Been a minute - dev question

[knucklehead]

Hey y'all - I got a bee in my bonnet to do something unusual and thought to hodgepodge boards from here as part of it.

The end-goal is an onboard active system for a three pickup bass - the plan is to isolate the signals from each of the pickups and dedicate passive tone pots to each of them, and incorporate an onboard boost to up signal strength.

I was looking at the Simple JFET Buffer for each of the pickups. Where I am confusing myself is if I run any two pickups in series do I lose isolation of the tone circuit? Is there a stereo buffer project that I could use in triplicate to get around series/parallel configurations?

As for the boost circuit - I am at an utter loss. ANY suggestions on a simple, clean opamp boost circuit is welcome.

 

[Nostradoomus]

@Passinwind

 

[jwin615]

And @JTEX

 

[peccary]

Blast from the past!

 

[Passinwind]

@Passinwind

Yeah, PPCB first of course, but I have various open source utilty board designs ready to go for stuff like that. I don’t have them up on Github and Oshpark yet but it wouldn’t take to make that happen. All of them use SMD opamps and resistors though, if that’s a deal breaker. Notthing super small, just SOIC-8 and 1206 parts.

As far as pickup configs, if using series mode l’d be wanting to keep that option passive since you want the coil inductances to interact, it‘s arguably the whole point. So I’d switch out at least one tone cap, have to think on the volume control ramifications. I think something like three of my Simple Gain boards and then one another of the various little mix/blend boards I’ve done. I think all of this would draw right around 1mA if using the opamps that @JTEX prefers. He may have some easier/ready built options though, I remember seeing a cool buffer/fixed EQ schematic that he did fairly recently.

 

[giovanni]

Hey y'all - I got a bee in my bonnet to do something unusual and thought to hodgepodge boards from here as part of it.

The end-goal is an onboard active system for a three pickup bass - the plan is to isolate the signals from each of the pickups and dedicate passive tone pots to each of them, and incorporate an onboard boost to up signal strength.

I was looking at the Simple JFET Buffer for each of the pickups. Where I am confusing myself is if I run any two pickups in series do I lose isolation of the tone circuit? Is there a stereo buffer project that I could use in triplicate to get around series/parallel configurations?

As for the boost circuit - I am at an utter loss. ANY suggestions on a simple, clean opamp boost circuit is welcome.

Maybe I don’t understand the question: if you have two pickups in series (or parallel for that matter, as long as they are mixed) don’t you lose isolation by definition because you are summing the two signals?

 

[Nostradoomus]

Yeah, PPCB first of course, but I have various open source utilty board designs ready to go for stuff like that. I don’t have them up on Github and Oshpark yet but it wouldn’t take to make that happen. All of them use SMD opamps and resistors though, if that’s a deal breaker. Notthing super small, just SOIC-8 and 1206 parts.

As far as pickup configs, if using series mode l’d be wanting to keep that option passive since you want the coil inductances to interact, it‘s arguably the whole point. So I’d switch out at least one tone cap, have to think on the volume control ramifications. I think something like three of my Simple Gain boards and then one another of the various little mix/blend boards I’ve done. I think all of this would draw right around 1mA if using the opamps that @JTEX prefers. He may have some easier/ready built options though, I remember seeing a cool buffer/fixed EQ schematic that he did fairly recently.

I just figured you'd have the answer regardless haha

 

[knucklehead]

Maybe I don’t understand the question: if you have two pickups in series (or parallel for that matter, as long as they are mixed) don’t you lose isolation by definition because you are summing the two signals?

Perhaps if each hot lead from each pickup is buffered and the buffered signal only goes to a specific coil's tone pot there will be no interactivity. But I wanted to ask the question as this notion has been a serious mind-f!ck.

I started down this path passively in a Telecaster harness. I sent the hot pickup leads to separate volume pot center lugs, and tied the center lugs to the tone pot circuit. If either pickup was rolled off I got tone isolation, but with increasing volume I got increasing interactivity as the hot send from the volume pots were common to the tip connection. Adding a third coil with a series configuration couldn't work passively and wanted to get some assurance it would work if it were buffered

 

[knucklehead]

Yeah, PPCB first of course, but I have various open source utilty board designs ready to go for stuff like that. I don’t have them up on Github and Oshpark yet but it wouldn’t take to make that happen. All of them use SMD opamps and resistors though, if that’s a deal breaker. Notthing super small, just SOIC-8 and 1206 parts.

As far as pickup configs, if using series mode l’d be wanting to keep that option passive since you want the coil inductances to interact, it‘s arguably the whole point. So I’d switch out at least one tone cap, have to think on the volume control ramifications. I think something like three of my Simple Gain boards and then one another of the various little mix/blend boards I’ve done. I think all of this would draw right around 1mA if using the opamps that @JTEX prefers. He may have some easier/ready built options though, I remember seeing a cool buffer/fixed EQ schematic that he did fairly recently.

Howdy stranger!

I don't see a problem w SMD opamps - I'm chasing clean and isolated, so how I get there is predicated on ONLY that. I DOES have to live in a bass' control cavity and I do have room built in to mine as they were designed forever ago with SD pre's as standard.

I'd prefer to keep the pickups passive and naturally interactive - I was/am uncertain if building in buffers eliminated passive relationships on the pup side.