Not so long ago i posted a question here.
and looks like the pot i need is a Blend-Balance Pot (MN Taper) like this, but I'm having an hard time finding them.

If i look for them on stores like Mouser or Digikey, if i type "MN taper" i get 0 results... "Balance taper" gives me the usual 5 or 6 Bourns Potentiometers.
Is there the magic keyword that I'm not using or I'm making some mistake in the research?
I need them with Pins and can find them only at Tayda but the quality is what it is.
Is it such a specific componente that is not really easy to find on the market or there is another word for them?

 

This is what is called a niche market. As such, mainstream distributors are very unlikely to carry it.
Your best bet would be an electric-guitar accessories shop, which specifically carries these niche components.

 

Potentiometers are nowhere near as common as they used to be, now that microprocessors do most of the audio mixing.
What's wrong with the one at Tayda? It's made by Alpha.
Google found this one but it has wiring tags.

 

i found some good ALPS or BOURNS but I haven't find a satisfying Alpha pot until now.
Also, Tayda doesn't provide a proper unique ID for the parts and this makes me always a bit suspicious and annoyed since I can't relate to the original part and for me that is just the "Tayda pot", rather the "ALPHA" pot.
I find it ok to play with but a bit unreliable. Anyway I ordered a couple of them and I will open them and inspect.

But beside this personal consideration.. I am interested in other manifactures that produce those kind of pots. I can't believe that only BOURNS (and ALPHA) make them.

 

For a balance pot I have used linear taper pots, with the center being neutral and the wiper tied to the audio common level. That worked for me.

 

Why are You not using this common arrangement with a standard Linear-Pot ?
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Why are You not using this common arrangement with a standard Linear-Pot ?
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View attachment 299996
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Because both signals will be attenuated when the potentiometer is in the center position.
This is all about this point.
In my case, one signal is the DRY and the other one is the WET signal.
The WET could also increase linearly (therefore have an attenuation at half pot rotation) but I need the DRY to remain unaltered untill the center position. After that, it get attenuated.
This because this part of the circuit is an effect RETURN. I want to be able to keep the RETURN pot at 12 o'clock without losing any power on the DRY signal, and sending the signal to the effect that will RETURN and be added.

And for this idea Is different from a simple summing amplifier since when the pot is at clockwise position, only the WET will be heard, at counterclockwise position only the DRY will be heard and at 12 o'clock both can be heard BUT the DRY remains 1:1

 

OK, now I am confused!! "Dry" and "Wet" audio signals??? I am an engineer and so I will be able to understand a more technical description of what the TS is describing using unfamiliar jargon. And it really is unfamiliar to me. High impedance, low impedance, I am familiar with, as well as the various levels, balanced line and unbalanced line.
AND, for stereo signals, both channels should have the same frequency response. In addition, in all common balance control arrangements, the resistance of the balance control is often great enough so that when centered it is not taking away half of the signal of each channel. Instead, when turned off center, one side is reduced quite a bit while the other side does not increase the same amount.
So unlike a STEREO balance control, the TS is asking for something else, mix of wet and dry, whatever that is.
OR, is this not stereo at all, but rather the bass channel versus the full range channel??. Or something else???

 

I was answering to the question of @LowQCab that also partecipated to this thread where i explained what i mean with DRY and WET.
I also referred and posted the link in the very first message.
I will explain here as well:
I'm working on an "Effect RETURN" section of a project that is quite similar to an audio mixer.
The "mixer" has a standard SEND output circuitry that sends an unbalanced stereo signal to an effect ( reverb, delay, whatever..). The outputs of the effect comes back to the mixer in the RETURN Input circuitries.
In the RETURN section , the signal coming from the external effect (called WET) gets mixed with the original signal without effects (called DRY).

 

OK, definitely not stereo.
What I have seen on published circuits of commercial effects boxes and pedals is that for the output togle linear potis connected, lhow much of the effect is added, a single control is connected between the input and the output, and the wiper ties to the hot terminal of the output connector. The internals of the effects box are adjusted for nity gain, so that the level stays constant as the wiper moves from one end to the other. So there is one option, used by many But it is inside the effects box, not in the mixer/amplifier panel.
I am a bit acquainted with "send" and "return", so I understand that part. But based on my musical talent, I decided on an engineering career. Not everybody can be a rockstar.

 

It would appear that the Thread-Starter does not completely understand the
concepts of "Wet" and "Dry".

When dealing with an "Audio-Effect", ( in this example lets talk about a Reverb-Effect ),
the "characteristics" or "personality" of the Reverb is preset, as if it were a "parallel Audio-Chain".
Both the "normal" and "Reverb" chains have a single Audio-Input, but create 2 different Outputs.

The "Reverb-Only-Output" "may" consist of only the "Effect" part of the Sound,
which may make it almost unrecognizable when compared to the original Input,
this would equate to a "100%-WET" Output.
The original Input equates to "100%-DRY" Output.
Therefore, a control is desirable to adjust the ratio, ( balance), of Wet vs Dry at a single Output.

The only situation where a "Balance-Control" between the 2 differing Outputs would be useful
is when the Reverb-Effect, ( minus the original Input-Signal ), is desired to be at 100% at the Output.

The Reverb-Effect already has a "Wet/Dry" Control as a standard Control-Feature.

A "Wet/Dry-Control" is not even remotely similar to a "Stereo-Balance-Control",
it simply "Mixes-In" the "Wet-Signal" into the already existing "Dry-Signal", to some desirable degree.

Most Mixing-Consoles which have an external "Effects-Loop"
have a control for "Mixing-In" the "Effects-Loop" into the "Dry-Signal",
the ones that don't have a "Mixing-Control" for the Effects-Loop,
and only have an "IN/OUT" Push-Button-Switch,
expect the operator to adjust the "Wet/Dry-Control" on the external Effect.

It would appear that the Thread-Starter is trying to re-invent the Wheel.
And it's a secret.
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It would appear that the Thread-Starter does not completely understand the
concepts of "Wet" and "Dry".

When dealing with an "Audio-Effect", ( in this example lets talk about a Reverb-Effect ),
the "characteristics" or "personality" of the Reverb is preset, as if it were a "parallel Audio-Chain".
Both the "normal" and "Reverb" chains have a single Audio-Input, but create 2 different Outputs.

The "Reverb-Only-Output" "may" consist of only the "Effect" part of the Sound,
which may make it almost unrecognizable when compared to the original Input,
this would equate to a "100%-WET" Output.
The original Input equates to "100%-DRY" Output.
Therefore, a control is desirable to adjust the ratio, ( balance), of Wet vs Dry at a single Output.

The only situation where a "Balance-Control" between the 2 differing Outputs would be useful
is when the Reverb-Effect, ( minus the original Input-Signal ), is desired to be at 100% at the Output.

The Reverb-Effect already has a "Wet/Dry" Control as a standard Control-Feature.

A "Wet/Dry-Control" is not even remotely similar to a "Stereo-Balance-Control",
it simply "Mixes-In" the "Wet-Signal" into the already existing "Dry-Signal", to some desirable degree.

Most Mixing-Consoles which have an external "Effects-Loop"
have a control for "Mixing-In" the "Effects-Loop" into the "Dry-Signal",
the ones that don't have a "Mixing-Control" for the Effects-Loop,
and only have an "IN/OUT" Push-Button-Switch,
expect the operator to adjust the "Wet/Dry-Control" on the external Effect.

It would appear that the Thread-Starter is trying to re-invent the Wheel.
And it's a secret.
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I feel quite some unnecessary sarcasm in here.
I thank you very much for your opinion

 

Zero sarcasm intended.
You have still not outlined exactly what it is that You are trying to do.
Only that You want a Custom-made Pot.
Please state what the problem is that does not have a well established solution.
There have been many "guesses" and "assumptions" offered to You.
Everybody here is trying to help You, including me.

I am well aware of the needs of a DJ.
I actually trained DJs to Mix for Flanigans & Big-Daddy's Lounges in the late '70's / early '80's Disco-Era,
( ~200 locations ), and designed, installed, and maintained the Sound and Lighting Equipment
in all of their Clubs in the Miami / Ft. Lauderdale area for 3+ years.
I've also Engineered many very slick and polished 30-second Radio-Spots and the "Disco-Dick-Radio-Show".

It sounds like You are trying to create a special sound or mixing Effect,
but You don't seem to be very experienced with building Electronics projects.
What You want to accomplish may, or may not be, practical, or even possible.
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I'm indeed not experienced as probably the 90% of the people of this Forum, that's why I believe that you could help.
You already did in the past.
I made a quick sketch + project description . This should clarify. The device I'm working on is the one in yellow in the center. The device is in series between the mixer and the amp stage.

It takes the stereo output of the mixer, allows you to play with bass, mids and highs of the audio signal, allows an external effect (send and return knobs) to be used and at the end it send the signal to the Amp stage.
NOT all DJ mixers have controls for "Mixing-In" the "Effects-Loop"

The yellow device is made for a DJ setup and it supposes to have the effect set with output 100% wet/effected.
One could simply use the DRY/WET knob that is (mostly) present on the effect itself, but when a DJ is performing, might find easier to have the controls in a single place.
There are also some other benefits to control this from the device in yellow, will explain shortly.

Until some time ago I was taking the RETURN signals from the effect (i assume this signal is Stereo) and summing it to the DRY signals simply through two inverted summing amplifier configuration, one for the LEFT, one for the RIGHT.
This is simple and straightforward "Wet/Dry-Control" and allows to increasingly sum the Effected sounds with the DRY.

Then I though that instead of a simple sum, i could crossfade the DRY and the WET instead (also this is quite a straightforward solution).
Benefits:
If the RETURN pot is Clockwise + the SEND is Clockwise
- The result is exclusively the WET signal at the output
If the RETURN pot is Clockwise + the SEND is CountercClockwise
-The result is No signal. The effected sound is not present and the DRY is attenuated. It might be an handy feature.

In some cases a DJ wants to close the RETURN pot, abruptively and quickly removing all the effect
But in other cases one can keep the RETURN pot at 50% of the rotation and play/turn the knob of the SEND.
This is, of course, different from opening and and closing the RETURN, because most of the effects used in this scenario have a "tail" (see delays, reverbs) and it can be nice to close the SEND and have the "tail" of the effect to slowly decay through the RETURN.


The drawback of this (and the whole reason why I was asking for advices):
in a normal Crossfade circuitry, when the potentiometer is at 50% of the rotation, both signals have some attenuation. Here you can understand how unpleasant can be when a DJ turns down the RETURN pot and there is a variation in volume (will get a bit louder).

MN Tapers have the perfect curve for this application because until 50% of the rotation, the signal remains unaltered and it gets attenuated only after that. This is exactly what i was looking for but, since the audio coming from the effect is presumably STEREO, I would need a MNTaper with four Gangs... and it doesn't exist.

What i can do, is (as also advised in the previous thread) use a normal Dual MN Taper to control the Voltage to open and close four VCAs.

There is no secret but I just thought that is very long, tedious and annoying to read.

 

I am well aware of the needs of a DJ.
I actually trained DJs to Mix for Flanigans & Big-Daddy's Lounges in the late '70's / early '80's Disco-Era,
( ~200 locations ), and designed, installed, and maintained the Sound and Lighting Equipment
in all of their Clubs in the Miami / Ft. Lauderdale area for 3+ years.
I've also Engineered many very slick and polished 30-second Radio-Spots and the "Disco-Dick-Radio-Show".

All of that while you were a repair tech for BMW?

 

Your Block-Diagram is very well done,
and the lengthy explanation is a requirement, not an arduous task.

Now, I'm quite sure that You will receive much more helpful responses from everyone.

One problem that I see is that this new Control-Box will be limited to the complete Stereo-Mix,
it would be great if this functionality was applied to
the Left-Turntable, as well as, the Right-Turntable, separately.

It's too bad your Mixer doesn't have any Effects-Loops built-in.
I would be searching for a Mixer that does have them included, that would be much more versatile.

The 3-Band-Tone-Control on the new Box should affect ONLY the "Send" Outputs,
this will allow killing the Low-Frequencies going into a Reverb-Effect,
which is a very desirable feature when using Reverb.
Many Reverbs do not handle Low-Frequencies well at all, while the Mids and Highs may be just fine.

The Box that You have in mind will work poorly, or not at all,
without several Op-Amps to provide Impedance-Matching and amplification.
I don't know what your Electronics experience level is,
so my current recommendation is to tell You to buy a new Beringer-Mixer.
It has all the "bells & whistles" and effects, already built-in.

Can You work with simple Op-Amp-Circuits ?
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One problem that I see is that this new Control-Box will be limited to the complete Stereo-Mix,
it would be great if this functionality was applied to
the Left-Turntable, as well as, the Right-Turntable, separately.

The 3-Band-Tone-Control on the new Box should affect ONLY the "Send" Outputs,
this will allow killing the Low-Frequencies going into a Reverb-Effect,
which is a very desirable feature when using Reverb.
Many Reverbs do not handle Low-Frequencies well at all, while the Mids and Highs may be just fine.

If I would be willing to buy a new mixer to solve the problem, then I wouldn't be here That's not an option.

Will keep those suggestions in mind when i will work on a new version. They are indeed interesting but now this project is almost complete.

I will just need to wait for the VCAs to try on breadboard and see how it performs when they are driven by a CV control coming from a MN Taper.

I ordered a bunch of AS2164 and some THAT 2162 to check if the difference in price is worthy or not.
This is becoming way off-topic but at this point i'm curious to know if someone can advise some different VCAs to try out (LM13700 excluded).

Here the part of the circuit that came out after reading the AS2164 datasheet(actually that's the SSI2164 datasheet, since the one of the AS2164 is quite poor).