InnerFidelity September 2012 Update

Some of the headphone amps accumulated for measurement routine development. Back row (L to R): Cary Audio's new HH-1; Woo Audio WA3; Woo Audio WA6: Burson HA-160D. Middle row: SicPhones prototype; Lake People G109; Apex Butte; Lake People G103; HeadRoom Balanced Desktop. Front row: Corda Rock; ALO RX MkII; HeadAmp Pico; HeadRoom Portable Micro Amp; JDS Labs NwAvGuy O2.

Headphone Amp Measurements
Lots of progress this month on the headphone amp measurement program. As you can see from the photo above, I've been collecting a wide variety of amps for the initial test development. It's important for Brian (NA Blur on Head-Fi) and I to have amps that will measure as variably as possible so that we can set the scaling and parameters of the testing sequence to include all possible test results. The O2 should push the lower limits; the tube amps will likely poke at the outer bounds. The SicPhones should give some speedy results with its 1MHz bandwidth. (This is an amp that will show up on Kickstarter soon, and is a single-ended, single stage, constant current source amplifier based around a newly introduced Silicon Carbide depletion mode trench JFET manufactured by SemiSouth. It's currently planned as a sub-$500 amp, and it sounded clean as a whistle and fast, fast, fast without being bright to my ears.) It's super cool to get my hands on the new Cary HH-1 hybrid amp. Haven't had a chance to listen yet, but it's hybrid design should offer an interesting measured result. Other amps to be in the mix but not in the photo are the Asus Xonar Essence One, HiFiMAN EF-6, and likely a few more.

I've been configuring the various tests on the Audio Precision tester that will be called by the main test program, and saving the data in little spread sheets. Meanwhile, Brian has his computer all set up to emulate the tester so he can develop the main program, and has finished the first pass of the Excel spreadsheet template that the data gets stored in. Brian's been a champ in the process, these first steps preparing and familiarizing oneself with computer programs are very time consuming. It's always a struggle to get things started and working well enough to get the kinks out and see a little daylight. He's made great progress---notwithstanding the flat spot on his forehead and the minor sheetrock repair he'll have to do at home. I told him to wait on the repairs, there's surely more head-banging to come. Here's the first pass on the datasheet---ignore all the problems, we're just getting started here.


Thanks Brian!!!

Headphone Measurements
Not many headphones through the lab this month but I did get my hands on the new Denons. As usual I've updated the AllGraphs.pdf of course, and added the cans to the measurement datasheets page. New additions include:

  • Got the I-Mego Throne. "Who!?" you say. I'd never heard of them either, but I said okay to a PR press release just because of their resemblance to the classic Shure Super 55 microphone. Unfortunately they sounded muffled and wooly, and measured as such.
  • Spider sent me their new PowerForce on-ear sealed headphone. Despite the redundant name and earpieces that look like little Apollo space capsules, this little headphone sounded pretty darn good. May be one of the better bass-head cans I've heard in fact. I'm going to have to cue up some dub step and re-listen to all my thumpers ... this may be a good little headphone.
  • You know what chafes my chaps? Makers who discontinue a perfectly good headphone and replace it with something inferior. Denon did it with the AH-D1001 when they replaced it with the very colored AH-D1100. And now they've done it again ... aarrggghhh! The AH-DX000 line has been discontinued and the replacements have arrived. Despite measurements to the contrary, the AH-D7100 highest treble octave seems to have gone missing, and the mid treble is significantly blurred by some of the most horrific ringing that I've seen in a headphone. The AH-D600 fairs about the same, and the AH-D400 is missing it's top as well. I tried to measure the in-ear AH-C300, but the ergonomics of the earpieces made it impossible to insert in my dummy head. I had the same problem with my ears. I'm going to have to add a :facepalm to the smily list. Big thanks to HeadRoom for loaning me the first batch through the door so quickly.

A Big Surprise!
Since InnerFidelity's day one, I've been lobbying management for a build-a-graph tool like the one at HeadRoom. It took a while---it's a rather unusual request from a publishers point of view, usually measurements aren't that strongly desired in the audiophile world, and it's not an easy thing for non-headphone enthusiasts to "get"---but to the great credit of the team of folks around me, they did keep listening and I've recently been given the go-ahead, budget, and resources to have one built. WOOT!!!

InnerFidelity's graph tool output will look something like HeadRoom's shown here.

This will be a great boon to InnerFidelity readers as it will allow you to compare graphs and post comparison plots in forum dialog. It will also make it quicker for me to write the measurement section of headphone reviews and articles with lots of graphs comparing cans as currently I have to do a lot of Excel diddling to make the plots. I'm stoked!!!

Out for a Bit
I'll be on vacation from Aug. 28 until Sept. 5. I'm riding my FJR to the Bonneville Salt Flats for the Bub motorcycle speed trials, and then to party with imaginary internet friends on a farm in Oregon. So if I don't answer your comments it's because I'll be grinning from ear to ear under my helmet.


Okay, all you youngsters out there, BACK TO SCHOOL!!!

Audioaddict's picture

It's extremely sad to hear this, but when you said a new headphone maker's new headphone wa s a major dissapointment, I thought it could of been the M-100 you got measured, and it sucked. If that would of been the case my heart would of broke. 

Phos's picture

Treble looks pretty shelved to me

Alondite's picture

Oh man...I was just starting to get a handle on the headphone graphs, and now I've gotta figure these amp graphs out! Nonetheless, it's nice to see new things on the way. I see a bright future for IF.

As always, keep up the good work Tyll.

khaos's picture

Is there a problem with the JDS Lab O2's measurements? I doubt that it drops to -5 dB at 5 kHz.

thune's picture

From the article: "Here's the first pass on the datasheet---ignore all the problems, we're just getting started here."

Sounds like Tyll and Brian are working on the entire automated test and datasheet production flow, still working out the bugs. The datasheet is just a sample, showing what would be included.

Tyll Hertsens's picture

Oh yeah, problems all over the place. Don't worry about it, it'll all be fixed before primetime.

khaos's picture

Good luck!

FLAudioGuy's picture

@Khaos: Refer to the section-

InnerFidelity Headphone Amp Measurement Program Update July 2012

By Tyll Hertsens • Posted: Jul 17, 2012


You can see the O2 as measured by both NwAvGuy and Tyll (JDS Labs built) correlate very closely. The graphs shown there practically overlay each other. I don't know why the example graphs seen in this current section show -5dB@5kHz & -20dB@10kHz, most likely just a glitch that is being worked on.


I have both purchased (JDS Labs) and self-built O2's and, to me, they are about as musically flawless as it gets. You can trust the musicality and quality of the O2 as built by JDSL.


[Edited for clarity]

Viennophile's picture

Thank's for updating the measurments-.pdf-file, Tyll. yes

Regading to the measurements of the new D600 and D7100 Denons, there is only one thing that comes to my mind, (even more so being a fan of rather neutral cans):


Has Denon tried to simulate the sound of LCD-2s and failed totally by doing so?!

What's going on there?

Despite these "measurments of horror", I think the new Denon series will find its buyers.

Maybe some former students, who own and like Monster Beats and now, being older, "wiser" and richer, want to step up and go therefor to the realm of the new Denons.

The looks of the new Denons and Monster Beats are definitely close to each other.

mikeaj's picture

What are you talking about?  They're clearly superior to the old AH-Dx000 lineup! isolation only.  crying  I'm hoping that miraculously they manage to still sound good, but I'm not betting on that, what with the information we have now.

dalethorn's picture

I must have been looking at the wrong page last month when I checked out the graph on the Philps Fidelio M1, and then purchased it. Taking another look, the treble is almost nonexistent. I have to wonder if the kiddies who buy it are cranking up the volume just to hear the details?

rhfactor1's picture

I feel sorry for dedicated Headphone retailers like trying to convince the public to purchase the new Denon headphones with clearly such flawed designs. What is Denon thinking? I'm glad I purchased my D1001 years ago.frown

Tyll Hertsens's picture

Call 'em and ask for a recommendation of a top-level sealed can.  I bet you don't get the 7100 in the answer.

Willakan's picture

All looks great! I have one question: how are the amplifier measurements going to be analysed when they are first presented? Are they going to be looked at strictly with regards to what is above the threshold of audibility and what is not, or are we going to have speculations as to subtleties in the measurements of amps (amps you would expect to be transparent from said measurements) associated with what an individual professes to hear in sighted listening?

Can Crazy's picture

Totally looking forward to the avalanche of upcoming Amp measurements. And it's back to school alright, since some reading to make sense of the measurements and data will -at least in my case- be quite necessary.

Also, totally looking forward to the new graph tool in development; that's a really great initiative and certainly a very much valuable tool. Specially speaking of value, since at least my pockets aren't endlessly deep when it comes to spending on new gear, and it is always good to count on more than just impressions, no matter how well trained and refined. This initiative should definitely be emulated. 

Have a blast on the bike!


jeckyll's picture


Enjoy your ride, keep the rubberside down :)

I just got back from 9 days to California and back, it's good to be on the road.  

Also, looking forward to the amp measurements!

FLAudioGuy's picture

Great job Tyll & Brian! Looks like things are progressing nicely! I have really enjoyed reading the reviews on all things audio. I believe that you are helping the industry and consumers by raising the bar on acceptable performance and revealing those areas where improvement is still needed.

zzffnn's picture

That SicPhones amp looks interesting. Its kickstarter project has been launched:

I may want to pledge $55 for its PCB and Silicon Carbide JFETs. There is an option of pledging $279 to get a finished amp as well.

I made a thread at Hedfi's DIY forum, in case someone is interested:

Willakan's picture

Unprecedented clarity! Unimaginable wonderfulness! No specs whatsoever!

Let's see how it measures up before we get over-excited. With what information has been provided about the topology, I'm not getting my hopes up.

zzffnn's picture

^ I did not get overly excited, which is why I would not pledge over $55 without more information. I could not find much information about that amp. The inverview at 6moons indicates that the amp was inspired by Nelson Pass' Zen amp. There have been discussions at diyaudio regarding silicon carbide FETs. Interesting stuff, but not much information about circuit implementation or measurements.

Beagle's picture

Great news on the build-a-graph option.

Alondite's picture

I respect your opinion and know that you have a  wide knowledge base, so I was wondering if you could recommend me a good, ideally neutral (or as close as possible) amp for the Q701? I can only spend $300 at the absolute most, but would rather not spend more than like $250. Thanks in advance.

Satya's picture

Tyll may respond as well, but the O2 is about as transparent and neutral as you can get, plus has more than sufficient power for the somewhat inefficient Q701s.  You can get the JDS version of the O2, with the ODAC option, for what you are prepared to spend :-)

Tyll Hertsens's picture

I think the O2 is a very good little amp ... very good. I'm enjoying the heck out of the JDS Labs on I have.

Alondite's picture

If I were getting the O2, I might just go with the combo unit if the ODAC is any good.

dalethorn's picture

Where it says Phiton PS500, would that be Phiaton PS500?
Ultrsone HFI-450 - Ultrasone? (don't know if you're abbreviating...)
Ulrasone HFI-780 - same

dalethorn's picture

Someone complained (not here) that this post is a ding for spelling errors. Definitely no. I like to be able to search the big PDF for make and model, and these don't show up in the search results.

dalethorn's picture

The major problem with severely recessed treble that seems to have evaded everyone's radar is youth hearing loss. They're going to turn the volume up much higher with the dark 'phones, and there you go.

Can-man's picture

Tyll, thank you for creating such a informative website which is subjectve and objective in it's reviews. Will you be doing a full review of the O2 and odac?

Tyll Hertsens's picture

... if I'll be doing the review, but I'm pretty certain it'll get done eventually. They seem worthy to me.