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MDAC first listen (part V)

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rtrt said:
iirc it's not about the number of bits - think you have to go a lot lower for that to be a factor. it's more about the audio signal being reduced whilst the digital noise level stays constant - at least thats how i remember it.
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Exactly my concern.

I'm not so concerned about the the digital attenuators in regards to "Loosing Bits" but rather the level of RF "crud". Digital products produce certain levels of RF crud which can upset the input stages of most amplifiers.

With a Analogue volume control, both RF and audio signal are attenuated - but with a Digital attenuation the RF is always at "full tilt" while the analog signal is attenuated... so at lower listening levels the RF level can start to be more "pronounced" compared to the analogue signal.

Using external attenuators to "pad down" the output level which reduces both RF and Analogue signals - which is desirable.

In fact thinking about it while I'm writing this post, and I'm going to add an internal -20dB attenuation option to the BDAC - thank you for making me think...!
 
mark.king said:
John

A lot of people on here are running the updated software. What's the delay in getting it released official. I am not desperate that is why I haven't asked to beta test it but do want to run my PVR through the MDAC for music programs and concerts insteafof my AV amp.

Sorry to go on about it again :)

Cheers
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Hi Mark,

There was a couple of small issues that needed tidying up - also IAG China where playing silly buggers and behaving stupidly - so we said sod it why should we bother... but we have spoken and its claimed down a little...

In the meantime we have also been able to find and fix a 192kHz lockup issue with Oppo players thanks to valid feedback from forum users :) - thank you.

Monday or Tuesday for the official release.
 
3dit0r said:
I don't know, you'd have to ask John- he advised that if going lower than -30dB to use attenuation. My guess would be that past that point one is beyond the point where the SNR would come into effect attenuating in digital domain- say if the DAC had 130dB SNR, then by the time you get to beyond -30dB you can start to hear it in the rest of the system? That is literally just my guess though, best ask him if you want the real answer!

Thanks for the CDQ/MDAC info, btw :)
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Most systems (power amplifiers / Pre amplifiers) typically have SNR of 90dB to 110dB so its not going to be the DAC that's going to limit the "System".

Is commonly suggested that the Digital attenuation is going to start losing resolution as some point - but what do you think happens with a analogue volume control? - it also starts burying the "Music signal" into the systems noise floor...
 
3dit0r said:
Thanks John, I'm on the latest iOS so should be fine- will be interested to see what the sonic benefits, if any, are. Should be a nice interface in any case, and potentially mean I don't have to buy a SBT or similar :)




Haha, sadly my mod powers haven't quite grown to that extent yet, at least not without a step-by-step :p

To be honest, if you're bringing out a unit with a disc spinner and async USB which is clock-locked to the M-DAC, I'll prob just wait for that.

The reason I was asking about the Apollo specifically is I know Rega employ proprietary software to attempt a very precise read of the disc. How are you planning to cope with that in the CDT? Just ordinary error correction, or does it use proprietary software to optimize for each disc (a la Rega/Cyrus) or multiple reads to a memory buffer (as Meridian), etc.? In fact, I'm not even sure I've read how you did it in the 8200CD... Or is it a secret? ;)
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We have FULL reed Solomon error correction 4x C1 and 4x C2 (which is the theoretical maxim that can be corrected). We also have multiple reads to a memory buffer + an option for the user to display the disk read error statistics (if any).

John
 
JohnW said:
Exactly my concern.

In fact thinking about it while I'm writing this post, and I'm going to add an internal -20dB attenuation option to the BDAC - thank you for making me think...!
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Or even -30db :D I'm currently listening at -38db!! :eek:

Still sounding great tho :cool:
 
JohnW said:
We have FULL read Solomon error correction 4x C1 and 4x C2 (which is the theoretical maxim that can be corrected). We also have multiple reads to a memory buffer + an option for the user to display the disk read error statistics (if any).

John
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It could be nice to use it as a cd ripping machine...
 
misterdog said:
Or even -30db :D I'm currently listening at -38db!! :eek:

Still sounding great tho :cool:
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Hi Misterdog,

At -38dB, with -20dB analogue attenuation dialed in, the Digital attenuation would be -18dB which is fine :)

I'll set at -24dB attenuation... :)

John
 
ADL said:
It could be nice to use it as a cd ripping machine...
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I know there's a whole load of internet "chatter" about CD read errors, but in reality there might only be 10 instances of C2 errors (where the Data is interpolated = Guessed) per CD, so its really not an issue.

We are "adding" the memory re-read / buffer feature not because we believe its needed - but because the CD chip-set we are using performs it by default.

John
 
JohnW said:
in reality there might only be 10 instances of C2 errors (where the Data is interpolated = Guessed) per CD
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John - much experience of ripping CDs on a computer at a typical speed 30× greater than the real time read of a player (the former showing precise stats. for various error types), suggests that C2 failures that entail interpolation are very, very rare on CDs in good nick.

I can typically go through 20 or 30 CDs and not encounter any C2s whatsoever. Unless your CDs are well and truly knackered, the evidence suggests that C2 correction operates far less often than you might think.

cf. data CDs. How often do you encounter a data error these days?
 
JohnW said:
Exactly my concern.

I'm not so concerned about the the digital attenuators in regards to "Loosing Bits" but rather the level of RF "crud". Digital products produce certain levels of RF crud which can upset the input stages of most amplifiers.

With a Analogue volume control, both RF and audio signal are attenuated - but with a Digital attenuation the RF is always at "full tilt" while the analog signal is attenuated... so at lower listening levels the RF level can start to be more "pronounced" compared to the analogue signal.
Click to expand...

Thanks John. It was you who told me originally - but it was about 3am my end (even later yours) so i didnt write any of it down! Still the gist of it seems to have stuck in my head somewhere - so thats all good :D
 
JohnW said:
In fact thinking about it while I'm writing this post, and I'm going to add an internal -20dB attenuation option to the BDAC - thank you for making me think...!
Click to expand...

Excellent idea! That'll save me the price of three sets of xlr attenuators for the teenagers promised the new BDAC and actives.
 
spacey said:
Jumped ship, that was quick! so another 2 years to go then ;) :p
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:):):)

There's a better description earlier in the thread but it's becoming hard to find stuff.

Anyway my interest is in one of these dacs and a pair of Adam Audio's new artist fives for a few friends of mine. Should be pretty damn good.
 
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