Electrostatic Headphone Amplifier Review & Comparison

[Degru]

Can you run a distortion sweep on the 313? I'm curious if there is extra distortion in the 2k area like I suspect, adding to the impression of "stax shout".

I guess I can finally have something to point to when I say energizers are crap. All of the Stax units I've tried have clipped on very high DR transients such as on Cincinnati pops 1812 overture recording. 80v max is not even reaching its rated spec, tho I suspect the load being 100kohm instead of the 140kohm that stax amps are designed for is part of the reason for such a low number, especially with real stats being capacitive rather than resistive.. Perhaps find a cheap damaged sacrificial lamb(da) and use that as a test load for more realistic results (preferably with the front sealed to not totally damage the diaphragm at high output).

Would be interesting to get top end stuff like KGSSHV in for testing, and compare it to an SRD-7 running from a good speaker amp (power would be dependent on speaker amp of course, but distortion behavior and FR would be interesting, tho also dependent on speaker amp and how it drives that particular load)

 

[Degru]

As many of you know, I do not use headphones. Aside from intellectual curiosity or a desire to be different and non-mainstream, what are the purported sonic advantages of electrostatic headphones vs. conventional headphones? Are they more accurate? Or are they superbly euphonic?

I have been a fan of ribbon and AMT tweeters in the past, but I know enough about human and consumer psychology to be aware that my preference for them is likely not strictly based on sonic qualities. I certainly do not promote or defend ribbons or AMTs as providing sonic nirvana.

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They are more accurate, mainly because the diaphragm is much lighter and faster than planars or dynamics as well as being driven more uniformly. That said, there are good and bad examples of any driver tech so it still depends on implementation, but generally estats have a mechanical advantage when it comes to detail resolution, transients, and distortion (THD, IMD, and non-harmonic).

 

[Degru]

I wonder if I can just use a high power speaker amp and still get less power supply noise than these...

You can just buy a Stax transformer and use a good clean ~50-100wpc amp. Hard to find pro bias ones tho.

 

[SpaceMonkey]

As many of you know, I do not use headphones. Aside from intellectual curiosity or a desire to be different and non-mainstream, what are the purported sonic advantages of electrostatic headphones vs. conventional headphones? Are they more accurate? Or are they superbly euphonic?

I have been a fan of ribbon and AMT tweeters in the past, but I know enough about human and consumer psychology to be aware that my preference for them is likely not strictly based on sonic qualities. I certainly do not promote or defend ribbons or AMTs as providing sonic nirvana.

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Estat headphones had low distortion for decades. They do offer light effortless sound which is not harsh and pleasant for me at least.

 

[o7_brother]

my preference for them is likely not strictly based on sonic qualities.

It's basically this, although electrostatics have some objectively nice things about them, low distortion being one of them.

What audiophiles usually claim is a sense of unmatched detail/resolution/transparency/transients.

As someone who owns ToTL Stax headphones, I think this idea comes basically from many of them being bright as fuck with uneven treble and an additional 1500 Hz elevation that brings out female vocals. This type of tuning annoys me to no end, thankfully EQ fixes it for the most part. The lack of distortion certainly helps, but regular headphones are ok in this aspect too.

Another common trait in these kinds of headphones is a sub-par bass extension, because their response is extremely dependent on getting a good acoustic seal on the sides of one's head. However, many of the Stax earpad designs do not allow for this, leading to a strange FR with a peak at 50-80 Hz and a sharp roll off below that. This variability depending on seal makes EQ'ing the bass quite difficult. Some models with more conventional ear pads like the SR-007 and 009 can be easily EQ'd to sound like planar magnetics in the bass department (low distortion, well extended bass).

Personally I would not use any of my e-stats without EQ. So, that sounds like a lot of negatives and not many upsides, why do I even own these things? After EQ, they sound quite amazing in my opinion, thanks to their well-extended treble and planar-like bass. That being said, if electrostatics did not exist, I'd be equally happy with a Hifiman or some other planar + EQ.

 

[o7_brother]

Also keep in mind that blind-testing headphones of different brands is essentially impossible because they feel different on the head. Therefore, all opinions on preference for electrostatic headphones over conventional ones are just that, opinions.

While I maintain that I subjectively preferred my Stax over my HD800 and HD6XX, when EQ'd to roughly the same target, there will never be a way to verify that for certain because I always know which one is on my head.

 

[Helicopter]

Also keep in mind that blind-testing headphones of different brands is essentially impossible because they feel different on the head. Therefore, all opinions on preference for electrostatic headphones over conventional ones are just that, opinions.

While I maintain that I subjectively preferred my Stax over my HD800 and HD6XX, when EQ'd to roughly the same target, there will never be a way to verify that for certain because I always know which one is on my head.

Agree. I will add, I would not want to test them just by sound either. I have never found an IEM to be remotely acceptable because none have fit well in my ears. I could care less how any of the ones I have tried sound because they already 100% fail before we get to sound. Some headphones feel great, some cheap, some painful, this is really important too, and most of it is going to vary based on the user's unique shape, etc.

 

[wje]

Will be interesting to test other after-market amps to see how they compare to these.

Maybe, someone will pony up the $6K HeadAmp Blue Hawaii? A lil' rich for my means, though.

https://www.headamp.com/products/blue-hawaii-se

 

[Helicopter]

Maybe, someone will pony up the $6K HeadAmp Blue Hawaii? A lil' rich for my means, though.

https://www.headamp.com/products/blue-hawaii-se

If some one wants to pony up $6k, I would be more interested in seeing if a brand new Keithley 2015 shows something surprising Amir's AP didn't.

I am not convinced there is a problem with 100kohm, but I am curious. Saying the magnitude is the same as speakers is a little like saying the difference in $.01 and $100 is the same as $100 and $1M. OK.

 

[sq225917]

Amir, do you honestly believe these measurements represent the actual performance of these headamps?

Aren't you concerned at the the huge chasm between your figures and those from Stax?

Your measurements clearly aren't accurate unless your tube headamps examples are faulty.

 

[amirm]

How old are these? Looks like mains leakage in the 006 (old capacitors?) is adding a lot of noise. Have you replaced the tubes recently? Wonder if new tubes and capacitors or whatever is needed to make the power supply perform better would improve these measurements?

They are 20 years old but rarely used especially the SRM-006t. Distortion is dominant in the measurements so the mains noise is not very material.

 

[amirm]

100kohm load is way to low to measure these amplifiers. And in fact without 120pf across the output, the results are meaningless.

AP has a shunt 200 pf cap for RF filtering. So it not a pure resistive load.

Remember, identical conditions are used to test all four:

The much higher distortion of the tube amp absolutely holds.

You need a keithely 2015 high voltage thd meter that does more than 500vrms with a 10 meg load resistance. And you still need the 120pf caps to get a real idea of what the high frequency response looks like. hint: its down more than 10db at 20khz at 200vrms

Good luck getting distortion curves like above out of that setup! All you can do is get a frequency response curve with a lot of pain which is not material in the testing I did.

The koss is lighting the current error light because of the 100k load. With a 10 meg scope probe its more than happy to do 2400 volts peak to peak balanced, or 1200 volts peak to peak measured with respect to ground.

That unit is not mine so I am careful about stressing it. I actually stopped the test short the moment it peaked.

 

[amirm]

Can you run a distortion sweep on the 313? I'm curious if there is extra distortion in the 2k area like I suspect, adding to the impression of "stax shout".

You mean distortion versus frequency?

 

[Helicopter]

I think the 2015 would be useful just to verify a few points of AP data. You could start by verifying the Kiethely 2015 on something everyone agrees the AP can measure acurately.

I am not sure it is necessary though. As I said, I agree 100kohm is a pretty good infinite resistive load.

 

[amirm]

Amir, do you honestly believe these measurements represent the actual performance of these headamps?

Well, subjectively yes. I clearly hear distortion as I turn up the volume on SRM-007t. I could not tell before if this was transducer dependent or amplifier but now, I am pretty convinced it is the amp.

Aren't you concerned at the the huge chasm between your figures and those from Stax?

I don't trust any manufacture single value numbers. No conditions are shown, no graphs, no nothing. On top of that we are talking about distortion measurements from 20+ years ago. What did they use to measure them?

That said, sure, there can be some issues here but remember, as a comparison the tests remain valid. Identical setup is used and comparison is made of 4 different amps. Both tube amps perform much worse than the two solid state ones. And both tubes more or less agree with each other and both solid state ones do as well.

The only hitch is that as I noted, I was afraid of cooking the KOSS so perhaps it is fine outputting way after its clipping light comes on. If one of you wants to pay for one if it gets damaged, I can push it harder.

 

[amirm]

I think the 2015 would be useful just to verify a few points of AP data. You could start by verifying the Kiethely 2015 on something everyone agrees the AP can measure acurately.

I am not sure it is necessary though. As I said, I agree 100kohm is a pretty good infinite resistive load.

The Keithly is not a high performance device. Here are its own specs:

Here is the SMR-311:

My measured SINAD is 20 dB better than Keithley's own internal distortion figures! It simply is not useful for distortion measurement of the type we are talking about.

 

[Helicopter]

... If one of you wants to pay for one if it gets damaged, I can push it harder.

Well along this logic, I am good with no Kiethely 2015 and no cooked Koss.

I learned a lot about electrostats here and I don't need anything more conclusive. Thank you.

 

[amirm]

Your measurements clearly aren't accurate unless your tube headamps examples are faulty.

"Clearly" not accurate? Based on what? You have measurements like mine that show different results? Or are you trusting single number spec value from Stax from two decades back with who knows what setup?

And what are the odds of both tube amps measuring as they did?

Here is a random tube amp distortion vs output:

See the sharp rising curve? Now here is the Stax tube amp:

You see the family resemblance?

So no, I don't know that the measurements are faulty and certainly not "clearly." You have independent measurements that show that, I love to see them and will analyze. For now, we have data with reasonable accuracy given what we have to work with.

 

[pjug]

The Koss in sharp contrast could be mistaken for a give-away kids toy in McDonald's happy meal.
/

I am not to interested in headphone stuff but I'm glad I read even the reviews of stuff I don't care about, because this had me laughing pretty good.

 

[okok]

i like gilmore's posts very much on the other site, learnt a handful of stuff that i could never imagine. since he's retired assume that he's busy with his personal projects i left the site. we both love to type without caps on

@kevin gilmore thank you sir for all these years