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MDAC First Listen (part 00111001)

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John
JohnW said:
Using Balanced and unbalanced outputs at the same time is not a great idea as this unbalances the balanced outputs due to the extra loading of the RCA cable on one phase of the balanced output stage.

Its strongly not recommended for the DD2A designs but "workable" with the more standard designs.
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John
So if you need 2 outputs (say beacause you want to run a sub) what is the best option - just split the balanced outputs?
Alternatively, how about if you want to run multiple subs and use a miniDSP 2x4HD for bass management. Presumably you could utilise one of the digital outputs and connect it to the miniDSP whilst using the XLRs for your main speakers? Is it possible that the latency of the MDAC2 and miniDSP would be so different that the timing of the bass would be out of sync?
 
PhilCTTE said:
Just checking my usb input on my MDAC and there are three pins . The plastic middle piece which supports the usb connection went a couple of years ago. I’m assuming one a snapped and that there should be 4?
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Phil,

Yes - there should be for pins, you might be lucking and the missing pin is +5V power which is not used on the MDAC - but if your lucks like mine I'd not count on it...

Send your board over and I'll replace the connector.
 
iansr said:
John

John
So if you need 2 outputs (say beacause you want to run a sub) what is the best option - just split the balanced outputs?
Alternatively, how about if you want to run multiple subs and use a miniDSP 2x4HD for bass management. Presumably you could utilise one of the digital outputs and connect it to the miniDSP whilst using the XLRs for your main speakers? Is it possible that the latency of the MDAC2 and miniDSP would be so different that the timing of the bass would be out of sync?
Click to expand...

The best option is to use a sub with balanced input and split....

We can make a small Balanced to SE Spliter box...
 
Ok. Any thoughts on my question on the latency position if using the digital output for the sub?
 
JohnW said:
Yes :) - Direct Digital 2 Analogue.... there is no "Active" Analogue stage..... just passive components with no feedback etc.

Output impedance varies, but at any setting below -12dB is about 5 ohms so VERY decent for a "simple" passive design*

* Subject to further optimisation.

The beauty is in the designs simplicity - the simplest cleanest signal path.
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Hi John. Congratulations on almost arriving at a production run.

I am waiting for the MDAC2 as a headphone amp/DAC. You have always designed/developed the MDAC2's output to be an exceptional headphone source as well as amp source. But will this still be the case for the DD2A version? It sounds as though this simplified output stage will be fine for driving an amp's input, but, with a high-ish and variable output impedance, may no longer be ideal for driving headphones directly?
 
JohnW said:
Phil,

Yes - there should be for pins, you might be lucking and the missing pin is +5V power which is not used on the MDAC - but if your lucks like mine I'd not count on it...

Send your board over and I'll replace the connector.
Click to expand...

Cheers John .. I knew I was pushing my luck and it ran out Saturday night unfortunately I was holding my 50th . I’ll be in touch with what to do
 
iansr said:
Ok. Any thoughts on my question on the latency position if using the digital output for the sub?
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Ian,'s

On one hand LF have very long wavelengths so some delay might not be too detrimental - but also consider the highest sampling rate via digital output is 192KHz with no DSD support.

Most of the MiniDSP boxes DSP's operate at a fixed sample rate of 96KHz - the SharkDSP ASRC used to up-sample sounds noticeably very poor... one of the reasons I'm not in too much of a hurry to implement DSP.

It boils down to - do the benefits of DSP outweigh the negatives so its each system to its own...
 
Mark Dirac said:
Hi John. Congratulations on almost arriving at a production run.

I am waiting for the MDAC2 as a headphone amp/DAC. You have always designed/developed the MDAC2's output to be an exceptional headphone source as well as amp source. But will this still be the case for the DD2A version? It sounds as though this simplified output stage will be fine for driving an amp's input, but, with a high-ish and variable output impedance, may no longer be ideal for driving headphones directly?
Click to expand...

Mark,

Thank you :) arranging production is very time consuming - I'm hopping about between one urgency to another and hit the bed recalling all the things I didn't have time to do that "day".

Whats the highest listening level you use with your headphones on the MDAC?
 
I'm using my beyerdynamic T1 at about the same max levels. Does the MDAC DDA limit headphone usage in any way?
 
Mark Dirac said:
Typically -20dB, with a maximum of -14dB, from MDAC's XLR o/ps. (Headphones at present are Audeze LCD3)
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Your fine, at your listening levels the Maxuim output impedance is 40 Ohms - 26Ohms at -18 and 18 ohms at -24dB and lower. We could design the DAC to half these impedances with SE headphones.
 
Thanks for the elaboration John. I reckon I'll stick with the MDAC2 "basic" variant with the conventional analogue o/p, partly because it has a low o/p impedance and because you designed it so meticulously over so many years with the driving of headphones largely in mnd.

Regards, Mark.
 
s1h1 said:
John, Can the DevDAC be used as a standalone DAC with USB and S/PDIF inputs?
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JohnW said:
Yes, *but it still requires the steamer board for system control.
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OK, Thanks.

I'm needing a DAC with USB and S/PDIF inputs. I don't want to buy the streamer board if it's not going to be used in the FDAC. The DevDAC isn't suitable then?
 
s1h1 said:
OK, Thanks.

I'm needing a DAC with USB and S/PDIF inputs. I don't want to buy the streamer board if it's not going to be used in the FDAC. The DevDAC isn't suitable then?
Click to expand...

The DevDAC requires the MDAC2 streamer board not only for streaming functions bit also as the system controller (the brains of the DAC) - at the time the MDAC2 streamer board is fitted to the MDAC2 we will have two options ready so the DevDAC board is still usable as a DAC.

1. Dedicated DevDAC streamer PCB.

2. DevDAC USB processor board.

The FDAC will have its own version of streamer PCB, so the MDAC2 streamer would only be usable in your case for the DevDAC.
 
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