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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

I would take a long hard look at the shift registers for the left output, and compare them to the right output shift registers.
If you probe around, pretty sure you will find a difference.

Hello Randytsuch,

I probed the shift registers, here are the values for VCC
First row: 4.02V
2nd row: -4.02V
3rd row: 4.02V
4th row: -0.11V which is left channel

So You were right, something is wrong with the board, I checked with a Lense to see if something obvious could be seen, but i didnt find anything. I’ll contact Soekris service department for an repair/exchange.

Nothing else to do right?

Faboz
 
Hello Randytsuch,

I probed the shift registers, here are the values for VCC
First row: 4.02V
2nd row: -4.02V
3rd row: 4.02V
4th row: -0.11V which is left channel

So You were right, something is wrong with the board, I checked with a Lense to see if something obvious could be seen, but i didnt find anything. I’ll contact Soekris service department for an repair/exchange.

Nothing else to do right?

Faboz

I would definitely call them, and see what you can work out since sure seems like the board is defective. I would guess Vcc to the forth row of SRs is open, so you are not really getting a voltage there.
Could be an open via somewhere, I've seen that happen on PWBs, and they may work when brand new, but fail after a little while if the via had a problem to begin with.

BTW, power to the 2nd and 4th rows are actually -4V goes to the ground pins and ground goes to the Vcc pins. So the SRs see +4V for their Vcc, but they are actually at -4V relative to ground.

Randy
 
Take a look.
 

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The only two ways to control the DAM volume is via the potentiometer or via serial commands.

So for foobar2000 on a PC, I think you'd have to write a foobar plugin that mapped the volume slider to serial commands (unless someone else has already written such a beast). Obviously, you'd also have to make the physical serial connection from the PC to the DAM 1021.

(I've never written a foobar2k plugin, I'm just assuming it's possible to customize the volume control.)
 
The only two ways to control the DAM volume is via the potentiometer or via serial commands.

So for foobar2000 on a PC, I think you'd have to write a foobar plugin that mapped the volume slider to serial commands (unless someone else has already written such a beast). Obviously, you'd also have to make the physical serial connection from the PC to the DAM 1021.

(I've never written a foobar2k plugin, I'm just assuming it's possible to customize the volume control.)

Hi Matt I have used Xonar D2X sound card with optical out to the DAM1021 with toshiba receiver and it worked fine with the foobar volume control. So I believe it must be working?
 
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In that case, you're using *software* volume control, rather than the DAM's hardware volume control. So yes, you could do the same with the Amanero.

Depending on who you ask, software volume control ranges anywhere from "pretty good" to "unlistenable". There are indeed different algorithms for doing software volume control, some better than others.

Generally, if your hardware has its own volume control implementation (as the dam1021 does), that's likely your best bet, but testing and listening is the only way to determine what you like best.

Also, in general, hardware volume control can be quite different from one device to the next. In particular, analog domain versus digital domain. If I remember correctly, the DAM does volume control in its fpga, i.e. the digital domain. So, in theory, you could have software volume control doing the exact same bit manipulation that the hardware is doing (if the hardware volume control indeed works in the digital domain).

That said, if you're using a computer for playback, software volume control requires no effort. If nothing else, it's an easy starting point.
 
Also, in general, hardware volume control can be quite different from one device to the next. In particular, analog domain versus digital domain. If I remember correctly, the DAM does volume control in its fpga, i.e. the digital domain. So, in theory, you could have software volume control doing the exact same bit manipulation that the hardware is doing (if the hardware volume control indeed works in the digital domain).

No you cannot do this in software on PC side in the same way. The DAM has 28 bit internal precision, while its USB input is limited to 24 bit. So the DAM internal volume control will be better. Even while attenuating with a factor 4096 (12 bits, about 72 dB), you can still achieve roughly 16 bit precision. And due to the sign magnitude design, the DAC does not require linearity up to 28 bits to achieve this attenuation with a good quality.

Fedde
 
In that case, you're using *software* volume control, rather than the DAM's hardware volume control. So yes, you could do the same with the Amanero.

Depending on who you ask, software volume control ranges anywhere from "pretty good" to "unlistenable". There are indeed different algorithms for doing software volume control, some better than others.

Generally, if your hardware has its own volume control implementation (as the dam1021 does), that's likely your best bet, but testing and listening is the only way to determine what you like best.

Also, in general, hardware volume control can be quite different from one device to the next. In particular, analog domain versus digital domain. If I remember correctly, the DAM does volume control in its fpga, i.e. the digital domain. So, in theory, you could have software volume control doing the exact same bit manipulation that the hardware is doing (if the hardware volume control indeed works in the digital domain).

That said, if you're using a computer for playback, software volume control requires no effort. If nothing else, it's an easy starting point.

what I read somewhere is that DAM digital volume control is buggy and pops when used? Is it so? Did u test it?
 
The DAM digital volume control used to be a bit weak on detecting invalid commands, responding rather "irresponsibly", but IIRC that has been remedied in later firmware releases.

There were never "pops" when changing volume.

As was stated previously, to utilize the DAM's volume control you need to send commands to the DAM through its serial port. The Amanero has no way of doing that.

Software volume control (done on the computer's side) will of course work with any USB interface of s/pdif port.