How to control 6 inputs with 1 pot???

[JojoD818]

Hi everyone,

I have a DVD player that has 6 outputs...

1. Front Left
2. Front Right
3. Center
4. Surround Left
5. Surround Left
6. Surround Center

Now the question is, if I will build a 6 channel amp, how do I control the volume? What I want is to control the volume of the 6 channels with one control. Is it possible?

Regards,
JojoD

 

[richie00boy]

Use VCAs (Voltage Controlled Amplifiers) or digital potentiometer/volume control chips, slaved off one pot/volume control.

 

[JojoD818]

Can you and others please point me to a circuit that uses vca for volumes. I also like the digital volume control but I don't know anything about digital electronics.

JojoD

 

[Da5id4Vz]

This is an interesting thread related to your question:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=22768

While this thread deals w/ a 2 channel implementation, others have done similar builds out to six channels.

The elusive APOX web site can be found here:

http://www.apoxcontrols.com/apox.htm

and the new site looks darned good too.

 

[Vinnie R.]

Take a look at

http://www.dact.com/html/attenuators.html

They have a stepped attenuator that can control 6-channels at
once.

Another option is the APOX kit, as mentioned above. You may or may not want the added complexity, but it does sound great and is an awesome kit!

 

[till]

I also like the digital volume control but I don't know anything about digital electronics.

very cheap and simple, without all the display, balance, etc. options the apox kit has as advantage, i made this. Should be easy to use for 6 channels. http://home.tu-clausthal.de/~tpa/PGA/index.html

 

[moamps]

Can you and others please point me to a circuit that uses vca for volumes.

Hi,
maybe TDA1524
Regards

 

[richie00boy]

Try this
http://www.thatcorp.com/datashts.shtml

 

[Solid Snake]

I also wanted to do something like you are doing. I wanted to use a digital volume control or maybe one of those digital pots but they are not very linear so I drew this up one day when I was bored in class, tell me if it makes sense.

 

[JojoD818]

I can't figure out the schematic...

Anyway, as for digital, aside for what you said, I don't like digital because I don't know a thing about it and can't implement such. AYour plan uses transistors, now that I can understand somehow.

Can you please redraw?

Thanks,
JojoD

 

[EchoWars]

I also wanted to do something like you are doing. I wanted to use a digital volume control or maybe one of those digital pots but they are not very linear so I drew this up one day when I was bored in class, tell me if it makes sense.

Good Lord man!! Get yourself a circuit drawing program!!!


As for a simple solution...find someone to sell you a 8 module Clairostat, like this: http://www.potentiometer.com/partdata.cfm?partno=389&session=2003112110113389

 

[Solid Snake]

MS Paint to the rescue...

 

[Solid Snake]

That first transistor is there to allow control by voltage, if you're using a pot, you can put it in the transistor's place.

 

[JojoD818]

Solid Snake,

Have you tried breadbording this? Any suggested values for the resistor and the transistor?

This is really interesting

BTW, Thanks for sharing.

JojoD

 

[Solid Snake]

No I haven't tried breadboarding this. It seems that a 470-1K ohm resistor on the input should work okay. For the ATT resistor you may want to try something like 100K, you can play with different values but don't go too low or it may burn up. You can use a 2N2222 and it's complement, since the signal doesn't actually go through the transistor I don't think it matters much. If you try this, let me know how it works for you.

 

[JojoD818]

Hi,

I will try to breadboard the circuit when I can. I will inform you of any developments asap.

JojoD

 

[EDUM]

Another option not mentioned yet is the use of toothed wheels and connect as many potmeters as you like. This option gives also the possibility to choose different quality potmeters for the main L/R channel and the "effect" channels.

Use toothed wheels with as many teeth as possible for the wheel diameter you can handle. Take care for the reversal of direction by mounting every second potmeter mechanicaly reversed as well.
This "simple" mechanical solution migth even offer a better channel separation. Or is usable for a "passive" upgrade for an existing stereo preamp.

success!

Ward

 

[JojoD818]

Great idea but...

EDUM,

Using gears for controlling several pots has already been in my mind but I am not a "mechanical" person and implementation could be extremely difficult however doable. But still, the idea is very good.

I just had this weird idea!!!!!!

Consider a resistive network (in series) of resistors with one end as the input and the other end connected to ground, with a CD4066 (bilateral switch??) I can select where to tap for the output using dc voltage right? Now isn't that an excellent idea? Maybe a patent?

I sure hope that I can "dream" of a solution in the design tonight.

Good Night,
JojoD

 

[subwo1]

This modification of the earlier circuit may work better because it isolates each of the six circuits more from the poteniometer.