High Quality Signal Sources

[preston]

>You can also use Amazon HD, which is cheaper than Tidal. I recently switched and been happy.

But with Amazon HD your music is stuck in the app right ? You don't have access to raw music files. Using this software https://www.audfree.com/store.html it seems like you can convert MQA and other Tidal files directly to wav or what you want. I know its cheap enough I should just sign up for a Tidal trial period and see for myself.
I also realize downloading music from tidal and using software like this to strip the DRM encoding and put it into a WAV file is a form of piracy. That's why I keep wondering if that's really how it would work.

Love this discussion, guys. I"ve been doing car audio for a long time and am technically savvy but the options for source and conversion are absolutely bewildering now even to people like us.

In my case I am definitely not moving away from my GMC Head Unit that is using the NAV-TV MOst50 interface to provide a digital signal to my Helix. I've been told that is a raw digital signal but I sometimes wonder if that's true (ie is there a conversion happening somewhere before or inside the MOST-50). For SQ listening I play WAV files off a USB stick or use the CD player.
For my car I have a P99rs head unit and no plans to install an outboard DSP so again its either CD player or USB. I really don't want a digital player hanging off the dash or for God's sake to have to plug in a phone all the time.
so while I would love to have some of these fancy higher res options they won't work for me as neither setup will play higher resolution than 44/96.

For the guy who said he couldn't tell the difference between high rate MP3 and other formats I haven't found that to be the case. I have often compared playing the CD or a WAV file to a 320 MP3 and its subtle but the higher res definitely has more "air", more "space", more realistic sound. I certainly coulldn't tell while driving though. The nice thing about that kind of comparison is its very easy to A/B it on the deck vs switching equipment around. That's also why I wish I had a setup where I could try higher res files but again not willing to hang crap off the dash or plug in a phone everytime I"m in and out of the car.

[tacofox]

To comment on audio files and whether or not you can hear the difference, and for me I like to listen to my music loud and playing a heavy metal song or edm with lots of complex sounds the difference I hear is in the very high end of the spectrum and also in the mid bass area. Things like high hats, cymbal crashes, electric guitar, all can blend together on a lower quality file and it eventually sounds like noise. same with the lower end it's loose and muddy. With a high bit rate FLAC file or tidal stream the biggest thing I notice is seperation, it feels like everything has more room to breath and the sounds don't overlap and sound so muddy. Hope this makes sense as I know audio can be very subjective.

Also for audio players I would say this is a preference more than anything, obviously a higher end conversion chip will give better performance (thd, Snr, etc) but at a certain level it is about how you like it to sound whether it be warm, soft, etc. But I will say the biggest difference I noticed switching from my lgv35 with quad dac to the tone board was the amount of extra volume I was able to get out of the higher end dac while still sounding great and not clipping at all

[Bnlcmbcar]

the usb-hec is still doing the pcm bitstreaming conversion to spdif, connected to the dsp with traces instead of wires. usb-hec presents its own challenges though, like long usb runs without any jitter or loss of signal at 5v. (thick enough conductors, big enough power supply at the phone/dap end, etc)

Helix HEC USB interface might a little different than a USB to SPDIF conversion as the USB HEC allows signal transmission to the DSP up to 192kHz/32bit where as the SPDIF protocol is capped @ 192kHz/24 bit.

But as you mention there is always something in the chain that will be a challenge or “bottleneck”. At least the USB HEC uses an asynchronous data connection and generates its own clocks instead of using the source signal clock.

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...

[Hankhowdy1]

kind of, but no... my alpine doesn’t play flac, the phone deals with the bitstream which is effectively flac and makes it digital pcm at cd quality, then the digital is sent to the headunit which then uses its inbuilt dac to make it analogue for the preouts... the issue is if the dac in the headunit is any good or not... hence me using a topping to make the usb bitstream a slightly different digital bitstream to then send on to the dsp

The head unit is a Clarion CX-505 that can’t play FLAC or Hi Res. I assume that spec concerns the file format for USB drive player? And I have no idea if the DAC is any good.

So, if I an iPhone and use a HD streaming service or stored Flac files played through an app like Onko app, lighting port to USB port on the head unit, then rca pre outs to Dayton 408 to amps would be capable of CD quality? Of course if the DAC is any good.


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[Hankhowdy1]

What’s the best solution for someone who wants to add an aftermarket head unit to have CarPlay? What are some options to play Flac and hi res while using an iPhone? Currently have a Dayton DSP, but willing to upgrade if I need to in order to play Flac and hi res.


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[dumdum]

If the dac is ok yes... but as an example the Sony GS-9 dac is worse quality by a fair bit than the 9 dollar lightening to 3.5mm headphone lead dac you get with an iPhone for free... make of that what you will as that’s a $1000 plus stereo...

[Audiogal]

i use tidal with a fair few master quality albums at 96khz, and I use the topping as a usb to coaxial digital output so no d/a involved bar the output of the helix

to answer your question on the helix usb hec, I have one, but last time I tried the usb hec wouldn’t play with my iPhone so it’s a none option for me, but from others who have tried it they don’t have the detail and resolution of something like the topping

the Bluetooth hec does work, but can’t stream anything more than way reduced quality as it’s Bluetooth, and even though it’s Bluetooth 5.0 codecs can’t get near to cd quality (APTX hd can, but isn’t used by much currently), so wired is the way forward until they bring out the audiostage unit which streams over WiFi and therefore has the bandwidth to stream very hires files if you have a capable source

I know in my own system I have measured my alpine 178bt with usb and bluetooth vs bt hec vs wired via a topping d10

results on initial listen were interesting, it sounded like the topping had the most detail, followed by the bt hec followed by the alpine which sounds identical using bt or usb, now I was expecting to find frequency response differences in mid range perhaps or the top end to explain what sounded like more detail...

Now on measuring I was shocked! From 200 to 19.5khz the response was identical...

above that I had 7-8db difference at 20khz

then I scrolled to the other end of the scale, with the topping with its flat response I had 12db more at 10hz, and 6db more at 20hz, this tapers down to roughly 200hz, I was blown away and had always put my lane bottom end down to poor transfer function in my sq vehicle

the bt hec has about half that difference at 20hz with 4db at ten hz and again the alpine was low at the bottom end, far from the +/-3db alpine claim from 20-20khz as the topping is a known entity and is flat from 10-22khz+ Which is how I deduce the alpine either has a subsonic on it or it’s bass frequency response is poor and rolls off as does the treble

i fully intend to make a dock for my iPhone and hide the gubbins and wiring behind the dash so it’s a tidy installed solution and will be put where it is most to hand, I’d considered putting it in the centre of the steering wheel and using the clock spring to run digital cables through to the dash

This is just a curiosity question. What is your test and measurement setup dumdum? I would be curious as to how the apple HDMI -> Toslink setup measures. Are you able to measure dynamic range (S/N) between the interfaces and BER?

I have not seen a SINAD measurement in years, lol. I used to do SINAD measurements for military communication systems through encryption , various spread spectrum scenarios and interference scenarios. I do not have access to that measurement equipment anymore otherwise I would be experimenting myself.


It will be interesting to see if the Audiostage measures as well as a good cable (wired) connection straight to the DSP.

[Hankhowdy1]

If the dac is ok yes... but as an example the Sony GS-9 dac is worse quality by a fair bit than the 9 dollar lightening to 3.5mm headphone lead dac you get with an iPhone for free... make of that what you will as that’s a $1000 plus stereo...

Why is this Head unit praised so much for its DAC? Wow!


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[Hankhowdy1]

Delete; I was way off.

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[nadams5755]

i fully intend to make a dock for my iPhone and hide the gubbins and wiring behind the dash so it’s a tidy installed solution and will be put where it is most to hand, I’d considered putting it in the centre of the steering wheel and using the clock spring to run digital cables through to the dash

lightning extension cords seem to work okay enough to hide most of the ck3 bundle/mess

they tend to break after 6 months but cheap enough to buy spares in the glovebox, i've tried a few different ones with the same results. oddly enough, polarity matters. when you're replugging to find the polarity between the ck3 and extension cord, also unplug the phone-end as well.

https://www.amazon.com/gp/product/B07PW993GR