hi all - just a question for everyone about pots for those who understand them better than I do.....
I'm using a volume pedal as a master volume for the clean and OD channels in passive fx loop of amp but the sound very slightly changes once you use 20 feet worth of cable and a volume pedal - I've tried several types of buffers/passive and active volume pedals and boosters in different positions and a dumbleator , but they all effect the sound , so my idea is to leave the signal where it is in the amp and feed the master volume pot ground to an external volume pedal then back in to amp ground - so you control the amount of signal being fed to ground via the external pot
I havnt tried this yet because I dont want to bugger around with the amp if it's a mad idea with no chance of working - so good idea or unworkable ?
ta,
phil
pot conundrum
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phillyhudson
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Re: pot conundrum
You didn't say what amp you are using. Sounds like the Effects loop isn't buffered so it can't drive the long cable. First thing to try is low capacitance cable.
Re: pot conundrum
More experts may chime in, but a few thoughts:
What you describe about tonal changes while using a master volume is ubiquitous with virtually all master volumes. I’m not certain where your effects loop is inserted in the preamp circuit, but that position will affect how the volume pedal attenuates the preamp signal, and determine what lies downstream to recover it. Do you have a schematic of your amplifier?
Long cable runs will always kill high end signal unless they are buffered properly, as you know. Either find low capacitance cable as previously recommended, or find ways to reduce the length of cable used in the signal path. One way is to design a rig where the effects sit right next to your amplifier, and then implement a midi controller to manipulate the effects how you like. That way you can be as far away from your rig as desired with no signal loss between your feet and your amp.
What you describe about tonal changes while using a master volume is ubiquitous with virtually all master volumes. I’m not certain where your effects loop is inserted in the preamp circuit, but that position will affect how the volume pedal attenuates the preamp signal, and determine what lies downstream to recover it. Do you have a schematic of your amplifier?
Long cable runs will always kill high end signal unless they are buffered properly, as you know. Either find low capacitance cable as previously recommended, or find ways to reduce the length of cable used in the signal path. One way is to design a rig where the effects sit right next to your amplifier, and then implement a midi controller to manipulate the effects how you like. That way you can be as far away from your rig as desired with no signal loss between your feet and your amp.
Just plug it in, man.
Re: pot conundrum
Passive fx loops are trouble.
The best Passive FX loop I have ever been able to pull off is a 470k + 15k voltage divider after the tone stack = 14.56k output impedance. 20ft cable = 1nF = 10.931kHz. Just with a cable you will hear that... it may even be nice. Maybe. Most people will not like this.
But, that is also not taking into account the volume pedal. Let's say it is a 250k volume. Worst case scenario is output impedance of 125k||125k = 62.5k . Into 10ft cable = 500pF = 5kHz. That will probably be a bit dark and actual corner frequency will depend on volume pedal setting.
Some passive FX loops are simply Send after a 1M master volume, so that is even a worse case.
1) Insert a Boss, or any non-true bypass effect directly at FX Send.
2) buffer with another non-truebypass pedal directly after the Volume pedal.
That should do it.
The best Passive FX loop I have ever been able to pull off is a 470k + 15k voltage divider after the tone stack = 14.56k output impedance. 20ft cable = 1nF = 10.931kHz. Just with a cable you will hear that... it may even be nice. Maybe. Most people will not like this.
But, that is also not taking into account the volume pedal. Let's say it is a 250k volume. Worst case scenario is output impedance of 125k||125k = 62.5k . Into 10ft cable = 500pF = 5kHz. That will probably be a bit dark and actual corner frequency will depend on volume pedal setting.
Some passive FX loops are simply Send after a 1M master volume, so that is even a worse case.
1) Insert a Boss, or any non-true bypass effect directly at FX Send.
2) buffer with another non-truebypass pedal directly after the Volume pedal.
That should do it.