I'm really liking my Gauss Drive and looking forward to the BB Mid Boost even more. But with the Gauss Drive I am running the bass knob at near maximum to get the sound I like. Is there a simple mod I could do to get a little more bass? I guess I could use a C50K pot for the bass to give myself the illusion that I had more bass on tap...
Gauss Drive - more bass!!
- Thread starter HamishR
- Start date
You seem to like a bit more Bass & Grunt to all your Builds, Crank some more into your Amp(s),Ha, Ha!
Nostradoomus
Well-known member
Maybe play around with the two 33n caps around the bass control, up their values. That’d be my first guess but wait for Chuck 
Chuck D. Bones
Circuit Wizard
Patience, Grasshopper.
Chuck D. Bones
Circuit Wizard
C4 is limiting the bass response before the distortion stage. Making that bigger increases bass and sludge.
C1 rolls off the low end below 12Hz. Making it bigger won't do much of anything.
The stock BASS control gives 20dB of boost or cut at 20Hz, but only 13dB of boost or cut at 100Hz.
R16 & R17 determine how much boost and cut you get. Try 2.2K and see how you like it. Now you'll have 16dB of boost or cut at 100Hz and 25dB at 20Hz.
R16 & R17 don't need to be symmetrical; R16 controls the boost side of the knob.
C11 and C12 determine at what freq the bass boost/cut starts. Making them bigger reduces the amount of bass boost/cut at 100Hz. Best to leave them alone.
I'll follow up with some plots of the TREBLE & BASS freq response.
C1 rolls off the low end below 12Hz. Making it bigger won't do much of anything.
The stock BASS control gives 20dB of boost or cut at 20Hz, but only 13dB of boost or cut at 100Hz.
R16 & R17 determine how much boost and cut you get. Try 2.2K and see how you like it. Now you'll have 16dB of boost or cut at 100Hz and 25dB at 20Hz.
R16 & R17 don't need to be symmetrical; R16 controls the boost side of the knob.
C11 and C12 determine at what freq the bass boost/cut starts. Making them bigger reduces the amount of bass boost/cut at 100Hz. Best to leave them alone.
I'll follow up with some plots of the TREBLE & BASS freq response.
Chuck D. Bones
Circuit Wizard
Here are the tone control responses. This is only the tone control stage. BASS at 0, noon and 10, TREBLE at 0, noon & 10. Note that when both controls are at noon, the freq response is flat at 0dB.
Stock:
With recommended mod:
Stock:
With recommended mod:
Well Chuck's answer might be a simple mod - it appears that if I swap one resistor I might get what I want. I might try reducing the value of R16 to see what happens. To do this I might just stick another 4K7 over it in parallel to see what happens.
Thanks to both of you.
Thanks to both of you.
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Chuck D. Bones
Circuit Wizard
Let us know how it turns out.
I've just been playing the Gauss Drive with the little mod for about an hour! All I did was put a 4K7 in parallel with the existing 4K7 at R16 and it's made a kinda small difference but one which is a big deal too. And yes, it looks way uglier than your visual, Mr 6000!
Actually it was a major PITA to add, but what it's done is remove any boxiness which the pedal had before. It's opened up the sound to be more natural IMO. There is still a midrange emphasis but it's strangely more open-sounding because the lows aren't artificially constrained. It's quite subtle and I don't seem to change the position of the bass knob much. I guess looking at Chuck's response curves explains why - the increase in lows is less near the midrange than further down.
So now the pedal sounds less like a pedal. I wouldn't call it especially "amp-like" yet but I really like it. The whole reason I stopped using the BB years ago was that it sounded a little artificial; a little too Tubescreamer. Now it still sounds like a BB but better.
Chuck you are a 'cking legend!
Actually it was a major PITA to add, but what it's done is remove any boxiness which the pedal had before. It's opened up the sound to be more natural IMO. There is still a midrange emphasis but it's strangely more open-sounding because the lows aren't artificially constrained. It's quite subtle and I don't seem to change the position of the bass knob much. I guess looking at Chuck's response curves explains why - the increase in lows is less near the midrange than further down.
So now the pedal sounds less like a pedal. I wouldn't call it especially "amp-like" yet but I really like it. The whole reason I stopped using the BB years ago was that it sounded a little artificial; a little too Tubescreamer. Now it still sounds like a BB but better.
Chuck you are a 'cking legend!
What effect would R18 & R19 have on the Mids
I guess I like the mids where they are right now, but I'm really looking forward to trying out the BB with mid boost. I am hoping I can cut and boost mids with it - I have no idea until i try it. It's really interesting the little mod has done... I played a hollow-body Gibson through it after my last post and it's definitely better even though it's subtle. I am super tempted to build another and use a 1K5 for R16. I think the (approx) 2K35 works as well as I could want but who knows? It may get too boomy.
To keep myself grounded while testing I continually compare it with my usual OD so I don't lose track of where I am. The extra mids inherent in the Gauss Drive/Flux Drive/BB can make it sound boxy anyway, but the extra low end helps make it sound more balanced and natural/less boxy.
I'll try it again tomorrow to see if the shine wears off but right now I am really happy with it.
To keep myself grounded while testing I continually compare it with my usual OD so I don't lose track of where I am. The extra mids inherent in the Gauss Drive/Flux Drive/BB can make it sound boxy anyway, but the extra low end helps make it sound more balanced and natural/less boxy.
I'll try it again tomorrow to see if the shine wears off but right now I am really happy with it.
Chuck D. Bones
Circuit Wizard
R18 & R19 set the Bass / Treble balance. If you want to mess with the mids, then the Chela (EQD Talons) might be a better bet. I have a Chela board, but it's not a priority at the moment. C9 - C12 have the biggest influence on the mids because they determine where in the midrange the Bass & Treble controls start taking effect.
I like to modify things on vero because it's much more forgiving of changing parts than PCBs tend to be. And there's also the fact that PedalPCB are out of Gauss Drive PCBs right now... BTW this circuit is a bugger to draw a good vero for.
So last night I drew one up of a modified BB/Gauss Drive. I used elements of both. I used 100µF and a 47µF as filters, a 1K5 to bass 3 in the tone stack rather than the 4K7 in the original, different diodes and an A500K gain pot instead of B1M. Findings? Well it's too late now to really crank it, but there is definitely more bass on tap which affects the way we perceive the midrange. Compared to my previously modified pedal it's even less boxy sounding and more natural - whether this will stand up at better volume levels I will see tomorrow, but it's looking promising. I might go to an A1M gain pot as I'm not sure about this A500K. I know I like the pairs of diodes better than single diodes, and the 1N4001/1N4148 pair is not a huge change from four 1N4148s. Pretty sure I used 2SC1815s in the first one but this one has 2N5088s. I wonder if that has any impact? I used 470K to Vref for the Base rather than the 510K the Gauss Drive uses for the 2SC1815s, as that's how it was (apparently) done in the BB.
I always felt that the BB was nearly a great pedal - maybe one or two tweaks is all it takes to make it great for me.
Let me know if anyone wants to see the Vero layout.
So last night I drew one up of a modified BB/Gauss Drive. I used elements of both. I used 100µF and a 47µF as filters, a 1K5 to bass 3 in the tone stack rather than the 4K7 in the original, different diodes and an A500K gain pot instead of B1M. Findings? Well it's too late now to really crank it, but there is definitely more bass on tap which affects the way we perceive the midrange. Compared to my previously modified pedal it's even less boxy sounding and more natural - whether this will stand up at better volume levels I will see tomorrow, but it's looking promising. I might go to an A1M gain pot as I'm not sure about this A500K. I know I like the pairs of diodes better than single diodes, and the 1N4001/1N4148 pair is not a huge change from four 1N4148s. Pretty sure I used 2SC1815s in the first one but this one has 2N5088s. I wonder if that has any impact? I used 470K to Vref for the Base rather than the 510K the Gauss Drive uses for the 2SC1815s, as that's how it was (apparently) done in the BB.
I always felt that the BB was nearly a great pedal - maybe one or two tweaks is all it takes to make it great for me.
Let me know if anyone wants to see the Vero layout.
