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JCM800 added gain stage


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2/11/2003 10:51 PM
mdc1 JCM800 added gain stage
Hi,  
 
apologies if this has been discussed before, I'm new  
to this board.  
 
I'm looking at this circuit from blueguitar.  
 
http://www.blueguitar.org/new/schem/marshall/modnotes/mvp_mod.gif  
 
What does this gain stage mod sound like when added to a JCM800 2203 circuit? How does it compare to Jackson, Metaltronix, and SLO amps and mods? Interested in the gain from a distortion perspective. Any mp3's around that provide a sample of the sound. Feedback from other that have implemented it would be helpful  
too.  
 
mdc1
 
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2/13/2003 5:25 AM
Chuck

I haven't heard that mod. But since no one seems to be picking up the ball, I'll put in my .02  
 
If you really want to cut holes and add tubes and try to build new circuits into an amp that has a PCB in it, Go ahead. But IME the 2203 can be modded for quite a bit more gain with the tube compliment it has. It's a really really simple mod. Not quite SLO gain but close. And IMO more honest and aggressive in a very good way.  
 
Let me look at my 2204 schem to see how to fit this mod in there and if your interested you can email me.  
 
Chuck
 
2/13/2003 7:50 PM
mdc1
>If you really want to cut holes and add tubes and try >to build new circuits into an amp that has a PCB in it  
 
Sorry about my original post as I may have not given enough context. I should have mentioned in the original post that this amp is an old plexi tremelo  
chassis that already has an extra tube socket. As the  
original circuit has been decommisioned/no longer necessary I had this wonderful idea to build a gain monster with this chasis without resorting to PCB's, etc.  
 
 
 
mdc1
 
2/14/2003 7:07 AM
Chuck

OH...Gotcha.  
 
Well, thats 4 preamp tubes...Right?  
 
There are alot of exsisting high gain circuits you could "clone" and then tweak to you own liking.  
 
I tend to prefere the sound of three cascades instead of the typical four found in most ultra high gain amps. You could actually do five cascades and still keep the cathode follower if you skip any fx loops and trem stuff. Most of the posts I read hear from ultra high gain attepts indicate that things are out of hand after four stages. If you want a schem for a KILLER three stage preamp my offer still stands.  
 
Chuck
 
2/14/2003 9:32 AM
jeff

Chuck, I would love a schem of that gain mod you talked about man. I have a 2203 and a 2204.  
 
My email is jeffoc79@aol.com
 
2/14/2003 3:05 PM
Ian Anderson

Any chance of sending it to me as well Chuck?, my email is: velatones@aol.com  
 
.. Ian :)
 
2/14/2003 7:03 PM
Damian

Chuck, one more..  
 
Could you send that schem too?  
My email is damian@nwlink.com  
 
Thanks
 

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