OR15 to Rockerverb pre amp mod

[jamme1961]

Haven't had the amp that long but have noticed something lacking high mid and upper treble. Read a bunch of posts here about jim root -Rockerverb - out of all that info -


Rockerverb preamp mod
Jump C11 (470pf tone stack treble cap) this will leave C12 giving you the value of 470pf TS treble cap- which is the value for jim Root & RV & most Marshalls.
Next change slope resistor R17 from stk value of 47K to RV value 39k
you can replace R17 or jump a 250K in parallel with it which will = 39K

[Les Paul Lover]

Did you find the treble lacking at higher volume too?
I'm wondering as these amps really brighten up a bit at volume.

I was wondering if that mode makes the high end a little bit too much when you open it up?

Interesting work, and thanks for sharing!

A forum member recently upgraded all his caps on his OR15 (has since sold it), he thought it was much better after that.

[jamme1961]

I didn't find the amp lacking in treble. I was very happy with the amp stk and wanted to look into a rockerverb- just to have a separate clean sound. I looked at the rockerverb schematic vs the OR15 and the preamps are very close. Just changing the tone stack treble cap value from the (two 470pf in series = 250pf) to just the one at 470pf is a big change, in the right direction (for me) This change alone sounds great to me, the amp opens up so when turning the guitar volume down I can get what I want, a semi clean rhythm crunch thing and turn up for leads and dynamics.Not going to harm this amp with any holes or crazy mods. I've used the RV schematic as a guide because I think these amps are fantastic. I also tried doubling the value of C7 to 4N7 this adds a lot of bass and sounds good (makes the amp sound even bigger) but you lose the bite- to much for me.

[Jondog]

Any chance you drew or have a schematic of the OR15?

[jamme1961]

I found it OR15 online here - http://music-electronics-forum.com/t34126/" onclick="window.open(this.href);return false;

tried to upload it here not working its a pdf file

found a Rockerverb schematic here you can compare http://www.orangefieldguide.com/OFG_SCH ... sheet1.jpg" onclick="window.open(this.href);return false;

[jamme1961]

after more time on this, I decided the amp sounds best with the RV preamp values. I have revised the info for anyone who might want to make the changes. Just two changes -treble cap and slope resistor. good luck

[pedecamp]

This is a very interesting subject, the OR15 and Rockerverb layout almost the same less a few components. I wonder what the Thunderverb50 layout is close to? My amp is so dark it requires a treble boost pedal, it would be nice to tweak a couple components to make it sound like another Orange that's not so dark like an OR50 or RV50 or whatever and not have to use any pedals. I might have to start a new thread on this and see what I find out.

[Slommyonrye]

When you doubled the C7, you said it loses bite, did you mean that it becomes less compressed? I’m kind of looking for something to open it up a bit more and have it work slightly better with drive pedals.

Also this is my first post, I made an account specifically because of this thread. I love this amp and want to see how far I can push it!