A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input) - Page 60 - diyAudio
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Old 6th November 2013, 10:06 AM   #591
dddac is offline dddac  Germany
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Quote:
Originally Posted by thommy View Post
I am getting the quantisation noise mentioned previously, but on my single deck DAC. It's worst at 192kHz and varies with sample rate.

I also have powerful amps with sensitive speakers, and the DAC is connected straight through with WaveIO for volume control so any noise generated in the DAC comes out of the speakers at full scale.

Would the extra capacitor mod between A and B apply to my situation?
Hi Thom,

Yes, this is digital noise and due to the extreme sensibility and the fact you use digital volume control, this becomes audible

Indeed, the small capacitor tweak helps here as well. Please use 4,7nF for one deck...

Another option, is to have switch at the output of the dac which lowers the volume when used for normal listening volumes.

I suggest following:

Instead of the 134 ohm, use two resistors in series . one of 100 and one 33. The 33 is against ground. Now you can tap the signal from the 33 ohm resulting in 12dB less volume, but also less noise.
Actually this has two good things:


1 lower output impedance
2 usage of more bits, as you reduce sound volume less digitally

ofcourse any combination will work. main Thing the two Needs to be 133 - 134 ohm
Good luck !

Best regards,

Doede
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Old 6th November 2013, 10:18 AM   #592
thommy is offline thommy  United Kingdom
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OK.

Is this OK for the capacitors? WIMA - FKS2D014701A00KSSD - CAPACITOR, 4.7NF, 100V Price For: 5 | eBay

And I need 4 of them, correct?

I am using balanced output with no resistors currently. The two resistors supplied with the kit I thought were for RCA outputs. I am not sure where to put them so they are still on my desk.

Lowering the output like this is the perfect solution, but I'm not clear on what you mean for the resistors for this case of my balanced output configuration.
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Old 6th November 2013, 10:26 AM   #593
PET-240 is offline PET-240  Australia
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Perhaps post a photo of your rig particularly the output side of the dac, this may help regards your situation and setup.
Your mention of resistors still on your desk is a little confusing is all.

Cheers

Drew.
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Old 6th November 2013, 10:39 AM   #594
thommy is offline thommy  United Kingdom
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Still on the desk, as in not used in the build.

Click the image to open in full size.

Click the image to open in full size.

So at the minute the output configuration for both left and right channels is:

GND -------------------> GND
+VE -->Mundorf 2.2--> +VE
- VE -->Mundorf 2.2--> - VE
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Old 6th November 2013, 11:06 AM   #595
dddac is offline dddac  Germany
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Quote:
Originally Posted by thommy View Post
So at the minute the output configuration for both left and right channels is:

GND -------------------> GND
+VE -->Mundorf 2.2--> +VE
- VE -->Mundorf 2.2--> - VE
look at the pdf may be that clarifies things. in your case you need this 4 times of course as you go out balanced

the capacitors are ok

wel, upload failed, don't ask me why, will send pm
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Last edited by dddac; 6th November 2013 at 11:12 AM.
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Old 6th November 2013, 12:21 PM   #596
thommy is offline thommy  United Kingdom
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OK so I am going to try splitting the rLoad resistors in the manner you suggest to achieve a 12dB gain reduction, plus add 4x Wima 4.7nF caps to reduce the quantisation noise itself.

At the moment my gain structure is all wrong, with full gain at the amp and 20 dB reduction at the source - should be the other way round but there is no preamp in this single source system. Reducing output gain on the DAC will allow me to increase the input gain and therefore drop the noise floor.

That's cool, thanks
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Old 11th November 2013, 08:35 PM   #597
Undarra is offline Undarra  United Kingdom
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Hi

I currently have an spdif board and a four stack dac set running from a single 12v power supply. Do you think there would be an audible benefit in adding another 12v supply to bower the boards independently?

Many thanks, Si
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Old 12th November 2013, 06:02 AM   #598
dddac is offline dddac  Germany
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Quote:
Originally Posted by Undarra View Post
Hi

I currently have an spdif board and a four stack dac set running from a single 12v power supply. Do you think there would be an audible benefit in adding another 12v supply to bower the boards independently?

Many thanks, Si
With things like that the proof is in the eating... ist tsays "high end Audio"

I could imagine it would make difference, but if you think it pays for a new power supply, that is personal
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Old 14th November 2013, 03:51 PM   #599
clivem is offline clivem  United Kingdom
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Default WaveIO firmware and sample rate LED questions

It's been a while since I checked-in.

A couple of questions.....

Doede, the WaveIO that was supplied with your kit is older than revision 0x0331, so my understanding is that it cannot be user upgraded to the latest firmware which supports 384k. It would need returning to Lucien for the update? Do you have an arrangement with Lucien? ie. should the board be sent back to you (as the OEM) or should I contact Lucien directly?

Secondly, my memory is a little hazy..... The sample rate LED's. "Host Active" and "Audio Streaming" are permanently lit while music is playing. The actual rate LEDs, ie. 44k1, 88k2.... were they ever meant to stay permanently lit? I can't remember whether they were. It's been a while since I noticed. The behaviour now is that they flash for about of a 1/10 second when changing sample rate and then stay off until the next change of sample rate. Something makes me think they used to stay lit.
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Old 14th November 2013, 05:32 PM   #600
dddac is offline dddac  Germany
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Quote:
Originally Posted by clivem View Post
It's been a while since I checked-in.

A couple of questions.....

Doede, the WaveIO that was supplied with your kit is older than revision 0x0331, so my understanding is that it cannot be user upgraded to the latest firmware which supports 384k. It would need returning to Lucien for the update? Do you have an arrangement with Lucien? ie. should the board be sent back to you (as the OEM) or should I contact Lucien directly?

Secondly, my memory is a little hazy..... The sample rate LED's. "Host Active" and "Audio Streaming" are permanently lit while music is playing. The actual rate LEDs, ie. 44k1, 88k2.... were they ever meant to stay permanently lit? I can't remember whether they were. It's been a while since I noticed. The behaviour now is that they flash for about of a 1/10 second when changing sample rate and then stay off until the next change of sample rate. Something makes me think they used to stay lit.
No real arrangement as you are the first to ask
I am pretty sure you can do this directly. just send me pm and we will get it arranged...

yes the LED are permanently lit, normally at the standard rate of your operating system when no music is playing.... for example, if you put iTunes in 192 kHz, the 192 led will always be in, till music plays and it will take the actual....

so if this is not the case I suspect your player software
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