advertisement


MDAC First Listen (part 00100101)

Status
Not open for further replies.
MDAC2 has several advantages - for starters the "Digital" Digital sections are on a separated PCB - the "Analogue" PCB is very clean when compared to the original MDAC design - if we start on the presumption of conducted RF via the Audio interconnects, then Lab measurement will be the real judge :)

We can use the conducted RF emission spectrum of the MDAC as a baseline and see where MDAC2 is by comparison.

The MDAC uses a 84MHz Clock, while the MDAC2 56MHz so the main spurie components will be in different locations, but we can still compare energy levels.
Yes that will be interesting/ I was wonderign though whether you ahve measured the spectrum of the M-dac 1 with and without case to see what effect the existing case is having.

Do you think there is any sense in having this sort of internally divided/screened layout
http://www.audio-gd.com/Pro/dac/NFB732/NFB7.321.JPG
If aluminium cases are such a bad thing, then does this make it better or worse? I suppose it might depend on the grounding.
 
Yes that will be interesting/ I was wondering though whether you have measured the spectrum of the M-dac 1 with and without case to see what effect the existing case is having.

Obviously for CE we measured with the unit within its chassis - but not without.

Once I get my lab installed it will be one of the first things I do.

Do you think there is any sense in having this sort of internally divided/screened layout
http://www.audio-gd.com/Pro/dac/NFB732/NFB7.321.JPG
If aluminium cases are such a bad thing, then does this make it better or worse? I suppose it might depend on the grounding.

The GD shielding is merely cosmetic, there is very little electrical connection to any of the shields (I cannot see any)...

Its certainly useful to divide up the Analogue / Digital sections, but that's only the first step - whenever I see GD designs I see only "cosmetic engineering" without the "in depth" knowledge required to offer any real benefit.

I've always felt that this is a shame, as they are trying hard, but without sound engineering knowledge they can only fall back on the primary sense of "Vision".
 
I've always felt that this is a shame, as they are trying hard, but without sound engineering knowledge they can only fall back on the primary sense of "Vision".
Sorry to drag you off topic, but what do you think of this ACSS current mode connection which they seem to be pushing.
 
Hi John,
Can you please let me know when is the deadline for people to join the mdac2 and help to support the project?
Thanks,
Ricardo

Ricardo,

Support at anytime is greatly appreciated :)

We have a "hard limit" of a maximum of 150 MDAC2's due to certain component (Crystal) that I have available. Taking into considerations potential Toy / Fusion owners "Officially" joining the project at this payment round, then we will be coming close to this limit.

A second aspect is that I don't really want to "Mass Produce" the MDAC2 - I'm a designer, and my lab is not set up as a "mass" production facility, although I have recently invested significant funds to install a small production / test bench.

The MDAC2 is a complex design - rather then using "Off the Shelf" integrated components such as Opamps, Regulators and Clock modules etc. each critical circuit section is a "Discrete" circuit design to optimise the circuits performance.

While discrete circuits offer the highest performance, this dramatically increases the PCB component count + design complexity resulting in a daunting task for anyone apart from the designer to understand the design and to be able to service / repair the unit, as such its not a design suitable for "Mass Production". With so many of the circuit sub-sections are "Novel" the design would be Alien to your average technician.

While I'll "happily" :) build say 150pcs - I have no intention to spend my life building MDAC2's... my skills are better served designing and not as a production engineer.

Basically, I hope only build as many units required to "cover" the development costs, so that I can design the best DAC I can within the MDAC chassie, and no more... :)
 
John, what's the position with M-DAC 2 firmware? Has it been specified, and what's the timescale for it being written?

I know nothing about programming embedded systems, but can't a functional specification only be written once the hardware has been nailed down?
 
Status
Not open for further replies.


advertisement


Back
Top