non pedal HPF

[Ggaa]

Have you checked whether your amp has a built-in hpf already? Or is there one and you want a higher frequency setting?

I think my Rumble 800 head has one around 40. My Fdeck usually ends up between 80-100.

 

[mrjim123]

You would need an adapter or two, but:

Home

IMO, a fixed 30 Hz HPF is not very useful. +1 to the Broughton always on (but adjustable) HPF. Yeah, you need a power supply, but it IS small.

 

[Rich Fiscus]

I like the idea of an always-on HPF. But it occurs to me that there might be a market for an always-off HPF. I think I could make one that is relatively inexpensive and highly reliable. Anyone interested?

As long as it’s active, I’m in. I don’t want to mess with a passive HPF.

 

[eddododo]

It’s a simple circuit. I am sure you could build one into a cable with a minimal enclosure. Especially since you want a fixed position.

Pssst, just had a wild hair. You could wire the output of your bass since it’s just a cap and resistor. Bury it in the cavity. Only problem is that wouldn’t account for your amp EQ. Hmmm.

Wiring a passive HPF into your bass will OBLITERATE your signal level, and the slope of the roll off will leave your signal hopelessly shrill and devoid of bottom, no matter how much makeup gain you add

 

[eddododo]

What I meant by the wrong forum is the effects forum. It's the flip side of not dissing effects in the effects forum. Some folks see even the desire to avoid a 9v powered thing on the floor on a rig without any of them as an affront.

The good news is I can literally breadboard a 2 stage fixed HPF tonight as long as I can find what I did with most of my gear. (and while the iron is hot I need to fix the faulty switchcraft $25 toggle on my passivated TMB105 with a cheaper but working import switch).

If you’d like a schem or layout for an active HPF I’d be happy to send one over. Also fdeck has a lot of tech info for his HPF that he generously posted on his site

 

[Killing Floor]

Wiring a passive HPF into your bass will OBLITERATE your signal level, and the slope of the roll off will leave your signal hopelessly shrill and devoid of bottom, no matter how much makeup gain you add

Wiring it behind your tone, before the jack is the same as a passive circuit on the floor in a box. With a fixed cut frequency it’s a resistor and a cap, same ingredients as a treble bleed but with different values. If it doesn’t ruin your tone in a pedal on the floor, or as an onboard amp control, it won’t ruin your sound on your bass.

 

[eddododo]

Wiring it behind your tone, before the jack is the same as a passive circuit on the floor in a box. With a fixed cut frequency it’s a resistor and a cap, same ingredients as a treble bleed but with different values. If it doesn’t ruin your tone in a pedal on the floor, or as an onboard amp control, it won’t ruin your sound on your bass.

Oh I’m sorry, I didn’t clarify. That will absolutely OBLITERATE your signal level on the floor in a box.

a first order passive filter, loading guitar pickups of course, just isn’t a solution, outside of a dedication to a very particular tone, with lows that slope away for a looooooong time, taking a lot of signal with it. Luckily, a very simple circuit will do it just fine, on your bass, or in a box, with an egg or with a fox

edit: this is not like a treble bleed, you are irrevocably choking your entire signal. Without a buffer, the rolloff curve could fit a parade along it before you even reach the corner frequency.

 

[Killing Floor]

Oh I’m sorry, I didn’t clarify. That will absolutely OBLITERATE your signal level on the floor in a box.

a first order passive filter, loading guitar pickups of course, just isn’t a solution, outside of a dedication to a very particular tone, with lows that slope away for a looooooong time, taking a lot of signal with it. Luckily, a very simple circuit will do it just fine, on your bass, or in a box, with an egg or with a fox

edit: this is not like a treble bleed, you are irrevocably choking your entire signal. Without a buffer, the rolloff curve could fit a parade along it before you even reach the corner frequency.

Open up your boutique HPF. What do you see? It’s the simplest circuit on anyone’s rig.

 

[eddododo]

Open up your boutique HPF. What do you see? It’s the simplest circuit on anyone’s rig.

Right, I’ve designed and built several. None of the HPF’s so beloved here are a box with a series capacitor and a resistor to ground. The Fdeck, all three versions, are active with a buffer. The broughton is active and buffered.

There may be a small niche of passive devices, but those are NOT for a bass guitar rig, and they’re still usually more sophisticated than a passive RC filter. That’s just not a thing

 

[superheavyfunk]

There may be a small niche of passive devices, but those are NOT for a bass guitar rig,

An earlier post on this very thread would tell you differently

 

[Fortyweight]

If you’d like a schem or layout for an active HPF I’d be happy to send one over. Also fdeck has a lot of tech info for his HPF that he generously posted on his site

Can I take you up on that offer as well?

 

[Passinwind]

Open up your boutique HPF. What do you see?

The entire bottom half of this:

Which is pretty standard fare for a 2nd order + 2nd order format like the fdeck et al.

 

[BEADist]

The biggest problem with a pedal solution is the need for power and I can’t think of a single amp that will allow you to power a pedal directly from it.

Sorry for slightly off topic, but the GR Bass One series of amps have a 9V / 250 mA outlet !
(coincidentally I know because I bought a GR Bass One Mini recently, the mini does NOT have this outlet btw.)

https://www.grbass.com/media/2022/05/Manuale-GR-Bass_One-350-800-1400.pdf

 

[eddododo]

An earlier post on this very thread would tell you differently

Okay I’ll address the one with three devices

the first device offers no specs. If it DOES work well, then it had an inductor, which is not a diy friendly option. It also means it’s 1st order, which will not do for this purpose

the second device offers specs, and get guess what it’s also a -3db first order filter. Whoops not gonna work again

the third one is literally a LOFI pedal. So..


Edit: And there may be a serviceable passive high pass on the market, it’s not an impossible thing to do especially if you can handle some signal loss, and the bulk of my response there was in response to the idea of doing it as a DIY passive box, which remains an impractical option

Even that RCA adapter mentioned above, that is intended for line level, and I would bet at least a few bucks on it having massive signal loss if you manage to run it in line with your bass signal

 

[eddododo]

OP, I do happen to have the schematic to what I believe is your amp, if what you have there is a PF 500

I looked over it briefly to see if there is already a strong high pass in the signal chain… I did not see anything at the entrance up to the first stage, but there’s a lot to look at and I gave it a very casual glance.. what I did see is that the corner frequency for the input stage is around 1.5 Hz, so that’s not going to help

when I get a chance later I’ll try to convert it from PDF to an image and post it here, maybe someone else feels like analyzing the circuit more fully… If I get bored I might take the street signal path into LT spice and see if it clamps that ~30hz range

 

[swarfrat]

It is a PF500. I've found a schematic for the power supply only, not the effects loop. In an effects loop by itself it should be easy to calculate if I can find the impedances. I was planning to just make it a fixed 90hz but it'd be simple to make it adjustable with a T filter.

30hz HPF is a safety feature, and while it is a HPF is not the same purpose as what most of the Fdeck/qStrip/et al are being used for.

After seeing the values needed for a 70-100hz hpf I really don't think an LC filter is the way to go. An RC T-filter gets you there with way more reasonable values. Insertion loss is going to depend on the capacitors used but in the nF range there should be some good choices.

Im kinda busy the next 48 hrs but when I get some down time in I'll run it through ngspice.

 

[dougjwray]

As a non-technical kind of person, I have absolutely no idea what you guys are talking about. But it's strangely entertaining to read!

 

[eddododo]

It is a PF500. I've found a schematic for the power supply only, not the effects loop. In an effects loop by itself it should be easy to calculate if I can find the impedances. I was planning to just make it a fixed 90hz but it'd be simple to make it adjustable with a T filter.

30hz HPF is a safety feature, and while it is a HPF is not the same purpose as what most of the Fdeck/qStrip/et al are being used for.

After seeing the values needed for a 70-100hz hpf I really don't think an LC filter is the way to go. An RC T-filter gets you there with way more reasonable values. Insertion loss is going to depend on the capacitors used but in the nF range there should be some good choices.

Im kinda busy the next 48 hrs but when I get some down time in I'll run it through ngspice.

You don’t see a lot of inductors in pedals, amps and guitars very often for a few reasons..

They’re HUGE, they have series resistance, they’re magnetic core which poses obvious and unobvious issues, they saturate, they can act as antennas, and did I mention how huge they usually are?

 

[eddododo]

It is a PF500. I've found a schematic for the power supply only, not the effects loop. In an effects loop by itself it should be easy to calculate if I can find the impedances. I was planning to just make it a fixed 90hz but it'd be simple to make it adjustable with a T filter.

30hz HPF is a safety feature, and while it is a HPF is not the same purpose as what most of the Fdeck/qStrip/et al are being used for.

After seeing the values needed for a 70-100hz hpf I really don't think an LC filter is the way to go. An RC T-filter gets you there with way more reasonable values. Insertion loss is going to depend on the capacitors used but in the nF range there should be some good choices.

Im kinda busy the next 48 hrs but when I get some down time in I'll run it through ngspice.

send me a PM, I’ll email you the schematic.

I intend to post it here, but it’s a PDF and I don’t feel like figuring out the super dumb way to make it a usable image via my phone right this moment

 

[swarfrat]

Yeah, that was in reaction to all the folks assuming this would be an LC filter.