multichannel volume control

[coloradosound]

I noticed that there are several threads for PGA2310/11,
CS3310 volume circuits but all seem to be stereo.
I want to control 6-8 channels simultaneously as well
as being able to make minor adjustments to each individual
channel (i.e. left rear down -2.5dB, Center up 1.5 dB,etc.)
Can anybody point me to the best thread or other
direction to accomplish this. Possibly using Microchip PIC
series with HD44780-Based LCD Modules.

[paulb]

You can gang up 3 or more of the devices you mention to get more channels. There is also the LM1973, by National. Do a search at this site.

[BrianDonegan]

Russ White had a way of doing this with mulitples of the Kookaburra using an additional circuit he called the Perch.

http://www.diyaudio.com/forums/showt...893#post892893

No display though.

[RCBandwidth]

Texas Instruments has a new 8 channel volume control chip soon to be released(PGA8311).The chip has an SPI control structure.

Cirrus Logic also has an 8 channel chip(CS3318)with a SPI/I2C interface,I am trying to get a sample of this device for an upcoming project.The Cirrus device has a much more robust command set than the TI chip.

Good Luck Bob C.

[RCBandwidth]

I forgot to mention the Analog Devices SSM2160 device.

http://www.analog.com/en/prod/0,2877,SSM2160,00.html


Bob C.

[CBS240]

How about a jfet VCR (voltage controlled resistor)....

[coloradosound]

I am asking specifically about the PGA2310's/2311's as
I currently have about 20 of each and also have the
HD drive16X2 and 20X4 LCD displays so I do not want
to reinvest by switching to different devices (esp.VCRs
and other methods). The new higher channel count
TI and Cirrus devices sound interesting, though, if
all 8 channels are individually controllable.

[morpheus82]

hmm...you have to explain better...you can place pushbutton up/down for volume and for every channel...i think the best way is to use a pic for every channel, i can't find another way, everyone counts the up/down volume and it's own button level, and then feed the pga2311, easy!
for the LCD it's quite hard if you want to use just one...because you have 8 different 8bit levels to read(64bits!!)maybe you can send serially but i'm not a pro for these things...

[coloradosound]

I would like to use either rotary encoder or up/down button
for master volume as well as maybe infrared remote that
will control all channels simultaneously as well as some type
of trimming of up to 8 individual channels by 0-10dB or so.
I will be using my own discrete gain stage so I only need to
use attenuation overal of 0-95.5dB thereby leaving the
internal PGA opamp in unity gain. I also heard that there is
a way to set the microcontrollers in sleep or standby mode
when there are no adjustments being made, shutting the
clock down so that no clock noise enters the analog sections.
The LCD display would be used to indicate input/output
swiching, overal volume level, and perhaps indidividual level
on the independent channel being adjusted.

[rtarbell]

"I also heard that there is
a way to set the microcontrollers in sleep or standby mode
when there are no adjustments being made, shutting the
clock down so that no clock noise enters the analog sections"

==> Yes; I know how to do so at least with PIC microcontrollers. You can put the device in "sleep" mode using the SLEEP command. In order to do this, enable the microcontroller's interrupts (like interrupt-on-change pins, depending upon what microcontroller you use). If your interrupt-on-change pins are the same as the pins used for push-button volume, then the microcontroller will "wake up" when a change in volume is made. Once the change is made, it can go back to sleep.

This method can also be used in the transmitter section for your remote control (a microcontroller in sleep mode consumes much less current, and thus extends battery life for the remote).

Also, you can control all 8 channels by using just one microcontroller because the PGA2310s use an SPI interface. Use 4 PGA2310s (two channels per device for a total of 8 channels). All of them can be controlled by the SPI protocol (look in to daisy chaining SPI devices).