Oddity / hen's tooth filter - Holmes Spectrum H-X6

[Tony Forestiere]

Applauding digi2t, and Strategy (and his friend) for pulling this off. STM for the breakdown. Nicely done.

[digi2t]

I have a break from the Rand-o-matic right now (waiting for parts), so I whipped up this vero.



This retains the original bypass scheme. It's narrow enough to easily fit into a Crybaby shell if you decide to go that route. Personally, I believe it would be much more useful in a wah form, with the treadle working the band pass.

[garcho]

subscribing. nicely done team!

[Strategy]

Wow!
I'm going to see if I can put together my first PCB attempt on this at some point in the near future. Is everyone on this thread OK if I bat my newb layout attempts back to this thread for review. 

[digi2t]

Wow!
I'm going to see if I can put together my first PCB attempt on this at some point in the near future. Is everyone on this thread OK if I bat my newb layout attempts back to this thread for review. 

Fine with me. No sense creating a new thread, this one isn't that long or convoluted. 

[garcho]

Do it! Count me in for a board if you end up going the fab route.

[digi2t]

Do it! Count me in for a board if you end up going the fab route.

Yup, me too. Would be nice to see something like this on a PCB that would fit a 1590BB. The vero is too big for a BB, but would be fine in a J.

[Strategy]

Bear in mind I'm every bit a newbie ...I opened up Eagle and felt so confused I didn't know where to start. I'm going to have to review the tutorials etc. 
Strategy

[digi2t]

Nice tracing job digi2t!

I took the liberty of rearranging the schematic for clarity in order to understand how it works.  As drawn the circuit is suitable for true bypass implementation.  I also added some extra comments in red.

The circuit is basically a state-variable filter with flexible frequency and resonance controls.  The EQ part reminds of the Craig Anderton SuperTone.

Sorry for the necro-bump, but I had to put something right here;

The simplified version of my schematic that stm presented contained an error. The LO, MID, and HI pots, lugs 1 of these pots go to ground and NOT vref as drawn by stm.

Pmow and I were in the process of working up a PCB for this, when I realized that there was a conflict between what I drew up, and what stm redrew. To make matters worse, I had no gut shot of the area in question to prove otherwise. Thankfully, strategy came to our rescue (YEAAAA strategy!!). His friend still owns the unit, and he confirmed that those lugs do indeed go to ground. Here's stm's schematic, with the correction;



And my original, which was lost during Hurricane Photobucket;

[pinkjimiphoton]

dino, put me down for a board twhen you and phil get it sussed out!!

did ya ever work up a vero for it?

outstanding work!

[Strategy]

When I build a pedal I usually don't know what I intend do with it, but I have very specific plans for Holmes Spectrum: use it on bass to clear off the highs for a more dubby reggae sound.
This way I can keep the round-wounds on my bass for times I want to be bright and just use the pedal to get more old school tones (rather than have to have two basses, or change strings)
The Lowpass filter and EQ on this gets some truly monstrous low end.
- Strategy

[Kipper4]

Looks like it would like a buffer up front or up that 220k on the +input.
For guitar ?

[snk]

Hello,
I just came across this unusual effect, and i am considering building it :
- Is the veroboard layout still available somewhere ?
- I have read that the bypass was strange, but what exactly is the issue with it ?
- There are 2 bipolar 2.2µF caps, and i was wondering if they are mandatory (well, i guess that the obvious answer would be "yes", but due to the quarantine, i think i have every other components except those 2 bipolar caps) ?
- Should I add a buffer at the input ?