Articles, Reviews and Measurements of Audio Products

Drop Ether CX Review (Closed Planar Headphone)

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This is a review and detailed measurements of the DROP + MRSPEAKERS ETHER CX CLOSED planar headphones (made by Dan Clark Audio for Drop). Company reached out to me a couple of years ago to see if I would review them. At the time I was not testing headphones so said no but that I could use a low impedance headphone to test headphone amps. They offered the Ether CX and that is the main role they have had. Currently the Ether CX costs US $900 from drop.com.

I have been remiss in reviewing these because I have so many loaner headphones to test. Alas, it seems every day someone reaches out to me asking when I will test them so here we are.

The Ether CX has a professional and stylistic look to it with the carbon fiber finish:

Drop Massdrop Ether CX Review planar headphone.jpg


Two sturdy XLR cables terminate in a 4-pin XLR with supplied adapters to other sockets.

Ether CX is a bit on the heavier side given its large size:

lightest palanar headphone review.png


I find them comfortable to wear despite the...

JDS Atom Amp+ Review (Headphone Amplifier)

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This is a review and detailed measurements of the JDS Labs Atom Amp+ headphone amplifier. It was sent to me by the company and costs US $99. It was announced today.

The Amp+ follows the same recent industrial design in JDS amps and dacs:

JDS Labs Atom Amp+ Review Headphone Amplifier.jpg


It is light but functional. Dual gains are provided and single 1/4 headphone jack. The input selector chooses between 3.5 mm and RCA connectors in the back:

JDS Labs Atom Amp+ Review back panel Headphone Amplifier.jpg


As you see power is provided through an external AC transformer.

JDS Labs Atom Amp+ Measurements
As usual we start with our "unity gain" setting which means the same input voltage is produced at the output. In the case of unbalanced amplifiers, I use 2 volts which is the nominal maximum output of desktop DACs:
JDS Labs Atom Amp+ Measurements Headphone Amplifier.png


I would expect stellar performance from JDS and that is exactly what we see. Distortion is incredibly low at -130 dB (15 dB better than threshold of hearing). A 60 Hz tone is also...

Bose NC700 Review (Noise Cancelling Headphone)

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This is a review and detailed measurements of the Bose NC700 Bluetooth noise cancelling wired and wireless headphone. It was kindly purchased by a member new and drop shipped to me. The NC700 costs US $379 on Amazon including Prime shipping.

I must say, this is one of the most luxurious looking and feeling headphone I have seen:

Bose NC700 Review Noise Cancelling Headphone Wireless Bluetooth.jpg


The material is super soft-touch reminding me of silicone insulation on wires with such. The adjustment mechanism is super clever with that sliding bar which even allows some amount of movement for the cup. Top dollars were spent on mechanical and industrial design to be sure.

The cups are pretty small but still, mostly fit my ear. Inside dimensions are 70 x 56 x 24 mm (height, width, max depth). The cup depth is highly variable as the baffle is angled. The light weight of the NC700 helps a lot in comfort:

best noise cancelling headphone review.png


It took me two days to test what should have been a 2 hour affair. As with all...

SMSL VMV A2 Review (Stereo Amplifier & DAC)

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This is a review and detailed measurements of the SMSL VMV A2 stereo "desktop" DAC and amplifier. It was sent to me by the company and costs US $999. VMV is the higher-end brand in SMSL lineup.

The look and feel of the A2 is similar to the latest line from SMSL:

SMSL VMV A2 Review DAC Stereo Amplifier.jpg


It looks nicer though in this "widescreen" presentation. The rotary encoder feels a bit looks physically but is very responsive.

As noted, there is an integrated DAC in the A2:

SMSL VMV A2 Review DAC Stereo Amplifier back panel DAC USB.jpg


I like the diagonal binding posts which gave me more room than I typically find in these smaller desktop amplifiers.

As set of stick on feet were provided that I did not like that much but they also supplied tall spikes which you may have to use to provide ample room for the little fan underneath to suck air into the unit:
SMSL VMV A2 Review DAC Stereo fan Amplifier.jpg


I could not feel much air moving though as the only exhaust are the two slots in the back. I rather have something moving air than...

Sennheiser HD 598 SE* Review (headphone)

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This is a review and detailed measurements of a Sennheiser HD 598 SE with replacement "leather" pads. It was sent to me by the owner with a funny note:

"Hello amirm. I have a pair of Sennheiser HD598s that I inherited. I hate them. I hate them the same way that one might hate a dog barking at 2 AM, or a romantic rival who stole one's lover. Please let me send them to you so you can justify my deep hatred. Then you can fire them into the sun."

The 598SE seems to be discontinued but it sold for $249.

I must say, I like the replacement pads as they felt quite nice to wear:

Sennheiser HD 598SE review open back Headphone.jpg


Helping with the comfort is the ultra low weight of these headphones:

lighest open back headphone.png


I am not going to give you the cup dimensions since they are not the originals.

Note: The measurements you are about to see are made using a standardized...

Rogue Audio Sphinx V3 Review (Tube Amplifier)

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This is a review and detailed measurements of the Rogue Audio Sphinx V3 integrated amplifier with tube buffer. It is on kind loan from a member and costs US $1,599.

The front panel of the Sphinx portrays a high-end look with its thick metal:

Rogue Audio Sphinx V3 SNR Review Integrated Tube Amplifier.jpg


Alas, that thin metal surrounding it, takes that impression away. I liked the very wide apart inputs and output terminals which "should" bode well for crosstalk measurements:

Rogue Audio Sphinx V3 SNR Review back panel phono Integrated Tube Amplifier.jpg


There is good bit of weight to the unit courtesy of power transformer. I like the inclusion of the balance control. As you see in the first picture, I had to use it to get same gain out of both channels.

Protection circuit was well done with automatic recovery and worked great no matter how hard I pushed it.

Internal amplification is provided by a pair of Hypex UCD 180 OEM class D amplifiers. A buffer state made out of tubes completes the picture.

The amplifier has won many accolades as indicated by...

OSD Nero Stream XD Review (streaming amplifier)

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This is a review and detailed measurements of the OSD Nero Stream-XD analog and digital streaming (wifi and Bluetooth) amplifier. It was kindly sent to me by a member for testing. It costs US $230 from Amazon including Prime shipping.

There is a bit of heft to this box considering its budget category:

OSD NERO STREAM-XD Review Streaming Amplifier.jpg


There is a rotary control for volume and input selection. Naturally with no display, you don't know the volume level. Various inputs are provided although USB is for storage device, not as a DAC:

OSD NERO STREAM-XD Review back panel Streaming Amplifier.jpg


I focused my testing on analog and Toslink inputs.

Like the inclusion of power supply in the unit which likely is the reason for some of its weight. In use, it got warm to touch but nothing concerning.

OSD Nero Stream-XD Measurements
Let's start with using the analog input and see how it does:

OSD NERO STREAM-XD Measurements Streaming Amplifier.png


Well, this is not good. There is strange/high noise floor plus plenty of distortion...

Combining measurement methods to get a more accurate EQ - MMM + Gated Nearfield + Klippel Measurements

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I posted this on the HTM-12v2 thread, but thought it was an interesting enough concept that people might want to do it with other speakers and thus I am posting the info here as well.

I had a fun little project today and wanted to add a layer of active EQ to my HTM-12v2 and wanted to compare various EQ possibilities and their results.

Based on the Klippel measurements I made an EQ filter in REW and then did moving mic method (MMM) measurements around my listening position (MLP) and got these results (results are separated to make them easier to see, and unfortunately I was running them with my subs, which are a little hot compared to the speakers.... so just ignore the low end to focus on what the EQ is going after)...

Monoprice THX-365IW Review (In-wall Speaker)

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This is a review and detailed measurements of the Monoprice THX-365IW THX Ultra certified, 3-way in-wall speaker. It was kindly purchased new by a member and drop shipped to me for testing. It costs US $400 from the company direct.

This is the first in-wall speaker we are measuring so I had to go through some prep to test it. Between the owner and I, we decided to build a back box using 2x4 American studs. The THX-365IW is made to hold on to drywall or plywood so I built the latter from scraps I had in my woodshop:

Monoprice THX-365IW Review In-wall Speaker.jpg


As you can see, the baffle is wider than the frame I built to give it some (small) approximation of it mounting on full wall. Clearly this is a compromise as making this much bigger would make it much heavier and harder to measure. I chose to not seal the back box enclosure as in typical application of it just mounted to a well, it enjoys a very large space behind it. I figured allowing leakage would reduce the back pressure on the...

DROP + SENNHEISER PC38X Review (Headphone)

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This is a review and detailed measurements of the DROP + SENNHEISER PC38X gaming headphone, i.e. has microphone included. It is on kind loan from a member and costs US $159 (normally $169).

The PC38X is made entirely out of plastic but somehow feels better than "cheap" with tightly fitting parts that have a touch of class:

DROP + SENNHEISER PC38X review Gaming Headset.jpg


Two sets of cups are provided, one is the knit-mesh which is what I tested and the other, velour. This is a very light headphone at just 250 grams:

lighest gaming headphone review.png


Cup inside dimensions are 69, 28, 31 mm (height, width and depth). The narrow width slightly pinches my ears but overall comfort is good. I almost forget I am wearing them.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so...
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