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Looking for a Low-Pass Filter with a Q or Peak control (State-Variable Filter)

#41
Question for @Passinwind or other DIY maven: how do you get rid of loud pops when actuating the stomp? Am I not grounding something I should?

I have the input and output jack grounds going to the little card (the one that you solder onto, then solder onto the 9 lugs on the switch) and the card's ground goes to the JTEX preamp (one of the two GND connections). And the power jack should also be grounded to its own dedicated input on the card.
 
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#42
600 Ohms said:
Question for @Passinwind or other DIY maven: how do you get rid of loud pops when actuating the stomp? Am I not grounding something I should?

I have the input and output jack grounds going to the little card (the one that you solder onto, then solder onto the 9 lugs on the switch) and the card's ground goes to the JTEX preamp (one of the two GND connections). And the power jack should also be grounded to its own dedicated input on the card.
Click to expand...
Is it anytime you hit the switch or only when engaging the preamp? When a design is turned into a pedal usually little tricks will be designed in to eliminate these pops with a true-bypass switch but you may have to do some experimentation here since this was a preamp not really designed to be engaged/disengaged when in the signal path.

I can’t recall, did you say you added an LED? The sudden current pull from the LED might be, but there could well also be an open cap on the preamp board holding charge getting immediately pulled into the circuit when you hit the switch (this is usually solved by adding resistors between the input of the preamp circuit and ground and output of the preamp circuit and ground so that when bypassed these capacitors are unloaded). Check out the second post on this DIY pedal thread for the basics on this: Invalid Link Removed

Maybe @Jerry Catanescu from Jtex could have some suggestions if he has played with adding bypass switching
 
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#43
600 Ohms said:
Question for @Passinwind or other DIY maven: how do you get rid of loud pops when actuating the stomp? Am I not grounding something I should?
Click to expand...
@sunbeast covered it pretty well. Quite a few switching schemes and daughtercards don’t bother with a switched grounding connection at the preamp input, and just use a pulldown resistor at the output to kill the virtual ground voltage (typically 1/2the DC supply, more or less). This simplifies.switch wiring a little and works fine until it doesn’t, for instance it may be fine when fed by a passive bass but pop when fed by an active one. The trick is to get the voltages on either side of the switch connections the same before flipping the switch, as much as possible.
 
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#45
sunbeast said:
Is it anytime you hit the switch or only when engaging the preamp? When a design is turned into a pedal usually little tricks will be designed in to eliminate these pops with a true-bypass switch but you may have to do some experimentation here since this was a preamp not really designed to be engaged/disengaged when in the signal path.

I can’t recall, did you say you added an LED? The sudden current pull from the LED might be, but there could well also be an open cap on the preamp board holding charge getting immediately pulled into the circuit when you hit the switch (this is usually solved by adding resistors between the input of the preamp circuit and ground and output of the preamp circuit and ground so that when bypassed these capacitors are unloaded). Check out the second post on this DIY pedal thread for the basics on this: Invalid Link Removed

Maybe @Jerry Catanescu from Jtex could have some suggestions if he has played with putting adding bypass switching
Click to expand...
I’ll reach out to Jerry.

Yes, I installed a pre-wired LED. I’m going to try to test for the pop with different sources ands see if it is a universal issue or dependent on certain factors.
 
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#46
Back to the original question - the new(ish) Broughton State Variable Filter works great - I had a SF2 I sold about 5 years ago (yes I regret it, but due to it being a rack unit i wasn't using it much) and as far as i can remember the Broughton does a similar job (albeit with 1 channel not 2) at a MUCH lower price.

Great dub sounds, great fingerstyle sounds, mixing in a frequency to your sound - works really well. 2 of them would be amazing.

I have a Pedulla Thunderbuzz 6 string that I have the East filter preamps in (1 filter per pickup), and you can really get a wide variety of sounds with it, i think putting a filter on each pickup works really well. It is finicky tho and takes a bit to get teh sound you want.

I'd love to see Broughton put 2 of these in an enclosure and have the option of putting them in parallel or series like the SF2 - great for getting a scooped slap sound.

Seeing how the new Alembic SF pedal is about $1200 (!), and a used SF2 goes for $2-3k, the Broughton SVF is a great deal.

IMG_5495.jpeg
 
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