I ask, because i can't be bothered to take it apart to look right now!! I have a '83 2205 that I got from Ebay and my first complaint was the harshness....my local amp tech removed a cap from the clean and boost circuit, that got rid of the harshness. The amp sounds more much more dark now. What year is your's? Maybe I can tell you which caps it was. Link to comment Share on other sites More sharing options...
Members axe2 2001 Posted December 19, 2005 Members Share Posted December 19, 2005 Hey Trace, Actually I wasn't the original poster. I was searchin for info on my 2205 and this was an old thread I bumped and am now hijacking! Heres the deal, It's an 84' 2205 I believe to be all original, and it's down right now which is what lead me to considering getting some work done. It used to have a loud pop at power up but it went away. I rehearse in a detached garage and it was cold. I heated the garage, let the amp warm up and played a while. Took a little break and it started freaking out, like some strange octave thing goin on then a loud hum. I checked all fuses and swapped out all the tubes and it's still messed up. So I guess to start with it's gonna need to be diagnosed. As far as modding, like I said I don't use reverb so if that's gettin in the way of tone, it could go. I'm concerned about this diode thing. Not because i'm buyin all the crap said about it, but because i'm finding that i'm playin with much less gain these days and I can hear a certain artificialness and harshness to it's sound. God forbid but I think after 25 years of high gain fizz, (other gear), i'm turning into a tube purist! I play everything from the Stones to Clapton to VH and Judas Priest, AC/DC etc.. so super high gain isn't on my need list. The only time I care for alot of gain is for certain lead passages and I use a modded SD-1 for that. So my thought was to see if this amp can get more of a sound like I read the 2204/2203's are getting. Alot of guys apparently say they don't have enough gain but I believe somthing like that is more what i'm after. I was actually lookin at some plexi's and JMP's but I think they would be way too loud for me. And I have an arsenal of quality OD pedals if needed. I've been doing alot of recording latly and it's funny how the gain keeps coming down to achieve what I thought was alot of gain!Same for live stuff. I mic up and i'm never past 1 or 2 oclock on the dirt channel. I'm trying to A: see if modding this amp will work sonicly and B; determine financially what's best. The 2203's and 2204's are getting pretty pricey these days. So enjoy you coffee and get back to me when you can. Feel free to email me direct at rob2001@sbcglobal.net . thanks for your help and happy holidays. To the original poster, Sorry I hijacked your thread, at least it's the same amp we're talkin about! Cheers, Rob Link to comment Share on other sites More sharing options...
Members Jeff Seal Posted December 20, 2005 Members Share Posted December 20, 2005 The single largest problem with the ch. switcher 800's is due to a very radical design change made around '85, so specific instructions only apply to which version you have..i.e "early" or "later" versions.... If you don't know which one you have, do the following: Turn power off and remove V2 (second 12ax7 closest to input jack).... turn the amp back on, one of the two channels will no longer function... while the other will work perfectly. If the "boost" channel no longer works, it's the early version. If the "normal" channel no longer works, it's the later version. Until you know which one you have, "mods" cannot be universally applied...... You can, in either case have it modded to PTP, thus ensuring you will get the tone you're after...but it's expensive and rather extreme. Of course, it is easily reversible since the original PCB stays intact and can be reinstalled with no affect on resale value. ...looks like this... Much simpler mods are available for the stock circuit, but again, that depends on which one you have.... Jeff Seal Link to comment Share on other sites More sharing options...
Members Hi-Gain Posted December 20, 2005 Members Share Posted December 20, 2005 That looks sweet!!! I was thinking about a turret board for mine, but do it in the later circuit version. How does it sound and did you do the work?? Link to comment Share on other sites More sharing options...
Members Voodoo Amps Posted December 20, 2005 Members Share Posted December 20, 2005 I've been doing alot of recording latly and it's funny how the gain keeps coming down to achieve what I thought was alot of gain! Actually that what you've been experiencing is very common when it comes to recording. Same for live stuff. I mic up and i'm never past 1 or 2 oclock on the dirt channel. I'm trying to A: see if modding this amp will work sonicly and B; determine financially what's best. The 2203's and 2204's are getting pretty pricey these days. We can certainly remove the diode clipping for you and restructure the gain in more of a classic way so that it will get you closer to the tones you are looking for. If you want to nail those tones then I would recommend checking out our V-Plex amp as it's a clone of a very early 1968 plexi. We also offer them with a Master Volume so you can get the cranked tone at any volume you like. So enjoy you coffee and get back to me when you can. Feel free to email me direct at rob2001@sbcglobal.net . Coffee is rockin' this morning and I dropped you a quick email as well. Happy holidays! Trace Link to comment Share on other sites More sharing options...
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