Catalinbread varioboost

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Petethefuzz

Active member
I just finished a clone of the Catalinbread Varioboost (pedal pcb mercurial boost) and it’s great. I only wish it had a variable q. The q is fixed and it seems rather narrow. I never made a mod to a pedal but was wondering if it would be possible to make an adjustable q of some sort? Or maybe just 2-3 fixed positions?

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I have only built about 10 pedals so far, but this is by far my favorite. I don't know why Catalanbread stopped making them. Maybe I am nutty for thinking that they are so amazing.

I built a Zapper which has an adjustable bandwidth and after building the Varioboost I thought it would be a really neat feature to build in to the Varioboost, but I don't have the skills to do such a thing. If you find a mod please share it here!

Also, that is a great looking build - how did you do the artwork? Is that printed and glued/painted on to the enclosure? It looks great and I really dig the design you chose.
 
It is an awesome circuit. I like to boost around 5-6 db on a set frequency but any more and it starts to quack to much. Great for lead work but too narrow a boost can be to much for rhythm work. What is the Zapper? Never heard of it. I’ll share the mod if I find any :-). The artwork is just an inkjet print and glued with clear coating with a paint brush. Then about three layers of clear coating.
 
Petethefuzz said:
It is an awesome circuit. I like to boost around 5-6 db on a set frequency but any more and it starts to quack to much. Great for lead work but too narrow a boost can be to much for rhythm work. What is the Zapper? Never heard of it. I’ll share the mod if I find any :). The artwork is just an inkjet print and glued with clear coating with a paint brush. Then about three layers of clear coating.
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My main instrument is bass and I love it because I can roll the tone way off and then boost around 600-800 Hz around 6db (I agree, going much higher than that and things get a bit wacky), and with the drive around noon to 2 o'clock it brings out all of these bright harmonics that add this aggression and grind to a fat, rolled off bass tone - something I haven't been able to really get before.

The Zapper is a PedalPCB board that is based off the Systech Harmoic Energizer: https://www.pedalpcb.com/product/zapper/

I'm not sure it's worthwhile to build unless you're looking for exactly that, or if you're a big Zappa fan, but it is kind of fun to play with and at it's extremes does give interesting results. I imagine that it is more useful on guitar than bass as I seem to be limited to pretty slim usable areas in bandwidth and frequency. The gain is also pretty timid on it.
 
Sound like a useful trick on a bass. Maybe the same will work on a guitar. I think i will build a clone of the haunting mids one of these day. It’s has at least to fixed setting for a narrow or wider bandwith. I can’t find any info on how wide it goes but I’ll give it a go.
 
I'm thinking changing the Q on this circuit will be ... difficult for me. Certainly is doing my head in trying to wrap my brain around it.

R7 and R8 along with their respective caps C2 & C3 would need altering, I think, and together — not just one R/C combo over the other.
I don't know of any quad-gang pots to alter each R/C at the same time (one gang for each of the resistors and a gang each to balance between parallel caps?), but a 4PDT toggle could go between a couple of settings... I'll have to consult online tonestack calcs, as well as somebody who really knows what they're doing.

I recken it'll be a juggling act to keep the frequency the same while just adjusting the Q.
 
Chuck D. Bones said:
Moving the 12dB control up and down is equivalent to a Q control. What needs to be modded is not the pedal, but how you think about it. :cool:
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Sort of like when the kid bends the spoon in the Matrix? “Be the spoon”... I get it ;-)

So moving the 12 db clockwise boosts the centered frequency but also more of the above/below frequencies? Like if the curve was an iceberg rising from water? In that case i’d like a less pointy iceberg 😁
 
Yes, adjusting the width of the Q...


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Petethefuzz said:
Sort of like when the kid bends the spoon in the Matrix? “Be the spoon”... I get it ;-)

So moving the 12 db clockwise boosts the centered frequency but also more of the above/below frequencies? Like if the curve was an iceberg rising from water? In that case i’d like a less pointy iceberg 😁
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This is the freq response with the 12dB knob at noon (green), 1:00 (blue) and so on up to 5:00 (gray).

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Chuck D. Bones said:
This is the freq response with the 12dB knob at noon (green), 1:00 (blue) and so on up to 5:00 (gray).

View attachment 12296
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I owe you like 20 beers for helping me understand shit better. Thanks, man.

Being able to visualize what's happening in a circuit seems to be the best way for me to actually gain some kind of understanding of it and probably the best argument for me getting an oscilloscope, one of these days. I feel silly spending that much money now, but maybe down the line I will snag one.
 
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On the Catalinbread, -12dB has a centre detent!
On my Build, I marked it with a Dot :

X

Final Build 3 of the current USPS shipping issue! I own the Original so this was a No Brainer. If you have a Guitar & want to see what it would sound like with different pickups this will get you close. It will also enhance your Guitar as a Boost A clever little Preamp/EQ Pedal!:
forum.pedalpcb.com forum.pedalpcb.com
 
peccary said:
I owe you like 20 beers for helping me understand shit better. Thanks, man.

Being able to visualize what's happening in a circuit seems to be the best way for me to actually gain some kind of understanding of it and probably the best argument for me getting an oscilloscope, one of these days. I feel silly spending that much money now, but maybe down the line I will snag one.
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A 'scope is a good thing to have, but you need more than a 'scope to plot freq response. All I needed to make that pic was LTSpice.

BTW, I'm running an LTSpice tutorial over at The Boneyard.
 
Chuck D. Bones said:
A 'scope is a good thing to have, but you need more than a 'scope to plot freq response. All I needed to make that pic was LTSpice.

BTW, I'm running an LTSpice tutorial over at The Boneyard.
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Thanks. I saw that post and have read through some of it. I have yet to download the program yet, but when I do I'll be walking through your tutorial.
 
Yes. I just happened to have a SPICE model of the Haunting Mids; here's the freq response. Turquoise trace is MID at noon. Lavender trace is MID at 2:30, switch on LO. Pink trace is MID at 2:30, switch on HI. Red trace is MID at 5:00, switch on LO. Gray trace is MID at 5:00, switch on HI. The HI/LO switch changes the Q. With MID at 5:00, the Q = 0.44 on LO, lower than the Varioboost. The Q = 1.7 on HI, about the same as the Varioboost. Notice how the shape of the red & pink traces are very similar, red is on LO, pink is on HI. The Q of the pink trace is 0.43. They won't sound exactly the same, but close.

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Chuck D. Bones said:
Yes. I just happened to have a SPICE model of the Haunting Mids; here's the freq response. Turquoise trace is MID at noon. Lavender trace is MID at 2:30, switch on LO. Pink trace is MID at 2:30, switch on HI. Red trace is MID at 5:00, switch on LO. Gray trace is MID at 5:00, switch on HI. The HI/LO switch changes the Q. With MID at 5:00, the Q = 0.44 on LO, lower than the Varioboost. The Q = 1.7 on HI, about the same as the Varioboost. Notice how the shape of the red & pink traces are very similar, red is on LO, pink is on HI. The Q of the pink trace is 0.43. They won't sound exactly the same, but close.

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That's great! not much difference there really...hmm... I'll guess I'll just have to wait and see if pedalpcb makes a pcb of the Stone Deaf pdf-2. It seems even more tweakable and I love how it sounds. How awesome would it be if pedal makers would provide us with models like these. It should be printed on the box :-) At least for drive/boost etc.
 
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