High Quality Signal Sources

[Audiogal]

mine is a very simple audio interface with rew... it’s not calibrated and I have no clue how accurate it is, all I know is the graphs in rew when measuring the input using the card and feeding the stereo and topping with a pre recorded sweep generated by rew it shows very clearly the ends of the free response falling off with the alpine

sinad measurements again I am relatively new to, it’s from audio science review which is a fantastic resource for physical measurements of devices using a 28k audio analyser with coax, usb, and all manner of stuff that’s way above my ability’s, I will be buying a new 192khz usb sound card with coax, optical, analogue ins and outs so I may just be able to measure a fair bit more in the future with more accuracy

When I get some time I am going to spend some time figuring out a PC based measurement system to play with myself.

[dumdum]

When I get some time I am going to spend some time figuring out a PC based measurement system to play with myself.

I am going to acquire some 12db attenuators so my 2v input usb soundcard can actually take in 8v also, then I can measure the helix outputs with usb hec, bt hec and from rca, coax, optical, all from the same source file on my pc to my phone or to cd

[Audiogal]

I am going to acquire some 12db attenuators so my 2v input usb soundcard can actually take in 8v also, then I can measure the helix outputs with usb hec, bt hec and from rca, coax, optical, all from the same source file on my pc to my phone or to cd

Nice, do you know the true S/N of the sound card? To be able to measure to a suitable bit depth greater than 16 bit some pretty decent spec's are required. Frequency response is not as much of an issue as most cards are good in that area. I am curious to see what you end up with and how it fairs. You should also be able to measure the DSP on its own looped back into the sound card as well and determine individual component and system measurements for analog and digital domain performance. Please keep me in the loop.

[Midway]

Looks like the USB HEC uses the USB Audio Class 2 standard (2009) which supports more data bandwidth than the S/PDIF protocol.

But on further thought your still right in the sense that even with the HEC USB input @ 32bit/192kHz the signal is still downsampled after the HEC unit to 24bit/96kHz to be processed by the DSP chips for DAC conversion.

Yet still an advantage to using a direct USB link like the HEC USB over Digital coax input, is the asynchronous synchronization. The audio data is sent over the USB in isochronous mode. Each frame of data contains a certain amount of data and the data arrives in packets at of information at distinct timing intervals.

With asynchronous synchronization the DAC sets up a feedback loop telling the USB HEC how much data to send. This allows for a fixed clock of high precision in the DAC. Hence, is why an asynchronous USB connection has very low jitter.

One of the the only differences between an asynchronous USB DAC and an asynchronous USB to SPDIF converter I can think of.. is that using the converter technically moves the clock out of the DAC.

Whether all this is audible...

I am getting a Helix DSP Ultra and wonder if it makes sense to run a USB cable while the URC.3 is being installed. The yet to be released HEC Audiostage HD-Audio WiFi-Interface comes with a USB port according to a Helix Facebook post..

I'm trying to find out if the USB port will support a direct connection to an iPhone similar, or better than the HEC HD-AUDIO USB-INTERFACE? I could use some of that "Further Information".

[nadams5755]

if you're running cables, run a coax/spdif, optical/toslink, and usb3 extension cord that's shielded with thick conductor cable. the expensive part is taking the interior apart and running cables, not the cables themselves.

(just keep the toslink ends covered until you need them)