Hello folks,
I have 4 amp boards and I am using them in a BiAmp architecture - 2 amps for the bass (left and right) and 2 amps for the treble (left and right).
I'm trying to find a way to use just a single knob as "tone control" - it will control the "volume" of these amps, in a way that when the knob is in "center", both pairs of amps have "no volume attenuation" (they are in 100% volume), but turning the knob counter-clockwise (until the "min" position), only treble pairs will be attenuated, and the bass amps remain in 100% volume. And turning the knob clockwise (until the "max" position), only the bass pairs will be attenuated, and the treble pairs remain in 100% volume.
I attached an image of the "schematic" I'm trying to archive.
So I ask you guys:
What kind of pots do I have to use?
I mean... how to "combine" pots to get this?
Or maybe using an already existing one which model does exactly this! (I have no idea which one)
Any tip/advice will be really (really) appreciated!!
Thanks in advance.
I have 4 amp boards and I am using them in a BiAmp architecture - 2 amps for the bass (left and right) and 2 amps for the treble (left and right).
I'm trying to find a way to use just a single knob as "tone control" - it will control the "volume" of these amps, in a way that when the knob is in "center", both pairs of amps have "no volume attenuation" (they are in 100% volume), but turning the knob counter-clockwise (until the "min" position), only treble pairs will be attenuated, and the bass amps remain in 100% volume. And turning the knob clockwise (until the "max" position), only the bass pairs will be attenuated, and the treble pairs remain in 100% volume.
I attached an image of the "schematic" I'm trying to archive.
So I ask you guys:
What kind of pots do I have to use?
I mean... how to "combine" pots to get this?
Or maybe using an already existing one which model does exactly this! (I have no idea which one)
Any tip/advice will be really (really) appreciated!!
Thanks in advance.
Attachments
A regular balance control should work, if connected at the right point.
Can you post a schematic of your electronic crossover?
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a 4 gang pot, one gang to each amp, centre position would feed equal to each amp.
Turning right would boost treble and cut bass, left would cut treble & boost bass.
putting a fixed resistor in series with the ground connection of each pot would move the range from 0%-100% to say 50%-100% which might be more useful.
Due to the bi-amp setup, this will not be a "normal" tone control effect. ie all treble frequencies would be boosted equally (except around crossover frequency).
If you just want to adjust levels once then forget, just use 4 separate trimmer pots.
Turning right would boost treble and cut bass, left would cut treble & boost bass.
putting a fixed resistor in series with the ground connection of each pot would move the range from 0%-100% to say 50%-100% which might be more useful.
Due to the bi-amp setup, this will not be a "normal" tone control effect. ie all treble frequencies would be boosted equally (except around crossover frequency).
If you just want to adjust levels once then forget, just use 4 separate trimmer pots.
That's not the way to do it...what you are trying to do with one pot may not even be achievable.
Typically, you have one master volume control, which controls everything, does not affect frequency. After this master volume, typically you have buffer, then you split the signal into upper and lower frequencies, ideally with the buffer on the output. Then you feed the upper pass into one amp, and lower pass into another amp. If each of the amps have its own volume pot, you just set the balance right to have the sound you want.
Its called active crossover.
Typically, you have one master volume control, which controls everything, does not affect frequency. After this master volume, typically you have buffer, then you split the signal into upper and lower frequencies, ideally with the buffer on the output. Then you feed the upper pass into one amp, and lower pass into another amp. If each of the amps have its own volume pot, you just set the balance right to have the sound you want.
Its called active crossover.
I am assuming bi-amping with passive speaker crossovers since the scheme shows no line level crossover.
A 2 gang pot on say the treble only amps and adjust overall volume with the master volume control is simpler. Bypass the tweeter series resister (if fitted) to compensate for the tweeter amp level attenuation.
A 2 gang pot on say the treble only amps and adjust overall volume with the master volume control is simpler. Bypass the tweeter series resister (if fitted) to compensate for the tweeter amp level attenuation.
That could work, indeed! A 4 gang balance control pot can do exactly what I need... unfortunely, I could find any model on eBay/Amazon... do you know any other place where I could buy it? thx.
I dont have one... the frequency cut is being made at the input of each amp... bass from 20 to 500... and for the treble from 500 to 20k.
I have biamp ready speakersboxes (with 1 woofer and 1 tweeter each).
What I am looking for is a way of control the volume of 4 channels, using a single knob, where turning to left will turn 2 channels down (letting the other 2 in 100%), and vice-versa.
I called it "tone control" just because these channels are going to amps that have cross-overs on it, so lowering 2 of them means lowering tweeters and lowering the others means lowering woofers.
It is just a "fine" adjustment, not a "real" tone control.
A 4 gang balance control would be what you need, I don't know if they make such a thing... it's not something that's usually done. You would probably have to somehow connect two dual gang balance controls together.
An alternative could be one like VR1 in Figure 7 here:
Potentiometers (Beginners' Guide to Pots)
In this type you put some resistors (R1, R2) in series with the signal paths and use the pot to bring one side or the other closer to ground. In the center position you lose a bit of signal, but you'd only need a dual gang linear taper pot which should be easy to find. Note that when turned all the way to one side it will be shorting that side to ground so make sure that's not going to harm your circuit.
An alternative could be one like VR1 in Figure 7 here:
Potentiometers (Beginners' Guide to Pots)
In this type you put some resistors (R1, R2) in series with the signal paths and use the pot to bring one side or the other closer to ground. In the center position you lose a bit of signal, but you'd only need a dual gang linear taper pot which should be easy to find. Note that when turned all the way to one side it will be shorting that side to ground so make sure that's not going to harm your circuit.
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Why is it so hard to use a normal stereo balance linear pot? (2 gang)
Simply set the input at senter tap and output bass tw at each of the other. Repeat for the other channel.
This gives a adjustable series resistanse to the amp, and only a few dB up down in level, that would hopefully bee within the requiered range. If not use paralell resistor at amplifier input or at balanse output to reduce volume.
Simply set the input at senter tap and output bass tw at each of the other. Repeat for the other channel.
This gives a adjustable series resistanse to the amp, and only a few dB up down in level, that would hopefully bee within the requiered range. If not use paralell resistor at amplifier input or at balanse output to reduce volume.
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