I finished a Neurocyton. It works as it should, but I'm wondering if I could cut some bass by changing a capacitor value somewhere? It gets flubby real fast. Sure, there is a bass control for EQ, but I'm wondering if I can make it more useful. I'm not sure if I would target C1 going into Q1 or somewhere else, like maybe a mod to the bass potentiometer. I made a similar mod to a Catalinbread Formula 55 (Drive 55), but I gave that pedal to a buddy. I can't remember what I did! I think I picked a later gain stage, like Q3 or Q4. In any case, I am curious to see what y'all might suggest.
Neurocyton Bass Cut?
- Thread starter pfmorton
- Start date
Feral Feline
Well-known member
@HamishR would be the one to speak on this.
I'd play around with C4, reduce the 33n to 22n perhaps. However...
The main one I'd target is off Q2's emitter — C5, knock that 22µ down to 10µ and see what that gets you.
I don't see any huge cap values, so I'm surprised you find it flabby — but everyone's rig/signal-chain is unique so I don't doubt for you it is flubby.
Just that messing too much with the caps may alter the inherent character to something you don't like, something the pedal wasn't designed to sound like.
Yeah, the more I think about it, C5 would be my main choice, but your best bet is getting someone that knows what they're talking about.
I'd play around with C4, reduce the 33n to 22n perhaps. However...
The main one I'd target is off Q2's emitter — C5, knock that 22µ down to 10µ and see what that gets you.
I don't see any huge cap values, so I'm surprised you find it flabby — but everyone's rig/signal-chain is unique so I don't doubt for you it is flubby.
Just that messing too much with the caps may alter the inherent character to something you don't like, something the pedal wasn't designed to sound like.
Yeah, the more I think about it, C5 would be my main choice, but your best bet is getting someone that knows what they're talking about.
There are several HPF in the circuit but they're all <10Hz and use pretty small caps with large resistors. You could adjust any of them but it will probably change the gain structure a little bit if you push one up to 300-400Hz.
Say. C1 and R3 from 22n and 2M2 to 15n and 27k would get you to 393Hz.
You could maybe swap R12 with a 250k trimmer and C7 to 22n. 150k and 22n gets you 48hz. 10k goes up to 700hz
But conversely, this doesn't look like a particularly bassy circuit either. Does the flub clean up if you roll the guitar or gain back? If so, maybe you're oversaturating the transformer?
Say. C1 and R3 from 22n and 2M2 to 15n and 27k would get you to 393Hz.
You could maybe swap R12 with a 250k trimmer and C7 to 22n. 150k and 22n gets you 48hz. 10k goes up to 700hz
But conversely, this doesn't look like a particularly bassy circuit either. Does the flub clean up if you roll the guitar or gain back? If so, maybe you're oversaturating the transformer?
I don't think C5 is the problem. In my limited experience C5 is more about gain than frequency response - reducing C5 to 10nF would reduce the gain rather than low frequency - but I may be wrong, hence the need for some Bones.. I think I would first do what @Chuck D. Bones would say to me first - Have you observed Bill's law? In other words check you have built it to spec first. If it seems that you have (and I know that can come across as patronising but it happens that we all make mistakes!) I would suspect a J201 myself.
I checked each component to make sure I didn't get something wrong. All was well. I tried some other J201's, but they are from the same batch I got from Amazon. I tried some other FET's that I have, but nothing really worked better than the J201. There was one, I forget which, that worked in the Q4 spot with all the others being J201's, but it wasn't much different than the J201. So, I tweaked and tweaked the trim pots for each transistor and got it to where I liked it.
Once I had it "tuned," I played it alongside a Benson Preamp, a Fuzzface, and a Fairfield Barbershop. It's a great unit and has its own voice alongside those. Thanks for the advice, fellas!
Once I had it "tuned," I played it alongside a Benson Preamp, a Fuzzface, and a Fairfield Barbershop. It's a great unit and has its own voice alongside those. Thanks for the advice, fellas!
almondcity
Well-known member
Mine is kinda flabby when bass gets turned up but I just make sure it doesn't get too much past noon. I love this pedal
Same. I guess that's what the bass control is for, eh?
C5 in combination with the source resistor R8 is about both gain and frequency response. At 10-22uF, it's almost a full-range boost. At 1uF, bass will be rolled off while the upper mids and above still get the full amount of boost. 10nF is too small to do anything useful and would indeed just decrease overall gain of the signal.
I'd rather tinker with C5 than any of the high pass filters to decrease the overall amount of bass, as it acts more like a shelving filter rather than a strict cut-off and will sound more natural that way.
