RETRO: Beyerdynamic DT 990, 600Ω, classic open-back circumaural headphones (circa 1991).

This week, I thought I would do a "retro" measurement of and listen to a headphone from the days of the Cold War. ;-)

Above, you see the 600Ω impedance Beyerdynamic DT 990 (forefather of the current DT 990 Pro, ~US$150), a pair of headphones lent to me by my buddy linnrd that he has had in his archives of audio equipment for quite awhile. As you can see on the box, these were made in W. Germany and purchased back in 1991, a couple of years after the fall of the Berlin Wall; either in Düsseldorf or nearby Essen I was told. The history of these headphones began back in 1981.

For headphones of this vintage (>30 years old), they are in great shape although in the image above, notice that I had replaced what used to be a thin layer of disintegrating black foam inside the earpiece with some bluish 1.5mm felt which I had used in my Dekoni Blue mod last year. So, not exactly a "stock" unit but pretty close.

REVIEW / MEASUREMENTS: CCA (Clear Concept Audio) C12 IEM - 1 Dynamic + 5 Balanced Armature Drivers - are more drivers better? (Plus new analogue disc technology, cable-maker Russ Andrews interview.)

Earlier this month, as I was preparing the final write-up for the KZ ZSN Pro review, I was impressed enough by the performance of those very inexpensive IEMs (less than US$25) to go ahead and grab these CCA (Clear Concept Audio) C12 (US$50) earphones to see how an upgrade at twice the price would perform in both listening and measurements. Note that CCA is a related company to KZ so when we look at the open-box image above, we see that the contents are similar. We have this time a braided ear-loop cable (that's still easy to get tangled), also 1.2m in length, a couple of info pamphlets, 3 extra sets of silicone ear pieces, same as the KZ ZSN Pro.

At twice the price of the KZ, the hope here is that these would represent a significant sonic upgrade across a number of domains. On the surface, a major talking point for these headphones is that they consist of a more complex arrangement of drivers which in theory could provide more accurate coverage across the audible frequencies. Drivers in each earphone include a single larger 10mm dual-magnet dynamic/moving coil driver, and 5 small balanced armatures (two of which are reported as Knowles 30095, not sure the others). So that's a total of 6 drivers per ear piece, 12 both sides - hence "C12".

 

REVIEW / MEASUREMENTS: KZ ZSN Pro - very inexpensive dynamic + balanced armature IEM. (And the importance of the audiophile "low end" and meaningful succession.)

Since I believe much of high-fidelity audio is already "mature" technology, these days a lot of what I find interesting are products that either present new features for the music lover (and audiophile), or devices that are of high value. In a present era of inflation and energy price shocks, "value" I think for most people has become even more important into the foreseeable future. As discussed in the past, the price of luxury items is usually a reflection of non-utilitarian benefits rather than actual sonic fidelity; that is basically the epitome of the "high end" moniker, behind which, much snake oil is allowed to thrive.

In this post, let's have a look and listen at an IEM which I think absolutely represents a member of the "high value" class of products! At less than US$25, the KZ "Knowledge Zenith" ZSN Pro IEM is at a price point that anyone can afford if you're in the market for some wired headphones these days (funny the designation "Pro" for something in this price point!). Considering the wide range of prices for headphones, it's the kind of thing you can throw in your travel bag and not worry if they get damaged.

The question of course is how do these sound!? Let's take a deeper dive into this...

MEASUREMENTS: 1MORE Quad Driver IEM (E1010)

For the post this week, let's have a look at the 1MORE Quad Driver IEM (~US$150 these days). These have been out for awhile; released in mid-2017 I believe. The specs on these are quite interesting given the asking price. Driver configuration seems complex with single dynamic driver and 3 balanced armature units within the relatively small capsule. The dynamic driver is advertised as being some kind of "diamond-like carbon" (DLC) that covers bass and mids with the balanced armature units filling in at the higher frequencies based on the advertising material.

Furthermore, the headphone also has an integrated volume/playback control as well as a microphone when making calls.

The brand also prides itself on this being the world's first "THX Certified Headphone". I'm not sure exactly what that certification means; presumably some combination of testing to ensure low distortion and frequency response thresholds must be in the mix.

MEASUREMENTS: Etymotic ER-4B - "Classic" In-Ear Monitor (IEM) / "Canalphone".

Nice box with accessories. Can't see it well in this picture but in the middle of the box is a small container of "damper"/"filters" and tool to aid in replacement when clogged.

Today, I want to expand the measurements of headphone-type devices to include examination of in-ear monitors. As usual, before posting measurements on a range of devices, I believe it's important to set the ground work as to how it's being done and to what relative "standard". I believe this is useful because when I use subjective descriptions, I think it's always nice to refer to context on the objective side. I have seen numerous reviews use things like star ratings or sometimes seemingly arbitrary "3.5/5"-type scores, but without more concrete, specific examples, often the reader is left without a sense of actually what is being described nor have a "hat to hang on to" when talking about relative differences with another product the reviewer might also be pointing to.

Similar to the AKG K371 back in April 2021 as a discussion of headphone measurements for circumaural (and supraaural) devices, today, I want to focus on one of the first IEM-type (In-Ear Monitor, also called "canalphone") transducers I bought back in the early 2000's. This is the classic noise-isolating Etymotic (often stylized as Etymōtic) ER-4B microPro Earphone. The very first ER-4 came out in 1991 and I believe the 4B version I have is reflective of the intent of that very first design.

While this specific ER-4B model has been discontinued for awhile now since early 2010s, there are still a number of ER-4 series products out there including the ER-4XR ("eXtended Response" meant for "music lovers" who want a bit more bass) and ER-4SR ("Studio Reference" for flatter frequency response). 

As suggested by the variants, Etymōtic makes these earphones for different target uses over the years. This '4B' model was meant for technically accurate "Binaural" monitoring purposes. Etymotic aimed for a flat response that follows a "diffuse field" target (great discussion here on the different targets BTW). 

MEASUREMENTS: 1MORE Triple Driver Over-Ear Headphones (H1707) with wired remote & microphone. And on Galen Gareis / Iconoclast Cables interview recently.

Alright folks, on the test bench this week is the 1MORE Triple Driver Over-Ear Headphones (let's just shorten name to 3DOE). If you've seen this headphone over the years (released around Christmas time 2018), you'll probably know that we need to clarify a couple of things.

First, they're not actually "over-ear" as in truly "circumaural" headphones. The earpads/cups are not big and unless you really have small pinnae, will sit "partially circumaural" with portions against the pinnae like supraaural designs.

Secondly, it's more of a "dual" driver design rather than "triple". There are 2 active drivers - a graphene-coated 36mm mylar dynamic driver, and a 10mm ceramic/piezoelectric driver for treble. The third "driver" is the passive "bass reflector", much like speaker passive radiators but inside a closed headphone reinforcing a certain amount of bass response.

The silver model like the one I have here is the graphene-coated version. There is also a gold-colored version out there which is a titanium driver without the graphene layer. I've seen comments that the sound is similar between the two versions. This one was bought through the regular Amazon retail channel (on sale for <US$150) and as far as I can tell, is the current model with an inline remote control plus microphone good for use with your smartphone.

REVIEW / MEASUREMENTS: (Mass)Drop + HiFiMan HE-4XX Planar Magnetic Headphones (with Brainwavz XL Round Hybrid earpads). Maintenance if the earcup detaches.

Well, as I've mentioned previously, I don't really need more headphones. ;-) Alas, I could not resist picking up these minty Drop + HIFIMAN HE-4XX Planar Magnetics locally used at a price I could not refuse! I also love how they look with the classic headband. The matte "midnight blue" color looks like a dark charcoal with a subtle powder bluish tinge.

I know there have been different opinions on the build quality of these headphones. Some of the early units had issues with right-left imbalance, driver failures, and broken hinges. According to this post, it looks like replacements with serial number 5XXX have many issues fixed. My unit here has serial number 57XX.

The hinge where it interfaces with the headband feels robust on this unit and I think the build quality is very good. The steel gimbal and metal sliders seem like they will be able to hold up to daily use. No complaints there. I did have an issue with the part interfacing the ear cup which I'll discuss below.

The stock cable is a little short for my taste at around 5'/1.5m (6' would be better for my desktop use). Notice that the cable is angled 90°, terminated with a 3.5mm connector which is fine for mobile use. I think a straight cable would have been preferred since most buyers would likely be using these open headphones at home almost exclusively. I like the soft, pliable nature of the cable although I have read some complaints that it can kink and fail. I don't think there's an issue, replacements are not expensive anyway.

REVIEW / MEASUREMENTS: Dekoni Blue ("Approved" Fostex T50RP Mk 3 mod). And the importance of the room for hi-fi reviews (Wilson Chronosonic XVX speakers in Stereophile).

As you can see in the image above and might know already, these are essentially Fostex T50RP Mk 3 headphones which have been out since 2015. In 2018, the Dekoni company (which makes aftermarket headphone pads and accessories mainly) decided to make a licensed version of the Fostex with their own earpads and blue esthetics - hence the Dekoni Blue (~US$250). If you want a little more background, here's Dekoni's "Short Essay..." on the product.

If you've used Fostex headphones before, I think you'll appreciate that the stock ear pads are thin and rather uncomfortable so upgraded earpads are mandatory for long-term use. When I got these, it was less expensive that a new Fostex + upgraded earpads.

MEASUREMENTS: Sennheiser HD650 (~2010-2012) and HD800 (~2010). A comparison of two "Reference Class" headphones, and a look/listen to the "Sennheiser veil / darkness". [Inexpensive 2TB SSD and inflation in consumer electronics...]

As you can see in the picture above, this is a bit of what the "box opening" looks like when you buy either one of these "Reference Class" Sennheiser headphones.

Much has already been said about the headphones being measured today. The Sennheiser HD650 was originally released back in 2003. Of interest historically, there was a fire in the Ireland factory back in 2004 so there probably are not many older pre-fire HD650's floating out there. Tyll Hertsens' article about the Sennheiser HD580/600/650 is a great summary and SolderDude has a ton of stuff on the HD650 on DIY-Audio-Heaven. SBAF has this "compendium" on the HD650 which I think covers everything... and more! Oh yeah, even NwAvGuy got one of these back in 2011.

These days, there's the Massdrop x Sennheiser HD6XX which would be the latest version of the HD650 discussed here, while the Sennheiser HD660S looks similar but has redesigned drivers.

Likewise, you already no doubt would have read about the Sennheiser HD800 over the years. These came out in 2009, sporting the large 56mm "ring radiator" driver (vs. 42mm transducer of the HD650). The HD800 has since been revised with the HD800S in 2016 (here's Tyll's take with mods discussions). Multiple reviews on Head-Fi. The HD800S sounds very similar to the HD800 to me.

For this post, let's look at measurements comparing the two and I'll put in my 2¢ on the sonic differences as I hear them.

REVIEW / MEASUREMENTS: Drop + THX AAA 789 Linear Headphone Amplifier. And on Audioholics' THX Onyx DAC/amp "review" with a dash of MQA nonsense...

With much of my soundroom and other parts of the audio system sorted out to my satisfaction these days, I thought it would be time to start paying a little more attention to the headphone side of things. As you can see, in the last few weeks we've talked about the AKG K371 headphone, and prior to that some discussions on impedance and power.

Prior to about 2013, I was very much into headphone stuff when the kids were babies and louder music playback was simply not an option. Thankfully this all changed when the basement man-cave became available! ;-)

When writing about headphones and reviewing, it's important to have a good foundation set-up for "reference" listening. This means I would need a good headphone amplifier on my desktop Workstation computer; one that would support and optimize playback of some of the more hard-to-drive headphones - those with challenging output impedances and lower sensitivities. In alignment with that goal, I have the Drop + THX AAA 789 Amplifier on my table these days as you can see above.

REVIEW / MEASUREMENTS: AKG K371 (closed-back, over-ear, dynamic driver) - An affordable, modern, standard studio headphone. (And on using the miniDSP [H]EARS rig.)

Hey guys and gals, the post here today will be on the longish side since this is the first time I'm writing a headphone review with some measurements. Best to take the opportunity to discuss the testing itself as well as product impressions.

As you can see above, today we'll be considering the AKG K371, an inexpensive (~US$120) "studio" 50mm dynamic headphone that's easy to drive, with a sound signature based on Harman research into headphone tonality - see this nice presentation from 2017 containing a review of the various research over the years.

I bought these headphones from the usual retail channels.

First let me show you some pictures of these particular headphones, and later, we'll get into measurements with the inexpensive miniDSP (H)EARS test fixture.

MEASUREMENTS / MUSINGS: Headphone impedance, sensitivity, efficiency, and amplifier output impedance. (And a quick thought on Darko's "All You Need Is...")

Some people have walls of headphones. Well the other day I thought I'd take out my little collection accumulated over the last few decades around the house, some of them used by the kids, and let's dump them on the sound room ottoman to have a look :-).

The majority are based on dynamic drivers with a couple of balanced armatures (Etymotic ER-4, 1MORE Quad Driver). I'm actually missing a few there that were in use that evening by others around the home - the Dekoni Blue (an officially sanctioned "modded" Fostex T50RP Mk 3) planar-magnetic, the AKG K371, and Apple AirPods Pro (wireless) which my wife had brought to work and "forgot" to bring home that evening.

I was curious about the impedances of these devices and thought it would be good to put together a summary article looking at this along with the power needed to drive headphones and correlating these characteristics with amplification.

Although I have spoken of the importance of mobile audio in the past, I really have been remiss in not putting enough emphasis on this trend or the importance of headphones in these blog pages over the years. Despite this, some of the most common E-mails I've received over the years have actually been about headphones. So let's make sure to incorporate some "head-fi" in the days ahead!

Redscape and Creative Super X-Fi Amp: Headphone Virtualization

Thought I'd take a little break this week from all the amplifier discussions recently and post on something rather different!

I enjoy headphone listening... But not as much as actual speakers in an actual room :-). I see headphones more as a tool for detailed listening, and will reach for them out of necessity when I'm on the road or for private listening. Otherwise, I would much prefer to be enjoying the sound from my speakers.

Beyond typical reasons such as comfort (no matter how comfortable, I'm just not a fan of things touching the ears or around the head), a big part of the issue is that headphones have never sounded natural to me. Subjectively, the "inside the head" sound, while I can get used to, just isn't an experience that I find particularly pleasurable. A reason I bought the Sennheiser HD800 a number of years back was because it was said that these headphones were capable of projecting sound so that the experience was more outside the cranium. Alas, if one is expecting any headphone to do this well, there will be inevitable disappointment; unless you're applying some kind of playback processing like crossfeed, the physics will not permit such a thing. As a result, I am intrigued by ways of making that head-fi experience more life-like which is what the products today can potentially do.

Quick Review: Inexpensive Spigen Legato Arc wireless Bluetooth headphone with aptX. And an attempt at "getting through"! (Magazines & blogs nothing more than audio Industry advertising?)

As I head off camping for the week, I thought I'd mention an inexpensive impulse buy the other day... Something to consider if you're thinking of getting into wireless Bluetooth headphones on a minimum budget. For ~$US60 (hmm, I just saw it's currently ~$70), here's the Spigen Legato Arc wireless headphone with aptX:

Comes with a couple sets of extra ear pieces in the bag (large, small), charging microUSB cable and manual. Notice that I extracted the left ear piece in the picture while the right side is compactly retracted.

I was in fact able to grab this for ~$30 on Amazon Prime Day recently (hence impulse buy :-).