MDAC First Listen (part 00011111)

[sprint]

It has been a while since I last checked the post.

Can somebody or John please advise the latest position with regards to the MDAC2?

Is it still a D.I.Y. single upgrade pcb or is it now a complete unit are there any options?

 

[ChrisPa]

It has been a while since I last checked the post.

Can somebody or John please advise the latest position with regards to the MDAC2?

Is it still a D.I.Y. single upgrade pcb or is it now a complete unit are there any options?

Still in design. We'll finally know the spec and how it will be available once the designs are complete

 

[timow]

Timow,

I understand your concerns.

But again I like to stress that the DSP / Bluetooth DOES NOT DELAY THE PROJECT - Dominik is handling the design of the Digital PCB - it will be completed before the final version of the Analogue board that I'm designing.

The additional Analogue attenuator sections are on the Analogue board so will have a slight impact on the project timeline - I'm about to reach that section of the design within this week - but the good news is I'm not having to rip-up the design to add the attenuators - so if anyone is unhappy because of the slight extra delay of adding the attenuators then they can Email me expressing there wish to pull-out of the project because of this additional slight delay and I'll understand - I'll happily return there pledged funds, I'll be VERY saddened to see anyone opted out because I truly believe the MDAC2 design will be better for the additions - as with any complex project there are always slight digressions from the original plan when things are found that can be improved or where not given there due consideration at the start of the project.

I'm trying to balance commonly requested features, and the Analogue attenuation is probably the most common "extra" requested - with some form of EQ / DSP as the second,

I added Bluetooth option because it cost so little, will not delay the project in anyway, and I'm sure nobody gave it any consideration unaware it was possible.

The Bluetooth is not about HiFi is just a connivance feature, that can be added for very little effort or expense and does not impact the SQ when not powered.

I cannot make 100% of the people 100% happy - I can however refund your pledge if your unhappy with this turn of events - but it will not stop me designing the very best product I can offer - I truly don't want to loose anyone in the process.

As this is a "Public project" I feel its better to have any proposed changes discussed here on the forum in public - not via private emails.

For those who feel strongly against the changes - there will still be the "Original design offered" - and I'll pledge to work even longer hours so that the addition of the Analogue attenuators does not impact the end design time of the Analogue board with any significance.

Thanks for clairification and it seems that it was only me who was concerning about some of new added features.

As you said it is not additional cost issue. For one example I was surprised to see that bluetooth will be added to MDAC2 PCB after all RFI discussions. I hope it will be possible to turn on and off bluetooth radio and all other added features in signal path if someone wants to do it.

 

[shaolin]

Thanks for clairification and it seems that it was only me who was concerning about some of new added features.

As you said it is not additional cost issue. For one example I was surprised to see that bluetooth will be added to MDAC2 PCB after all RFI discussions. I hope it will be possible to turn on and off bluetooth radio and all other added features in signal path if someone wants to do it.

Yes, it can be turned completely off.

 

[JohnW]

I was surprised to see that bluetooth will be added to MDAC2 PCB after all RFI discussions. I hope it will be possible to turn on and off bluetooth radio and all other added features in signal path if someone wants to do it.

Tim,

As I stressed before, you still have the option to choose the MDAC2 build without the DSP / BT & Analogue attenuation - the "Basic" version.

The power and signals to the Bluetooth module are powered down / set low when not active - and the audio quality of Bluetooth is not high enough to be concerned about any sonic degradation during its use - BT ultimate audio quality is limited by the audio data compression, not any RF effects on the MDAC2.

I believe its correct to say that the primary reason everyone has invested into this project is to achieve the best sound quality from the design – certainly for me as the designer, sound quality is the number one requirement – and non of the features will negatively effect this – DSP / BT can be totally bypassed / powered down if not required – and again I stress that if anyone has concerns, the basic unit is available.

 

[Ale79]

Yesterday evening and this morning I finally managed to listen to my MDAC (Toy). I plugged it in, turned it on and got the music going: it sounded absolutely fine!
I started wondering what all the talk about warm up was about... I left it on all night and had a good listen this morning. I stopped wondering.
This dac is a brillant music machine, great work John!!!

 

[Bob L]

Count me in too for the DSP version.
Has the MDAC 1.5 idea been abandoned?

 

[JohnW]

Count me in too for the DSP version.
Has the MDAC 1.5 idea been abandoned?

No - its still on the cards, but much depends how quickly the PCB design "Flows", we might be able to sidestep the MDAC1.5 and go straight to MDAC2.

 

[JohnW]

Yesterday evening and this morning I finally managed to listen to my MDAC (Toy). I plugged it in, turned it on and got the music going: it sounded absolutely fine!
I started wondering what all the talk about warm up was about... I left it on all night and had a good listen this morning. I stopped wondering.
This dac is a brillant music machine, great work John!!!

That great news I was a little worried that we had not heard from you

 

[rundll32]

Tim,

As I stressed before, you still have the option to choose the MDAC2 build without the DSP / BT & Analogue attenuation - the "Basic" version.

The power and signals to the Bluetooth module are powered down / set low when not active - and the audio quality of Bluetooth is not high enough to be concerned about any sonic degradation during its use - BT ultimate audio quality is limited by the audio data compression, not any RF effects on the MDAC2.

I believe its correct to say that the primary reason everyone has invested into this project is to achieve the best sound quality from the design – certainly for me as the designer, sound quality is the number one requirement – and non of the features will negatively effect this – DSP / BT can be totally bypassed / powered down if not required – and again I stress that if anyone has concerns, the basic unit is available.

Wow, really nice. I hope you have (bluetooth) aptX in mind. wikipedia - aptX - Consumer audio products incorporating aptX
Edit: I'm afraid it requires licensing because it's proprietary. Oh well.

 

[JohnW]

Now that would come in very handy, even if it takes a outboard AD conversion first

There will be no need for outboard conversion......

The final piece of the jigsaw puzzle is High Quality ADC conversion - as we have extra PCB space (with the digital sections moved and isolated to a second PCB) - and we have Analogue input connectors in the form of the Analogue bypass, I'd very much like to add ADC to the PCB - the ADC will have varoius modes:-

1. DSD 64

2. DSD 128

3. PCM 44.1, 48, 88.2, 96, 176.4, 192, 352.8 & 384

4. "Analogue Mode" where the independent ADC's are operated at 14MHz per channel for the very highest Audio quality to support Analogue input "pre-amplifier", Gain and RIAA & Room EQ etc.

The ADC version can only be ordered in combination with the DSP versions as the DSP is required for "downsampling" to PCM - the DSD Bitstreams modes are "Pure" unprocessed DSD.

Once again the ADC cost an extra GBP100 for design and development + material cost (about GBP20) - so somewhere around GBP120 for a pretty much state of the art ADC system

I would like to demonstrate the differences between DSD & PCM - my past experience has shown that DSD is pretty much transparent - so great for archiving LP's etc.

For turntable users will require an external "Gain Stage" which can be located near the turntable, we will design this unit once the MDAC2 is completed - or any existing Phone stage can be used.

So the MDAC2 will be offered in 3 build versions:-

1. Basic unit

2. DSP+ Bluetooth + Analogue attenuator (+ GBP100 & attenuator material cost)

3. DSP+ Bluetooth + Analogue attenuator + Hi Performance ADC (+ GBP200 + Analogue attenuator & ADC materiel cost).

The above amounts are based upon additions to the cost of the basic MDAC2.

The ADC section is based upon earlier designs so will add only a couple of weeks to the timeline - this will be the LAST addition to the MDAC2 design... the jigsaw is complete I Promise!

 

[mark.king]

There will be no need for outboard conversion......

The final piece of the jigsaw puzzle is High Quality ADC conversion - as we have extra PCB space (with the digital sections moved and isolated to a second PCB) - and we have Analogue input connectors in the form of the Analogue bypass, I'd very much like to add ADC to the PCB - the ADC will have varoius modes:-

1. DSD 64

2. DSD 128

3. PCM 44.1, 48, 88.2, 96, 176.4, 192, 352.8 & 384

4. "Analogue Mode" where the independent ADC's are operated at 14MHz per channel for the very highest Audio quality to support Analogue input "pre-amplifier", Gain and RIAA & Room EQ etc.

The ADC version can only be ordered in combination with the DSP versions as the DSP is required for "downsampling" to PCM - the DSD Bitstreams modes are "Pure" unprocessed DSD.

Once again the ADC cost an extra GBP100 for design and development + material cost (about GBP20) - so somewhere around GBP120 for a pretty much state of the art ADC system

I would like to demonstrate the differences between DSD & PCM - my past experience has shown that DSD is pretty much transparent - so great for archiving LP's etc.

For turntable users will require an external "Gain Stage" which can be located near the turntable, we will design this unit once the MDAC2 is completed - or any existing Phone stage can be used.

So the MDAC2 will be offered in 3 build versions:-

1. Basic unit

2. DSP+ Bluetooth + Analogue attenuator (+ GBP100 & attenuator material cost)

3. DSP+ Bluetooth + Analogue attenuator + Hi Performance ADC (+ GBP200 + Analogue attenuator & ADC materiel cost).

The above amounts are based upon additions to the cost of the basic MDAC2.

The ADC section is based upon earlier designs so will add only a couple of weeks to the timeline - this will be the LAST addition to the MDAC2 design... the jigsaw is complete I Promise!

Well that all took a bit of getting my head around but I like the idea of the ADC. So you say it can be used for archiving so it will appear as a recording device on a PC as a soundcard would?

 

[Akasha]

There will be no need for outboard conversion......

sounds more and more promising, a built in upgradeable DSP multitool, but if it has option of RIAA EQ, will it then be necessary to have a gain stage in front, for high output cartridges ?

 

[fred sonnen]

...I'd very much like to add ADC to the PCB - the ADC will have varoius modes:-
...
4. "Analogue Mode" where the independent ADC's are operated at 14MHz per channel for the very highest Audio quality to support Analogue input "pre-amplifier", Gain and RIAA & Room EQ etc.

Hallo John

I am not sure if I understand the benefit of an ADC.
Even with ADC the MDAC2 isn't a PreAmp with fully integrated analogue input, right?
Did I need ADC to get RoomEQ or better RoomEQ?

 

[Mikas]

I'm up for the DSP option. I really like the idea of the tone control too - miss these. So much easier than piddling around with wires when you just want to boost things a bit. Probably makes me a hifi heretic but hey ho...

Messing with tone control or equalizers in the analogue domain could and usually is a bit messy. There's a lot more components along the signal path.
Messing with them in the digital domain is not and I don't thing that's heretic at all. They can be as usuful in our living room, as they are in our cars.

Good luck with your speakers project. ...and of course, I suggest you consider JBL drivers.


Michael

 

[JohnW]

Well that all took a bit of getting my head around but I like the idea of the ADC. So you say it can be used for archiving so it will appear as a recording device on a PC as a soundcard would?

Yes that's the idea - both for DSD & PCM Modes

You can also use it as a pre-amplifier with analogue inputs, with Gain and any EQ handled in the digital domain with a 14MHz sampling rate! slightly higher then CD's 44.1Khz - ok x300 times higher then CD hopefully at this sampling rate Digital will not sound so DIGITAL!

 

[Mikas]

Hallo John

I am not sure if I understand the benefit of an ADC.
Even with ADC the MDAC2 isn't a PreAmp with fully integrated analogue input, right?
Did I need ADC to get RoomEQ or better RoomEQ?

Volume control and RoomEQ or tone controls are done in the digital domain, so yes, we need any analogue audio source to be converted into digital.

Michael

 

[misterdog]

Could we play Vinyl direct through the MDAC then. ? ( using a suitable Phono stage )

I.e is analogue to PCM/DSD conversion done on the fly ? or do we need to rip to a hard drive first.

 

[mark.king]

Yes that's the idea - both for DSD & PCM Modes

You can also use it as a pre-amplifier with analogue inputs, with Gain and any EQ handled in the digital domain with a 14MHz sampling rate! slightly higher then CD's 44.1Khz - ok x300 times higher then CD hopefully at this sampling rate Digital will not sound so DIGITAL!

Great well I'm in for that. Beats my Yamaha n12 recording/mixing desk which does 96khz

 

[Bigbobby666]

You can also use it as a pre-amplifier with analogue inputs, with Gain and any EQ handled in the digital domain with a 14MHz sampling rate!

This for me is indeed the last piece in the puzzle!

Full DAC with Analogue input with volume control, and bluetooth for the wife! = no need for an extra preamp box - right?

John i'm currently having an issue with Vinyl through the analogue in of my current DAC (MF M1SDAC) where the analogue 'line in' is limited to 1volt so i get clipping on loud recordings, what will the equivalent voltage be on the MDAC2 for the analogue in?

Cheers.
Rob.