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Discussion Starter #521 (Edited)
I'm very much in the "bits are bits" camp where one competently designed DAC will sound like the other (at least those designed to be neutral).


However I have had the occasional puzzling experience. We bought a volvo something like 8 years ago. It came with two different inputs for external audio devices, e.g. ipods at the time: a digital connection and an analog (where you could just plug the ipod in via the headphone jack). I was excited about the digital connection - cleanest most direct connection I figured.


But I found it unlistenable! Everything sounded unnaturally "hard," steely, aggressive. Back in the CD vs vinyl wars, anti-digital audiophiles would talk about "digititus" - the claim that digital sound was anti-musical, artificially hardened, bright, mechanical sounding. Most of those claims were bogus and based on technical ignorance (I adopted CDs very early). But if anything actually fit that description, the sound through the digital connection to my car did. I kept having to turn the volume down because it bothered my ears that much.


Whereas if I used the analog connection, mini-jack out from the earphone connection, it was like "aaaahhh" normal, smooth, enjoyable sound.


I tried the digital connection occasionally over the years, only to suffer the same thing. It reminds me of badly compressed audio.


I'm wondering what the explanation could be. Maybe a crappy converter used by the car's digital system?
iPhones have a digital out, other than lightning port, which consumers can use?:confused: You sure?

"It reminds me of badly compressed audio."

Well typically the audio in iTunes is compressed: AAC.
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On my Yamaha AVRs the default mode on some digital inputs is "(Cockamamie) ENHANCER ON" and only if you have an advanced understanding of their stupidity would a consumer know there's a need to turn that off for digital inputs. Similarly in some Blows Bose gear there is a secret, non-defeatable "enhancer" circuit. I wouldn't be surprised if some Volvo engineer who thought they knew better had some similar such circuit.
 

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iPhones have a digital out, other than lightning port, which consumers can use?:confused: You sure?

I referenced ipods not the iphone (I was using the classic ipod).




"It reminds me of badly compressed audio."

Well typically the audio in iTunes is compressed: AAC.


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I don't have any problem with AAC or most other decent digital compression schemes, even in my hi-fi rig some lossy streams sound great. I'm referencing really bad compression. There was a sort of hissy, steely glare that is off-putting.








I wouldn't be surprised if some Volvo engineer who thought they knew better had some similar such circuit.

Could be something like that. It does seem like something in the volvo's implementation.

In our newer Volkswagon I used bluetooth with my iphone and it sounds great, even on lower res internet streams.
In the Volvo I use my iphone with the Apple dongle converting the digital lightning port signal to analog, then to the analog mini-jack in to the volvo sound system, and it sounds excellent. It's only the volvo's direct, digital input that sounds bad.
 

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Doesn't a DAC have an analog amplifier section that affects the sound quality just like any other analog amplifier?
 

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Discussion Starter #524
Doesn't a DAC have an analog amplifier section that affects the sound quality just like any other analog amplifier?
Depends on if by "DAC" you mean a DAC chip or a stand alone box you buy called a DAC. In the case of this $7.99 DAC in my opening post's test (you ought to take) it indeed has analog electronics too, yes.

The electronics can be used as just a variable line level out to RCAs (how I used it) or even as a headphone out. It is not super powerful but it comfortably drives everything I typically use to the levels I need. People with inefficient headphones or who apply heavy bass boost (which greatly saps available amplifier power) might feel differently about it though.
 

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Discussion Starter #525 (Edited)
I get your point. It would probably be unimportant to many people, however from my way of thinking "they win" if they can demonstrate

- any individual
- using any music they want
- through any playback system they want, including state-of-the-art, price no object setups

. . . can hear a difference with the agreed upon statistical significance.

If they have to keep listening for 6 weeks straight to the same cut to "get it"*, OK, they are allowed to and they win.

*Meaning finally audibly hear the subtle distinction.
I call this "The Roger Bannister Principle". He was the first person to successfully run a sub 4-minute mile under carefully controlled conditions in 1954. Prior to this there was a debate in the world if it would ever happen. Once he did the debate disappeared. We didn't need a bunch of people to run a sub 4-minute mile, we just needed one to prove it could be done.

Similarly in audio many people claim they can hear differences in music between different modern day, competently designed DACs (like this $7.99 one) but so far there is no documented person who can demonstrate this under double blind, level matched, song synchronized conditions. Should we someday find such a person they become the "Roger Bannister" of DACs!

My uploaded test tracks for this Foobar ABX test provides the means for anyone in the world (with internet access to download the material) to demonstrate to us they indeed have this ability, but so far not a single posted score sheet shows anyone can.
 
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I finally remembered and took some time to sit down and do a proper ABX test today. I had listened back and forth between your two samples previously with my headphones and could clearly identify small differences between the two so I knew it would be easy to pass the test. I ran through the ABX with my tower speakers first:

7/16

Well, that's okay, my headphones are more revealing than my speakers, and I had clearly heard the differences with my headphones. So I ran through the test again with my headphones, I knew I nailed it no problem. Final result:

9/16

Bias is a *****.

I actually went and picked up the Apple headphone adapter, because $10. I can CLEARLY hear a difference between it and my computers headphone jack........ :wink: :laugh:
 

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Discussion Starter #527 (Edited)
I actually went and picked up the Apple headphone adapter, because $10. I can CLEARLY hear a difference between it and my computers headphone jack........ :wink: :laugh:
Thanks for posting.

Just to reiterate: my testing of an Apple A2049 USB-C to 3.5mm headphone jack DAC suggests it is "good" but not quite as good as the Apple A1749 Lightning to 3.5mm headphone jack DAC I used in this test. I suspect it would be found to be "perfect to the ear" as well however.
 

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Discussion Starter #528 (Edited)
I actually went and picked up the Apple headphone adapter, because $10. I can CLEARLY hear a difference between it and my computers headphone jack........ :wink: :laugh:
For some people they (theoretically) can hear an improvement through the use of an outboard DAC not because it is a "better DAC" but simply because the circuity is kept further away from the noisy electrical environment inside a computer/laptop which has all sorts of electromagnetic fields and RFI going on inside [from hard drives, processors, cooling fan motors, etc.]. In some instances these EMI/RFI generators can (potentially) add faint noise/buzz to an analog audio path traveling nearby. Less so in modern designs than older ones but still "possible".
 
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Thanks for posting.

Just to reiterate: my testing of an Apple A2049 USB-C to 3.5mm headphone jack DAC suggests it is "good" but not quite as good as the Apple A1749 Lightning to 3.5mm headphone jack DAC I used in this test. I suspect it would be found to be "perfect to the ear" as well however.
It was the Lightning to Headphone adapter I picked up, like the one you used in your test. I don't have any USB-C devices.

For some people they (theoretically) can hear an improvement through the use of an outboard DAC not because it is a "better DAC" but simply because the circuity is kept further away from the noisy electrical environment inside a computer/laptop which has all sorts of electromagnetic fields and RFI going on inside [from hard drives, processors, cooling fan motors, etc.]. In some instances these EMI/RFI generators can (potentially) add faint noise/buzz to an analog audio path traveling nearby. Less so in modern designs than older ones but still "possible".
I put smiley faces after saying I could clearly hear a difference between the adapter and my computer, since in the first part of my message I thought I could hear a difference and I couldn't, but I clearly could between the computer and the adapter as soon as you take away the ABX. NOT!! Ya, I can't tell the difference. I was poking fun at the subjectivists who, when proven something, still go back to their old beliefs that have been shown to be wrong lol. If anything, I would want to say the computer jack sounds better, since my motherboard supposedly has high quality DACs and is isolated on the board away from all the noise to provide a very clean sound. But that's sighted bias talking. In a double blind test, I doubt I could reliably tell the difference - both are very clean and sound great.
 
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I've used computers that had noisy headphone outputs, they were really noisy and it would actually change pitch depending on what the computer was doing.
 

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Discussion Starter #531 (Edited)
I've used computers that had noisy headphone outputs, they were really noisy and it would actually change pitch depending on what the computer was doing.
When the noise differs in frequency based on CPU/hard drive use that's often indicative of a ground loop. Alternator whine in a car stereo (also a variety of a ground loop) similarly varies in frequency depending on the speed of the alternator/engine so the whine changes based on how much you rev the engine. Ground loops can be difficult to overcome.

A ground loop means the system is seeing two (or more) grounds and it doesn't know which to use. It tends to prioritize the one with the lower resistance [just like lightning seeks the path with the lowest resistance] but that isn't always clear cut.

People often have faint ground loops but they don't realize it. All they know is there is some noise/buzz. They read deceptive advertising by snake oil companies insisting "the problem is your USB connection quality including its shielding". A lie.

Thing is, they swap USB cords and invariably the new wire will have a slightly different ground path resistance and hence the ground loop noise will also change (sometimes worse and sometimes "better"). This then implants in their mind "USB cables do indeed sound different; I heard it myself". Convincing them of what is really happening is next to impossible because the deceitful advertisers got to them first and their world view is now fixed.:(
 
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I've used computers that had noisy headphone outputs, they were really noisy and it would actually change pitch depending on what the computer was doing.
The Universal Serial Bus is really a bad venue for audio out from a computer. It's terrible on my PC. Trying to run powered speakers that way results in a bunch of noise.

This was the main area where optical proved far superior. It has no conductive connection (no metal) to the source so is effectively decoupled.
 

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Discussion Starter #533
Optical is the best digital connection because it is inherently bulletproof against ground loops, RFI, and EMI right from the get-go. The deceitful audiophool magazines never endorsed it, however, and of course their lies and scaremongering about its alleged "horrible jitter/low level linearity/ smearing of micro details" makes it into the general public's zeitgeist and onto our sighted bias filled threads.
 

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Someone disabuse me if this is wrong, but it seems to me that if a USB connection adds a bunch of noise to powered speakers, the design of the speakers is seriously flawed. There's are an awful lot of gear out there using USB audio, it's not the format that's at fault. As for optical, there's a pro-audio format ADAT, or ADAT-Lightpipe, derived from digital tape format, that uses the same TOSLINK cable/connector, but is 8-channel. If there were such problems like jitter and smearing of micro details, they would likely be magnified by a factor of 4 in ADAT, but hey, why think the pros know what they're doing? And 'linearity'? What does linearity even mean in a digital format?

There's another Mark Waldrep video if anyone interested.

 

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The USB "cable" shouldn't be a problem if properly constructed. The issues usually are introduced by one or both of the devices at each end of the USB connection.
 

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Discussion Starter #536 (Edited)
The USB "cable" shouldn't be a problem if properly constructed. The issues usually are introduced by one or both of the devices at each end of the USB connection.
Also to add to that when one does have a ground loop problem it is not so much the wire's fault nor the components' but rather the overall system's layout/topology. For instance, if you have two components wired together and there's some nasty ground loop noise you may be able to erase it simply by plugging both devices to the same AC power strip instead of using different ones or even worse different outlets. Neither the devices nor their interconnection link has changed yet the problem is (hopefully) gone so it tells us the devices and wire were never the issue; it was how you powered them.

This methodology is called "star grounding" because all the devices lead their (hopefully equal length and equal resistance) grounds (for example, the third prong of power cords) back to the exact same point of origin, sort of like rays of light coming out of a star all lead back to the same point of origin and are the same length (hence resistance).


https://www.ap.com/technical-library/recommended-test-system-grounding/
 
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Discussion Starter #537 (Edited)
There's another Mark Waldrep video if anyone interested.
Thanks. I hope to watch it when I get the time but I quickly scanned it. Sounds like he is working on an AES paper on how Hi-Re$ is a scam (as I have been saying for decades). WOO HOO :) Good for him.
 
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Discussion Starter #538 (Edited)
And 'linearity'? What does linearity even mean in a digital format?
The low level linearity means the DAC's ability to properly reproduce sounds at the correct level when the music is at a very low level, i.e., super duper quiet. Usually in modern designs they are excellent so we need not worry about it. Problems only arise at levels which are too quiet to detect even in most very quiet rooms.

Here for example is the low level linearity of the $7.99 USB-C Apple Dongle (not to be confused with the Lighting connection version I used for this thread's test) according to ASR:

https://www.audiosciencereview.com/forum/index.php?attachments/apple-iphone-usb-c-headphone-adapter-audio-linearity-measurements-png.18465/

It is dead perfect to about 100dB below full scale level, 0dBFS. Certainly perfect to the ear to -107dB, and starts to become possibly detectable (if you super amplify the signal or place your ear an inch away from the speakers) at around -110dB and lower.

Analog media such as LP and Reel to Reel don't really exhibit this because with them the signal is so swamped with noise many 10's of dB before this sort of level I guess we just don't really know what happens down there.
 
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Discussion Starter #539 (Edited)
My $7.99 Apple DACs can't do any higher than 48kHz sampling rate so I bought a new one which does a whole bunch, even going up to 384kHz/in 16, 24, or even 32bit.

Preliminary tests show good but not great performance. I can't be sure though because my testing rig has developed a ground loop problem.:( I'm waiting for a ground loop isolator which is on back order so it may be a couple of weeks until I can take measurements..

Anyway, guess how much this the new, USB-C, Hi-res capable [it has the logo and everything] DAC costs?

I think it is the least expensive USB DAC (that runs on Windows) you can buy at the big river. No instructions and hardly any web support so you have to learn by trial and error.

At first I thought it was broken but then I discovered (for reasons I can't explain) it insists on using USB 3.0 ports not 2.0 [Which is weird because DACs usually communicate at 2.0 speeds, not 3.] Retracted. It now works on a different USB 2.0 port. I might have a bad jack on my laptop.
 

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384KHz*4*2 *8 That's still only 24-25 Mb/s, USB 2.0 is 480 Mb/s. I keep forgetting how pokey audio data rates really are. I think I might have to get one of those just to play with. If it's $5.99 on amazon, it's probably $3 on ebay.


I answered your previous post but I think I must not have actually posted it, I get easily distracted, blinking lights, a new Harbor Freight sale, ... and I forget what I was doing. I was thinking linearity in the transport of digital signals where it's all bits in and bits out, it's one of the primary reasons for going digital, to get away from linearity issues.
 
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