Preventing audio bleed in a stereo output

Pickups, wiring schemes, switch techniques and onboard active electronics for guitars and basses
Post Reply
User avatar
Ferniff
Information
Posts: 6
Joined: 16 Sep 2022, 22:25
Completed builds: Midi controller
State Variable Filter
Has thanked: 1 time

Post by Ferniff »

Quick question; got a bass with 2 pickups. Each pickup goes to it's own active pre-amp and then to it's own output (a 5 pin output (audio left, audio right, ground, V+, V-)). Pickup > Pre Amp> volume > output.

I'm having an issue where I'm hearing the bridge when I'm plugged into the jack that should just be the neck, or vice verse. What can I do to fix that? Would a big resistor by the input or output help?

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 179 times
Been thanked: 458 times
Contact:

Post by soulsonic »

Does each preamp have it's own power filtering/decoupling? It might be the signals are getting mixed together via the power circuit. More filtering and decoupling can solve that if that's the cause.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
Ferniff
Information
Posts: 6
Joined: 16 Sep 2022, 22:25
Completed builds: Midi controller
State Variable Filter
Has thanked: 1 time

Post by Ferniff »

soulsonic wrote: 16 Apr 2023, 22:44 Does each preamp have it's own power filtering/decoupling? It might be the signals are getting mixed together via the power circuit. More filtering and decoupling can solve that if that's the cause.
No, they are sharing the same line for power

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 179 times
Been thanked: 458 times
Contact:

Post by soulsonic »

If you insert a simple RC filter in series with the power going to each preamp, this could decouple the two channels from one another well enough to stop the problem. I would try a 150ohm resistor with 100uF electrolytic cap to ground. You'd split the line coming from the power and feed each channel in parallel, each with this filter in series. Since you said it has V+/V- bipolar power, you'd need four of these filters: two for the two V+ and two for the two V-. Does that make sense?
You may also need larger size electrolytic caps for the filters, but I've used 100uF many times and it has always worked without needing larger values - you can also increase the value of the resistor, but 150ohm should be enough.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
Ferniff
Information
Posts: 6
Joined: 16 Sep 2022, 22:25
Completed builds: Midi controller
State Variable Filter
Has thanked: 1 time

Post by Ferniff »

soulsonic wrote: 17 Apr 2023, 00:33 If you insert a simple RC filter in series with the power going to each preamp, this could decouple the two channels from one another well enough to stop the problem. I would try a 150ohm resistor with 100uF electrolytic cap to ground. You'd split the line coming from the power and feed each channel in parallel, each with this filter in series. Since you said it has V+/V- bipolar power, you'd need four of these filters: two for the two V+ and two for the two V-. Does that make sense?
You may also need larger size electrolytic caps for the filters, but I've used 100uF many times and it has always worked without needing larger values - you can also increase the value of the resistor, but 150ohm should be enough.
Thank you. I think I have a coupling capacitor at each power input, 100nf each. Here is the schematic I'm working with, it's a slimmed down version of the Alembic Super Filter
Here is the schematic:

I'm using a 5 pin cable/jack for Neck, Bridge, V+, V- and ground.
https://www.amazon.com/5-pin-din-connec ... +connector

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 179 times
Been thanked: 458 times
Contact:

Post by soulsonic »

That imgur thing does not work for me. Please upload all images here as attachments.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
Ferniff
Information
Posts: 6
Joined: 16 Sep 2022, 22:25
Completed builds: Midi controller
State Variable Filter
Has thanked: 1 time

Post by Ferniff »

Image

Attachments
Capture.JPG

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 179 times
Been thanked: 458 times
Contact:

Post by soulsonic »

Looks like what I suggested won't work, because you have both channels sharing the same ICs. Each channel would need to have its own for what I suggested.
And maybe sharing the same ICs amongst both channels is the cause of your problem in the first place.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

Post Reply