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 Post subject: Pi2AES renderer/streamer
PostPosted: September 7th, 2021, 8:48 pm 
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Received the Pi2AES last week after the projected 3-week wait. Very, very nice. Comparable to the Allo USBridge Signature with Digione Sig hate, but maybe just a tad better. The AES connection has a bit more depth and naturalness than the coax output, but the coax seems a little crisper if that's what you prefer. Running it on an Rpi4 with gentooplayer. The Pi and hat are powered through a very well-made regulation circuit on the Pi2AES board that calls for a 24vdc power supply. I got the recommended Meanwell. You can power the Pi separately by removing a small jumper on the Pi2AES. You can also bypass the power regulation on the board and use a 5v LPS. Instructions are here, along with measurements:

https://goldensound.audio/2021/07/22/pi ... tructions/

I tried all three ways with my Shanti LPS from Allo and frankly there's not much difference in my system, though Golden Sound shows a lower noise floor with a 5V input. I don't have a 24v LPS so can't comment on that. The 24v input does offer surge protection, which is nice. For that reason the manufacturer recommends not bypassing it. I also have not compared the Allo DigiOne Sig hat directly on the Rpi4 board. I don't imagine there's a huge difference. The price difference also isn't huge. The Pi2AES comes out at about $285 with Pi, case and PS. The Allo setup is about the same, but the recommended Shanti LPS is an extra $150.

I'm using a Mogami Gold AES/EBU cable. You can spend thousands on an MIT rig. Maybe someday. ;-)

I'll say this. I'm done with USB. For the price of a halfway-decent USB cable alone, this is better than any budget USB renderer I've tried. It's clean, zippy and accurate.

The setup also works with Moode Audio, which is free (unlike gentooplayer). You set for a Hifiberry Digi+ Pro. Be sure you set the time zone to your location, and choose the 64-bit option for the Rpi4, otherwsie it can be glitchy.

Michael is currently out of stock but check the web site for production uipdates. He's also working on a full-bore streamer with storage.

https://www.pi2design.com/


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PostPosted: September 8th, 2021, 1:29 pm 
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Joined: July 17th, 2016, 6:24 am
Posts: 1087
Grover,

Those Jitter measurements don't make sense.

He is measuring Jitter in digital domain below 2 pico seconds which comes to 20GHz clock speed. There is no CPU/Processor which runs at fast. Fastest CPUs are under 5GHz.

USB Clock speed is only 48 MHz. I havent check the clock speeds of SPDIF and AES Audio but dont thing they run any faster than USB clock speeds.

GoldenSound is a very talented reviewer. He is primarily a headphone user. I would appreciate his audio impressions but on the subject of audio engineering and standards, he is a beginner. He just received a Audio Precision APx555 analyzer. I get the feeling he is just playing around with APx555 at this time.

He recently stated in one of his reviews:
"we can all agree you do miss out when using headphones is that in your chest full body experience you get with a powerful 2 channel setup especially with a subwoofer."

With his talent and dedication, I see in a couple of years, I see him becoming one of the popular reviewers.


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PostPosted: September 8th, 2021, 4:49 pm 
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I know nothing about measurements so I can't speak to that. I included the link mainly for the 5 volt mod to the board. I've landed in between--24VDC supply for the hat and 5 volt LPS for the Pi. Sems to offer the best sound.


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PostPosted: September 8th, 2021, 6:56 pm 
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Location: Parkville, Maryland
Grover Gardner wrote:
I'm using a Mogami Gold AES/EBU cable. You can spend thousands on an MIT rig. Maybe someday. ;-)

Since the AES/EBU standard was created to enable studios to use balanced-line microphone cable, just about any XLR interconnect can get the job done -- some better than others.
I found that ribbon cable terminated with XLR connectors really stays out of the way and enables the DAC to strut its stuff. I attached the only photo I have for an example.


Attachments:
Example_AES_EBU_Ribbon_Cable-04_27_21.jpg
Example_AES_EBU_Ribbon_Cable-04_27_21.jpg [ 214.81 KiB | Viewed 7688 times ]

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PostPosted: September 8th, 2021, 8:19 pm 
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SoundMods wrote:
Grover Gardner wrote:
I'm using a Mogami Gold AES/EBU cable. You can spend thousands on an MIT rig. Maybe someday. ;-)

Since the AES/EBU standard was created to enable studios to use balanced-line microphone cable, just about any XLR interconnect can get the job done -- some better than others.
I found that ribbon cable terminated with XLR connectors really stays out of the way and enables the DAC to strut its stuff. I attached the only photo I have for an example.


I understood that you want to use a 110 ohm cable so I specifically went for an AES/EBU. At such short lengths perhaps it doesn't matter. But the Mogami Gold is often mentioned as a good cable for digital. I have no plans to buy an MIT. ;-) The always-reliable Blue Jeans sells two types for a very affordable price. I like their coax cable a lot.


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PostPosted: September 8th, 2021, 9:25 pm 
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Joined: April 22nd, 2013, 12:58 pm
Posts: 285
I always liked the Belden Twinax cable for AES/EBU
This one's 100 ohm, plenum rated......
https://www.altex.com/belden-plenum-twinax-electronic-instrumentation-cable-100-ohm
https://www.wireandcableyourway.com/uploads/file/89207%20Technical%20Data%20Sheet%20(English).pdf


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PostPosted: September 8th, 2021, 10:18 pm 
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FerdinandII wrote:


Thanks. Guess I could terminate it myself. ;-) Blue Jeans offers the Belden 1800 and Canare L-4E6S.


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PostPosted: September 8th, 2021, 10:34 pm 
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FerdinandII wrote:

I find that stranded conductors seem to be counter to the needs of low jitter transmission. I have been getting the best result with a Stealth Indra balanced line that uses 50-ga. Electum (gold/silver alloy) solid conductors laid out in a Helix pattern suspended in an open-cell Teflon structure with a shield. This after trial runs with every XLR cable I own including the ribbon cable (which performed unexpectedly well) plus some shot-gunned Illinois Wire and W.L. Gore Phase Flex micro-wave cable. BTW -- the Phase Flex is a close second to the Stealth. Of course a lot depends how the digital signal is sourced (direct drive or through a pulse transformer) and how it is loaded on the receiving end either with a characteristic resistive-load or another damn pulse transformer.

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PostPosted: September 8th, 2021, 11:06 pm 
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Joined: April 22nd, 2013, 12:58 pm
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SoundMods wrote:
I find that stranded conductors seem to be counter to the needs of low jitter transmission. I have been getting the best result with a Stealth Indra balanced line that uses 50-ga. Electum (gold/silver alloy) solid conductors laid out in a Helix pattern suspended in an open-cell Teflon structure with a shield. This after trial runs with every XLR cable I own including the ribbon cable (which performed unexpectedly well) plus some shot-gunned Illinois Wire and W.L. Gore Phase Flex micro-wave cable. BTW -- the Phase Flex is a close second to the Stealth. Of course a lot depends how the digital signal is sourced (direct drive or through a pulse transformer) and how it is loaded on the receiving end either with a characteristic resistive-load or another damn pulse transformer.


What's wrong with pulse transformers, besides the fact that the industry doesn't want to pay any more than they would for a resistor in the same spot, thus leading to crap performance?


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PostPosted: September 9th, 2021, 10:42 am 
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FerdinandII wrote:
SoundMods wrote:
I find that stranded conductors seem to be counter to the needs of low jitter transmission. I have been getting the best result with a Stealth Indra balanced line that uses 50-ga. Electum (gold/silver alloy) solid conductors laid out in a Helix pattern suspended in an open-cell Teflon structure with a shield. This after trial runs with every XLR cable I own including the ribbon cable (which performed unexpectedly well) plus some shot-gunned Illinois Wire and W.L. Gore Phase Flex micro-wave cable. BTW -- the Phase Flex is a close second to the Stealth. Of course a lot depends how the digital signal is sourced (direct drive or through a pulse transformer) and how it is loaded on the receiving end either with a characteristic resistive-load or another damn pulse transformer.


What's wrong with pulse transformers, besides the fact that the industry doesn't want to pay any more than they would for a resistor in the same spot, thus leading to crap performance?

Pulse transformers ring like any other transformer. Designers wiling to spend the extra money and time will make the source active with a differential emitter follower circuit or high performance op-amps. The receive end has only to have the proper termination. I've been having unexpected success with damping pulse transformers. The improvement in sound quality has not been subtle -- just cleaner and more open. Attached is a photo showing "dampers" added to the primaries. The secondaries were taken care of on the foil side of the board. The value is not really critical -- say 2K to around 4K -- but the resistors should have very low self inductance. Vishay bulk-film resistors have a self-inductance in the uH range at 100-kHz. I have also used Anstrom glass hermetic resistors to good effect.


Attachments:
Pulse Xtransformer Damping.JPG
Pulse Xtransformer Damping.JPG [ 438.19 KiB | Viewed 7658 times ]

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