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Old 30th October 2016, 06:27 AM   #1
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Default Output for Pro Audio | Isn't 2V good enough?

I've had several discussions with people who state that miniDSP products have consumer grade I/O and would probably not suit pro audio use.

I want to create a digital crossover and use FIR filtering to tune my sound system. The miniSharc and the miniDAC seem like the perfect combo.
This setup has a few limitations when considering pro audio:
  • unbalanced output
  • no compressor (most pro audio systems have this)
  • 2Vrms output signal

Lets touch on the output signal first. I always thought that line level output meant 1V. Pro Audio balanced output is 1.23V. Why wouldn't the 2V output of the miniDAC be good enough?

Do I have this wrong?
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Old 30th October 2016, 06:50 AM   #2
sangram is offline sangram  India
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'Line level' is -10dBV, which is about 316mV RMS.

'Pro' level is +4dBU, which works out to 1.3V RMS.

Note the 'RMS' is extremely important. Most DACs run off 5V supplies or close enough, and thus cannot deliver 2V RMS. That is probably the P-P rating, which is 0dBV (0.775 mV RMS).
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Old 30th October 2016, 07:00 AM   #3
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Here is the technical specs for the miniDAC8.

It states max output level: 2Vrms unbalanced output
And this unit does run off a 5V supply.

What do you think?
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Old 30th October 2016, 11:14 AM   #4
sangram is offline sangram  India
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My bad, 0.775Vrms is 3.1V P-P.

2Vrms = 2.8Vp = 5.6Vpp

Not sure how that is possible from a single 5V supply and a voltage out DAC. Maybe you should ask the manufacturer.

Last edited by sangram; 30th October 2016 at 11:16 AM.
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Old 30th October 2016, 05:09 PM   #5
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Can you explain the conversion or math you did?
Not sure what is pp?
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Old 30th October 2016, 05:22 PM   #6
sangram is offline sangram  India
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Hi

Look at this link for a detailed explanation and a way to work out voltages and powers:

LINK
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Old 30th October 2016, 05:36 PM   #7
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@sangram
Very nice link. Thank you!
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Old 30th October 2016, 05:38 PM   #8
flo is offline flo  Switzerland
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Quote:
Originally Posted by sangram View Post
My bad, 0.775Vrms is 3.1V P-P.

2Vrms = 2.8Vp = 5.6Vpp

Not sure how that is possible from a single 5V supply and a voltage out DAC. Maybe you should ask the manufacturer.
The DAC (AK4440) uses a charge pump to generate a -5V rail for the output opamp.
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Old 30th October 2016, 05:44 PM   #9
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What would be the best way to convert the unbalanced output to balanced?
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Old 30th October 2016, 05:48 PM   #10
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You should look at your gain structure and the amplification in your amps.
Remember that you loose 6 dB when your signal is single ended and you connect it to a balanced input of an amp.
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