I thought you might be interested to see my latest product, it's a stepping stone to a relay switched attenuator I'm building.
I've noticed a few people are interested in digital volume controls. There are lots of chips out there to do the job, but interfacing to them is not something everybody has the skills for.
This prototype uses 2 x 4-channel AD5204 digital pots which were fairly cheap . They have a THD of 0.004% and are arranged as 'pseudo-logarithmic'. There are no caps in the signal path and all signal grounds are isolated from the system ground.
There are a number of alternate devices such as the Cirrus CS3308 through the PGA2310 series which have higher performance and also offer some gain, but they are expensive parts. They all have serial interfaces and the system can easily be reprogrammed to accommodate them.
If the number of channels is reduced to 2 then source selection can be accommodated using relays without increasing the size of the assembly drastically, and there are also a number of volume controls from ST with source selection built in and Loudness control although THD in these cases is 0.01%.
w
I've noticed a few people are interested in digital volume controls. There are lots of chips out there to do the job, but interfacing to them is not something everybody has the skills for.
This prototype uses 2 x 4-channel AD5204 digital pots which were fairly cheap . They have a THD of 0.004% and are arranged as 'pseudo-logarithmic'. There are no caps in the signal path and all signal grounds are isolated from the system ground.
There are a number of alternate devices such as the Cirrus CS3308 through the PGA2310 series which have higher performance and also offer some gain, but they are expensive parts. They all have serial interfaces and the system can easily be reprogrammed to accommodate them.
If the number of channels is reduced to 2 then source selection can be accommodated using relays without increasing the size of the assembly drastically, and there are also a number of volume controls from ST with source selection built in and Loudness control although THD in these cases is 0.01%.
w
Of course this prototype was hand made, I had to scratch the button design on the perspex by hand, I've found somewhere that will laser-engrave them.
This is more like what the illuminated display looks like to the eye, the camera doesn't do it justice in bright light.
There's an IR receiver lurking behind the black fascia, so it's remote controllable too. Normally it'd be mounted in a rectangular cut-out in a panel, so the illuminated edges would be invisible.
w
This is more like what the illuminated display looks like to the eye, the camera doesn't do it justice in bright light.
There's an IR receiver lurking behind the black fascia, so it's remote controllable too. Normally it'd be mounted in a rectangular cut-out in a panel, so the illuminated edges would be invisible.
w
It is in fact working with the current AD5204 chips. Changing to PGA2310 or CS3308 is easy. However I see this on ebay:- PGA2311 Volume control Remote Pre-amplifier Board + LCD on eBay (end time 11-Mar-11 10:06:04 GMT)
Obviously PGA2311 with 2 channels and 3 source selectors for $35.5 US, shipped. I can make mine do this with little effort, but it's hard to compete with these prices. 4 x PGA2310 @ $20 is $80 already.
I decided to show it here to get some feedback as to whether there was any interest, and exactly what configuration people would prefer.
Thanks for the feedback.
w
Obviously PGA2311 with 2 channels and 3 source selectors for $35.5 US, shipped. I can make mine do this with little effort, but it's hard to compete with these prices. 4 x PGA2310 @ $20 is $80 already.
I decided to show it here to get some feedback as to whether there was any interest, and exactly what configuration people would prefer.
Thanks for the feedback.
w
Signal Quality and noiseless operation is key. Price is not. Level adj on each channel, remote control are musts. The alternative is a surroundreceiver using preouts - Cheap and no hassle. I think the interest is in a high end alternative to the surroundreceiver using the 8 analogue outs from an upmarket BD-player without noisy video cirquits.
1 - 2 8 ch inputs and 3 - 4 stero inputs will do it I think.
1 - 2 8 ch inputs and 3 - 4 stero inputs will do it I think.
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