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MDAC First Listen (part 00101111)

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JohnW said:
Bob,

If you have the Cable I can confirm if its wired correctly. I searched fro your headphones but could not find any technical Data.

The FDAC had a very different output stage design to the MDAC so not to judge these results - the FDAC's is more of a power stage.

Its also possible that your headphones sound better with less damping (the MDAC has a current sensed output stage).
Click to expand...

Sorry, John, my typing went astray. They are AKG 701s, not "700s", and according to a post on Head-Fi they are 62 ohm, with sensitivity 92dB/mW. I have the internal wiring somewhere at home, but I’m not back until tomorrow. Thanks for the offer, though I have a feeling other people might want you to spend your time on the FDAC……
 
Hey JohnW,
I have not been following the threads on daily basis for the past weeks and may have missed some posts with relevant information, but can you please give an update on where we are with the Vfets? No pressure here, just really to know when you are planning to have them ready and what are the next steps?
Have a great weekend!
 
Hi guys
I have a problem with my mdac. I can't use the Optical inputs because the sound keeps "cutting" for a fraction of a second every now and then. The Display keeps toggeling between 24bit/48khz to 24bit/48001hz and 24bit/48000hz etc. I have tried different sources, and now I wonder if anybody else have had this problem?

cheers/Patrick
 
Rjpcardoso said:
Hey JohnW,
I have not been following the threads on daily basis for the past weeks and may have missed some posts with relevant information, but can you please give an update on where we are with the Vfets? No pressure here, just really to know when you are planning to have them ready and what are the next steps?
Have a great weekend!
Click to expand...

Richard,

I completed the designed the schematic for the VFET output stage and we are looking to hire a 4th team member to layout the VFET PCB - if we we don't find anyone suitable, then I'll work on the PCB as soon as the Analogue PCB has been completed for the FDAC - but I'm hoping to have the PCB designed before the FDAC listening sessions as we really need to improve the Power amplifiers we have in the lab system, they are our systems weakest link.

A month or so ago I purchased the last "large" batch of VFET's pairs (P & N Channels) available for spares (and for a pair of amps for Jarek) - we now have a significant stock pile of VFETs, maybe the largest single stock holding of VFETs in the world - Jarek often jokes that the value of VFET's we have sitting here is more then he has in his back account!

I'm really pushing to have the VFETs prototyped ASAP - after Munich show I might spend a week on the PCB if we have not managed to employ a PCB designer by then.

I also meet with a coil vendor to design the high current inductor for the VFET Current dumping bridge - I have the samples sitting here... but we need the PCB too test.

Lets say within 2 months the prototypes will be built.
 
BE718 said:
Hi John,

Roon have just released the Linux versions of their roonbridge endpoint. Is it going to be possible to get this running on the beagle in the fdac?

https://kb.roonlabs.com/LinuxInstall

Edit: just seen this saying it works fine on a BBB
https://community.roonlabs.com/t/roon-1-2-feedback-thread/9463/158?u=be718
Click to expand...

BE78,

We don't foresee any problem getting Roon endpoint on the FDAC (even with the RPi code - even better now that its been complied for the BBB) - the most time consuming aspect is implementing the UI.

In the above post you can see a video of the FDAC Touch panel operating with a simple Qt UI script.

Now that the hardware interface has been prototyped we can start building the initial realise software.
 
Thanks for the update John,
Excellent news.
Can't wait for the day! :D

JohnW said:
Richard,

I completed the designed the schematic for the VFET output stage and we are looking to hire a 4th team member to layout the VFET PCB - if we we don't find anyone suitable, then I'll work on the PCB as soon as the Analogue PCB has been completed for the FDAC - but I'm hoping to have the PCB designed before the FDAC listening sessions as we really need to improve the Power amplifiers we have in the lab system, they are out systems weakest link.

A month or so ago I purchased the last "large" batch of VFET's pairs (P & N Channels) available for spares (and for a pair of amps for Jarek) - we now have a significant stock pile of VFETs, maybe the largest single stock holding of VFETs in the world - Jarek often jokes that the value of VFET's we have sitting here is more then he has in his back account!

I'm really pushing to have the VFETs prototyped ASAP - after Munich show I might spend a week on the PCB if we have not managed to employ a PCB designer by then.

I also meet with a coil vendor to design the high current inductor for the VFET Current dumping bridge - I have the samples sitting here... but we need the PCB too test.

Lets say within 2 months the prototypes will be built.
Click to expand...
 
Hi John,
Great to see the progress. Can I volunteer to check the spelling on the FDAC display? (I have many years of editing experience.) ;)
Matt
 
:) We will be more then happy for any suggestions on the FDAC UI. (and Please forgive our spelling skills, seems Thomas is no better then me... but then his is 100% Czech unlike my 50% English mix!) :)

If you have Qt5 experience then we can forward the files.
 
Great to hear that many parts of the Detox, FDAC and VFET projects are coming together. I'm sure John "wellcomes" the day the hardware will be in the hands of the project supporters!
 
JohnW said:
:) We will be more then happy for any suggestions on the FDAC UI. (and Please forgive our spelling skills, seems Thomas is no better then me... but then his is 100% Czech unlike my 50% mix!) :)

If you have Qt5 experience then we can forward the files.
Click to expand...

John, you've stumped me with QT5. I'd need text files, so I'm probably useless. :(
Matt
 
Matt,

Well we will post YouTube videos - don't worry I'm just as stumped with Qt5, I've just purchased a couple of books to get a basic handle so that I can atleast have a conversation with Thomas on the UI implementation without appearing a total fool...

You need to have C++ skills before working with Qt5 - I'm a "BASIC" man myself thanks to the day so of the ZX81!

Tesla use Qt5 for there Dashboard UI so we are in great company...
 
Well, it sounds spiffing and will no doubt result in a fantastic UI. Thankfully I don't need to get my hands dirty with such stuff. :)
Matt
 
JohnW said:
the most time consuming aspect is implementing the UI.
Click to expand...
That was my reason for the "overreaction" to squeezelite before I realized it's a UI-less process (which is completely fine and easy to implement). I assumed you'd be trying to fit a full fledged Squeezebox Touch UI onto the FDAC.

The problem is that we don't live in 8bit era anymore and altering things to one's image isn't that easy. To run another app like an audio analyser or any 3rd party application, you would need a way to switch between FDAC fullscreen UI (presumably simple, like MDAC) and anything else. This would probably need X11 server running (which you wouldn't need for Qt thanks to its own embedded display server) and some way to intercept a front panel button press to force the FDAC UI in the foreground.

Not impossible to do, but significantly more complex than just having a single fullscreen Qt app. Also a lot more error-prone.

There are ways to make it much safer (ie. starting X11 instance for each such app, confining any related processes within a cgroup, etc.), but one has to keep them in mind. :) I'll probably give it a shot, depending on what solution Jarek/Thomas choose.
 
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