Review and Measurements of Teac HA-501 Headphone Amp

[LTig]

I recall a very old MP3 encoder listening test in which the candidate with hearing damage performed the best, but I don't have that handy.

Well, I do, but in german language only.

In march 2000 the german computer magazine ct' did an extensive blind listening test to find out whether MP3 and CD sounds identical or not. The resuIt caused quite a stir in the audio community therefore ct' repeated the test with selected readers who wanted to show better, and there was a price for the listener with the best hearing. Here is the link to the article which covers the second test.

The official winner was a student in electronics who had a hearing impairement. In the article he is cited to say:
Since an accident with explosives I hear only until 8 kHz on the left ear, and on the right ear I had a persistent tinnitus until shortly. Nevertheless I can hear those typical flanger artifacts of the MP3 filter banks, and I can hear them better then my friends - maybe because of the hearing damage.

The article continues with this:
There may be some truth in it: the psychacoustical model of the MP3 compression assumes a person with normal hearing. Someone who hears only up to 8 kHz will not hear a high beat on a cymbal or triangel - but he can hear the sound from the filter control in the lower frequency range, when those parts of the spectrum are removed which are masked by the content in the higher frequency ranges. Deep notch filters as used in MP3 encoders create flanging effects (jet effect) when they move fast in frequency.

 

[GGroch]

Well, I do, but in german language only.

Here is a slightly more complete English version (referenced in your link).

Very Interesting stuff. I am not knowledgeable enough about statistics to judge the validity of this test, but a lot of the information is there for statisticians to make some judgement.

12 Official Subscriber Participants (Plus One Invited Expert Participant)
17 Pieces of Music (each with 3 samples to rank)
Maximum Score Possible: 51 Score Achieved through Chance: 14.1

The author says those who achieved more than 14.1 "had actually heard differences in quality." This seems wrong to me, because in a group of 17 some will make more correct guesses than others just by chance.

The best score of 26 was not achieved by the hearing impaired participant, but by the invited expert. The hearing impaired participant was the top scorer among subscribers at 22. And the next best score, of 20, was shared by 2 participants with professional audio backgrounds. The hearing acuity of the other 12 participants was not disclosed.

The test group was small enough that it seems to me the results are quite interesting, but are perhaps more anecdotal than statistically valid.

On the other hand, we know that Neil Young, who we can assume has significantly damaged hearing, can easily identify the benefits of Hi Res Audio, so there is that

 

[Jimster480]

Another shit SNR measurement from a supposedly highly resolving dac.

This isn't a DAC though. Its just an amp.
The performance is still poor.

Just an observation , and for @amirm 's consideration in future reviews for DAC Amps / HF amps.

i) Do the subjective listening tests as a base note before any measurements are taken. Note down all your listening observations first.

ii) Then move on to the measurements.

iii) And then reconcile them.

Doing the current measurements and then moving on to subjective listening tests will inevitably introduce "affirmation bias" in the listening tests. I seem to detect that in some of the comments of the tests.

Even if its not the case, I would think it helps to keep reviews that wee bit more balanced.

Subjective reviews are pointless in the first place, but its kinda fun to see if you can hear the distortion.

 

[restorer-john]

This photo shows voltage configuration of the primary tappings. It looks like there may simply be a country configured jumper to set for local voltage. PCB fuse is also specified as 250V rated which means it is likely a single value, universal world model with a compliance label/jumper change only.

This is good news for 230-240V countries (like Australia) that don't officially import the HA-501. I'd be interested to see if the US version is the same inside. (this pic from HiFishock is of a 120V unit)

 

[T.J. Turner]

Good catch.

But listening first could lead to "affirmation bias" when subsequently editorializing upon the measurements.

Back to square 1.

The whole purpose of the amp is to listen to it, not measure it. I think by that principle listening test and documenting the observations should always be done first. How much does it matter If it sounds great, but measures poorly?
A the end of the review Amir made this comment: "As the measurements predict, there was more than sufficient amount of power to drive these to produce excellent bass (they sound anemic otherwise). The authority and clarity erased any memory of less than excellent measurement graphs."

This isn't a DAC though. Its just an amp.
The performance is still poor.

Subjective reviews are pointless in the first place, but its kinda fun to see if you can hear the distortion.

I've owned a HA-501 since 2015, I've only seen positive reviews, and I have never heard distortion in the form of noise, glare, or dullness.

 

[restorer-john]

The whole purpose of the amp is to listen to it, not measure it. I think by that principle listening test and documenting the observations should always be done first. How much does it matter If it sounds great, but measures poorly?

With respect, you have bought one, owned it since 2015 and cannot offer an unbiased opinion. Subjectivity and emotional investment rules supreme.

Testing produces unbiased, objective and verifiable facts. What consumers do with those facts is ultimately up to them.

 

[T.J. Turner]

With respect, you have bought one, owned it since 2015 and cannot offer an unbiased opinion. Subjectivity and emotional investment rules supreme.

Sure I can offer an unbiased opinion! There's no reason for me to protect this amp, I'm not a Teac employee or fan boy, and I would tell you if it sounded like crap if I needed to. I'm just an audio enthusiast who like to to sample and compare different stuff. The HA-501 is not the first and only headphone amp I own. The hobby is just for fun. I can compare it to a variety of amps I've owned such as the The Atom, Schiit Magni 3, Asus Xonar Essence One, SMSL SH-8, Schiit Ragnarok, Schiit Jotunheim, Beyerdynamic A2, THX 789, THX 887, Oppo HA-2.
In comparison the HA-501 in my unbiased opinion is a good value.

 

[pkane]

Sure I can offer an unbiased opinion! There's no reason for me to protect this amp, I'm not a Teac employee or fan boy, and I would tell you if it sounded like crap if I needed to. I'm just an audio enthusiast who like to to sample and compare different stuff. The HA-501 is not the first and only headphone amp I own. The hobby is just for fun. I can compare it to a variety of amps I've owned such as the The Atom, Schiit Magni 3, Asus Xonar Essence One, SMSL SH-8, Schiit Ragnarok, Schiit Jotunheim, Beyerdynamic A2, THX 789, THX 887, Oppo HA-2.
In comparison the HA-501 in my unbiased opinion is a good value.

I’ll offer a more objective opinion of this piece in a little while

I’ve had it for a couple of years.

 

[LTig]

Sure I can offer an unbiased opinion!

There are none. It's either unbiased (fact) or an opinion. Don't take it personally, that's just the way our brain works, in all of us.

The paragraph above is a fact, not my opinion.

 

[pkane]

My (mostly) objective results are a bit better than what Amir posted. I've had this headamp for a few years, and it served me well, until I started using HE-560s. With these, it often didn't have enough oomph to produce the desired output level. Don't know why, as HE-560s are not that insensitive, but it worked great, with plenty of head room with HD-650s.

Measured with Apogee Element24 ADC and REW. SINAD of 98dB on line out, and 94dB on headphone output (at 3.5v).

Line output (may need to recheck grounding and connections to see if the 'grass' around 1kHz tone can be eliminated, much less of it is visible on the headphone jack below):

Headphone Output:

Multi-tone test:

Square wave at 1kHz:

Frequency and phase response:

This is about 11dB better SINAD performance than Amir measured, flat frequency and phase response and a decent-looking multi-tone test. Subjectively, other than when used with difficult loads where it may run out of power, this amp performs well and sounds good to me. It's not close to the newer THX-xxx models in terms of absolute performance, but it's certainly capable of delivering quality sound to a lot of headphones. Can also be used as a remote-less preamp in a pinch, since the line outputs can be set to fixed, off, or variable.

 

[Tks]

The whole purpose of the amp is to listen to it, not measure it. I think by that principle listening test and documenting the observations should always be done first. How much does it matter If it sounds great, but measures poorly?
A the end of the review Amir made this comment: "As the measurements predict, there was more than sufficient amount of power to drive these to produce excellent bass (they sound anemic otherwise). The authority and clarity erased any memory of less than excellent measurement graphs."




I've owned a HA-501 since 2015, I've only seen positive reviews, and I have never heard distortion in the form of noise, glare, or dullness.

I actually agree with you here. The confirmation bias of doing listening tests post-measurements makes them less worth than the slew of subjective-only listening tests done everywhere else. Likewise it's simply a bad look for a place like this to mount on such a bias for what this place is.

Ray talks about "editing" the review if the listening tests produce counter intuitive conclusions to the measurements (in order to save face being the most driving factor for an edit like that). But I'd rather a test be edited, than a near-pointless subjective listening test. That way if there was ever evidence of an edit to the measurements post conducting of them.. There would be all the more reason to move on instead of being strung along due to a dishonest practice that could've occurred anytime even in the past for whatever other reason.

But because we're all here now, we at least have that faith in Amir that he isn't doing all of this work in order to fake graphs (seeing as how some of his measurements were verified by other outlets).

I think the subjective portion should either come first, or simply just include subjective thoughts on everything except the sound properties. Like build quality, impressions of using the device and things of that nature.