Captain Bit for Bass - Blend?

[sean2damax]

I was planning on building a captain bit for a bass playing buddy and thought I should probably add a blend knob. I was looking at the schematic and noticed 4 of the knobs look like they’re already blending in the effect. If I’m correct there, does this make a blend knob totally redundant?

 

[Danbieranowski]

I was planning on building a captain bit for a bass playing buddy and thought I should probably add a blend knob. I was looking at the schematic and noticed 4 of the knobs look like they’re already blending in the effect. If I’m correct there, does this make a blend knob totally redundant?

The controls for this effect are pretty interesting, but none of them are a true "blend" of your clean signal with the effected signal.
Here's how it works.
If the "Base" knob is all the way down, and you have the Sub, Down, and Up knobs down you'll just have silence.
As you roll up the Sub, Down, or Up knobs it will roll in the octave fuzz effect for that octave without your original guitar/bass signal present.
As you roll the "Base" knob up it will roll in your original guitar/bass (KIND of like a blend) but it will apply fuzz to that signal. So yes, you're right that there is a blend, but it's not a blend with your clean signal. It's a blend with your instrument through a fuzz, and you as you roll up the Sub, Down, or Up knob you are basically mixing in those octave bands.
If you have Sub, Down, and Up turned all the way down and just roll up the Base knob it'll just sound like your instrument through a fuzz circuit. So basically, the pedal is like a 4 channel mixer, with the 4 channels being your instrument through a fuzz, a sub octave, a down octave, and an up octave, and you mix those 4 knobs to taste.

It's not a true clean blend, but if you want that you can achieve it with a combo build with a board like this: https://guitarpcb.com/product/buff-n-blend-add-a-blend-control-to-any-circuit/

 

[sean2damax]

Man, this forum is awesome. That's super helpful. I don't have a probe, so i'm just looking at the circuit here. Is the square wave coming from the 386 or from a feedback loop through the TM-011? I've done quite a few builds but I still have a lot to learn about how things are functioning haha.

 

[Danbieranowski]

Man, this forum is awesome. That's super helpful. I don't have a probe, so i'm just looking at the circuit here. Is the square wave coming from the 386 or from a feedback loop through the TM-011? I've done quite a few builds but I still have a lot to learn about how things are functioning haha.

It looks like the 386 handles the fuzz piece because the Base "lane" of the schematic only passes through that. It looks like the CD4024 handles frequency division for the low and sub octaves and the transformer handles the frequency work for the up octave. Maybe @Mcknib or @Chuck D. Bones or @Nostradoomus could confirm?

 

[phi1]

nice work! Yeah, I would add that the transformer and diodes are creating octave up by rectifying the signal (making all negative parts positive). The frequency is doubled, but there’s a bit of a jagged shape. Thats why analog octaves all sound a bit fuzzy. All analog octave circuits are doing basically this rectify operation, green ringer and eqd sunn life Use transistors and diodes, bit commander and octavia use transformers and diodes, and there’s several more examples using one of those techniques.

the octave down is done by the CD chip by flip flopping at half the frequency of the input (which is a almost a square wave after the fuzz treatment). So the chip spits out square waves at the lower octaves sort of like by counting the input state changes (simplified explanation).

 

[Danbieranowski]

nice work! Yeah, I would add that the transformer and diodes are creating octave up by rectifying the signal (making all negative parts positive). The frequency is doubled, but there’s a bit of a jagged shape. Thats why analog octaves all sound a bit fuzzy. All analog octave circuits are doing basically this rectify operation, green ringer and eqd sunn life Use transistors and diodes, bit commander and octavia use transformers and diodes, and there’s several more examples using one of those techniques.

the octave down is done by the CD chip by flip flopping at half the frequency of the input (which is a almost a square wave after the fuzz treatment). So the chip spits out square waves at the lower octaves sort of like by counting the input state changes (simplified explanation).

Love the illustrations. Definitely helps!

 

[Mcknib]

Here's a couple of links the Valve Wizard link is mainly his own u boat circuit and how it works but has some good general info on methods used etc

http://moosapotamus.net/files/stompboxology-freq-div-sub-synth.pdf
The Valve Wizard

 

[daeg]

Keep in mind that this effect has zero dynamics -- you input is squared and totally squashed by a headphone amplifier run at max gain. Then the paths split and the octave down part goes through what you'd describe to the layman as a clock counter.

I'm not a Bass player, but balancing that flat explosion of sound with a dynamic clean signal sounds like a mess. Go with a 'Clean' octave down instead. They use a different technique that use the frequency divided square wave to morph your clean signal, instead of just blasting out a negative square wave.

You'll have to go elsewhere for the PCB. Wish we had one here...
https://diy.thcustom.com/shop/u-boat-v1-1-pcb/
https://www.parasitstudio.se/store/p50/U-235_Suboctave_Generator_PCB.html
http://guitar-fx-layouts.42897.x6.nabble.com/Chopped-Boss-OC-2-compact-layout-td13851.html

 

[Mentaltossflycoon]

As a bass player who has built the captain bit, I do not require a clean blend when I use this pedal. That's not what this thing is about. No subtlety going on here.