Intrest Check : Pretty Simple Digital Preamp / Volume Control

[theAnonymous1]

rhysh,

If you would like to do the board with THS4131/OPA1632 I have a large supply of these as well. I also have something like >50 DRV134 if you decide to use these and need more.

[bwaslo]

I'm currently using a PGA2310 homebrew preamp and controlling it through a Microchip microcontroller. I'm very happy with it, since I'm one of those people who are constantly fretting about whether the vol control is still balanced, and this keeps it stable at all volume settings. I'd really like to be able to add IR remote control to it, though, where do you get info on how to do that?? I searched through the internet a while back but couldn't find an easy way to to do that (at least not with regular "universal" remotes).

BTW, rather than rotary encoders, I'm using the ADCs on the microcontroller to read DC voltages off a couple of cheap linear-taper pots, and using that reading to determine where to set gain and balance for the two channels. That makes for very inexpensive knob operation and works really well. It feels and acts to the user as if it were a regular volume pot and a balance pot, except that the channel to channel tracking is accurate (and of course the signal never goes through a pot). I didn't like the idea of having the micro running all the time and possibly making noise so I have it sleeping normally, but waking up when either knob setting changes. The DC pot voltages run to a couple of comparators that wake the micro on changes.

Anyway, one thing sorely lacking is remote control. Any pointers on how to attack that would be appreciated.

[rhysh]

Originally posted by bwaslo
I'm currently using a PGA2310 homebrew preamp and controlling it through a Microchip microcontroller. I'm very happy with it, since I'm one of those people who are constantly fretting about whether the vol control is still balanced, and this keeps it stable at all volume settings. I'd really like to be able to add IR remote control to it, though, where do you get info on how to do that?? I searched through the internet a while back but couldn't find an easy way to to do that (at least not with regular "universal" remotes).

BTW, rather than rotary encoders, I'm using the ADCs on the microcontroller to read DC voltages off a couple of cheap linear-taper pots, and using that reading to determine where to set gain and balance for the two channels. That makes for very inexpensive knob operation and works really well. It feels and acts to the user as if it were a regular volume pot and a balance pot, except that the channel to channel tracking is accurate (and of course the signal never goes through a pot). I didn't like the idea of having the micro running all the time and possibly making noise so I have it sleeping normally, but waking up when either knob setting changes. The DC pot voltages run to a couple of comparators that wake the micro on changes.

Anyway, one thing sorely lacking is remote control. Any pointers on how to attack that would be appreciated.

bwaslo,

Thankyou for your comment, i have looked into ADC's and using a pot instead of a rotary encoder, but i have decided i do not want to re write the firmware i have allready found to use on my board, i agree that it feels a lot nicer to the touch but its somthing i would never get round to. I agree, the micro should be sleeping when not in use, this is part of the reason why i decided not to use extras like a lcd display etc.

About the remote control, i have also searched pretty much the whole internet for pointers on how to do this remote control efficiantly. I have came up with two quite good resources and source codes for decoding philips remote controls, one of them using a PGA2310 itself.

1. http://avr-mcu.dxp.pl/rc5+remote+con...+assembly.html

2. http://www.latke.net/blog/punkengine...ve/000049.html

I hope this helps, as i am also pretty confused on how to start on this, (im a php programmer ).

[rhysh]

Originally posted by theAnonymous1
rhysh,

If you would like to do the board with THS4131/OPA1632 I have a large supply of these as well. I also have something like >50 DRV134 if you decide to use these and need more.

Thankyou for the offer, can i ask if you have SMD versions of the IC's?

[jan.didden]

Originally posted by bwaslo
I'm currently using a PGA2310 homebrew preamp and controlling it through a Microchip microcontroller. I'm very happy with it, since I'm one of those people who are constantly fretting about whether the vol control is still balanced, and this keeps it stable at all volume settings. I'd really like to be able to add IR remote control to it, though, where do you get info on how to do that?? I searched through the internet a while back but couldn't find an easy way to to do that (at least not with regular "universal" remotes).

BTW, rather than rotary encoders, I'm using the ADCs on the microcontroller to read DC voltages off a couple of cheap linear-taper pots, and using that reading to determine where to set gain and balance for the two channels. That makes for very inexpensive knob operation and works really well. It feels and acts to the user as if it were a regular volume pot and a balance pot, except that the channel to channel tracking is accurate (and of course the signal never goes through a pot). I didn't like the idea of having the micro running all the time and possibly making noise so I have it sleeping normally, but waking up when either knob setting changes. The DC pot voltages run to a couple of comparators that wake the micro on changes.

Anyway, one thing sorely lacking is remote control. Any pointers on how to attack that would be appreciated.

Bill,

Contact me through the forum, I may be able to help you.

Jan Didden

[rhysh]

As requested, switched drv134 opamps with THS4131, the resistors around the 4131 set the gain, the BOM will default this at 1.

I have just used the implamentation from the datasheet.

[bwaslo]

Rhysh, thanks for the links, I'll check them out.

Jan, you have mail!

Maybe now I'll be able to reach my ultimate goal of total couch-potatoness!

[theAnonymous1]

Originally posted by rhysh
Thankyou for the offer, can i ask if you have SMD versions of the IC's?

Yes, these are only available in SMD. Which are you interested in, THS4131 or OPA1632?

Also, you will want some PS decoupling caps as close to the these as possible. I use 100nF X7R.

[rhysh]

Originally posted by theAnonymous1


Yes, these are only available in SMD. Which are you interested in, THS4131 or OPA1632?

Also, you will want some PS decoupling caps as close to the these as possible. I use 100nF X7R.

I am intrested in the THS4131's. Yes, i will be placing the decoupling caps on the board, i forgot about those.

[rhysh]

Ok everyone, here is the deal.

I can either do this, with a LCD and a remote (no rotary)
OR
Do this with the rotary encoder, no LCD and no remote.

What do you think?