# Gauss Drive - more bass!!



## HamishR

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...


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## music6000

HamishR said:


> 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...


You seem to like a bit more  Bass & Grunt to all your Builds, Crank some more into your Amp(s),Ha, Ha!


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## HamishR

I really do!


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## music6000

After watching a few different Demo's, It seems to be in the 2 to 4 O'Clock region so...
Replace Input 22nf with a 47nf or 68nf


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## HamishR

I thought of trying that but I'm a little reluctant because often that just means more low end gets distorted leading to flubbiness, and i like the tightness as it is. I might try it if I can't find another solution though - thanks!


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## Nostradoomus

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


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## HamishR

I was wondering about that.  How did you guess I was waiting for Chuck to turn up?


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## Chuck D. Bones

Patience, Grasshopper.


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## Chuck D. Bones

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.


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## Chuck D. Bones

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:


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## music6000

You said you wanted a *Simple* mod, I gave you one.
If you want a* Technical* mod, Ask Chuck!


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## HamishR

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.


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## music6000

HamishR said:


> 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.


Crikey's, It Gonna look Ugly!!!!!


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## Chuck D. Bones

Let us know how it turns out.


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## HamishR

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!


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## music6000

Chuck D. Bones said:


> Let us know how it turns out.


What effect would R18 & R19 have on the Mids


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## HamishR

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.


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## Chuck D. Bones

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.


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## HamishR

Chuck I've been experimenting some more with my modded Gauss Drive and I'm absolutely stoked. It sounds great with all of my guitars.  Weird how such a modest change can make it so much better.  Thanks!


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## HamishR

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.


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## HamishR

Oh, and a pic, because you fellas love your pics!


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## BurntFingers

What's the little thing to the right of the ICs? Looks like a jumper with a thing in the middle.


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## HamishR

Probably a jumper.  I like to keep my poly caps to 2-3 rows.  I could have stretched one to 4 rows but used a jumper instead.  I was trying to get the treble connections to the left side of the board and the bass to the right.  Nearly got there! I also usually try to get the gain leads closer to the gain pot - ie upper left, and volume leads upper right. This was a difficult circuit to layout for me.

Maybe this will make it clearer (I've made a few changes since the pic posted) It's very much a Flux Drive/BB but more open sounding:


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## HamishR

Oh - maybe you meant the jumper with the blob in the middle? The blob is where I wrap some thinner wire around the jumper and poke it through the hole to make another connection. I use some wire cut from a resistor and make it into a U shape and poke it either side of the jumper through the hole.


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## Chuck D. Bones

Very clean!  I'd say perfect, but it's not symmetrical like PedalPCB layouts .


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## HamishR

You got me!  It's interesting to me that lowering that resistor to Bass 3 from 4K7 to 1K5 has increased bass only slightly - when turned fully open there is more bass but where I have bass set it's not much different.

What is more apparent is the reduction in TS-type mids, which is why it sounds so much more open and frankly better to me. With lots of playing I'm finding I'm still running the bass pot up around 3.00. But because the mids are reduced I'm finding I don't have to run the highs so high. So I am turning treble to around 2.00 instead of 3.00.

So to appease my need to experiment I might change the bass pot to a C50K. The sound is as good as I think I'm going to get from this circuit - it's actually becoming my favourite overdrive because it can do most of what the Majestic/Caliber 45 pedals can do but has a very slightly fuller tone.


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## HamishR

Alright - I reckon (with Chuck's incredible help) I have got myself a cracker of an OD here!  The change to R16 made the midrange perfect - not all congested like a TS. but it also meant the extreme low-end was now possibly over-bearing. So with's Chuck's advice I made C7 22nF. I should have thought to reduce it from the 1µF because on the BB schematic it's 100nF, not 1µF. In my mod 22nF is perfect.  I also made C13 and 15 1µF because 10µF was huge and I still can't hear a difference!

So if anyone has played a BB or Gauss Drive but though it had too much midrange and sounded like a glorified Tube Screamer, here is one way to make it a more open sounding, base overdrive. I really like this one and suspect it may become my main OD.


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## Bobbyd67

Slap like now!
Subscribe !
Send Bass!!
Epico!!!

Sorry couldn't help myself... Been watching too much davie504 :/


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## HamishR

Oh, ok...    

I don't know who davie504 is but he sounds really good.


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## Bobbyd67

HamishR said:


> Oh, ok...
> 
> I don't know who davie504 is but he sounds really good.


He's a bassist YouTuber, he's kinda young so lots of zoomer mêmes but he's a very good bassist.


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## Bobbyd67

Here is a bid he made today ... One with almost no comedy and just playing. He's a better musician than i'll ever be


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## HamishR

Aha!  Ok I get it now!  Cheers. what is it about bass players?  I know lots of bass players with weird senses of humour...


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