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Old 15th October 2012, 04:25 AM   #21
Bonsai is offline Bonsai  Taiwan
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Try lowering Vd - the digital supply.

I have no clicks, noise or any other problems on my implementation. However, I took a lot of care in the layout - the uController is isolated competely from the PGA via optos. The rise fall times on the digital control signals are as a result quite slow was well (a few us) and this also helps since you don't have fast rising edhes in the vicinity of the chip.
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Old 15th October 2012, 08:18 AM   #22
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Quote:
Originally Posted by Bonsai View Post
I have no clicks, noise or any other problems on my implementation. However, I took a lot of care in the layout - the uController is isolated competely from the PGA via optos.
Is this the schematic of your implementation?
http://hifisonix.com/wordpress/wp-co...tion-SC-11.pdf

Would you care to share your layout? Or critique mine?
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File Type: jpg PGA_PCB_Top.jpg (264.0 KB, 242 views)
File Type: jpg PGA_PCB_Bottom.jpg (866.9 KB, 239 views)
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Old 15th October 2012, 09:25 AM   #23
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Yes, thats the one.

I'll try to take a look at your layout later tonight.

Just to confirm, when you are changing volume you are hearing clicks? Any other noise/hum you are pickingup?
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Old 15th October 2012, 09:26 AM   #24
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Quote:
Originally Posted by Bonsai View Post
Just to confirm, when you are changing volume you are hearing clicks? Any other noise/hum you are pickingup?
No clicks for me, just high noise floor (not hum).
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Old 15th October 2012, 09:28 AM   #25
Bonsai is offline Bonsai  Taiwan
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How are you coupling your control signals to the PGA - is it a cable, or does the controller plug onto the pins?
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Old 15th October 2012, 09:29 AM   #26
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ok - if you short the inputs, what happens
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Old 15th October 2012, 09:52 AM   #27
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"USB DAC ---> PGA ---> Hypex Amp ---> Speakers = Noisey""

I am willing to bet you have radiated noise from your Hypex units, or, mains conducted noise from the SMPS I see in your photo.

If you have a common mode choke, you might try that on the mains cable. Only other alternative is to move the hypex modules further way. If the noise goes down when you do this, it likely radiated noise - if not, look at mains conducted noise.
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Old 15th October 2012, 02:50 PM   #28
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reading comprehension not your best skill, huh?
I can tell a gambler from a designer by the language he uses any day.
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Old 15th October 2012, 04:30 PM   #29
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Originally Posted by counter culture View Post
I can tell a gambler from a designer by the language he uses any day.
Enough with the trolling, you're not really contributing to this thread!
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Old 15th October 2012, 04:31 PM   #30
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Quote:
Originally Posted by Bonsai View Post
How are you coupling your control signals to the PGA - is it a cable, or does the controller plug onto the pins?
See the attached picture. The thing on the top left of the case is the Arduino which is connected to the encoder, USB and the PGA module. The PGA modules gets Vd from the Arduino/USB. Before you suspect the USB for the noise, I've tried setting the volume and then disconnecting the power to the Arduino as once the PGA volume has been set it stays even when the digital section is not powered. I've also tried battery power.

Quote:
Originally Posted by Bonsai View Post
ok - if you short the inputs, what happens
Short the input to the Hypex amp or the input to the PGA? When the PGA input is shorted, there is noise. When the Hypex input is shorted, it is silent.

Quote:
Originally Posted by Bonsai View Post
If you have a common mode choke, you might try that on the mains cable. Only other alternative is to move the hypex modules further way. If the noise goes down when you do this, it likely radiated noise - if not, look at mains conducted noise.
Both the Hypex Amp and the PGA module power supplies have mains filters, similar to this thing. I tried plugging the PGA module into the mains on the other side of the room, no change.

I appreciate your input
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