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

#21
600 Ohms said:
It wouldn't derail it, it would be genuinely helpful. I'd love to know for example how to connect a 9V plug to avoid battery use into a Hammond enclosure. If you took a simple circuit, like a Distiller, I'm imagining:

1. TS jack input (but how to wire to the card? There are too many wires)
2. Need two holes, one for frequency and the other for the switch
3. Standard 9V socket
4. TS jack output

But I've never done this before. It's within my capabilities, just need the instructions.
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There are all the same amounts of inputs/output connections in a pedal vs in a bass. +/- from pickups become +/- from pedal input jack. +/- from output jack of bass become +/- from output jack of pedal. +/- from 9V battery in bass become +/- from pedal 9V jack in pedal (just make sure to get proper orientation since standard pedal power uses center - power). The grounds can usually all be connected directly together, just as in a bass. If you use a battery instead of (or in addition to) pedal power then you will wire the battery - to a TRS input jack the same way you'd wire it to the TRS output jack of a bass so that you only connect the battery when a cable is plugged in. If you use both pedal power and battery option then you wire the pedal power jack so it bypasses the battery when pedal power is plugged in.
 
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#22
sunbeast said:
It's super simple- just replace the input connections with an input jack's connections and the output connections with an output jack's connections. You can hook all the grounds together (just make sure you have a ground attached to the preamp). If you want to use pedalboard 9V power instead of a battery, just make sure you get the + and - connections right to the preamp (standard pedal power is center-negative). Depending on the power supply though, know that you will potentially experience a higher noise floor than when powered with a battery (battery power will always be the cleanest, though a nice isolated power supply should be fine). If you want a battery, then use a TRS jack for the input and wire it the same way you'd wire the output jack on an active bass (so that the battery - goes to the ring connection of the TRS jack and is only sent to ground and completing the circuit with a jack plugged into the input). If you want a battery AND 9V pedal power options then use the typical switching pedal power jack wired to bypass the battery when there is a jack plugged into the 9V input. If you want a bypass stomp footswitch and LED then it gets a bit more complicated to describe, personally I have done both and don't really use the footswitch. there are countless diagrams on the net on how to wire a basic bypass footswitch and LED. If you want a volume control, then I'd recommend adding a 10-25K ohm audio taper one between the output of the pre and the output jack.
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That is the sort of substantive, actionable reply you just don’t expect in forum land!

I would be happy not to do a stomp bypass if I knew that the preamp in question simply passed the full range of what my highest frequency response bass was putting out when the knob was up at max.
 
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#23
600 Ohms said:
That is the sort of substantive, actionable reply you just don’t expect in forum land!

I would be happy not to do a stomp bypass if I knew that the preamp in question simply passed the full range of what my highest frequency response bass was putting out when the knob was up at max.
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All of the existing filter pres I have tried have some cutoff when turned all the way up (they don't go up to 20K), but in my experience it isn't substantive enough for me to care about in my rig (many of my passive pickups themselves start to roll off earlier with their passive controls). They are all slightly different- just looked at the Jtex page and his Distiller says up to 8K, the single Lusithand says up to 4K, ACG EQ-02 says 6.3K. I'm not sure on the pedals like the Broughtons
 
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#24
sunbeast said:
All of the existing filter pres I have tried have some cutoff when turned all the way up (they don't go up to 20K), but in my experience it isn't substantive enough for me to care about in my rig (many of my passive pickups themselves start to roll off earlier with their passive controls). They are all slightly different- just looked at the Jtex page and his Distiller says up to 8K, the single Lusithand says up to 4K, ACG EQ-02 says 6.3K. I'm not sure on the pedals like the Broughtons
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I have EMGs in one bass which is why it’s a concern. Or I just put the bypass in.
 
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#29
I had an ACG EQ-02 with a single filter with continuous Q pot (the first of these types of preamps I mounted in an external box), and honestly didn't find myself adjusting the Q that much. I currently have an EQ-01 (dual filters) in a bass and do use the Q controls more when blending two filters (usually one more flat, one more peaked).

Not mentioned here yet are Underhill preamps (I haven't yet tried one, but they are getting good reviews from other TBers), made by TB'er @bowthing Filter Preamps | Underhill Bass
He has preconfigured filter pres available, but also offers all the parts in a modular format which is super enticing to me ( Preamp Modules & Parts | Underhill Bass ) so you can build a preamp to fit your own needs from what he offers- including an LPF with continuous Q control on a stacked knob: FV Variable Q Filter | Underhill Bass I think you'd also need to add a buffer before as well as one of his connection cables for the most basic single input, single filter option: BP Buffer | Underhill Bass and of course you'll need your 1/4" jacks, 9V power input jack, etc

Maybe @bowthing will chime in with suggestions! I'm hoping to eventually build out a bass with a dual-filter plus attack-boost preamp (Ala Wal) using his components
 
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#30
sunbeast said:
I had an ACG EQ-02 with a single filter with continuous Q pot (the first of these types of preamps I mounted in an external box), and honestly didn't find myself adjusting the Q that much. I currently have an EQ-01 (dual filters) in a bass and do use the Q controls more when blending two filters (usually one more flat, one more peaked).

Not mentioned here yet are Underhill preamps (I haven't yet tried one, but they are getting good reviews from other TBers), made by TB'er @bowthing Filter Preamps | Underhill Bass
He has preconfigured filter pres available, but also offers all the parts in a modular format which is super enticing to me ( Preamp Modules & Parts | Underhill Bass ) so you can build a preamp to fit your own needs from what he offers- including an LPF with continuous Q control on a stacked knob: FV Variable Q Filter | Underhill Bass I think you'd also need to add a buffer before as well as one of his connection cables for the most basic single input, single filter option: BP Buffer | Underhill Bass and of course you'll need your 1/4" jacks, 9V power input jack, etc

Maybe @bowthing will chime in with suggestions! I'm hoping to eventually build out a bass with a dual-filter plus attack-boost preamp (Ala Wal) using his components
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Yeah this looks like a cool option too, and great value. But I agree for now, I think the three position switch is good and will avoid option anxiety.
 
#33
I got my JTEX Distiller and managed to wire it up with an LED and it's in a 125B. Unfortunately the template I used for top jacks was a bit off and the I/O jacks aren't in properly, kind of at a weird angle, so I'll probably move them to the side until maybe finding a new enclosure and starting again. But I will try it out today.
 
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#34
600 Ohms said:
I got my JTEX Distiller and managed to wire it up with an LED and it's in a 125B. Unfortunately the template I used for top jacks was a bit off and the I/O jacks aren't in properly, kind of at a weird angle, so I'll probably move them to the side until maybe finding a new enclosure and starting again. But I will try it out today.
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A lot of times you can just ovalize the mounting holes to get the jacks further away from the enclosure sides, assuming that's the problem. A rat tail file or a Dremel grinder both work fine. Fill in the new space with JB Weld, or use a bigger washer to cover it. It's a very common DIY mistake, in any case. ;)
 
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#35
Passinwind said:
A lot of times you can just ovalize the mounting holes to get the jacks further away from the enclosure sides, assuming that's the problem. A rat tail file or a Dremel grinder both work fine. Fill in the new space with JB Weld, or use a bigger washer to cover it. It's a very common DIY mistake, in any case. ;)
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Yeah, it really makes you wish for a jig. These paper printouts are a bit jive. I'll dremel and get 'er done.
 
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#36
600 Ohms said:
Yeah, it really makes you wish for a jig. These paper printouts are a bit jive. I'll dremel and get 'er done.
Click to expand...
Different enclosure variants for a given nominal size designation have different tolerances to the screw capture ribs, different wall angles, and so on. So something like a Tayda drill template can easily be hosed if using say a Hammond box.

PedalPCB and others do sell drilling jigs, I haven’t used any of them myself though.
 
#37
Despite my janky drill job, I'm happy. It does just what I was hoping it would. I also managed to pick up a good deal on the Broughton SVF from a fellow TB'er, so I will compare. If I end up liking the Broughton more, I could easily see replacing the passive tone control on one of my P basses with the JTEX. It sounds really close to how I remember my old Series I electronics did. But so far my favored usage is mellowing out my active J basses and giving them a more passive honk while eliminating the sparkle (when you want to do that). I've NEVER liked passive tone knobs and this scratches the itch for me.
 
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#38
Got the Broughton and it's very similar in tone to the JTEX but has all the features of an SF-2, which is appealing. Both are great. My guess is I'll keep the Broughton on the board and fix up the JTEX pedal and give it to a friend. Appreciate all the advice here. It was certainly my foray into DIY and that alone was worth starting a thread about it.
 
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#39
600 Ohms said:
Despite my janky drill job, I'm happy. It does just what I was hoping it would. I also managed to pick up a good deal on the Broughton SVF from a fellow TB'er, so I will compare. If I end up liking the Broughton more, I could easily see replacing the passive tone control on one of my P basses with the JTEX. It sounds really close to how I remember my old Series I electronics did.
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It was reputedly cloned directly from the maker’s own Alembic bass with just a few well considered tweaks, so not too surprising. ;)

And BTW: JTEX is no longer shipping to the US, due to stuff and things.
 
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