Name: Ed
Email: goforthsound@yahoo.com
Subject: RD-50 110
Thread: 297
Time: Tue, 4 Dec 2001 02:59:46 UTC
hi Dave, the limit channel, had a 1.5k (R-8)resistor off the bass pot to ground, and a .0047uf (C-46) treble cap, where the clean has a 820 ohm (R-19), less midrange along with a .0033uf (C-12) treble cap. The updated mid shift circuit has the 820 ohm (R-8) from the bass pot (RC-7)to ground, and the treble cap is still .0047uf, in series with a .01uf(C-4), which might be too much mid boost for some folks, see the mid shift switch shorts out the .0047uf, so that the .01uf lets more boosted mids through, having the .0047uf back in series should get the total capacitance close to .0033uf like the clean channel. I would use a smaller cap than the .01, maybe a .0033, and a .0047 for the boost, so its not so drastic. There is also a 10k (R-6)slope resistor thats like a Q or center frequency of the tone controls, 12k or 15k scoops out some midrange, 10k, 8k etc, would go the other way, maybe a better method of mid boost, the way the GT Soulo 75's mid circuit is done. I changed the 1.5k (R-8)from bass to a 820 ohm as on the latest rev (revision E), and it is better, but I wanted a bit more low end on that overdive, so I changed out C-8 .01uf to .022uf. From my viewpoint, and thats just me, but the 12ax7 was not getting enough voltage and was sounding mushy, farty and unusable stock, so I have been tweaking the parts in there to get the voltages up to where the overdrive is more dynamic. I like a overdrive that responds to the touch and you can dial a reasonable amount of overdrive from the guitar, with out it getting too honky or midrangy when the gains up. One way to do this is to use 2 1n4001 diodes + and - from ground to the wiper (center lug) of the gain pot. At lower gain settings the drive sounds pretty much unaffected, when maxing the amps gain, it gets more focused and articulate, more Santana-like Europa, and sustainy. THis just limits the high gain and clips the signal to a more focused overdrive, Changing the Plate, cathode resistors help also in bringing out a more vocal/singing overdrive. THe Rev E has some nice changes to the overdrive, but I have even tweaked it further. Its getting close to a Dumble ODS/Boogie Mark I overdrive, but I am still working on it. THe clean channel has had some of the extreme briteness tamed down with a .001uf(C-45) added across the brite switch. THe first stage (input stage) also has had the gain padded down a bit too, so its not so in your face. I still need to redo the Driver circuit, there are some diodes and resistor changes that are in the newer revisions. I have not found the schematic to show the driver circuit in this amp, its totally different than the RD-50 drivers, its almost like the RD-65 driver! But its 6L6 tubes. No 12ax7 for the driver, just the JE1692's, so I am still learning about this amp haha! I will try different tubes in the overdrive too, just got some different types. I must have confused the heck out of ya, if you got this far,sorry for so much blow... :^)
thanks
Ed