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Squeezebox Alternative or Chasing the Pegacorn


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Bit of a late reply, but you're right.  The BNC SPDIF waveform was not good (slow notchy rise) and TDR looked nothing like 75 ohms on a 50ns timescale.  Also there is no DC blocking on the pulse transformer, so is operates with a DC bias.  Ugh.

So I removed the existing transformer, and replaced with Newava S22083.  Fed via 169 ohm resistor and 0.1uF DC block on the input end (from the 74HC74 driver already in there), 43.2 ohms in parallel with the secondary and 39 ohms in series.  This gives the correct 0.5V p-p output, optimally loads the transformer, has a TDR that has a couple of 50 millirho 500ps long features from the connector itself, and the waveform has a clean 1.5ns rise and fall time.

Thanks for the answer, reminded me to do some homework and dig up this thread:

http://www.audiocircle.com/index.php?topic=45330.0

I was thinking about doing a similar exercise for the schiit yggdrasil's BNC input but the space and cost for a TDR is holding me back atm. Pat spooked me enough about RF measurements that I don't want to just blindly follow the values and pray it works properly...

Have you tried/measured/listened to the effects of an RF attenuator at the BNC input on the Transporter? I figured since you have the setup you'd easily be able to evaluate this

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Olive one?

This strikes me as the right answer. Put it in a big box with a touch screen and use it directly, or use it as a server with a rpi or tablet as the player.

It's not really a laptop though.....it's a micro-size desktop that easily fits in my shelf.  My situation is such that - with the KVM - it's easy to control and work.  

Yes - that was exactly the thread that got me thinking, along with the choice of transformer.  Fortunately I have a pretty extensive lab, so I have three generations of Tektronix TDR, right from the late 1950's 1S2, to the mid 1970's 7S12/S52/S6 to the self contained 1502.  The last two operate to 25ps response time - less than 10mm at the speed of light to put it into context,

So I'm kind of spoiled for choice.

I even have a 75 ohm power splitter, so I can tap into an SPDIF data stream and look at what the overall waveform looks like on a link.

The thread you link to shows TDR pics from an 1S2 (or possibly an HP sampler), which is fine for the job since it has an 80ps response time, but has no readout on the screen.

I haven't tried attenuators - all mine are 50 ohm ones and you need 75 ohm ones.  In any event, you run the risk of the SPDIF receiver failing to lock securely.  And yes - you have to fix the receive end too!

Edited by Craig Sawyers
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I ordered some mini circuits 75r attenuators- 3,6,10db that are good up to 500M. I can't measure anything but I can at least determine how much attenuation the Yggdrasil can handle before it refuses to lock. 

Everyone seems to recommend sticking this on the rx side but wouldn't it also make sense to place something on the tx side as well? 

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Hmmm. Built in streaming and a probably decent DAC at a reasonable price. Maybe I won't have to resort to Squeezeplay in a raspberry pi after all.

(The Touches survived the lightning strike, BTW, so not an immediate concern. The music server wasn't so lucky. But the hard drive is ok. So, with any luck, I'll be able to slap the drive in a new junky old box and music will flow again. )

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I ordered some mini circuits 75r attenuators- 3,6,10db that are good up to 500M. I can't measure anything but I can at least determine how much attenuation the Yggdrasil can handle before it refuses to lock. 

Everyone seems to recommend sticking this on the rx side but wouldn't it also make sense to place something on the tx side as well? 

I guess this is worth a try.  But I'm left with the suspicion that adding attenuation until the DAC is close to losing lock actually makes jitter worse - because it would be triggering towards the top of the rise time of the SPDIF wave, where it is flatter.  Helps with reflections though due to bad design of SPDIF interfaces though, so there may be an optimum.

Not being able to measure leaves you in a suck it and see situation.

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  • 2 months later...
On 15/9/2015 3:24:25, cetoole said:

Auralec Aries mini looks rather interesting for a squeezebox replacement. Anyone try yet?

Yes I do :)

I got my hands on the "DEMO ONLY NOT FOR SALE" unit the Distributor had for a recent Show here in Madrid. I got my hands on it and for some reason it went into my backpack and home... two weeks testing before the inevitable call arrived asking WOH was the Mini...

Short version: very nice unit, I want at least one to replace one of my Touch'es, maybe more.

Long version, I have to say good things and some not so good (but nothing wrong), let's see in reverse order those:

-you  NEED an iThing to activate/setup it (reset=hotspot connection to its WiFi ONLY with iPhone/iPad and Auralic own App)

-no remote, no display, just some buttons to reset it, so the above comment is significant (!!). Once setup, you can use an Android to play (even any DLNA controller) but you will not have access to setup nor some streaming possibilities (Tidal, Spotify, AirPlay to name some).

-the Auralic App (and some iOs hardware) lets you navigate your networked or attached (Mini has an internal bay and external USB) hard disks, but only streaming service available (to me) was Tidal (working great btw). If you want to use Spotify, you need to first activate Airplay (Auralic App) then go to your Spotify App (on iOs) and stream to 'other unit' (Auralic Mini). Works fine, but every time I wanted to go back from Airplay to Tidal or my files, the Mini crashed :(

-it can stream DSD files but they play only to the digital output (if previously configured that way). Strange, and I assume this (and above crashes) will change in next Firmware versions.

+streaming is solid even over WiFi (up to 352kHz/32 bit with no drops).

+SQ is excellent: from digital output I would say betters the Sqzbx Touch in image stability (deeper, wider, better focused stage) (speaker setup).

+SQ is excellent too (to my surprise?) from the analog outputs (only RCA available). I opened to see what was going on inside: after the external SPS (15V DC) there is some good filtering and regulation inside, a nice-modern board, and Sabre ESS9018K2M DAC with couple of LME49740 (quad) opamps for analog out duties. I liked it so much I was not able to decide in Mini/vs/Touch+Buffalo head to head (yep!).

+Using the Auralic App and iOs, the user/listening experience was very good using my own libraries or Tidal. 

I miss it and would recommend it to those looking for an easy way to stream (specially those who already use iPad/iPhones, I am an Androidman and had to battle with the wife to have access to its iPad... easier said than done).

Long ago since my last post around here, happy to be helpful... Regards!

 

 

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