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PecanPi® DAC, Streamer and USB - Rev 2.0

orchardaudio

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#1
The PecanPi® DAC just underwent an upgrade and is now able to drive balanced headphones.
https://orchardaudio.com/pecanpi

All measurements below are for XLR outputs driving 300ohm loads, performance does not change with load and the outputs are able to drive all the way down to 32 ohms.

I will start off with bench mode as Amir likes to do.
Capture.JPG


Dynamic Range (No Weighting)
Dynamic Range - AES17_NO_Weighting.jpg


Frequency Response
Frequency_Response.jpg


Linearity
Linearity.jpg


Signal to Noise Ratio (No Weighing)
SNR_No_Weighting.jpg


THD+N Ratio Vs Level
THD+N Ratio vs Level.jpg


Jitter Spectrum and Noise (256k FFT, 16 Averages)
Jitter_Spectrum_and_Noise .jpg


THD+N Ratio vs Frequency
THD+N Ratio vs Frequency.jpg


Intermodulation Distortion (IMD)
SMPTE Ratio.JPG


128k FFT of -20dB 1kHz Output
FFT_-20dBFS.jpg
 

Veri

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#2
That 1kHz FFT looks very clean indeed. Up to par with Topping D90. Jitter is very very low, too! I wonder why SINAD isn't higher though. Some inherent noise? In any way, you seem to have squeezed the maximum out PCM1794A

Some questions though
-Any way to see what is PecanPi rev 2.0? Currently I see no indication on the site
-Could you tell us briefly about the changes from 1.0 to 2.0? :)
 
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orchardaudio

orchardaudio

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Thread Starter #3
I wonder why SINAD isn't higher though. Some inherent noise? In any way, you seem to have squeezed the maximum out PCM1794A
Exactly, the PCM1794A is the SINAD limiting factor.

I will answer your other questions shortly.
 
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orchardaudio

orchardaudio

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Thread Starter #4
Any way to see what is PecanPi rev 2.0? Currently I see no indication on the site
All pictures on the website are of Rev 2.0 board, except for the PecanPi USB, I have not yet updated those.
https://orchardaudio.com/pecanpi-dac -- scroll down to the photo gallery
https://orchardaudio.com/pecanpi-streamer -- scroll down to the photo gallery

Could you tell us briefly about the changes from 1.0 to 2.0?
Changes are as follows:
  • DAC is now able to drive balanced headphones directly, supporting impedances down to 32-ohm.
  • DAC no longer has built-in RCA connectors but comes with included custom XLR to RCA adapters.
 
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Veri

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#5
  • DAC is now able to drive balanced headphones directly, supporting impedances down to 32-ohm.
  • DAC no longer has built-in RCA connectors but comes with included custom XLR to RCA adapters.
  • Does this require some kind of adapter? 2x XLR 3-pin to XLR 4-pin?
  • custom XLR to RCA, I suppose pin 3 is floating?
Cheers
 
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orchardaudio

orchardaudio

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Thread Starter #6

Veri

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#7
Yes adapter needed if your headphones do not plug into 2x 3-pin XLR
Note that this is most of all headphones :) 2x 3-pin XLR is a pretty niche headphone cable/termination. Really.
I think pairing the XLR>RCA breakout with a RCA-headphone adapter would be a more common use case :)
 

Pillars

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#8
Well, it's kind of a DAC streamer that happens to be able to drive headphones... I don't know, for the money it's a pretty hard place to be in.

For the price I think the unit should be

Streamer, DAC w/XLR+RCA, Digital volume control (remote if possible) - just scrap the headphone ability if you don't have space. If able, just do 1/4 plug.

I really like the chip choice though.
 
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orchardaudio

orchardaudio

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Thread Starter #10
Streamer, DAC w/XLR+RCA, Digital volume control (remote if possible) - just scrap the headphone ability if you don't have space. If able, just do 1/4 plug.
It already has all this minus the 1/4'' plug and remote...

You control the unit remotely with your smart phone...
 

Veri

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#11
Hey Orchard this terminates to 4-pin male. Balanced headphones tend to also be terminated on 4-pin male, so that won't work.
You'd need such an adapter that goes to 4-pin female, so you can plug your headphones into that.

That's why I mentioned it, this is a pretty niche/uncommon set-up. Very few headphones terminate on 3-pin xlr connectors.
XLR>RCA adapter, and RCA>headphone adapter would still be far easier to connect a headphone to.. :)
 
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orchardaudio

orchardaudio

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Thread Starter #12
Hey Orchard this terminates to 4-pin male. Balanced headphones tend to also be terminated on 4-pin male, so that won't work.
You'd need such an adapter that goes to 4-pin female, so you can plug your headphones into that.

That's why I mentioned it, this is a pretty niche/uncommon set-up. Very few headphones terminate on 3-pin xlr connectors.
XLR>RCA adapter and RCA>headphone adapter would still be far easier to connect a headphone to.. :)
I posted the link to wrong one sorry:
https://www.amazon.com/Female-Balanced-Adapter-Hi-end-Silver/dp/B018ZN9IXI

Also, a headphone adapter for the RCA is already sold as an option with the unit.
 

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