jormajj said:
JoshK said:Do you know what that 6ch Vol Control on decibelhifi uses? The wolfson wm8816?
Guys,
I think that equipment is like one that I saw in a Silicon Chip magazine.
If it's so:
Volume control made by 3 x LM1973 and a PIC16F84A, witch controls the LED indicators, receive and decode IR from a remote control and, of course, the audio level of the LM's.
If it isn't... sorry
Regards,
Graham Maynard said:Hi Jan,
Surely digital volume controls are not being developed for the benefit of stereo listeners ?
Well, some are. The DS1808 was explicitely developed for this use. It sports a very low distortion figure over the whole audio spectrum. But it's not a "digital volume control". It's a digitally-controlled attenuator.
Granted it's better not to use anything at all ;-) (or just a few very high precision resistors), but I'm convinced that if you use a purely digital control of the volume (ie., multiplying the individual samples with a scaling factor), you'll get worse results than using an attenuator such as the DS1808. Not only in terms of dynamics (obviously), but also in terms of distortion. Unless you have a good digital overhead - that is, for instance, if your original audio signal was quantified in 16-bit, then you'd compute the final signal in 24-bit and output it on a 24-bit DAC. And even so, simply scaling the signal numerically might create nasty side-effects. You may need some kind of dithering to improve this. Not trivial.
As for using resistors and a switch: why not. But if you use standard resistors, that will most likely be worse than a laser-trimmed integrated attenuator. Even regular 1% metal film resistors might not cut it in terms of precision (you might not care) and temperature drift (that you would care).
My 2 cents.
Hey guys you can buy that 6 ch vol control from here cheaper, i think its in kit form. it seems like a pretty good unit, i got the issues of silicon chip magazine at home somewhere, its got all the specs on it, will see if i can dig it up, but i wont be able to post any schematics on here due to copright stuff.
http://www.altronics.com.au/index.asp?area=item&id=K5600
cheers
Bowdown
http://www.altronics.com.au/index.asp?area=item&id=K5600
cheers
Bowdown
Thanks Pedro,
Looks like a good kit for the money, although Altronics has it much cheaper than Decibelhi-fi. Anyway, not a bad place to start, but I really need balanced in/outs.
Will the LM's control vol on a balanced channel if I change the corresponding opamps to deal with this?
Looks like a good kit for the money, although Altronics has it much cheaper than Decibelhi-fi. Anyway, not a bad place to start, but I really need balanced in/outs.
Will the LM's control vol on a balanced channel if I change the corresponding opamps to deal with this?
Hope nobody kill me for this...
Look in the schematic:
You have 6 inputs and 6 outputs.
If you need balanced, with one kit you get 3 ch volume control.
Just make another pcb with LM1973 and connect the data wires from the original pcb to the cloned.
Get the idea?
Look in the schematic:
You have 6 inputs and 6 outputs.
If you need balanced, with one kit you get 3 ch volume control.
Just make another pcb with LM1973 and connect the data wires from the original pcb to the cloned.
Get the idea?
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