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Author Topic: FLAC files sound flat compared to WAV  (Read 7206 times)

GuitRdone

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FLAC files sound flat compared to WAV
« on: September 30, 2015, 08:55:12 pm »

I'm about to use MC to re-sample all of my CDs to something other than lossy, and I'm trying to decide what format to use for the library.

My system includes MC20, set to transfer PCM 24 and to do no format conversion, a Sony STR-DA5800ES DLNA receiver, and Polk RTI A9 mains (bi-amped), the RTI center channel, and a 12" Polk subhefter. It sounds wonderful with pretty much anything I give it.

But I have noticed that the same file in FLAC format has a lower volume and just doesn't sound as present and precise to me even after adjusting the volume.

I did some testing to try to understand the difference I am hearing. I used MC 20 to convert the FLAC files downloaded from HDTracks for Don Henley's The End of the Innocence, which is wonderfully recorded, to WAV files. I then did A/B testing against the WAV files of the same title downloaded from HDTracks.

The converted WAV files are within one kb of the file sizes of the files from HDTracks, and they are sonically indistinguishable from the downloaded WAV files. So the "lossless" and "bit perfect" nature of FLAC seems to be confirmed by these tests.

Yet the FLAC files do not sound as good as the WAV files. What am I doing wrong?
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HT#1: Sony STR-DA5400ES, Polk RTi 7.1 speakers
HT#2: MC30, Frankenstein PC, Sony STR-DA5800ES, Polk RTi 3.1 speakers (bi-amped A9 mains)
Id: Original 120GB SSD NUC
Mobile: HIFI Walker H2 and H2 Touch

Spike1000

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Re: FLAC files sound flat compared to WAV
« Reply #1 on: October 01, 2015, 12:34:41 pm »

I'm no DNLA expert as I stopped my experiments in using DNLA them when I found my devices weren't doing what I wanted them to do (or indeed working as I expected them to).

There is no reason why a FLAC should sound any reason to a WAV on the same equipment; my thoughts are the DNLA 'link' between JR and the Sony *is* actually converting the FLAC (or at least streaming it) in some lesser format over the wire/ether (because that's what DNLA does).

It could be 24bit is not supported so it's being converted to a lesser format or it might not be configured correctly. (As I said I'm not an expert but have played with DNLA and hit limitations with the kit I had very quickly).

There's a tool mentioned in many DNLA postings here that can run against your DNLA devices and it will report on what formats are properly supported by your kit. It'd be worth running that to see what it says.

It's by AndrewFG
Whitebear Digital Media Renderer Analyser - http://www.whitebear.ch/dmra

Spike

GuitRdone

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Re: FLAC files sound flat compared to WAV
« Reply #2 on: October 01, 2015, 12:48:11 pm »

Thanks Spike.

The display from my Sony receiver says "PCM 4.6m" when I'm streaming a 96/24 file, and it says "PCM 9.2m" when I'm streaming a 192/24 file, whether it is FLAC or WAV. So from the receiver's perspective, it looks like there is no difference for the two file types.

I do notice that the bit rate shown by MC will decline for the FLAC version. A WAV file from a CD, for instance, will show 1440, while the same data in FLAC form will show something around 1000, say 962. Is that normal for FLAC?

What should I check to see if MC is somehow treating FLAC files differently?
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HT#1: Sony STR-DA5400ES, Polk RTi 7.1 speakers
HT#2: MC30, Frankenstein PC, Sony STR-DA5800ES, Polk RTi 3.1 speakers (bi-amped A9 mains)
Id: Original 120GB SSD NUC
Mobile: HIFI Walker H2 and H2 Touch

ferday

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Re: FLAC files sound flat compared to WAV
« Reply #3 on: October 01, 2015, 01:48:49 pm »

of course FLAC is lower bitrate, it's a compressed file!  quieter / simpler pieces will be rendered with lower bitrates.  encoding silence will be near 0 and of course the maximum is uncompressed (1411 for CD)

if you go to tools>options>media network>add or configure DLNA you can check any transcode settings there

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blgentry

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Re: FLAC files sound flat compared to WAV
« Reply #4 on: October 01, 2015, 04:12:41 pm »

I'm suspicious of using DLNA for "high fidelity" usage.  Look how much effort people go to, to purchase products that use specific types of digital connections.  Most seem to agree that AES/EBU is the most pure digital connection with the best clocking and the lowest jitter. They pick this over optical digital and over coaxial digital.  All three of these are dedicated wired connections that send nothing but digital audio.  Yet the hardcore audiophiles pick one over the other.  If there's a difference (and many people say there is), this implies that the timing and the connection method make a difference.

Given that, a network is almost the worst possible transport method.  Especially given that ethernet and wifi are CSMA/CD and do retransmission when required.  Digital audio needs a constant flow of continuous data.  It's not like receiving a file.  This is a real time process.  Anything delivered via the network is suspect.  I would not use a DLNA networked connection for high fidelity audio.

So, if you believe me and my reasoning, you should be using a different method to connect to your receiver, IF high fidelity audio is your goal.  What's the best way?  A direct digital connection *if* you trust the DACs in your receiver.  If you don't, then an external DAC, connected between your PC and your receiver is the way to go.  PC to DAC with USB, coaxial digital, or AES/EBU (unlikely), and then DAC to receiver with RCAs.

I've heard strange things about HDMI connections and high fidelity audio.  Again, I think it's related to timing issues and/or jitter.  I haven't personally researched this; it's just what I've heard from people at high end audio shops.

Perhaps you can borrow an external DAC from a friend and repeat your experiment?  Or perhaps you have a digital out on your PC you can use to repeat the experiment?

Just some things for you to think about.

Brian.
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BryanC

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Re: FLAC files sound flat compared to WAV
« Reply #5 on: October 01, 2015, 04:36:44 pm »

I'm suspicious of using DLNA for "high fidelity" usage.  Look how much effort people go to, to purchase products that use specific types of digital connections.  Most seem to agree that AES/EBU is the most pure digital connection with the best clocking and the lowest jitter. They pick this over optical digital and over coaxial digital.  All three of these are dedicated wired connections that send nothing but digital audio.  Yet the hardcore audiophiles pick one over the other.  If there's a difference (and many people say there is), this implies that the timing and the connection method make a difference.

Given that, a network is almost the worst possible transport method.  Especially given that ethernet and wifi are CSMA/CD and do retransmission when required.  Digital audio needs a constant flow of continuous data.  It's not like receiving a file.  This is a real time process.  Anything delivered via the network is suspect.  I would not use a DLNA networked connection for high fidelity audio.

So, if you believe me and my reasoning, you should be using a different method to connect to your receiver, IF high fidelity audio is your goal.  What's the best way?  A direct digital connection *if* you trust the DACs in your receiver.  If you don't, then an external DAC, connected between your PC and your receiver is the way to go.  PC to DAC with USB, coaxial digital, or AES/EBU (unlikely), and then DAC to receiver with RCAs.

I've heard strange things about HDMI connections and high fidelity audio.  Again, I think it's related to timing issues and/or jitter.  I haven't personally researched this; it's just what I've heard from people at high end audio shops.

Perhaps you can borrow an external DAC from a friend and repeat your experiment?  Or perhaps you have a digital out on your PC you can use to repeat the experiment?

Just some things for you to think about.

Brian.

Isn't this the purpose of a buffer?
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blgentry

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Re: FLAC files sound flat compared to WAV
« Reply #6 on: October 01, 2015, 05:12:36 pm »

Isn't this the purpose of a buffer?

If that were true, then the digital connection method would make no difference.  It's a widely held belief that it *does* make a difference.  I'm inclined to believe that there is a difference based on anecdotal (not scientifically verified and tested) evidence.

But even if a buffer could fix timing issues, it would have be very carefully implemented to make sure the timing was correct.  I'm not a digital audio engineer, so I don't intimately understand every step of digital audio reproduction.  I *do* have a BSEE and I have designed and built audio equipment.  I'm an enthusiast!  :)  I've studied enough about jitter to believe that the effect is real and that trying to make low jitter playback is a challenge.

Brian.
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dtc

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Re: FLAC files sound flat compared to WAV
« Reply #7 on: October 01, 2015, 09:40:37 pm »

Have you tried the flac and wav files on a usb drive plugged directly into the Sony?
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DarkSpace

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Re: FLAC files sound flat compared to WAV
« Reply #8 on: October 02, 2015, 04:23:57 am »

Have you perhaps enabled Volume Leveling during playback?

In that case, it's possible that you didn't analyze the audio of the source .wav files, which means that MC's Volume Leveling will lower the volume by 10dbB as a default value.
If your flac files' audio has been analyzed, MC will apply appropriate Volume Leveling based on the files' individual volume levels, and it's entirely possible that this results in a volume decrease of more than 10dB, which would mean that the flac files are indeed played back quieter than the wav files. Now, I don't know this for certain, but I believe that it is entirely possible that, if you used MC to convert the files to flac, MC also analyzed the audio during this process, and wrote the results to the resulting flac files' tags.

If you actually want Volume Leveling, then (if this is actually true) the flac files' playback volume is actually 'correct'. That's because the wav files' volume is too loud compared to the volume that Volume Leveling attempts to achieve, which is because Volume Leveling doesn't know the wav files' characteristics.
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GuitRdone

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Re: FLAC files sound flat compared to WAV
« Reply #9 on: October 02, 2015, 02:11:31 pm »

Thanks everyone for your ideas.

I definitely know that I have auto leveling turned off. I will check on the transcoding settings.

I will try to put the media directly on the receiver and see what happens.

However I can say that I don't think the problem has to do with the local network, because the same differences between FLAC and WAV playback exist when I'm listening to the computer speakers on my MC machine.
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HT#1: Sony STR-DA5400ES, Polk RTi 7.1 speakers
HT#2: MC30, Frankenstein PC, Sony STR-DA5800ES, Polk RTi 3.1 speakers (bi-amped A9 mains)
Id: Original 120GB SSD NUC
Mobile: HIFI Walker H2 and H2 Touch

blgentry

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Re: FLAC files sound flat compared to WAV
« Reply #10 on: October 02, 2015, 04:22:33 pm »

However I can say that I don't think the problem has to do with the local network, because the same differences between FLAC and WAV playback exist when I'm listening to the computer speakers on my MC machine.

"Computer speakers" meaning something with a 3" driver or less?  Or "computer speakers" meaning something substantial and closer to hi-fi?  If this is something you can hear on little dinky computer speakers, I think something is wrong.

Brian.
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GuitRdone

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Re: FLAC files sound flat compared to WAV
« Reply #11 on: October 03, 2015, 10:20:57 am »

Yeah, they are dinky, but they are also Polks, so not too bad.

I found a USB port and plugged up a media drive last night. There is no difference in volume, and only a slight difference in detail between FLAC and WAV (maybe I just need a psychiatrist).

So what could be causing the FLAC files streamed from my MC20 computer to be played differently than the receiver plays them from a local drive?

BTW, THANKS for the wonderful idea to test that way.
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HT#1: Sony STR-DA5400ES, Polk RTi 7.1 speakers
HT#2: MC30, Frankenstein PC, Sony STR-DA5800ES, Polk RTi 3.1 speakers (bi-amped A9 mains)
Id: Original 120GB SSD NUC
Mobile: HIFI Walker H2 and H2 Touch

GuitRdone

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Re: FLAC files sound flat compared to WAV
« Reply #12 on: October 03, 2015, 03:08:12 pm »

OK! I found it. There is more than one place to check for volume leveling!

I found it enabled in:

Tools>Options>Media Network>Add or configure DLNA Servers>Generic DLNA>Advanced>DSP Studio>Volume Leveling

Problem fixed. I still think WAV files sound better than FLAC files. Time to start a thread on the next issue- DSD streaming.

Thanks to everyone who helped me with this!  ;D

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HT#1: Sony STR-DA5400ES, Polk RTi 7.1 speakers
HT#2: MC30, Frankenstein PC, Sony STR-DA5800ES, Polk RTi 3.1 speakers (bi-amped A9 mains)
Id: Original 120GB SSD NUC
Mobile: HIFI Walker H2 and H2 Touch
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