Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. The sunn still shines online!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

rat tone

1/24/1999 8:28 PM
hys chip

rat tone
I would like to add a baxendall(ala color sound od) or a more flexable style tone control to the rat, yet I am unshure what parts to remove or if I should remove anything from the circuit,  
will this work ? would say a fender or marshall tone stack work ?  
what problems could I run into here ?  
I have a rat layout at my site, done from a  
RG Keen scem, that Jack Orman can be seen at aron nelsons page.  
any help here would be great  
1/25/1999 3:36 AM

I've been messing around with Fender and Marshall tone stacks on op-amp based distortion pedals and pre amps for about six weeks now, and I'm having real problems with impedance matching. I know the idea ought to work, but everything ends up a bit quiet! If anyone could give me an idea of starting values it'd be pretty cool. So far I've just been putting the tone network on the clipping stage output.  
I've not tried this on RAT circuit yet. I actually really like the standard RAT "filter" control. I expect this is the biggest problem you'll have, though.  
1/25/1999 3:50 AM

Look at the Tube Amp book for the op-amp based preamps in the MusicMan schematics. They use basically Fender tone stacks, but the impedance is scaled (lower). A couple of them also feature something like a "logarithmic amp" (with a transistor in the FB loop of an op-amp) as the source of distortion. Some of them have built-in phasers too.  
If you don't like the standart tone control in the RAT I would rather go for a baxandall style than a Fender stack. The Coloursound OD may be a good place to start.  
1/25/1999 10:44 AM
Mark Hammer

I was just flipping through my Aspen Pittman book to the Music Man section while watching the hourglass cursor as your note loaded, so I guess we're in agreement here.  
In case you don't have access to the relevant schematic, the values are as follows:  
treble and bass pots - 25k  
resistor going to junction of treble and bass pots - 10k  
cap going to treble pot - .0033uf (3n3)  
cap going to bass pot - .22uf  
midrange pot - 2k  
These values tend to be pretty generic across all the Music Man amps that have either a totally solid-state, or hybrid, front end, and are configured exactly the same as the standard Fender tone stack, except that they are preceded by an op-amp instead of a tube. In most cases, the wiper of the treble control (which goes to the next stage) has a 0.1uf cap after it to block DC and limit low end.

  Page 1 of 1