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MDAC First Listen (Part 00101001)

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adamdea said:
The output data is isolated electrically from the input data, but not actually from the host's power.
Click to expand...

Help, I'm lost - is the power from the "PC" the power source - so that its not electrically isolated from the PC? - the PC is the Host device.

Maybe a more simple question is there electrical (Galvanic) isolation between the devices?
 
jamjar784 said:
Hi John

This is an interesting idea. Many posts back on this long thread there was discussion about HQ PSU's - I think there are at least two 3rd party versions for the MDAC - and that these could improve SQ by feeding clean stable PSU voltages even though the MDAC already has built in filtering and regulation.

Would it be possible to kill two birds with one stone and plug the existing MDAC rectified AC adapter into the new USB isolator? So we'd have 2 outputs: clean DC into MDAC PSU input, and isolated/regenerated 96KHz USB. Hopefully this would be cheaper than building another complete PSU as only rectification/smoothing/regulation would be required?

Just a thought :)

KR
Click to expand...

JamJar,

The AC Adaptor only powers the ReGen USB Hub circuit - it can also power low current USB powered DACs & the USB input section of the FDAC but ts not required for the MDAC as the MDAC does not require power from the USB for its operation.
 
JohnW said:
Help, I'm lost - is the power from the "PC" the power source - so that its not electrically isolated from the PC? - the PC is the Host device.

Maybe a more simple question is there electrical (Galvanic) isolation between the devices?
Click to expand...
Not completely I don't think due to the powering of the optical to electrical converter. I believe that there may be other devices which do have complete isolation, but in order to do so I think you would need to have the dac end of the optical cable powered by the dac (or independently)
 
MPerkins said:
Can anybody give me any tips on how to remove the cover, including the torx driver size.
Click to expand...

Hi Mike,

have a look at the MDAC Service Manual. On page 4 you'll find an exploded drawing.

Remove the rear panel with all the screws (even those on the connectors/sockets). Remove the 4 front panel screws. Carefully remove the flat ribbon cable from the front panel and then slide the mainboard+powerboard out of the case. Maybe it's possible to relocate the front panel, so you can slide it through the case without disconnecting the flat ribbon cable.

Michael

Edit: Oh and it's T6 :)
 
davidjt said:
With the right tools it's not difficult to have a look, and absence of leakage would put your mind at rest.
If it is leaking, the gunk is corrosive, so cleaning it up would at least prevent further damage. (It's not strictly necessary to detach the front panel: there's enough slack in the ribbon cable to tilt the panel and slide it out along with the two boards.)

IIRC the main pcb is multi-layered, and is therefore next to impossible for an amateur without the right gear to work on. (I assume heat from a simple t/c iron will soak away, and increasing the temperature could either lift the track and/or de-laminate the board.)
OTOH, if the psu board is single layer, I'd be confident enough to tackle that.

John?
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Thanks Davidjt, some good advice here. As you suggest, I'll have a quick look and if required have a careful cleanup (with some isopropyl alcohol). Thanks for the warning about the main pcb...I won't take my soldering iron there for sure!
 
Hawtin said:
I'd get one should this go forward.
Click to expand...

+1.

If JohnW says an increase in SQ for the MDAC is/maybe possible with this proposed USB-Hub device with its own Linear PSU...I'll take such a unit....worth a punt I guess, if it's below the £100 mark?

A single box if possible please.....I don't like too many gubbins!

Also since this is expected to help iron out quality control issues for the FDAC......And it gives me something to play with while I wait for the FDAC...I'm in....:D
 
fusion5 said:
Hi Mike,

have a look at the MDAC Service Manual. On page 4 you'll find an exploded drawing.

Remove the rear panel with all the screws (even those on the connectors/sockets). Remove the 4 front panel screws. Carefully remove the flat ribbon cable from the front panel and then slide the mainboard+powerboard out of the case. Maybe it's possible to relocate the front panel, so you can slide it through the case without disconnecting the flat ribbon cable.

Michael

Edit: Oh and it's T6 :)
Click to expand...

Nice to have the service manual...Thanks fusion5...Sooo many caps in such a small space!:eek:
 
I can think of 3 solutions for USB2.0 (480 Mbps) galvanic isolation:

Icron's fiber based USB 2.0 / USB 3.0 range extenders: http://www.icron.com/products/icron-brand/usb-extenders/fiber/

Adnaco's PCI Express Over- Fiber-Optic Solutions: Directly with Adnaco-S3B USB 3.0/2.0/1.x Over Fiber Optic Extension System or indirectly with Adnaco-S1B 5Gb/s Over Fiber Optic Expansion System (plus a PCIe USB Adapter)

Intona's High Speed USB Isolator, apparently the first in-the-box solution. Something like the classic Olimex, but more complex. Not available yet.
 
JohnW said:
Yes, but it does not offer electrical isolation (Galvanic isolation) as far as I can tell so its pretty pointless!
Click to expand...
I wonder whether it can be hacked to allow one to power the optical to electrical converter independently. Curiously it seemed to work for Archimago in reducing packet noise.
 
fusion5 said:
The purpose of this cable is to exceed the length limitations of passive USB cables.
Click to expand...

Yes, I had hoped it would offer Galvanic isolation - but sadly despite the optical cable data path, the Copper power connections break the Galvanic isolation barrier so making it pointless unless you need a very long USB cable.
 
adamdea said:
I wonder whether it can be hacked to allow one to power the optical to electrical converter independently. Curiously it seemed to work for Archimago in reducing packet noise.
Click to expand...

Yes, I wondered the same :)

I'm guessing the high resistance of the very thin copper power lines acts as a simple passive filter - but the same results could be achieved by a dedicated USB filter...
 
Hi Everyone

What I find it hard to grasp is the fact that I can copy a data file of any sort a trillion times over, even via USB to my computer to HDD, unchanged...yet some mystical 'musical' data seems to be plagued by all sorts of phantom problems in the stratosphere and solar flares unanimously.

Surely some simple re-clocking device in the FDAC like NuForce did in the Oppo NXE could be possible once all the data arrives, as it does with a PC ? I mean a 1 second buffer even should be more than enough with today's available processors?

We currently transfer 48-64GBpsec of data across our DMDW long distance links at my place of work perfectly and I would use a NAS to stream all of my data...my Blurays ripped to Hard Disk appear to be transferred pixel-perfect (one cannot tell any difference even with a paused frame, I am
convinced), so why is musical data, which is far less intricate, so complex...it baffles me, being honest here.

Surely there is a better way to send the data to a DAC than this, not requiring a regenerator? 8-/
 
John
When using slave units with a master unit and using them together as an active digital crossover, will the volume control on the master unit also control the output volume on the
slave units ?
 
ti33er said:
Hi Everyone

What I find it hard to grasp is the fact that I can copy a data file of any sort a trillion times over, even via USB to my computer to HDD, unchanged...yet some mystical 'musical' data seems to be plagued by all sorts of phantom problems in the stratosphere and solar flares unanimously.

Surely some simple re-clocking device in the FDAC like NuForce did in the Oppo NXE could be possible once all the data arrives, as it does with a PC ? I mean a 1 second buffer even should be more than enough with today's available processors?
Click to expand...

Long Memory buffers are a pain in use...

The problem is that as soon as you allow any Data with Jitter yo enter the device it leaks RF energy and noise that's spectrally related to the Jitter - this then finds its way into the Analogue domain.

Having a memory buffer where numerous cells are clocked at the incoming "Jittery" clock rate just increases the number of active components radiating RF and Noise.

With adequate screening and care the effects can be reduced, but I prefer to eliminate the timing and noise issues before they enter the DAC then having to deal with there negative effects "afterwards"...

The problem with Audio is that you have such a huge Dynamic range - there are very few other areas in engineering that need to deal which such a Dynamic range and with low distortion.
 
iansr said:
John
When using slave units with a master unit and using them together as an active digital crossover, will the volume control on the master unit also control the output volume on the
slave units ?
Click to expand...

Yes - the Master unit will control the volume of the slave units, so the slave units can be hidden.
 
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