[ultrabike]

Some folks in this and other threads have asked about the ADP and how it compares to the HD650 and DT880 classic cans. Specific concerns have been brought up about ADP mid-range distortion.
 
The ADP has significant amounts of distortion in the midrange. This is due to the T50RP driver and is common to most other T50RP based cans. Distortion may be very driver to driver dependent. Some sample T50RP drivers have quite a bit of distortion, some are better behaved.
 
Here are distortion plots for the ADP

And comparatively for the DT880 (250 ohms)

And HD650

 
 
As can be shown, the ADP has much higher distortion numbers in the midrange, the DT880 has a distoriton peak between 2 and 3 kHz, and the 650 shows better behavior. Higher distoriton numbers in the DT880 and 650 in the bass area are expected given they leak sound, while the ADP is a closed sealed pad headphone.
 
In terms of performance,  the HD650 is technically superior to the ADP in the mid-range and treble region (distortion / fidelity). I've had the pleasure to listen to both HD650 and ADP cans. HD650s are more resolving and scale better. HD650s are also more open souding and less fatigue prone. The HD650 is more comfortable. If the ADP is able to provide seal (there Fostex inherited construction variations here too), bass will be superior on the ADP. If it fails to provide seal, ADP will sound fairly poor.

 

[hans030390]

I don't think the real issue is how good or bad the Primes or other T50RP mods with similar distortion sound, but more a question of pricing. I can see why some might see this and some of the product variation issues as a very hard sell at $1k (even some may feel $600 for AD is pushing it).

Update: Wanted to post some links to Tyll's measurements of MrSpeakers headphones:

Mad Dog (Pro, I believe): http://www.innerfidelity.com/images/MrSpeakersMadDog2014.pdf
Alpha Dog: http://www.innerfidelity.com/images/MrSpeakersAlphaDog2014.pdf
Alpha Prime: http://www.innerfidelity.com/images/MrSpeakersAlphaPrime.pdf

I even picked up some distortion messiness on the Alpha Dog I used to own when I measured it (keep in mind my measurement rig has some limitations, especially with THD in the bass): http://www.head-fi.org/products/mrspeakers-alpha-dog-t50rp-mod/reviews/11615

Then with some of the other measurements floating around for various MrSpeakers headphones, I think it's safe to assume these aren't the cleanest when it comes to distortion.

Again, part of this is T50RP driver limitation, and part of it is just how Dan does his thing (IME there are other well-known T50RP mods that have lower/smoother distortion characteristics). Product variation will play a role, across both the T50RP drivers and how closely Dan matches each unit. Then you have to consider what volume you listen at, as lower volumes aren't going to put out this level of distortion on the T50RP. What sort of music you listen to will affect how much of a role this distortion plays, as will personal sensitivities to it. I know some are more sensitive to distortion than others.

Like I said, I have not heard the Prime, but I own the MD 3.2 and owned the Alpha Dog. I never found the distortion on those two to be subjectively problematic. But I think I might hesitate to spend $1K on the Primes due to these limitations.

 

[wahsmoh]

I still think measurements can be moot when it comes to the subjective/objective performance of a headphone. Like you mentioned above, the T50RP driver to driver variation can account for differences people hear between the AD and AP models.
 
I have spent a considerable amount of time with the HD650/DT880 and although they measure better performance wise, that is hardly the telling tail when I heard them together at numerous events(and at home).
 
I always found the HD650/DT880 to be not as realistic when it comes to image/depth of soundstage, even in comparison to a closed headphone like the AD. Tonality wise the AD is spot on, the HD650 and DT880 have catching up to do.. how could they sound more realistic when tonally they have more faults??
 
The HD650 is less fatiguing than the DT880 and I am sure that has mostly to do with the mild treble spike that the DT880 has. I listened to the HD650 though with Vinni Rossi's LIO at CanJam 2015 and found it had a similar treble spike as the DT880 (albeit with better/deeper bass and more clamp force) The unmodified HE-560 was even worse when it came to that lower treble spike I heard... I heard all of the following (except the DT880) on the same setup so maybe I could attribute that to the source more than the headphones themselves? I am delving deeper into territory that is very very debatable.. are these spikes attributable to the headphones or the DAC?? 

 

[mrspeakers]

Certainly at $1K people are justified in being more demanding, but I think the THD conversation has some problems that I'd like to put my $.02 in to discuss. 
 
First, I think Tyll's measurements are very representative of Prime. 
 
Second, the other headphones Ultrabike compared to Prime are open.  This is worth noting because open and closed phones serve different purposes and have different strengths and weaknesses.  Also, IMHO it's easier to get better measurements in open phones, as they don't store energy off the back of the driver.  And while their THD may be lower, not only does that tell you nothing about how they sound, but a 650 and 880 would surely suck on a plane or bus, or many other applications where isolation matters.  Our specialty has been making closed headphones that someone who has open phones can use when open is not useful, or for someone who wants one headphone for general use at home or about.  We don't claim we're better than open, only that we have a closed phone that can deliver an experience some find "open" while having isolation.  Comparing open headphones to closed without considering usage is like comparing a convertible to a sedan with a moon roof, which one is better is not obvious without factoring the users' needs, and once the needs are considered the choice may be obvious.
 
So to the data; looking at the THD chart Ultrabike pulled, at 90dB (red and blue) THD is very well behaved and consistently at or below 0.5%, with several blips it's roughly 2x the THD of the other phones except for a pop to 1% at 600Hz.  Yup, the 650 and 880 are better above 200 Hz by roughly a factor of 2 in THD.   But if you look at high-end closed cans from Innerfidelity you'll see THD is more competitive.  That'd be a bit more apples/apples. 
 
Moving on, at 100dB (green and yellow) distortion increases in two midrange THD peaks but decreases in the lows, lower mids and highs.  I'd rather it decreased everywhere, but there are limits to the Fostex driver and this is one. 
 
The THD spikes are about 75Hz wide where they cross the 1% THD line at 500-575Hz, mapping to middle C, C# and D. The two THD peaks above 1% are two notes wide at 100dB while THD drops most everywhere else to very low levels, so there's a bit of give and take. I suspect most people view a headphone in a more holistic sense, and a single variable is one of many to weigh, especially if the variable only comes into play at 100dB.  And at 90 and 100dB, bass THD is extremely flat and low.
 
Most people don't listen much at 100dB continuous, or if they do, harmonics are the least of their problems.  Yes, we have higher THD in these two midrange bands at 100dB, but the focus here on this has totally ignored the fact that the bottom four octaves have way better THD than the open cans, and that the extremely solid frequency response, square wave, isolation, and impulse measurements Tyll measured with Prime look really good.  With all the obviously good attributes Prime has, why  focus on THD as if that's the only thing that determines a phones sound? Maybe for some this is the case, but I suspect for most people the conversation or listening is a bit more nuanced than one variable.  Is horsepower the only determinant of car quality? 
 
In the end, there are many reasons to like a can; color, weight, fit, frequency response, PrAT, inner detail, THD, transient response, waterfall response, whatever.  Prime performs really well on every test Tyll ran, except THD at 100dB, where there were both negative and positive changes in the THD.  I think most people consider frequency response, impulse response, isolation, comfort and many factors, and treating THD as the Holy Grail kind of misses the big picture, but that's just my view.  Maybe I'm stupid, or nuts, or both. But I look at the headphone as a total solution.  In my view, THD is important, but it's only one parameter that affects sound. 
 
I am really proud of this headphone, and enjoy it a lot.  For those who don't like the mids, or any part of the experience, thanks for giving them a try.  Maybe next time!.  And for those who enjoy it I'm really glad, that's why I go to the office every day.
 
I appreciate the time and thought that's been put into all these postings, pro or con, and I sincerely hope nobody thinks I am saying their impressions and perceptions are wrong.  I felt that when it comes to data interpretation I had to say my piece, as I think the topic is complex, interesting, and that a few assertions were made seemed technically incorrect, or perhaps incomplete.

 

 

[money4me247]

* at above post. very insightful & straight talking feedback

edit: typo frowny face in the kudos. used a smartphone touch screen =S

 

[TMRaven]

Dan, I think you misinterpreted Ultrabike's bass distortion comments by saying he misinterpreted it.  He never said sound leakage or lack of isolation leads to excess bass distortion numbers.  On the flip side, he's most likely saying that a lack of seal leads to less than ideal low bass control, which in turns can lead to rolloff and/or distortion in the low bass.

 

[mrspeakers]

  Dan, I think you misinterpreted Ultrabike's bass distortion comments by saying he misinterpreted it.  He never said sound leakage or lack of isolation leads to excess bass distortion numbers.  On the flip side, he's most likely saying that a lack of seal leads to less than ideal low bass control, which in turns can lead to rolloff and/or distortion in the low bass.

 
I re-read it, yes, I mistook what he was saying.  Edit coming!  Thanks for pointing that out.

 

[vtrinidad87]

  Certainly at $1K people are justified in being more demanding, but I think the THD conversation has some problems that I'd like to put my $.02 in to discuss. 
 
.....

 

(Shortened your quote for browsing convenience.)
 
I'm a big fan of your views, conduct, ear for music, etc.
 
I appreciate your hard work and love your products! Keep it up!

 

[ultrabike]

  ... 

 
I understand that open and closed headphones have different issues to contend with and indeed could be considered to belong to different classes. However, folks specifically asked about comparisons between the ADP, 650 and 880.
 
I don't think THD plots are the Holy Grail of audio performance. But I wouldn't minimize them, and I do feel they contribute to perceived audio performance.
 
To compare "apples to apples" here are the THD plots of some pretty decent closed type cans that have IMO good frequency response, isolation, presentation, square waves, color, weight, PrAT, inner detail, transient response, waterfall curve, impulse response, and whatever. 
 
Focal Spirit Professional:
 

 
NAD Viso HP50:
 

 
Here is the ADP again:
 

 
Also at 90 dB, distortion is not < 0.5% across the board. For this particular ADP sample it is over 1% between 600 and 700 Hz. It may not be a big deal for some though.

 

[mrspeakers]

Yup, that's the same 1% I noted.

 

[SanjiWatsuki]

In all honesty, we probably shouldn't concern ourselves too much with the raw THD+N numbers.
 
We know that distortion at higher signals is less perceptible than distortion at lower signals [0]. Due to the masking effect, we've also observed that even low order distortion as high as 42% can be inaudible to some individuals [1]. Furthermore, the masking effect increases with higher frequencies [0].
 
For this specific example, the ADP has distortion in lower frequencies around 500-575hz. The distortion is heaviest at louder listening volumes, so the masking effect may help hide it.
 
The real question is what order distortion is making up the THD+N numbers? If the number has a good amount of higher order distortion, it could be noticeable*. We know from research that even 0.1% distortion, if far enough away from the excitation frequency, is enough to be noticeable by untrained college students with normal hearing sensitivity [2].
 
* "Noticeable" distortion would sound perceptibly off, but not like static or anything extreme like that. 
 
[0] Geddes, Lee. Auditory Perception of Nonlinear Distortion I. 2003.
[1] Temme, Brunet, Qarabaqi. MEASUREMENT OF HARMONIC DISTORTION AUDIBILITY USING A SIMPLIFIED PSYCHOACOUSTIC MODEL - UPDATED. 2013.
[2] Geddes, Lee. Auditory Perception of Nonlinear Distortion II. 2003.

 

[takato14]

  In all honesty, we probably shouldn't concern ourselves too much with the raw THD+N numbers.
 
We know that distortion at higher signals is less perceptible than distortion at lower signals [0]. Due to the masking effect, we've also observed that even low order distortion as high as 42% can be inaudible [1]. Furthermore, the masking effect increases with higher frequencies [0].
 
For this specific example, the ADP has distortion in lower frequencies around 500-575hz. The distortion is heaviest at louder listening volumes, so the masking effect may help hide it.
 
The real question is what order distortion is making up the THD+N numbers? If the number has a good amount of higher order distortion, it could be noticeable*. We know from research that even 0.1% distortion, if far enough away from the excitation frequency, is enough to be noticeable by untrained college students with normal hearing sensitivity [2].
 
* "Noticeable" distortion would sound perceptibly off, but not like static or anything extreme like that. 
 
[0] Geddes, Lee. Auditory Perception of Nonlinear Distortion I. 2003.
[1] Temme, Brunet, Qarabaqi. MEASUREMENT OF HARMONIC DISTORTION AUDIBILITY USING A SIMPLIFIED PSYCHOACOUSTIC MODEL - UPDATED. 2013.
[2] Geddes, Lee. Auditory Perception of Nonlinear Distortion II. 2003.

This is a good point actually. Tyll's measurement rig sums all of the distortion orders together for the sake of simplicity. However, there are measurements available of the Alpha Primes done on a rig that has all of the individual distortion orders plotted instead of Tyll's summed plots. On these, D2 is by far the highest, but D3 and D4 have a lot of tall, narrow peaks as well. The HE-560, HD600, and HE-500 have far lower distortion numbers in all orders when measured on the same aforementioned measurement rig.
 
As for the question of audibility, everyone's ears are different. If you can hear it, fine, the headphone probably isn't for you. If you can't, that's fine too, keep it and enjoy. Just don't belittle people who disagree with you. Your personal experience is the only thing that matters.

 

[hans030390]

 
I understand that open and closed headphones have different issues to contend with and indeed could be considered to belong to different classes. However, folks specifically asked about comparisons between the ADP, 650 and 880.

 
Don't forget the closed, planar PM-3. Funny how the open PM-1 and 2 are the ones that struggle with distortion, haha.

 

[SanjiWatsuki]

  This is a good point actually. Tyll's measurement rig sums all of the distortion orders together for the sake of simplicity. However, there are measurements available of the Alpha Primes done on a rig that has all of the individual distortion orders plotted instead of Tyll's summed plots. On these, D2 is by far the highest, but D3 and D4 have a lot of tall, narrow peaks as well. The HE-560, HD600, and HE-500 have far lower distortion numbers in all orders when measured on the same aforementioned measurement rig.
 
As for the question of audibility, everyone's ears are different. If you can hear it, fine, the headphone probably isn't for you. If you can't, that's fine too, keep it and enjoy. Just don't belittle people who disagree with you. Your personal experience is the only thing that matters.

 
I've edited my post to reflect that the inaudibility of the distortion in this case is constrained to certain individuals and is not universal.

 

[dusk]

I just got my primes with some doggy treats.. is there a guide for tuning the bass port and the driver somewhere? I couldn't find anything on Dan's site.