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Moondrop May USB-C Headphones Review

Phenoez8

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Hello! This is a review and measurements of the new Moondrop May headphones. This is my personal pair and it costs US $65.

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I have been browsing ASR for a while now, but I have never posted anything here. I decided to write my very first review on this budget friendly USB-C DAC and headphone combo, as I am intrigued by the new wave of these DSP enabled headphones. This review will cover both the electrical performance of the DAC and the acoustic performance of the headphones driven passively.

Packaging and Physical Characteristics

I have to say I especially liked the box art on this product. Just look at the details here.

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The suit of clubs motif is because this suit is called Meihua(梅花) in Chinese, which directly translates to plum blossom. The name of the product, May(梅), translates to plum.

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Here is the information on the back of the box.

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Moondrop May headphones come with a USB-C DAC cable with a mic, inline controls, and interactive DSP, which you can control with an Android APP. The headphones themselves uses a hybrid driver design consisting of a 10mm dynamic woofer and a 6mm planner magnetic driver. Even with two drivers, the size of the headphone is nice and small, and I find it to be very comfortable to wear. Here is a size comparison with the Truthear Zero headphones, which also uses a two-driver design. I find the Moondrop to be quite a bit more comfortable than the Truthear.
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DAC Performance

I measured this USB-C dongle DAC. I believe this is the same DAC on the Moondrop Free DSP IEM cable.

Let’s start with the AP dashboard
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Performance is quite good. Max voltage output at the headphone terminals is about 1Vrms, which is lower than the thumb drive style DACs on the market today but is comparable to other dongle style DACs.

Let’s also check the dynamic range:
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Excellent performance.
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Jitter performance is good for its class but not state of the art.
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Since the headphones have an impedance of 33Ω, that’s what I tested the distortion with. The max output power is on par with products like the Apple Dongle. THD+N ratio is very low.
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Linearity on the DAC is not perfect. Personally, I’m not sure what would cause a problem like this. Please share your insight on the potential causes for this problem.
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Multi-tone performance is decent, but again not state of the arts.

Let’s check the frequency response and different tuning options that comes with the May. To change the tuning on the amp, you MUST have an android device and download the Moondrop app, which can be an inconvenience. Another surprise is that out of the box, a flat tuning is loaded on the DAC, NOT the Standard Tuning they advertise on the back of the box. If you haven’t checked the tuning on your May yet, I strongly recommend you do so.
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Setting the DSP to flat the DAC doesn’t have any issues. Let's check all the turning presets in the APP for May.
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As we can see, all the tuning presets are relatively conservative with the EQ, suggesting that Moondrop is starting with a solid acoustic setup and only using the EQ to fine tune the response.

Acoustics
Acoustic measurements are made with the IEC 60318-4(711) ear simulator and the medium sized ear tip that is included in the box.
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Channel matching between the left and right headphones is very good.
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The above measurement is imported into REW for easy comparison with target. When driven passively, the agreement to the Amir’s target is very good. They are basically within 2dB from each other until the dip at 6kHz.

Distortion performance is very good.
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I also measured the acoustic response with the standard tuning applied to the DAC, and here are the results
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Now the agreement with the target is even better, these two curves are within 3dB from each other until 12kHz. That is pretty well tuned.

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Finally, here is the impedance measurement of the headphones.

Conclusions
For $65, you are getting a package with good atheistic, comfort and impressive performance. The interactive EQ adds an extra layer of fun to the product, although the APP can be improved, and Moondrop should load the standard tuning at the factory to match the box advertisement. The DSP cable and the headphones are good enough to be standalone products, and Moondrop combined them in a way to amplify their individual strengths. I can recommend this product, and I am looking forward to seeing what Moondrop can come up with in the premium segment with this new form factor.
 

MCH

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Thanks for the review and measurements!
Question for you. Did you have the chance to measure if there was any performance decrease (say, for instance, SNR) when the DSP was engaged (=not flat)?
Thanks!
 

Jimbob54

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Good work.

My 3 biggest gripes with them:

No chin woggle on the cable above the remote (I need it)

Not enough length above the remote to add a woggle (those little velcro cables can be used)

App is woeful even if it "works'.

I ended up using the cable on another pair of iem and swapping for a dongle and a Zonie.
 
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Phenoez8

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Thanks for the review and measurements!
Question for you. Did you have the chance to measure if there was any performance decrease (say, for instance, SNR) when the DSP was engaged (=not flat)?
Thanks!
Hello! Thank you for your suggestion. I will consider adding this test to the thread later.
 
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Phenoez8

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If it's better than Truthear Zeros in the fit department then that's pretty epic. Truthear Zero has been my best fitting IEM so far.
There is nothing wrong with the fit of the Truthear Zero, but the May is noticeably more comfortable. The Truthear product is rather large and blocky with mostly straight surfaces, which is not exactly the shape of the human ear.
 
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Phenoez8

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Good work.

My 3 biggest gripes with them:

No chin woggle on the cable above the remote (I need it)

Not enough length above the remote to add a woggle (those little velcro cables can be used)

App is woeful even if it "works'.

I ended up using the cable on another pair of iem and swapping for a dongle and a Zonie.
Also the ear tips included in the box were way too difficult to put on.
 

Jimbob54

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Also the ear tips included in the box were way too difficult to put on.
Oh yes, mentioned that in my thread about them. Forgot as I gave up and used 3rd party (would have anyway)
 

Jimbob54

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I am looking forward to seeing what Moondrop can come up with in the premium segment with this new form factor.
The upcoming B3 Dusk will be the acid test. The app (and physical aspects of the cable) need some work before then or it will be a flop.
 

mc.god

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Thank you, really appreciated.
1 volt max output seemed a bit disappointing, then you think about this not being a dongle which you can plug whatever headphone you want or use it as a line output but can drive only iems and suddenly it seems more than enough.
Very nice measurements both the cable and the iems, hope the app will be improved soon.
 

DOuG pRATt

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I have a couple of almost-free USB-C DAC adapters. One came with the first generation of the 7Hz Salnotes Zero. Both of them have the low-level hiss that I associate with cheap op-amps. Neither is as bad as plugging into the earphone jack of a Roku remote, but the noise is definitely present. How is the Moondrop DAC/amp in this regard?
 
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Phenoez8

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I have a couple of almost-free USB-C DAC adapters. One came with the first generation of the 7Hz Salnotes Zero. Both of them have the low-level hiss that I associate with cheap op-amps. Neither is as bad as plugging into the earphone jack of a Roku remote, but the noise is definitely present. How is the Moondrop DAC/amp in this regard?
There is no audible hiss when no audio is playing.
 

Ron Texas

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$65 is a nice price and they measure well. Maybe I'm old school and love my HD650's too much.
 
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Phenoez8

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It means the cable is removable from the iem? So it means it is a DAC you can use with the app to power any iem mechanically compatible?
Yes. Moondrop sells just the cable with a different name. It is the Free DSP cable if you just want the cable.
 
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