Rat Mods ?

[rockford]

I just got Jack Orman's rat book, and I wondered if newer rat 's would be good to try out. Are they true bypass ? Should I be looking for an older one, or should I just get a kit from
GGG or BYOC ? I want to try maybe the Ruetz mod, and some chip swap, compensation cap fiddlin'. They get good press from some folks, other's say they are a waste. Please share your opinions .

[petemoore]

  GGG's got HQ kits, JD's my buddy so I can't say I like him !!1 lol
  BYOC...HQ kits.
  Breadboard: try every mod ever concieved for every dirtbox unknown to man, then get every answer and then some, but in 'sound information' [much more communicative than attempts to convert 'sound information' into words] then try a different circuit topology on it once you get your last breadboarded dirbox made.
  Old Rat...probably can find a deal on a working unit with every last little thing that makes a Rat, assembled on it. Get two, mod the crap out of one, have a working example of an 'original Rat' when the mods get tough.
  Being opamp and diode dirtbox, I think variances of the same circuit from unit to unit to clone would be very small, as in slight adjustment would produce Rat type sound from random units.
  Do you see how fickled I can be?
  I just went to 5w testamp, but now I'll tell you I'm totally convinced the 308 just got blown out of the Rat by the LM741 I salvaged from a fire, gain went up.
  I can't rule out other causes though either, and don't have another 308 handy to try in there...
  Bypass caps through pot mod seems to be working differently [gain increase could do that here I think], it seems to go from bass to [more] mid-treble voice now.
  And...now the diodes are different too, the lowest threshold I had preferred [1Si> and <si/Ge] sounds low gain and muddy, the Si/Si sounded preferrable today...
  For HB's I was thinking slightly smaller input cap would keep the 'swamped OA' sound from occuring, perhaps that and the bypass cap pot turned more trebly would be slight improvement, but the bypass cap pot is now working that out...here, using another cap 'series insert' right on the bypass switch will be an easy mod, I use HB's on Rat anyway, easy to choose 1 input cap value, not sure the same type mod for output couldn't be put right on the volume control [going smaller value cap, like going larger value resistor is sometimes easy].
  For diode swap to lower threshold value diode, I'd put the low threshold right 'over' [parallel] the diode...low one prevents the high one from seeing it's threshold so you hear only the low one, can be done with testclips or little wire or diode soldered over diode [if you leave a little leg and heatsink or are ~quick to not overheat it].
 

[darron]

i put a ne5534an opamp in someone's rat once and they liked it more. also, it needs an LED... (:

[rockford]

Hmmm..., the chip swap.   sounds interesting , I'll have to be on the lookout for a use unit now, and investigate diode changes.

[JHS]

IMHO both the Keeley- and Landgraff-mod sound fine, hard to beat classic RAT-tone. For more tweaking ability build a Fulltone Distortion Pro.

JHS

[MikeH]

beavisaudio.com has a cool rat-mod article as well.