8ch dac for AL and Roon?

jtwrace

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Thread Starter
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Mar 12, 2019
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84
Location
Orlando, FL
My AV System  
Main Amp
(4) Hypex NC502MP
DAC
Topping D90
Front Speakers
JBL M2
Subwoofers
(2) Rythmik FM8, (1) UM18, (1) Custom DIY Ciare 18
Other Speakers or Equipment
BSS BLU 50
Streaming Equipment
RPi4 using RopieeeXL
Streaming Subscriptions
Tidal
Other Equipment
All Belden 1800F and 1313A
Maybe it is just me, but I don't understand how you will get an RPi based audio source to work with Audiolense?
RPi is the endpoint for Roon which has the Convolver for AL.

 

jjazdk

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Aug 17, 2018
Messages
70
RPi is the endpoint for Roon which has the Convolver for AL.

Ahh... I assumed you where using the Audiolense Convolver, which you clearly are not. Now I understand.

If RPi's have difficulty with USB sound cards, I would discard the RPi solution for good.
 

jtwrace

Member
Thread Starter
Joined
Mar 12, 2019
Messages
84
Location
Orlando, FL
My AV System  
Main Amp
(4) Hypex NC502MP
DAC
Topping D90
Front Speakers
JBL M2
Subwoofers
(2) Rythmik FM8, (1) UM18, (1) Custom DIY Ciare 18
Other Speakers or Equipment
BSS BLU 50
Streaming Equipment
RPi4 using RopieeeXL
Streaming Subscriptions
Tidal
Other Equipment
All Belden 1800F and 1313A
Ahh... I assumed you where using the Audiolense Convolver, which you clearly are not. Now I understand.

If RPi's have difficulty with USB sound cards, I would discard the RPi solution for good.
I will not run a hardwired connection. So that basically leaves the Okto and exaSound s88. I was hoping for a surprise. :)
 

2234rew

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Nov 24, 2020
Messages
197
If RPi's have difficulty with USB sound cards, I would discard the RPi solution for good.
Most pro audio interfaces don't do well with Linux for over 2 channels (not officially supported).

So it's not an RPi specific problem. Moreo Linux support
 

2234rew

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Nov 24, 2020
Messages
197
A good forum for pro audio Linux users:


There are some manual patches created by very clever people for multichannel but I wouldn't do this personally.

I don't want any unexpected static sound / big pop sound during music playback, due to a manual hack that's not been fully tested by the interface maker.
 

Omid

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May 28, 2017
Messages
36
Just a small correction.
When I talked about my MOTU DAC I said I use Roon's DSP volume which is 'not ideal'. I stand corrected. It turns out Roon's DSP volume control is apparently better than a harde wired volume control:
 

2234rew

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Nov 24, 2020
Messages
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Just a small correction.
When I talked about my MOTU DAC I said I use Roon's DSP volume which is 'not ideal'. I stand corrected. It turns out Roon's DSP volume control is apparently better than a harde wired volume control:
Please correct me if I misunderstand but on his final page of his whitepaper he even mentions if your power amp has SNR = 100dB, then 30dB digital attenuation will result in best case SNR = 70dB.

A transparent analogue volume control should allow you to maintain SNR = 100dB of the power amp ? As long as this preamp is not the weakest link (hence transparent) ?
 

Omid

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May 28, 2017
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Please correct me if I misunderstand but on his final page of his whitepaper he even mentions if your power amp has SNR = 100dB, then 30dB digital attenuation will result in best case SNR = 70dB.

A transparent analogue volume control should allow you to maintain SNR = 100dB of the power amp ? As long as this preamp is not the weakest link (hence transparent) ?
I’m not sure I understood your question. can you explain a bit more?

I think he’s saying that Roon has a lower noise floor than a pre-amp (esp with a 24bit signal), but that in the end it’s irrelevant since an amp’s noise floor is high enough that unless you listen full blast the dynamic range will be limited anyway (70dB in his example).
 

2234rew

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I’m not sure I understood your question. can you explain a bit more?

I think he’s saying that Roon has a lower noise floor than a pre-amp (esp with a 24bit signal),
Noted, I interpret his entire whitepaper as showing Roon's volume control is as lossless as any digital volume control needs to be.

But there are analogue pre-amps with better than 100dB SNR. So matched with SNR 100dB power amp, then in theory allows SNR = 100dB at the listening position when digital volume control is at max setting.

But I may misunderstand his whitepaper.
 

Omid

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May 28, 2017
Messages
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In the example of a preamp with -100dB SNR, the noise floor is at -100dB, fixed, regardless of the signal amplitude. If you play a full volume signal, the ratio of signal to noise is 100dB. If you turn the volume down, the signal is reduced by say 30dB. The noise floor does not go down with it, the signal to noise ratio is thus reduced to 70dB.
 

juicehifi

Audiolense
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Feb 5, 2018
Messages
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The Roon paper is pretty good, IMO, since it takes any scepticism against digital volume serious.

My take on this is that a digital attenuator that operates at 24 bit int, 32 bit float or higher is practically transparent as long as the rest of the digital chain never drops below 24bit int (or 32 bit float) …. which is hardly ever the case with today’s converters. You will lose dynamic range at very low level, but what you loose will be way below the threshold of hearing.
 

juicehifi

Audiolense
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Feb 5, 2018
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It is true what you say, provided the analog attenuator is 100% transparent, which is highly unlikely. With an analog stepped attenuator you will typically either have an extra buffer behind …. or effectively a «passive» solution hooked to the amp. Both of these will often reduce the sound quality.

It is very difficult to beat a digital volume, folkowed by a sota dac directly hooked up to the power stage.
 
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