Modding my 900! (All tube, with clips)

[Kelia]

I'm still rocking it.. it's my go-to amp for lead tones and anything else my class 5 can't do by way of marshall sounds. I just recorded this with it actually. I used a dual recto for the rhythm but the lead is all 900DR with almost no processing.. just a little bass removal and compression.

I can't remember what I biased it at tbh

Wanna thank you Iron for this great thread ,......hope more 900’s owners read this !!

Did you keep the Liam R15 bass mod fianally ?

Cheers !!

 

[Kelia]

Ha.. glad it worked out for you!!

More thump canbr easely done. But I am bit busy right now.... Remind ok? contact me via www.sgravenmadeamps.com

[/MEDIA]

 

[tschrama]

Rock on bro, have fun!

 

[Kelia]

Rock on bro, have fun!

Tx !.........Sent you a message asking for bass thump mod

 

[iron broadsword]

Here’s a small demo just nooddling around , I’ve put a 12au7 in V3 and a 12ax7 HG in V1 . The volume is a little less brutal with the 12au7 .
Hope you like it !
Tx Tschrama and @iron broadsword

Right on the money.

 

[Kelia]

Rock on bro, have fun!

Will do

 

[Kelia]

I prefer the modded DR over a stock MKIII, but then again, a modded MKIII will be even better
[/QUOTE

Thx

 

[Kelia]

FRIG YEAH. Check this out!

http://ghostsauce.net/hidar.m4a

PRS Singlecut > JCM900 4100 > V30 > SM57. Amp was on ChB with the gain maxed. Master volume was 0.5.. low enough to hear my pick on the strings and it still sounds friggin amazing! Lead has some delay added after.

Hey Iron,.....I know this is an old thread but do you still have that clip ? the link doesn't work .

 

[iron broadsword]

Hey Iron,.....I know this is an old thread but do you still have that clip ? the link doesn't work .

I reuploaded the clip here. Recorded at bedroom volume (can hear pick on strings) and added a bit of delay on the lead, else it's totally raw.




This clip was also done with this amp but has some EQ and compression in post. No bass guitar here, just el34 thump

 

[Kelia]

I reuploaded the clip here. Recorded at bedroom volume (can hear pick on strings) and added a bit of delay on the lead, else it's totally raw.




This clip was also done with this amp but has some EQ and compression in post. No bass guitar here, just el34 thump

Thank you my friend !! those clips are gold for someone who is wondering !

 

[GrayFox14048]

Hello there!
I'm here again because I want to mod my JCM900 model 4500 dual reverb 50w.
Unfortunately, no one of all youtube video here are still available.
So I have found this MOD:
1] C27, (4n7)snipe one leg off
disables the nasal sounding tone stack that it feeds into..good mod

2] C35, (220pF) to 100pF
lowers the bright cap on lead channel for less shrill tone..good mod

3] R42, (10k) piggy back another 10K over it.
increases gain in lead channel..if too much try 15k, 22k, 47k..good mod, to taste

4] D10, (diode) snipe one leg off
this disables the diode bridge clipper..little more organic tone, will need to turn gain pot up to compensate

R60, (470k) Pickybag 47K over it
increases the signal pad, necessary because you will get a big boost from losing the voltage drop across the diode bridge you clipped
R13, (220k) snipe one leg off
this one I don't know

you might try snipping a leg of c8 if things get muddy..that's a low end boost that makes it harder to get the sound to clean up with guitar volume in lead channel

edit: checked out R13..it's a negative feedback resistor ..snipping it will give a big gain boost..might try going from 220k to 330k for a more moderate boost.

I have few questions:
- I must do all the steps or just someone (like only the leg off for example)
- If I have undestood, I need to cut sum legs from some capacitor or replace something else, right?

Thanks to all the amp heroes that can help me to mod my JCM!!!

 

[8bit Barry]

What happened to this thread?

Hello there!
I'm here again because I want to mod my JCM900 model 4500 dual reverb 50w.
Unfortunately, no one of all youtube video here are still available.
So I have found this MOD:
1] C27, (4n7)snipe one leg off
disables the nasal sounding tone stack that it feeds into..good mod

2] C35, (220pF) to 100pF
lowers the bright cap on lead channel for less shrill tone..good mod

3] R42, (10k) piggy back another 10K over it.
increases gain in lead channel..if too much try 15k, 22k, 47k..good mod, to taste

4] D10, (diode) snipe one leg off
this disables the diode bridge clipper..little more organic tone, will need to turn gain pot up to compensate

R60, (470k) Pickybag 47K over it
increases the signal pad, necessary because you will get a big boost from losing the voltage drop across the diode bridge you clipped
R13, (220k) snipe one leg off
this one I don't know

you might try snipping a leg of c8 if things get muddy..that's a low end boost that makes it harder to get the sound to clean up with guitar volume in lead channel

edit: checked out R13..it's a negative feedback resistor ..snipping it will give a big gain boost..might try going from 220k to 330k for a more moderate boost.

I have few questions:
- I must do all the steps or just someone (like only the leg off for example)
- If I have undestood, I need to cut sum legs from some capacitor or replace something else, right?

Thanks to all the amp heroes that can help me to mod my JCM!!!

Did you ever manage to do this? I have read this thread with intention of doing the same to a 4100