The bottom lug of the 1K resistor at G10 needs to move down one row so it's connected to row H / pin 6 of the IC. On my build, I moved the 47R to col 1 and the 1K over to col 8 so it could have a space on row H. now she's playing like a dream :)
do you happen to still have a schematic handy for the DOD FX100 Integrated Tube Even Harmonic Overdrive? the ones I'm finding on FSB don't quite look right, and I'm trying to troubleshoot a build. thanks!
Its been years since I did the DOD FX100 layout so I don't have the schematic with me anymore.:-/ However, I noticed a bug in the first listed schematic at FSB. The 1K resistor at A11 and D11 needs to be 1M! Otherwise the signal will be dumped to ground. The layout is updated.. https://dirtboxlayouts.blogspot.com/2019/09/dod-fx100-integrated-tube-even-harmonic.html
I've been tinkering with this a lot. Some of my findings... I didn't have 5458s so I tried to swap for what I had on hand, 5457, j201, j112, j113, 2sk30a. I surprised me that it made a lot of difference, I thought for buffer it wouldn't matter much. So J201 had least gain, 5457 and 2sk30 were middle gain and j112/j113 was loudest - too much I think, it made the effect sound awful. Interestingly, on output buffer, 5457 produced asymmetrical waveform, like some sub-bass frequencies interfered... with others it was nicely compressed and centered. By ear I settled with 5457 on input and 2sk30 on output (with some leg twisting - different pinout). Used LM301 instead of 308. A pair of leds works nice in soft clipping sections, a bit less compressed, I made it optional. Used yellow ones, green leds or no diodes made it low self oscillate (ticking) and distort awfully. 1.6k resistor defines the brightness for filter in the brightest position (adds to tone pot resistance), if you like it brighter, you can go with lower value, I swapped it for 300r, because I like fizzy. Overall, I think it sounds fantastic. Infinitely better than Rat clone I have (Little-Bear), maybe I should pull out LM308 out of it and see how it sounds in the build...
Makes sense that the JFETs would make a difference in this specific build as for some reason the Brat uses them as common source amplifier boosters where the original Rat uses the output JFET as a common drain amplifier buffer.
What I don't get about this pedal.... When I watched the demos it is pretty much indistinguishable from the standard rat. It was cheaper than a rat. So it uses twice the amount of parts, costs less yet sounds the same... I'm scratching my head 🤔
Haha, that is weird. It's probably just supply and demand. Probably an unsuccessful attempt at keeping the Rat fashionable throughout the changing trends. They probably could've stuck a stock Rat in an EXTREME enclosure and called it a day. Until thegearpage gets ahold of it and smears them. Haha
The bottom lug of the 1K resistor at G10 needs to move down one row so it's connected to row H / pin 6 of the IC. On my build, I moved the 47R to col 1 and the 1K over to col 8 so it could have a space on row H. now she's playing like a dream :)
ReplyDeleteThanks a lot! That was fast...
DeleteLayout is updated and tagged.
do you happen to still have a schematic handy for the DOD FX100 Integrated Tube Even Harmonic Overdrive? the ones I'm finding on FSB don't quite look right, and I'm trying to troubleshoot a build. thanks!
DeleteIts been years since I did the DOD FX100 layout so I don't have the schematic with me anymore.:-/
DeleteHowever, I noticed a bug in the first listed schematic at FSB. The 1K resistor at A11 and D11 needs to be 1M! Otherwise the signal will be dumped to ground.
The layout is updated..
https://dirtboxlayouts.blogspot.com/2019/09/dod-fx100-integrated-tube-even-harmonic.html
I've been tinkering with this a lot. Some of my findings...
ReplyDeleteI didn't have 5458s so I tried to swap for what I had on hand, 5457, j201, j112, j113, 2sk30a. I surprised me that it made a lot of difference, I thought for buffer it wouldn't matter much. So J201 had least gain, 5457 and 2sk30 were middle gain and j112/j113 was loudest - too much I think, it made the effect sound awful. Interestingly, on output buffer, 5457 produced asymmetrical waveform, like some sub-bass frequencies interfered... with others it was nicely compressed and centered. By ear I settled with 5457 on input and 2sk30 on output (with some leg twisting - different pinout).
Used LM301 instead of 308.
A pair of leds works nice in soft clipping sections, a bit less compressed, I made it optional. Used yellow ones, green leds or no diodes made it low self oscillate (ticking) and distort awfully.
1.6k resistor defines the brightness for filter in the brightest position (adds to tone pot resistance), if you like it brighter, you can go with lower value, I swapped it for 300r, because I like fizzy.
Overall, I think it sounds fantastic. Infinitely better than Rat clone I have (Little-Bear), maybe I should pull out LM308 out of it and see how it sounds in the build...
Makes sense that the JFETs would make a difference in this specific build as for some reason the Brat uses them as common source amplifier boosters where the original Rat uses the output JFET as a common drain amplifier buffer.
DeleteWhat I don't get about this pedal.... When I watched the demos it is pretty much indistinguishable from the standard rat. It was cheaper than a rat. So it uses twice the amount of parts, costs less yet sounds the same... I'm scratching my head 🤔
ReplyDeleteHaha, that is weird. It's probably just supply and demand. Probably an unsuccessful attempt at keeping the Rat fashionable throughout the changing trends. They probably could've stuck a stock Rat in an EXTREME enclosure and called it a day. Until thegearpage gets ahold of it and smears them. Haha
Delete