MDAC first listen (part VII)

[Plutox]

fair enough, although I'd be interested to know the relationship between jitter and the bit-perfect test in the MDAC... would a high-jitter source pass?

Yes - up to the point where the jitter was so high that the data was not 100% recoverable.

Remember the purpose served by jitter in the audiophile's world. It is the anchor for the audiophilia nervosa sufferer to latch onto that enables him to 'prove' that the signal arriving at his DAC, or whatever, is less than perfect.

 

[mbaudis]

So the big question is do you have an Audiolab product which is a brand you have looked to own for years or a John Westlake product. Don't know about you but when I show off my iPad to my kids I do not mention Steve Dobbs.

Steve Dobbs? Decent guy; stopped his car in the middle of a Stanford crossing to let us (2 bikes with kid's trailers) pass. So I mention his name every time I touch a Maple product (i.e., constantly).

 

[cstanpfm]

Hi John, I know that the V0.99 seems to solve the preamp switching issue.

I am still on V0.90. And it seems that as long as the input selected is USB, the preamp can be switched correctly. Even power off after selecting the enable or disable (instead of pressing the vol button) works. If it is coaxial etc, it does not work. Same behaviour on both my units.

Maybe it is the same case as the filters. Only in USB input the selected filters are loaded correctly.

FYI. Please ignore if you feel that the issue is solved in V0.99.

 

[JohnW]

Hi John, I know that the V0.99 seems to solve the preamp switching issue.

I am still on V0.90. And it seems that as long as the input selected is USB, the preamp can be switched correctly. Even power off after selecting the enable or disable (instead of pressing the vol button) works. If it is coaxial etc, it does not work. Same behaviour on both my units.

Maybe it is the same case as the filters. Only in USB input the selected filters are loaded correctly.

FYI. Please ignore if you feel that the issue is solved in V0.99.

cstanpfm,

Not sure if I understand your posting correctly.

Have you tested V0.99?

If you have tested V0.99 does it solve the Pre Amplifier selection issue?

If you have tested V0.99, is there a reason that you still use V0.90?

I keep trying to recreate the issue with my unit (V.99) but with no luck.

If your on V 0.90 then you could try selecting "Nominal Frequency" option within the Menu, and see if these solves the issue on Pre-amplifier selection while on SPDIF inputs.

If selecting "Nominal Frequency" does solve the Pre-amplifier selection issue while on SPDIF inputs - then I'm happy to say that we have solved the issue on later builds.

It would have been due to the heavy Bus traffic that also prevent the correct selection of Digital filters while on SPDIF with V0.90...

John

 

[JohnW]

with the new firmware (.99) and my GX300 speakers, only perfect albums I use the XD filter... the normal transient and DD sound better for me now... the XD on bad recordings reveals too much information! both good and bad....

So even more details with the V0.99 software?

Would not surprise me...

John

 

[JohnW]

fair enough, although I'd be interested to know the relationship between jitter and the bit-perfect test in the MDAC... would a high-jitter source pass?

yes - a high Jitter device 99.99999% of the time will pass the Bit perfect test unless the Jitter was SO HIGH that we where unable to recover the Data correctly.

The Bit Perfect test says little to nothing about Jitter levels.

If Jitters was so high to effect the Data recovery - then there's a very serous problem... Your not likely to encounter this in a typical domestic situation.

John

 

[JohnW]

Just because it's bitperfect doesn't mean it's jitter perfect, they can still measure differently and thus sound slightly different.

SQ correct.

Data's correct - great, that's the very first requirement for HiFi reproduction met...

However the "timing" - I should say "timing variation" of the data is also important.

Async. USB has an advantage here over SPDIF as with Async USB the Clock is local to the DAC and does not need to be "recovered" from the input data - so the input sources "Data timing / Jitter" should have no first order (Direct) effect on conversion Jitter.

 

[JohnW]

That Chinese brand...erm thingy have managed to bring some great products out though. Same can be said for most speaker brands and nearly all electronic brands at similar price points. All Chinese using different designers. You spend under a grand and chances are its coming out of china. John and Dom would of just been woking under orders. Glad they did though as the Mdac I have is the best purchase I have made

Thank you

 

[JohnW]

To be honest I never looked to own an Audiolab product (let alone for years).., and have only bought the Mdac because of the excellent feedback. I have to say though, having now found out about the excellent quality of John and Dominick's engineering work and their extraterrestrial customer service, I will be looking attentively for all the products they are going to design!

Thank you

 

[bigmarcelo]

So even more details with the V0.99 software?

Would not surprise me...

John

Sure thing to my ears..... SBT ->USB->MDAC->Cayin->GX300=audio nirvana

 

[JohnW]

Quick question: replaced the CDQ with a Cambridge Audio BD650 as a transport (liberating the CDQ for the second system).

When connected using the digi coax, the MDAC would show the cd playback time when playing cds, but this doesn't happen with the BD650 when connected and set to output PCM. JohnW, is that to be expected?

It does show this when set to output Bitstream data but the MDAC doesn't seem to work with Bitstream inputs as no sound is heard.

Yes, Some / most Blue ray players don't encode the track / Time data within the SPDIF stream... Shame really.

Bitstream is and encoded AC3 surround sound format that needs to be decoded via an external "Dolby / THX" decoder...

 

[JohnW]

Just a little, John. I'm currently using the Minimum Phase filter & find the dynamics, bass & detail improved over v0.96. I have no way to confirm (unless I reload) but I also suspect this version is improved over the original (v0.90?)

If users find it a little tiring then perhaps the "Optimal Transient XD" will suit better. As has been pointed out, the filter choice can depend on the recording but hell, I'd prefer to settle on just one filter! Did the absolute phase get inverted in 0.96?

Output Phase has not changed since V0.90 - but can now be selected in V0.99

 

[JohnW]

Just FYI, my random BPT errors turned out to be a cable issue after all. Tried a new one and it's perfectly stable with no more random errors. Am also using an old laptop as a dedicated machine to serve the M-DAC via USB so no concerns about CPU or USB bandwidth being sporadically diverted to other applications.

Also want to concur with other comments about the amazing beyond-the-call-of-duty support I've received from John. Am very very grateful for that (and future firmware releases!)

Best regards
Krisposs

Krisposs,

Glad the cable seems to have helped - unusual your first cable was so bad to have caused issue - unless it was a very poor quality "China" cable...

John

 

[JohnW]

Just updated to firmware 0.99 which went smoothly from my Windows 7 PC and there appears to be quite a marked improvement in sound quality. Quite a lot more detail and tightening up of the presentation. This is a welcome bonus. Didn't expect the firmware update to improve the sound. Thanks John and Dominik!

I'm still keen to try a real A/B comparison between 0.97 & 0.99 - I've been offline most of this week designing the MAMP... I'm really keen to have a decent system once again...

 

[arthur]

I'm still keen to try a real A/B comparison between 0.97 & 0.99 - I've been offline most of this week designing the MAMP... I'm really keen to have a decent system once again...

Lo John. I'm intrigued;

I assume you'll be using M-amps into the ML's, but what digital source will you use?

The Bdac, Mdac+ or the new fangled CDQ?

I really am looking forward to the latter next year, hence even though poverty is slapping at my door I'm keeping both the Mdac and CDQ.

Best of luck with the M-amps. I wanted to try them too, but I've been converted to Active speakers.

 

[kaydee6]

John,
I'm currently connecting the iPad+cck USB to the mdac. Do you kmow how different the digital data is being extracted from ipad compared to say a wadia dock+iPod? It seems that company like Wadia is paying a license fee to extract digital data from i devices. I'm thinking of moving to the Wadia dock with iPod but connection will be limited to spidf and the jitter reduction may not be as good as Asynchronous USB which I'm using now. Just like to dig your brain for more knowledge on source selection.

 

[TwoSeventy]

I'm still keen to try a real A/B comparison between 0.97 & 0.99 - I've been offline most of this week designing the MAMP... I'm really keen to have a decent system once again...

Hi John,

I updated from the original firmware (guessing 0.90) to 0.99 and there was an obvious sonic improvement!

 

[sq225917]

Kaydee, the data will be identical, the timing of that data may not be. Neither the camera kit for the iPad nor the Wadia reclock the data. I had a wadia-podia when they first came and used to use it into my Cambridge Audio 840c (cd player with dac input). Like the Mdac the 840 reclocks the data to remove jitter and the sound quality was just as good as the 840c playing a cd.

In short, i doubt the camera kite or wadia-podia will sound different into an Mdac.

 

[kaydee6]

Sq, thanks for the insight. The only problem for me is iPad storage is running out! I'm looking to iPod for more storage but have to spend on a decent dock. If only the cck works with an iPod

 

[JohnW]

John,
I'm currently connecting the iPad+cck USB to the mdac. Do you kmow how different the digital data is being extracted from ipad compared to say a wadia dock+iPod? It seems that company like Wadia is paying a license fee to extract digital data from i devices. I'm thinking of moving to the Wadia dock with iPod but connection will be limited to spidf and the jitter reduction may not be as good as Asynchronous USB which I'm using now. Just like to dig your brain for more knowledge on source selection.

Good Question

The Wadia dock functions as a Host device and has two major deficiencies.

1. Its Clock Jitter is off the scale - very poor quality SPDIF output and clock Jitter.

2. It can only support 16 Bits to 48KHz.

The iPad via Camera connection kit allows Async operation (Zero interface Jitter), upto 96kHz / 24 Bits Bitperfect audio and the added benefit that MDAC Remote control also operates the iPads iTunes...