Headphone Amplifier Testing and Measurements

[oivavoi]

Don't get hung up on just circum-aural phones though such are often used by better heeled headphonophiles. Most people use earbuds. On ear or in ear or near ear clip on phones with cell phones for a source. So as well as testing some headphone amps, and dedicated music players, test the output of popular phones. Iphones, Galaxies etc. plus some tablets. Oh, and definitely get some of the Etymotics.

Maybe after trying a few representative headphone amps for a baseline, you'll have something like the budget DAC thread. Phones or cheap players that compete with expensive rigs. I also think some low priced prosumer recording gear will have surprisingly good headphone amps for surprisingly little money with lots of capability thrown in for nothing.

Much like some exotic speakers, headphones and headphone amps create something of a vicious circle. Exotic unreasonably hard to drive quality headphones create a need for super duty amps which fuel the market for energy guzzling exotic headphones. Your Stax needing something like a real power amp are an old niche example. Though Koss preceded them (those Koss ESP phones were sweeter sounding than the Stax though).

I often find myself preferring my Soundsport earbuds from Bose, compared to my Sennheiser 598s. I get a strange and locked-in feeling from most over-ear headphones. Doesn't feel natural. The Soundsports, on the other hand, let in some external sounds, and in a way that feels much more natural. The only headphones I've tried so far which didnt make feel locked-in were the Hifiman Edition X V2. Felt open and natural, and played extremely well. Can be driven by a phone also. When I get the funds, I will probably buy a pair of those together with that thingy which recreates the HRTF and provides the feeling of listening to speakers in a room.

 

[watchnerd]

I suggest a minimum a ban from further posting in this thread, and from posting images for one month. How offensive!!!!!

I rejoinder with the typical trope. McDonalds sells the most meals, it doesn't make them world leading gourmets.

It's easy to diss Beats for their popularity and their garish color schemes, but wouldn't it be fun to measure a pair?

What if Beats are the Behringers of the headphone world?

 

[Blumlein 88]

It's easy to diss Beats for their popularity and their garish color schemes, but wouldn't it be fun to measure a pair?

What if Beats are the Behringers of the headphone world?

https://www.innerfidelity.com/images/MonsterBeatsSolo.pdf

https://www.innerfidelity.com/images/FocalUtopiasnA1BEHG003253.pdf

https://www.innerfidelity.com/images/BeyerdynamicDT880250ohm.pdf

https://www.innerfidelity.com/images/SennheiserHD600.pdf

https://www.innerfidelity.com/images/StaxSR007.pdf

 

[Blumlein 88]

Since we have this thread going, might as well post some research into headphones and their testing. This is a good interview with Sean Olive. Skip the first few minutes and play it at 1.25X to get through it faster:


Interesting point regarding using EQ to achieve a target curve with any headphone to improve fidelity.

Slide 52 is pretty damning. Price to performance correlation: -.16 yikes

Then EQ a $50 pair and get some of the best performance.

 

[watchnerd]

https://www.innerfidelity.com/images/MonsterBeatsSolo.pdf

Yowza.

 

[watchnerd]

Slide 52 is pretty damning. Price to performance correlation: -.16 yikes

Then EQ a $50 pair and get some of the best performance.

It seems to be specific to IE cans, though no reason others wouldn't have similar correlations, I would bet.

 

[amirm]

Slide 52 is pretty damning. Price to performance correlation: -.16 yikes

Then EQ a $50 pair and get some of the best performance.

Indeed. Here is the slide for people who don't want to watch the video:

Negative correlation means the reverse happened, i.e. as the price went up, quality dropped.

In fairness, this is an estimate based on preferred frequency response, not actual listening test.

 

[Blumlein 88]

Yowza.

Did you dig that Beats impulse response?

 

[watchnerd]

Did you dig that Beats impulse response?

It looked like a fart.

 

[amirm]

I thought I share this newly released video on Tyll Hertsen who does headphone reviews and measurements for stereophile's sister publication, innerfidelity:

 

[Blumlein 88]

Well nice video. You feel like you have an idea who this Tyll Hersten is behind the reviews you read. I have a better opinion of him than a certain fellow who is a big champion of LP's at Stereophile.

But you are not fooling anyone Amir. You mainly were attracted by the part about the camper van.

 

[amirm]

My secret is out!!!

 

[mindbomb]

I think a thd+n x V graph at 32 ohms 1khz can pretty much sum up a headphone amplifier's performance. Let's you see if they are lying about the power specs and tells you how clean the amp is. Output impedance at 100hz and dc offset are good to know and are easy to check. Then if possible, I think distortion vs frequency and ccif imd, at 32 ohms, 1vrms would be interesting to look at. Also, a capacitive load test might reveal stability problems with an amp.

In the headphone community, I think the schiit magni 3 headphone amplifier has a lot of hype and is probably going to be frequently recommended, and is probably going to be pretty popular. It would be nice to know how it compares to other amps objectively, especially the the o2 headphone amp.

 

[watchnerd]

I think a thd+n x V graph at 32 ohms 1khz can pretty much sum up a headphone amplifier's performance. Let's you see if they are lying about the power specs and tells you how clean the amp is.

What about for 300 ohm cans?

 

[amirm]

I think a thd+n x V graph at 32 ohms 1khz can pretty much sum up a headphone amplifier's performance. Let's you see if they are lying about the power specs and tells you how clean the amp is. Output impedance at 100hz and dc offset are good to know and are easy to check. Then if possible, I think distortion vs frequency and ccif imd, at 32 ohms, 1vrms would be interesting to look at. Also, a capacitive load test might reveal stability problems with an amp.

Welcome to the forum and great suggestions.

On capacitive loading, what would the target be? I guess I could measure one of my headphones and use that. Or is there some common number people look at?

 

[amirm]

What about for 300 ohm cans?

I will include something for that as the Sennheiser HD650 is a super pain to drive!

I have all the parts now to build a dummy load with different load resistances. Once i get into it and see how much work it is, I can either include all the values you all suggested or the common ones.

 

[amirm]

In the headphone community, I think the schiit magni 3 headphone amplifier has a lot of hype and is probably going to be frequently recommended, and is probably going to be pretty popular. It would be nice to know how it compares to other amps objectively, especially the the o2 headphone amp.

Thanks for this too. My son had bought the original version I think a few years back. I don't recall if he had some issues with it or not. I was originally going to test that but seeing how they have gone to later revisions and it is pretty cheap, I went ahead and ordered the Magni 3. Should be here by end of next week since they say it is in stock.

 

[amirm]

Boy, this is some fine print in the Schiit return policy:

"2-Year Warranty and 15-Day Return Policy
Magni is covered by a limited warranty that covers parts and labor for two years. That’s 2x the coverage of most amps in this price range. And, if you don’t like your Magni, you can still send it back for a refund, minus 15% restocking fee, within 15 days of receiving your amp."​

Only 15 days instead of 30 and 15% restocking fee? They don't seem to be very confident of their product to have shrunk that from 30 days and no restocking fee from a few years back if I remember correctly.

 

[mindbomb]

Welcome to the forum and great suggestions.

On capacitive loading, what would the target be? I guess I could measure one of my headphones and use that. Or is there some common number people look at?

I'm not sure. I just remembered that when nwavguy checked his macbook, adding .01 uf in parallel to his earbuds made it freak out.
http://nwavguy.blogspot.com/2011/12/apple-macbook-air-5g.html

But maybe just using headphones would be more relevant to people.

 

[tomelex]

I'm not sure. I just remembered that when nwavguy checked his macbook, adding .01 uf in parallel to his earbuds made it freak out.
http://nwavguy.blogspot.com/2011/12/apple-macbook-air-5g.html

But maybe just using headphones would be more relevant to people.

I think the HD650 is about 800 pico farads, we are not measuring a standard power amplifier here, which would not like 0.01 microfarads too much either