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MDAC First Listen (part 00110100)

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[*]Make everything read-only. This is what I'd like to use for FDAC - use squashfs for the actual system, so it cannot be modified during runtime, only a separate piece storing front panel GUI configuration will be writeable. The advantage is that it's very fast to start up and given the fast random access times of SD/eMMC, it's still very fast during runtime (and repeatedly started programs are cached in page cache anyway, so they won't be read from the flash).

I'm not an expert, but if you did this you presumably wouldn't be able to run LMS and squeezelite, say, on it because I'm assuming they would need to write to the SD. Wouldn't you be very limited in what you could do? Or have I misunderstood what you are saying?

- Richard.
 
Just because you can run the server software on the RPI does not mean it is a good idea.

My personal opinion is that it is much better to just have the client on the RPI (Squeezelite or RoonBridge) and run the server on faster computer. That also leads to less bloat on the RPI.

Running everything on the RPI only works if you have a small music library or is very patient.
 
The way I'm thinking is to get both the MDAC2 (this summer) and the FDAC L3 (hopefully by year end). When the FDAC arrives, the MDAC2 will go into a second system or for a top class headphone listening setup. I reckon the original MDAC is getting too old and liable to fail soon, so its money well spent upgrading it (about £300).

And the Detox is a must as I use the USB input.

I was hoping to use my MDAC, whilst waiting for the FDAC and then for it to become the 2nd system DAC. I really don't need 3 DACs + the old Beresford that I'm running currently. I appreciate your point about the age, but I'm hoping when I get mine back it should last me a for a while longer. Or does the MDAC2 use parts of the MDAC - chassis etc, so the MDAC is effectively no more at that point & i'd be upgrading in quality, functionality and just as importantly longevity?

I'm really looking forward to the FDAC and its DSP features. My living room has a nasty room mode (~20dB@60Hz) which definitely needs some sort of room correction. Right now I'm running an Acourate based room correction on my HTPC, but I'd prefer something for all my sources (Blu-ray, TV).

Pretty much in agreement here. I've played with REW and a UMIK and would like to have EQ in separate MDAC/FDAC hardware, so my turntable / LPs can benefit from EQ as well as digital audio. As well as attenuating room modes, i'd like to apply a room curve -not sure thats the correct term.
 
I haven't as yet (discovered this late last night) - I could connect my MacBook and give that a try. I have tried several Squeezeboxes and two hubs, and no-hub, and the problem is the same. Its quite random, so it takes time to be sure its happening, especially when quite a few producers like to add vinyl noise to their digital content!

I'll do more experiments and report later...

Now listening to Tidal from the Mac via USB and (so far) no clicks... SBT via coax - no clicks.

I've sort of solved the problem, but I'm no nearer to a proper explanation...

baffled :confused:
 
Or does the MDAC2 use parts of the MDAC - chassis etc, so the MDAC is effectively no more at that point & i'd be upgrading in quality, functionality and just as importantly longevity?

It does. The “MDAC2“ consists of a replacement mainboard, a matching backpanel plus a new external HQ psu.
 
Thanks to EIffel and the CA forum I am also able to rip SACD's ;-)
As a nice Amazon Service the BR-palyer comes with an German Power Plug. So I could start immediately.

Greetings from Germany
F.S.
 
Listening to tracks on Youtube while working on the MDAC2 PCB - adding a "Reduced power mode" so the MDAC2 can be lefted powered but not operating at full ClassA dissipation. Both PSU's (ClassA current Shunts) and Output stage's need to be switched to "lower power mode".

So MDAC2 (and FDAC??) will have a standby power mode? And it'll go into standby after a certain amount of time not in use? Have I understood this correctly? Could you possibly expand on this?

My wife and kids cannot be trained to switch kit off, so a standby mode is crucial for me (indeed enough to get me back on board the project :) ).
 
I hate to propose ideas about more work and products you could take on John, but given the absence of decent and well priced 'do no harm' digital equalisers, do you see a space for a separate DSP box at any point in the future?

I really want one but am nervous about buying a MiniDSP device given my experience and the views of some who claim the same is true for other products they do.

If there were a DSP (and perhaps even a Detox) in a single box, I would buy that. I would even care about DRC, I'd just want a parametric EQ.

Anyway, just thinking out loud - there seems to be a niche. In the mean I'm trying to source a DSPeaker Antimode 2 DC but I don't expect amazing things from the DAC so look forward to whenever the FDAC is likely to be...

I like the idea about standby btw.
 
I was hoping to use my MDAC, whilst waiting for the FDAC and then for it to become the 2nd system DAC. I really don't need 3 DACs + the old Beresford that I'm running currently. I appreciate your point about the age, but I'm hoping when I get mine back it should last me a for a while longer. Or does the MDAC2 use parts of the MDAC - chassis etc, so the MDAC is effectively no more at that point & i'd be upgrading in quality, functionality and just as importantly longevity.

The MDAC2 is a DIY replacement board for the original MDAC and so uses the MDAC case, display and front panel....the original MDAC board will be redundant... You may like to consider just waiting a bit longer for the FDAC.

The MDAC2 will allow connection to the superior lakewest PSU which will provide a further considerable SQ upgrade...aside from all the other features of the MDAC2 that take it way beyond the original.
 
So MDAC2 (and FDAC??) will have a standby power mode? And it'll go into standby after a certain amount of time not in use? Have I understood this correctly? Could you possibly expand on this?

I primarily designed the standby mode to reduce heat dissipation within the smaller MDAC chassis - and allow the unit to be left permanently powered for best sound quality (no warm-up time required).

The Auto "Reduced Power mode" will bring the MDAC2 dissipation to near MDAC levels - while in use the MDAC2 output stage will be operating at x4 times the ClassA bias current of the MDAC.

We can build various levels of "Power Saving" modes...
 
The Auto "Reduced Power mode" will bring the MDAC2 dissipation to near MDAC levels - while in use the MDAC2 output stage will be operating at x4 times the ClassA bias current of the MDAC.

John, My MDAC gets rather hot in use and so is placed on its own with plenty of space around...I routinely play it at volume settings -8db and sometimes flat out on +3db....With 4x the heat from an MDAC2 board I'm concerned its going to get very hot. Maybe a glue on external heatsink may be required?

The MDAC definitely sounds much better once warmed up...I've not measured the temperatures but it feels hot to the touch, not just warm after a couple of hours pushing it to its limits.
 
You don't have to have the music itself on the pi - you can connect to networked drives.

- Richard.

My comment was based on using a network drive or directly attached USB drive.
I tested Volumio with the music files on a NAS and found it to be very slow.
I used a RPI 2 and I know a RPI 3 will be faster but you will never get the same performance and user experience as with a separate server doing the hard work.
 
John, My MDAC gets rather hot in use and so is placed on its own with plenty of space around...I routinely play it at volume settings -8db and sometimes flat out on +3db....With 4x the heat from an MDAC2 board I'm concerned its going to get very hot. Maybe a glue on external heatsink may be required?

The MDAC definitely sounds much better once warmed up...I've not measured the temperatures but it feels hot to the touch, not just warm after a couple of hours pushing it to its limits.

Tim,

The MDAC exterior chassis only gets to around 35Deg in free air - in the world of electronics thats not considered hot.

Thermal image below:-

https://dl.dropboxusercontent.com/u/86116171/MDAC Thermal 15.6V.jpg

The MDAC2 has 16 heatsinks for the output stage and related PSU.
 
My comment was based on using a network drive or directly attached USB drive.
I tested Volumio with the music files on a NAS and found it to be very slow.
I used a RPI 2 and I know a RPI 3 will be faster but you will never get the same performance and user experience as with a separate server doing the hard work.

RPI3 running LMS and Squeezelite with 13000+ WAV files in external HDD is using 2-3% of CPU on playback. It have worked without any problem via USB with MDAC and Mojo so far.
 
I'm not an expert, but if you did this you presumably wouldn't be able to run LMS and squeezelite, say, on it because I'm assuming they would need to write to the SD. Wouldn't you be very limited in what you could do? Or have I misunderstood what you are saying?

- Richard.
Why would they want to write to the SD (eMMC)? If they need temporary files, /tmp will be on ramfs or tmpfs, so that will work fine. Any other storage can also be read-write, it's just the OS disk image itself will be read-only.

(You can still modify it externally, just not while running the system from it.)
 
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