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MDAC First Listen (part XXVI)

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Hi John,

This is my first post ever on pfm. I've been following this thread ever since episode XVI IIRC, in admiration for your hard work and dedication to the community.

A month ago, I purchased a second-hand silver MDAC and will now add my name together with the necessary details to the list of pledges to support with monthly installments.

Keep up the good work, all the best for the MDAC2 PCB development!
-alloja
 
jirij said:
I use an AD blocker for a long time, so I haven't really noticed, sorry.

I fixed some headers, links and tables (semi automatically) and the site timeouted / sent a conn reset on every of my attempts to save the page. Perhaps somebody is deliberately DDoSing the sites we put content on?

I'd say better wikia with its advertisements would do a better job, as long as it has a powerful backing infrastructure.

If you get the chance to submit it (tables + headers + links below that), http://paste2.org/11nGJ27y . I've been waiting here 30 minutes for the wiki page to save and have to leave now.
Click to expand...

Hello jirij,

just to tell you I've taken the liberty to add download links to A09 and A10 firmwares to the MDAC referata page, as I've just noticed the google cached version of the wiikki.org page was gone. Fortunately, I still had a locally cached version on my Android tablet, from which I copied (and checked) the links. I will now continue with links to previous versions, which are still available from the cached version at web.archive.org

All the best,
-alloja
 
JohnW said:
Nick,

Yes, that's the idea behind the AV bypass, you can connect your MDAC directly to the power-amps & connect an external pre-amplifier (or AV system) via the AV bypass inputs.

With MDAC2 you will be able to select the AV bypass mode via front panel / RC.

Even with modified MDAC's you 'could' select AV bypass via the Front Panel / RC but we would need to release a new software version...
Click to expand...

Hi John,

I need one then, what's the fastest way of me getting one? Was considering buying a used M-Dac anyway.
 
Nick1881 said:
Hi John,

I need one then, what's the fastest way of me getting one? Was considering buying a used M-Dac anyway.
Click to expand...

Buy an MDAC now (even second hand as we will guarantee the whole unit once upgraded to MDAC2).

Then add yourself to the Pledge list and sometime between Christmas / Feb 2014 we will start shipping the new MDAC2 PCBs for DIY home upgrade (Or you can return your MDAC to us in Czech Rep. and we will upgrade the unit for you) :)
 
alloja said:
Hi John,

This is my first post ever on pfm. I've been following this thread ever since episode XVI IIRC, in admiration for your hard work and dedication to the community.

A month ago, I purchased a second-hand silver MDAC and will now add my name together with the necessary details to the list of pledges to support with monthly installments.

Keep up the good work, all the best for the MDAC2 PCB development!
Click to expand...

alloja said:
Hello jirij,

just to tell you I've taken the liberty to add download links to A09 and A10 firmwares to the MDAC referata page, as I've just noticed the google cached version of the wiikki.org page was gone. Fortunately, I still had a locally cached version on my Android tablet, from which I copied (and checked) the links. I will now continue with links to previous versions, which are still available from the cached version at web.archive.org
Click to expand...

Welcome to PFM, and thank you for pledging support the MDAC2 :)


Also, a big thank you for helping restore the re-hosted Wiki...
 
JohnW said:
After the MDAC2, IMO what is really required is a small decent matching Power Amplifier - the MIMP... I have a design, but what I really need is someone who can help with the PCB design - if anyone knows of a person who wants and job in HiFi and can design PCB's and does not mind to escape to Czech Rep. land of cheap beer, beautiful weather and lady's then let us know!...
Click to expand...

Hi John,
I took the liberty of pasting your post to one of CZ DIY forums, here http://hifi.slovanet.sk/bb/viewtopic.php?t=13687&start=45
There are other cz forums like www.audioweb.cz , as well.
I believe you know or knew some of CZ designers, some of them might be interested in your offer above.
Just my 2 cents :)
Pavel
 
PavelPinkFish said:
Hi John,
I took the liberty of pasting your post to one of CZ DIY forums, here http://hifi.slovanet.sk/bb/viewtopic.php?t=13687&start=45
There are other cz forums like www.audioweb.cz , as well.
I believe you know or knew some of CZ designers, some of them might be interested in your offer above.
Just my 2 cents :)
Pavel
Click to expand...

Hi Pavel,

Thank you very much - yes been thinking of PavelD but he is based in Prague, and I'm not sure if he can learn our PCB CAD package... - maybe a great position for a student from Brno university...
 
JohnW said:
Buy an MDAC now (even second hand as we will guarantee the whole unit once upgraded to MDAC2).

Then add yourself to the Pledge list and sometime between Christmas / Feb 2014 we will start shipping the new MDAC2 PCBs for DIY home upgrade (Or you can return your MDAC to us in Czech Rep. and we will upgrade the unit for you) :)
Click to expand...

Please add me to the MDAC2 DIY home upgrade list OR where do I go to "put myself on the list"

Thanks

Ben
 
JohnW said:
Welcome to PFM, and thank you for pledging support the MDAC2 :)
Click to expand...
Thanks a lot, John!

Also, a big thank you for helping restore the re-hosted Wiki...
Click to expand...
You're welcome! Silly me: I only discovered the link to the latest cached version @ mee.la when I was nearly done using the other two, incomplete caches :rolleyes:

I just double-checked all links on mdac.referata.com against the mee.la version, and am confident in thinking we've now got 100% mirroring...
 
JohnW said:
No internal PCB card, but an external USB to SPDIF/Clock Lock is on the drawing board.
Click to expand...
Hi John,

Please advise this USB to SPDIF converter with Clock Lock will be powered from USB or will have external PS?
Also please advise the expected release date as well as the expected price.

Nick
 
snick99 said:
Hi John,

Please advise this USB to SPDIF converter with Clock Lock will be powered from USB or will have external PS?
Also please advise the expected release date as well as the expected price.

Nick
Click to expand...

Nick,

The isolated / clock locked USB interface can be self powered from the USB port - or external power can be provided where the external USB host cannot proved the required power (such as the Apple CCK).

The external USB port is a development of the MTRN's which will be released after MDAC2 and the Mimps... At the moment we are searching for a PCB designer to help reduce our development times... but its will not be released until next year.
 
JohnW said:
Jo,

I'd like to include a Analogue input with volume control - again time will be the limiting factor - so I'm thinking along the lines of adding connectors and mounting holes on the MDAC2 PCB to support the option later (user installable)...

I'll see if its possible once I start the PCB design.
Click to expand...

John,

Thanks for your reply, that sounds like a very good option.

Jo
 
Hi John

I am interested in upgrading my MDAC, to the MDAC2 with the 'Toy' option. Could I please be added to the list and PM'd with payment details/schedule.

Many thanks

Ryge
 
TheRyge said:
Hi John

I am interested in upgrading my MDAC, to the MDAC2 with the 'Toy' option. Could I please be added to the list and PM'd with payment details/schedule.

Many thanks

Ryge
Click to expand...

Ryge,

I've added you to the pledge list - Thank you.

http://mdac2.referata.com/wiki/Main_Page#Pledges_to_support_with_monthly_installments

The payments will be spread over 3 instalments of £100 as we progress with the design of the MDAC2 PCB – These “development” pledges will most likely be 1-2 months apart - with the final payment covering the PCB cost + Shipping (£100 to £200).

I’d like to be able to gift ourselves the MDAC2 for Christmas – but I’m notoriously unrealistic with timescales – but we should certainly start shipping the first MDAC2 boards sometime between Christmas and Feb 2014…

I’m just about to ship a batch of 5 upgraded MDAC’s this week, once these have been shipped then I’ll officially start the project and accept the pledged funding. While I still have a few MDAC’s to upgrade, to help meet the delivery schedule, Dominik will then start with the Software development platform and also help with the PCB layout of the Digital sections.

Despite the added complexity (and thus risk to timescales), Dominik and I are leaning towards adding some real FPGA (DSP) horsepower on the PCB so MDAC2 well in time have the advanced firmware features we had been considering for the TDAC (where essentially all the digital processing is offloaded from the ESS DAC and handled externally in the FPGA) – this allows us far greater scope with future firmware upgrades etc – we have some very exciting plans to put this FPGA to good use – this also means that owners of MDAC2 will be able to improve its performance via firmware upgrades in significant steps as we build-up the firmware’s capabilities over time - so the MDAC2 should get even better over time :)
 
Hi John,

I hope you, and other forum members, will bear with me as I relate my observations of a problem which has been troubling me for some months. As there are so many others using the M-DAC with the Squeezebox Touch and Triode’s ‘Enhanced Digital Output’, it may be of wider interest.

John, I wonder if you could give me your thoughts on this problem as it’s been bugging me for too long now. I previously posted I was experiencing a degraded M-DAC SQ when playing files from a NAS via SBT as compared with the CD played using the 8200CDQ as a transport. (Actually it was a concert pianist friend who asked to hear the streamed version versus the CD direct, something I’d never done, who observed the effect first). That was back in May when I only had the CDQ.

A very brief description of the impairment would be a loss of detail, a collapse of the 3-dimensionality of the soundstage, sibilants are spread laterally and detached amorphously from the lower registers of the voice. The ‘clean’ good versions are also so much ‘easier’ to listen to and fatigue-free.

When a got the M-DAC I found the same problem existed. Since then I’ve done so many things to try to find a resolution it would fill a chapter or two.

Firstly the bit-perfect tests are passed without any problem. The USB buffer hovers around the 50% mark. On the SBT I can see the momentary frequency changing indication true Async operation. The degradation occurs with any source to the M-DAC from the Squeezebox Touch via the USB input when in Async mode. The sources could be either NAS or PC connected via a Netgear router, by either Wi-Fi or Ethernet cable, to the SBT. The same degradation occurs with internet radio sources. It doesn’t matter if files are transcoded on the server or the SBT, or sent over the network as wav files.

I have two SBTs both with Triodes EDO, two (different) USB 2.0 hubs and two USB isolators. The SBTs cannot output digital coax or optical at the same time as USB but I can stream the same content to the two SBTs and have one unit output SPDIF and the other USB and switch between them. Always the SPDIF is superior to the USB input. Running without a USB hub with Triode’s workaround does not change anything SQ-wise.

I can now also confirm I cannot detect any difference in SQ between either of the streamed SPDIF outputs from the SBT and the direct output from the CDQ. When swapping the SBTs over the Async USB input is always inferior.

So the situation is:
CDQ -> (coax or optical) M-DAC GOOD
NAS or PC -> streamed via Wi-Fi or Ethernet cable -> SBT -> (coax or optical) M-DAC GOOD
NAS or PC -> streamed via Wi-Fi or Ethernet cable -> SBT -> (Async USB) M-DAC BAD

I thought I had tried all user changeable menu settings but last night came across DPLL settings on the SPDIF inputs. By chance I played around with these and much to my astonishment found I could degrade an otherwise good SPDIF output from the SBT by selecting ‘High Bandwidth’.

To my ears the magnitude and character of the degradation when in ‘High bandwidth’ mode matches that of the Async USB input. So to summarise:
Streamed via Wi-Fi or Ethernet cable -> SBT -> (Async USB) M-DAC BAD
Streamed via Wi-Fi or Ethernet cable -> SBT -> (coax or optical) M-DAC (auto or low BW) GOOD
Streamed via Wi-Fi or Ethernet cable -> SBT -> (coax or optical) M-DAC (high BW) BAD

My M-DAC came with software v0.99/v0.97installed. (Raw digital supply is in the range 17.7v/18.0v). I wondered if a firmware change might have any effect. Today I tried installing the original v0.90 firmware but this wasn’t so useful as DPLL settings are not available but USB was still bad. I now have A10 firmware installed and I can replicate my findings exactly as I found last night.

As an aside I notice the ‘Actual frequency’ is displayed on the SPDIF inputs only when ‘Auto’ or ‘Low’ bandwidths are selected. ‘Actual frequency’ is not displayed with Async USB but there is also no DPLL option there.

It was my understanding, in Async mode, the M-DAC master clock controls everything and this sort of impairment should not be taking place – other things being equal it would be the preferred transfer mode. Nevertheless, using the same SBT stream, the Async USB input is behaving, as far as the degradation in SQ is concerned, as if it had an SPDIF input operating adaptively with high bandwidth DPLL selected. Although it shouldn’t be necessary, I am wondering what the effect might be (even if it were possible) of utilising all those stages of jitter reduction available on the SPDIF inputs?

I have for some time felt the impaired SQ was jitter related and what I have found this weekend seems to support that. Have you still got your SBT, John? Any chance you could have a listen when you have time please? And can anyone else please confirm my findings?

Roger.
 
Hi Roger,

Welcome to the world of digital jitter!!! - I have ALWAYS stated that I've found the most obvious effect of jitter is the "collapse of sound stage" - it amazing how sensitive our ears are to this effect.

As you set the DPLL settings from narrow to high the jitter attenuation is reduced - hardly any measurable difference but... your ears ARE telling you the truth...

I believe you have second order effects at play - the USB interface is not isolated and the SBT is a very noisy RF environment. The SPDIF inputs on the MDAC are transformer isolated and also offer a large degree of common mode rejection. RF injection during USB operation is upsetting the sound of the MDAC - I hear the effect here.

Im glad that you are sensitive to "3-dimensionality of the sound stage" as this is an area of Sound quality that I'm especially sensitive too - many people simply don't care or appreciate 'Sound stage" - in fact so many 'HiFI' systems are just plan 'flat' and 'between the speakers' and thus so unreal to me...

There is also a second effect at play WRT Jitter - which I'd rather discuss with you in person when we next meet as we might apply for a Patent in the future or at least "Hide" our solution to prevent others commercially capitalising on our development work. Its one of the reasons we plan to add FPGA power to the MDAC2 platform. So if you can live with the SBT/ MDAC via SPDIF until MDAC2 is released where we will have a solution for you :)
 
FPGAs would be a very interesting proposition! I guess first priority will be integrating the physical FPGAs for first release, with firmware updates enabling them once the PCB is complete?
 
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