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Review and Measurements of Teac HA-501 Headphone Amp

amirm

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#1
This is a review and detailed measurements of the Teac HA-501 headphone amplifier. It is on kind loan from a member. The HA-501 in black costs $549 including Prime shipping from Amazon. Oddly, the silver color is much cheaper at $354! Black anodizing must have become very expensive. :) The black does look a lot nicer though so it would be tough to settle for silver.

The HA-501 is one of the most attractive desktop audio products. If you are a fan of the 1970s and 1980s hi-fi gear, the Teac is the best way that look could have been modernized yet hold its retro appeal:

Teac HA-501 Headphone Amplifier Audio Measurements.jpg

The controls feel fantastic and the head of the class for sure.

Controls are not unusual other than addition of "damping factor" which simply adds a resistor in the path of the headphone output (measurements later).

The other odd thing is the auto-muting. When you unplug the headphone, the red audio mute LED comes on and will not go off until you turn the volume all the way down to infinity and then back up. This is to assure you never plug in a headphone and have it play at exceedingly high levels. I am not sure that is worth the effort it takes to reset it every time if someone has multiple headphones they use often.

The back panel shows the generous inputs and outputs:

Teac HA-501 Headphone Amplifier Audio Review.jpg

If it were up to me, I would make balanced XLR inputs mandatory on every headphone amp. :) So useful in getting around ground loops.

Nice to see switch selectable pass through RCA outs.

Being a proper audio companies, regulatory certifications are there and can be relied upon to mean this is a safe device that doesn't spit out a bunch of RF.

Overall, a headphone amplifier doesn't get much nicer than this from look and feel point of view.

Headphone Audio Measurements
Let's start with our dashboard output, driving the HA-501 using XLR inputs (same input was used for all the tests):

Teac HA-501 Headphone Amplifier Audio Measurements.png


I set the volume to pass through (4 volt in, 4 volt out). Even at this reduced volume level, the amount of distortion is quite high for a top of the line headphone amplifier. The distortion is from third harmonic which sets the SINAD by itself to 83 dB. As a way of comparison, the Massdrop THX AAA 789 clocks at 117 dB while producing 5.8 volts output! That is an incredible gap in performance.

Signal to noise ratio is spec-compliant:
Teac HA-501 Headphone Amplifier SNR Audio Measurements.png


The 50 millivolt output which measures how well an amp drivers ultrasensitive headphones is not so good though:

Best Headphone Amplifier SNR Audio Reviews.png


Measuring THD+N versus frequency at my standardized 5.8 output level shows how much more the distortion rises with volume:
Teac HA-501 Headphone Amplifier THD vs Frequency at 90 kHz Audio Measurements.png


Even at 2 volt output the HA-501 is not competitive.

Intermodulation distortion distortion versus output power shows the same:

Teac HA-501 Headphone Amplifier Intermodulation Distortion Audio Measurements.png


But also indicates that the HA-501 has more power than THX 789's single-ended output. We can see this clearly in THD+N versus output power at 300 ohm:

Teac HA-501 Headphone Amplifier Power at 300 ohm Audio Measurements.png


Switching to 33 ohm for a more current limited load we get:
Teac HA-501 Headphone Amplifier Power at 33 ohm Audio Measurements.png


Here, the rise in distortion is more severe but we still have ample amount of power at 1.4 watts.

Channel imbalance is very good until the end:
Teac HA-501 Headphone Amplifier Channnel Imbalance Audio Measurements.png


Finally, output impedance is very good at high damping factor setting:

Headphone Amplifier Output Impedance Review.png


The amount of resistance at low damping factor is still modest at 6.2 ohm. I thought it would be higher than it is.

Headphone Listening Tests
As usual, I start my listening tests with the Sennheiser HD-650. 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.

The situation was nearly the same with Hifiman HE-400i. There was plenty of power although I thought maybe at the limit it got a tiny bit distorted. Never mind as I could not listen at that level for more than a couple of seconds.

Using the HE-400i, I played with the damping factor. It makes quite a bit of difference going from High to Low, causing both the level and bass response to suffer greatly in Low setting. Of course this is not the main use of it but thought it was a good tool to measure the effect of high output impedance subjective.

Conclusions
The Teac HA-501 nails a number of my review criterias from look, feel, safety, reliability and amount of power. Subjectively it also meets its target of producing ample power to drive just about every headphone you throw at it.

Objectively it is far from top of class given the game changing headphones amps: Massdrop THX AAA 789 and JDS Labs Atom. These two amps have basically left everything else in the dust. Where they lose to Teac though is in overall feel and look. Even the THX falls behind by good few points.

So you have a choice to make: go with heart that is pulled by the look and subjective sound quality or engineering excellence as represented by the competitors. I am not here to solve that equation for you. :) I want both and Teac HA-501 doesn't have both.

------------
As always, questions, comments, recommendations, etc. are welcome.

This year I like to get an early start on my Christmas shopping. Being too cheap to spend my own money, I thought I ask for yours. So please donate using:

Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
 

Tks

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#2
That muting function is nice and smart.

I've come to the conclusion that with the top measuring AMPs/DACs we have today. The only thing left is to chase creature comforts in DACs and AMPs.

Things like this device, and the DX3 Pro are filling those requirements. All that's left is for refinement on such creature comforts, and that is where companies can truly begin to differentiate themselves and their product offerings - things like nice volume knobs, and just basically features that make operation a pleasure or easier, and products like the RME ADI 2 DAC that add serious DSP and such. Things like gambling on performance shouldn't be -a thing- anymore. Companies peddling luxury covered all over poor performance have be rife in the industry apparently for quite some time, and still are in some respects. Products like this (hopefully the next iteration with better performance) are the direction we need to go in. As well as folks like Amirm paving the way for thinking about how we should be seeing out products (as informed consumers), is something that I hope will proliferate and eventually antiquate ridiculous long-standing paradigms that have only existed due to a massive level of marketing induced ignorance.

The only way we get to this proper place, is the sort of democratization of information and knowledge like we have here.

Great review amirm!
 
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#4
This is a first-class case design. The Teac UI just oozes quality and it looks great. These were all over Japan 5 or 6 years ago but they weren't so popular.
 

restorer-john

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#5
Another s**t SNR measurement from a supposedly highly resolving dac.
That's just heckling from the sidelines and not remotely useful commentary, is it? It's not a D/A converter. It simply a headphone amplifier.

The S/N is pretty good at @109dB and as you can see, the power supply noise contribution is very low in this product. It is the THD that kills it. That said, I'd like to see it tested against its specifications (1V in 1V out) before condemning it. After all, if it meets advertised specifications, there is absolutely no justification in calling it out.

1556490838671.png

Some good shots of the internal construction here: http://www.hifishock.org/gallery/electronics/teac/headphone-amplifier/ha-501-3-teac/

1556489945863.png


They make great fanfare of the NJR Muses 8920, a current flavor-of-the-month opamp used in this product (pdf attached).
http://audio.teac.com/product/ha-501/

Consider we are simply amplifying/buffering a line stage to drive headphones. Do we seriously need this level of complexity (that's just one channel in the foreground)? Do we really need a discrete Class A power amp for headphones when an opamp and a buffer stage will do?
 

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rmo

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#6
That's just heckling from the sidelines and not remotely useful commentary, is it? It's not a D/A converter. It simply a headphone amplifier.

The S/N is pretty good at @109dB and as you can see, the power supply noise contribution is very low in this product. It is the THD that kills it. That said, I'd like to see it tested against its specifications (1V in 1V out) before condemning it. After all, if it meets advertised specifications, there is absolutely no justification in calling it out.

View attachment 25437
Some good shots of the internal construction here: http://www.hifishock.org/gallery/electronics/teac/headphone-amplifier/ha-501-3-teac/

View attachment 25436

They make great fanfare of the NJR Muses 8920, a current flavor-of-the-month opamp used in this product (pdf attached).
http://audio.teac.com/product/ha-501/

Consider we are simply amplifying/buffering a line stage to drive headphones. Do we seriously need this level of complexity (that's just one channel in the foreground)? Do we really need a discrete Class A power amp for headphones when an opamp and a buffer stage will do?
Correction, not a dac but a THD of 83 or so is garbage
 

GGroch

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#7
I see the Amazon Silver price is down to $336 (they must have seen your review ;). That is an exceptional price for the unit, well below eBay and other vendors. Most are above $700 on it. The construction quality certainly seems above the pricing. It appears to have been released over 5 years ago.
 

LTig

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#8
They make great fanfare of the NJR Muses 8920, a current flavor-of-the-month opamp used in this product (pdf attached).
http://audio.teac.com/product/ha-501/
If the Muse is more expensive than an OPA2134 or similar then I'd say it's wasted money.
Consider we are simply amplifying/buffering a line stage to drive headphones. Do we seriously need this level of complexity (that's just one channel in the foreground)? Do we really need a discrete Class A power amp for headphones when an opamp and a buffer stage will do?
For 300 Ohm load an integrated buffer should be sufficient. For 33 Ohm load I'm not sure, but I have no oversight about current buffer products.

Based on the powers measured by Amir I conclude that the amplifier runs with a supply of +/-15 V (215 mW at 300 Ohm require 22.6Vpp). The peak current through such a stage is determined by the power of 1.4 W at 33 Ohm to 290 mAp. A class A stage would then dissipate 2 x 15V x 290 mA = 8.7 W per channel. That is quite a lot. If the Teac gets warm even in idle mode it might be class A, if not it must be class A/B and this means that you need a lot of discrete parts.

In my DIY preamp I used a very simple single ended class A stage consisting of just a MOSFET and 2 resistors, but it was designed for 300 Ohm load back then with 50 mA standing current. (I should measure its THD some time). It could be adapted to 30 Ohm load but then with much higher dissipation.
 

Nango

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#9
All that Amazon stuff are often not brand new items but refurbished or pre-owned or returned items, don't trust Amazon (Edit: based on my own experience)!!
 
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GGroch

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#10
.......don't trust Amazon!!
No offense meant, but I am sure 99.9% of the U.S. members here and in excess of 95% of everyone else already has their own opinions of Amazon based on experience.

Anyone who would change their view based on one forum poster would not be acting in alignment with the objective, scientific perspective espoused here.
 

trl

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#12

Patrick1958

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#14
Archimago's measurements from http://archimago.blogspot.com/2013/05/measurements-teac-ud-501-pcm-performance.html shows the 3rd harmonic at -110dB instead of -85dB and 4th and 5th harmonics are simply not there...strange thing. He used RMAA and I think 0dB is 1V RMS; also, he used RCA, so not balanced measurements. The 60Hz and 180Hz are still there and at about the same amplitudes.

Archimago's measurements are for the UD-501 (dac/amp combination).
Amir's mearsurements are for the HA-501, amp only.
Both are in the same line up but are different devices.
 

Shadrach

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#15
Not over keen on the retro look and expected better performance given the company and price.
 

trl

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#16
Archimago's measurements are for the UD-501 (dac/amp combination).
Amir's mearsurements are for the HA-501, amp only.
Both are in the same line up but are different devices.
Thanks Patrick, seems that my morning coffee had some troubles to do its "wake-up" effects. :)

BTW, kinda lame for a headamp to have it's 3rd harmonic so high; today, even power amps are having first two harmonics below -90dB.
 
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#17
thank you for the work and this review! ive always been wondering if teacs hpa is worth the 500... now i know.
one suggestion: i know this is a science forum and from an objective scientific point of view its correct to compare every newly tested device to top-measured devices, but as far as it goes for "recommendations" (wich, i guess, go for folks beeing interested in BUYING this/any hpa), Massdrop THX AAA 789 is simply NOT AVAILABLE (or is it?) and i really wonder if it ever will be again... so, from someone whos interested in bying a hpa and his perspective point of view, it simply makes no sense to recommend the THX789 over and over again. I SIMPLY CANT BUY IT... (can i?) :cool:
 

Shadrach

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#19
thank you for the work and this review! ive always been wondering if teacs hpa is worth the 500... now i know.
one suggestion: i know this is a science forum and from an objective scientific point of view its correct to compare every newly tested device to top-measured devices, but as far as it goes for "recommendations" (wich, i guess, go for folks beeing interested in BUYING this/any hpa), Massdrop THX AAA 789 is simply NOT AVAILABLE (or is it?) and i really wonder if it ever will be again... so, from someone whos interested in bying a hpa and his perspective point of view, it simply makes no sense to recommend the THX789 over and over again. I SIMPLY CANT BUY IT... (can i?) :cool:
There are alternatives.;) A brief look through the reviews should give you some ideas. At the level of measured performance we are talking about any of the units mentioned in the top tier of products will likely be indistinguishable from one another.
Buy what you like the look of.:)
 

maxxevv

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#20
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.
 
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