advertisement


MDAC First Listen (part 00100000)

Status
Not open for further replies.
I preseme that anlog ins will remain, but I'm getting a tiny bit confused. isn't the L3 supposed to have a sort of pod attached for additional inputs.

Is that still going to be the case once it goes L4 or the the pod going to disappear?

The Digital section is in a state of flux until I start to working on the Digital board PCB design.
 
Just putting together the results and pictures for the MDAC2 PSU / Clock Prototype.

Top view of the PCB (the Large though hole components are mounted on the underside of the PCB to allow me access to the tiny surface mount devices during testing of the prototype PCB).

You can also see the MDAC's PSU input board (The Blue PCB to the left) used to power this PCB. (The large Gold Power resistor is used to simulate the extra load of the ESS DAC etc. which will be powered from this section).

https://dl.dropboxusercontent.com/u/86116171/MDAC2 section2.JPG

The underside of the PCB showing the components which would normally be mounted on the topside of the PCB on the production units:-

https://dl.dropboxusercontent.com/u/86116171/MDAC2 section3.JPG

Thermal images of the PSU under full load:-

https://dl.dropboxusercontent.com/u/86116171/17V 750mA MDAC2 PSU & Clock PCB Zoom1.jpg

https://dl.dropboxusercontent.com/u/86116171/17V 750mA MDAC2 PSU & Clock section Full view.jpg

The Thermal imaging shows no device hotter then 75 DegC localised to the device die - the PSU is supplying "full load" - a load resistor has been attached to emulate the load requirements of the ESS DAC's etc (295mA). Total 6.5V Bus load about 750mA.

The PSU is very high efficiency, allowing us to use the MDAC's original AC Adaptor despite the greatly increased power requirements of the MDAC2 design (High Current ClassA output stages, Twin ESS DAC's, PECL Logic clock distribution, Twin ADC's, FPGA & DSP etc).

The output of the PSU showing the noise floor at -170dB (0dB Ref. 3.4V) 8192K points FFT:-

https://dl.dropboxusercontent.com/u/86116171/OP6TH3V4.jpg

The noise floor at -170dB (and the mains related spurie) are artefacts of the measurement system & and hum Pickup on the lab bench.

Combined with the Clock measurements I'm extremely happy with these results :)

Clock and PSU performance result are "limited" by my "state of the art" test equipment - which I guess I can see say is decent days work (OK it was months of work) :)
 
So, it is still possible to get an MDAC2 if i just pay the first three installments and the 4th later? I want to have the MDAC2 board sent to me when its ready and install it myself. Is that still possible with latest MDAC2 design? How about the z-foil resistors, do all the L1, L2 and L3 have them or are they priced separately? Or are they now obsolete?

The L2 option seems most interesting at the moment.
 
The PSU is very high efficiency, allowing us to use the MDAC's original AC Adaptor despite the greatly increased power requirements of the MDAC2 design (High Current ClassA output stages, Twin ESS DAC's, PECL Logic clock distribution, Twin ADC's, FPGA & DSP etc).

The output of the PSU showing the noise floor at -170dB (0dB Ref. 3.4V) 8192K points FFT:-

https://dl.dropboxusercontent.com/u/86116171/OP6TH3V4.jpg

The noise floor at -170dB (and the mains related spurie) are artefacts of the measurement system & and hum Pickup on the lab bench.

Combined with the Clock measurements I'm extremely happy with these results :)

Clock and PSU performance result are "limited" by my "state of the art" test equipment - which I guess I can see say is decent days work (OK it was months of work) :)
That does look impressive. Sorry if i am being thick but is this an ac supply (ie 3.4v at 50hz) or a dc supply (3.4v at 0hz). I can't make it out.

Either way the spuriae seem at a low level (especially if they are hum pickup).
 
So, it is still possible to get an MDAC2 if i just pay the first three installments and the 4th later? I want to have the MDAC2 board sent to me when its ready and install it myself. Is that still possible with latest MDAC2 design? How about the z-foil resistors, do all the L1, L2 and L3 have them or are they priced separately? Or are they now obsolete?

The L2 option seems most interesting at the moment.

Elviz,

Yes, we are down to the last few PCB slots.

Please note the cost of MDAC2 L2 is the first three installments and the 4th later + the PCB sold "At Cost".

The PCB can be installed by yourself.

The L2, L3 (& L4) will have a basic set of Zfoils (4 resistors) with the option to increase the number of circuit locations the ZFolis are used as a "Fusion" upgrade at extra cost.

Renata's not here to confirm, but don't you already have an upgraded (Toy / Fusioned MDAC)? If so, then you already qualify for an MDAC2 L1 "At cost" and you just need to pay the difference for the other versions (so an extra GBP100 for the L2 + Build cost).
 
That does look impressive. Sorry if i am being thick but is this an ac supply (ie 3.4v at 50hz) or a dc supply (3.4v at 0hz). I can't make it out.

Either way the spuriae seem at a low level (especially if they are hum pickup).

3.4Vdc is set as the 0dB reference - so the noise floor is -170dB relative to 3.4Vdc (as the measured output is 3.4Vdc).
 
icnoble,

The original Toy / Fusion upgrades where based upon hand modifications to the original MDAC PCB.

Due to undesirable production variance between the original units - the modifications ended up taking about 5 days for each PCB - this was crazy - and despite my best efforts there was still a variance between PCB even after the rebuild / modifications.

The whole saga drove me to despair - and to remedy the situation the MDAC2 project was conceived, owners of Toy / Fusion units quality for an MDAC2 L1 "At Cost" as a way to say "well I did not get it 100% perfect the first time, hopefully these new PCB's will make up for it" :)

The MDAC2 will be in a totally different league in every respect....
Will my non modified mdac be upgradable then?
 
Yes - MDAC2 upgrade is a replacement set of PCB's (the MDAC's single mainboard is replaced by a pair double stacked).

Once the mainboards are ready it can be replaced by yourself, or you can send your unit to Czech Rep. and I'll install and test the PCB.
 
Please note the cost of MDAC2 L2 is the first three installments and the 4th later + the PCB sold "At Cost".

What is the current projection for the PCB price? L1, L2 and L3 has different price i suppose.

The L2, L3 (& L4) will have a basic set of Zfoils (4 resistors) with the option to increase the number of circuit locations the ZFolis are used as a "Fusion" grade an extra cost.

Ok, Any idea when that decision is to be made. I suppose, you are going to do that work yourself after you get the pcbs? Or is there going to be different productions for different quantities of zfoils?

Renata's not here to confirm, but don't you already have an upgraded (Toy / Fusioned MDAC)? If so, then you already qualify for an MDAC2 L1 "At cost" and you just need to pay the difference for the other versions (so an extra GBP100 for the L2 + Build cost).

Yes, i have the Premium Fusion model, but i am planning to keep it alive here with me as it is. No organ donation. At least as a spare dac. Does the "only pay the difference" deal still apply?

edit: if get the model with all the bells and whistles, (zfoils, everything) is that going to be somewhere close to £1000? less or more?
 
What is the current projection for the PCB price? L1, L2 and L3 has different price i suppose.

It not possible to have exact price for the "At Cost" PCB until the design is completed, but guide pricing:-

L1 GBP200 to GBP300

L2 GBP250 to GBP350

L3 GBP300 to GBP400

Ok, Any idea when that decision is to be made. I suppose, you are going to do that work yourself after you get the pcbs? Or is there going to be different productions for different quantities of zfoils?

I'll be able to define the "Fusion package" once I've been able to tweak and listen to a board.

Yes, i have the Premium Fusion model, but i am planning to keep it alive here with me as it is. No organ donation. At least as a spare dac. Does the "only pay the difference" deal still apply?

If you wish to keep your current MDAC, you still quality for the L1 "At Cost" upgrade, but you will need to source a second hand "standard" MDAC as a donor unit.

Lets say GBP400 for the L3 PCB + 2x GBP100 for the additional L1 to L3 development installments = GBP700 for a Basic version of L3.

For the L3 Fusion, lets say an additional GBP200 for a set of Fusion resistors... so worst case lets say GBP900 for a "Fusioned" L3 (for Toy / Fusion upgrade owners).
 
Lets say GBP400 for the L3 PCB + 2x GBP100 for the additional L1 to L3 development installments = GBP700 for a Basic version of L3.

For the L3 Fusion, lets say an additional GBP200 for a set of Fusion resistors... so worst case lets say GBP900 for a "Fusioned" L3 (for Toy / Fusion upgrade owners).

Ok. That cleared the confusion. Thanks John!
 
That does look impressive. Sorry if i am being thick but is this an ac supply (ie 3.4v at 50hz) or a dc supply (3.4v at 0hz). I can't make it out.

Either way the spuriae seem at a low level (especially if they are hum pickup).

This is the input from the MDAC input PSU board to give you an idea how much the MDAC2 PSU section cleans things up :)

Before:-

0dB Ref. 17V

https://dl.dropboxusercontent.com/u/86116171/INPUT17V.jpg

And after:-

0dB Ref. 3V4

https://dl.dropboxusercontent.com/u/86116171/OP6TH3V4.jpg

(With a 3.4V Signal the Analyser is hitting its dynamic range NF at about -170dB).
 
LMS 7.9 does support DSD, internet radio and has a web interface as well as there are great apps for tables/phones.
So why look at other options?

LMS now support DSD and can playback via squeezelite as DoP. I have yet to add native linux support for DSD streams (calling the linux ALSA layer with DSD output, but this could be added to squeezelite). It would need a kernel driver for the DSD output to the DAC though...

If you are choosing a SoM for this then I would suggest something more powerful than a PI would be best give the lifetime I'd expect you to want for it. IMX6 (Wandboard, Cubox etc) seem quite performant and offer multiple core options.

Adrian
 
Rear panel space is gong to be an issue, maybe the L4 version will have only a couple SPDIF inputs and an output - the rest dedicated to the USB / MicroSOM ports :-

2x USB "A" (Host)

1x RJ45

HDMI

SD Card Slot

Maybe WiFi Antenna (I'm not sure if we will include internal WiFi, depends on screening and emission)

Power connector for the MicroSOM section

So we'd have 2 wall-warts with the L4? I take it this is because you've utterly squeezed the last few drops out of the existing brick/PSU?

Would it make sense to 'delay' the L4 to co-exist with the TDAC such that all of it could live in a new case with a nice big heavy linear PSU?
 
LMS now support DSD and can playback via squeezelite as DoP. I have yet to add native linux support for DSD streams (calling the linux ALSA layer with DSD output, but this could be added to squeezelite). It would need a kernel driver for the DSD output to the DAC though...

If you are choosing a SoM for this then I would suggest something more powerful than a PI would be best give the lifetime I'd expect you to want for it. IMX6 (Wandboard, Cubox etc) seem quite performant and offer multiple core options.

Adrian
Hi Adrian. Massive fan. Assuming that John plumps for one of the Micro Som modules, would it be necessary to have a special build of squeezelite or would the standard build work. Also could you possibly comment on whether it would be likely to work smoothly having LMS (standard build?) running on the same machine.
 
Adrian,

Unless we discover a major problem, I've pretty much decided to use a Micro-SOM i2 module...

http://www.solid-run.com/products/micro-som/

You now far more then me when it comes to Linux, would you care to comment? :) any feedback will be gratefully considered :)

Yep - looks very similar to the wandboard som, but with the advantage that the micro sd slot is not on it. I think this is an advantage as it means the micro sdcard can be removed and reprogrammed externally (avoiding the chance of "bricking" the CPU module)
 
Status
Not open for further replies.


advertisement


Back
Top