Planar Magnetic IEMS - An emerging segment?


I see, I am in the process of trying different combinations out now. I do hear some differences subjectively but I wonder if that would be the same if I were to do a blind test. I have yet to find any cable combination that has a very drastic difference in sound presentation. What I did find so far, in terms of measurements, is that seems that due to the lower resistance of silver cables in particular (or even the particularly shorter cables), the signal amplitude and thus loudness seems to be increased (albeit only slightly at about 2 to 5 db based on my measurements).

@pennstac I do own a set of Stax SR-001 MKIIs (fat cat modded). I found there was a significant difference in terms of bass after the mod than before. In my opinion, it seemed that the electronics on the amplifier was the limiting factor rather than it being an “electrostatic IEM”, that was preventing it from producing more bass. Even when I just switched the battery supply from the AA 1.5v series Alkaline batteries to parallel 3.7v Lithium Ion Cells (before starting the Fat Cat mod), there was already a noticeable increase in bass. I guess there were some limitations back then when Stax was first designing the SR-001s and these were addressed with the many mods that we see around.

Anyways, wishing you guys a happy 2019 and another great year of listening! :grin:


Happy New Year @DanicoLabs. You definately wont find a cable that makes a drastic difference anywhere IMHO. Cables will only bring very small differences. And it is a point of debate that they change sound at all. I am a believer but it won’t change much. Many will say it’s placeno and it may well be. But to my ears I hear subtle differences. Though I won’t pay huge amounts for cables.

You may find that in the end you don’t hear any change in sound for you personally. And that’s fine. At least you’ve remained open minded enough to try it. Also your point about resistance change may indeed be the cause of subtle sound differences. For me personally using a balanced cable made more of a difference than materials it was constructed from. As always it just my personal opinion. :grin:.


I agree wholeheartedly. IMO, cables make a difference up to the point of electrical functionality with a safety margin, but then (at best) they may slightly change the color one way or another. I strongly advocate buying low priced balanced cables, and spending more money on better headphones, balanced amps, and balanced DACs. In that order.

Recently I’ve been testing the resistance (ohms) on a whole lot of cables with my multimeter. With probe-to-probe contact it reads 0.2 or 0.3 ohms. With any cable I’ve tried it reads 0.4 to 0.9 ohms.

Regarding balanced cables, their potential impact can be demonstrated very simply with a multimeter. For example, I tested a TRS connector on one set of headphones – ground to left ~75 ohms, ground to right ~75 ohms. Left to right ~150 ohms. So, the common ground doubles the resistance and clearly can carry a signal to the other channel. With a balanced TRRS cable there’s no way to directly connect the left to right grounds, and no way to cause substantial interference with the other channel [barring shielding issues and cable damage.]


I’ll be getting a loaner of the RHA CL2 soon from RHA. Excited to hear what the polarizing fuss is all about. The measurements show some crazy upper-mid spike that seems to be very polarizing. I tried to EQ my UM ME1 to have the same measurement response and it was weird, but I’m excited to hear it for real now.


Wow nice! Will you be posting any review of it? :grin:


I’ll probably post some impressions for sure


I this the RHA iem with Ceramic driver? I should probably look this up myself. :grin:. Anyway it’ll be good to hear your impressions.


RHA CL1 is ceramic driver. CL2 is planar magnetic


Unique Melody ME1 (left) and RHA CL2 (right) Planar Magnetic IEM buddies

I was out last night so didn’t get a lot of listening time. My quick initial impressions are: very comfortable. great build quality. very detailed and fast. lean bass. a little too bright and slightly off timbre. good soundstage and imaging.


Here’s some I took today using EARS and Dayton IMM-6 + 2mm wall thickness rubber tubing:

RHA CL2 vs Unique Melody ME1 (CIEM) – EARS Diffuse Field Compensated (based on Etymotics ER4)

This a comparison of the raw measurements from my two measurement setups for each IEM

This is a Waterfall CSD chart using the Dayton IMM-6 setup. Basically looks like the RHA CL2 is faster in the mids and treble, while ME1 has similar bass response. I think the bass region on the charts is probably not very accurate. I think the CL2 attack is probably faster than the ME1.


These are interesting measurements. Actually shape of the curve of the UM ME1 seems to remind me somewhat of the i-Sine 20. There is an initial peak at around 3-4 Khz and thereafter it remains flat in the mids and tapers downward after 10K.

Whereas the shape of the RHA CL2 follows a V-shaped profile with a similar peak at around 4 Khz and then another peak at around 12-15 Khz. I wonder if the closed design of the RHA reflects the higher frequencies more efficiently as opposed to open designs like the UM ME1 and the i-Sine 20.

To your ears, would you say the highs of the RHA CL2 are sharper than the UM ME1? Did the V-shaped profile affect your perception of soundstage


Here is a post I made on another forum where the CL2 sound is more controversial :slight_smile:

My weekend impressions with it so far seem to think that male vocals sound fine and female vocals are slightly veiled. The boost in that upper mid/lower treble region makes guitars and strings really emphasized so that you can hear every little pluck and cymbals extra splashy, but I find to sound a bit unnatural, especially when you listen to other headphones and IEMs and listen to speakers or a live show – I was at a concert this weekend for example. I actually do prefer headphones with a slight boost in this region – a couple of my favorite headphones/IEMs have a slight boost here, but this CL2 boosts an additional 5+ dB more, which I find a little more than necessary.

Sounds a little “tinny” in “Dreams”.

Switching tips does help tone some of it down, but still find it unnatural. The speed and attack is awesome but also, I think, makes it sound a little unnatural too.

EQ does help soften it though, and makes this sound a lot better.

Now to answer your questions:

The profile may look V-shaped, but the bass does not sound large. It actually sounds a lean and I think that has a lot to do with the fast attack and decay it has, so that the bass never hangs around long enough to sound like a mid-bass hump. In reality, I feel the ME1 has more weight to it, and sounds much more rich and filling.

The highs on the CL2 are significantly more sharper than really anything I’ve heard in a higher priced headphone. It reminds me of a cheap tinny V-shaped headphone in that sense, but it’s speed and clarity are really good. I feel like the clarity is really due to the lift in the treble, and not that it’s actually more clear than the ME1. The ME1 has a lot of detail in it but the sound profile is much more balanced, and leans a little dark with it’s treble roll-off.

The large peak in around 4KHz and at 12KHz makes some strings and cymbals very troubling and higher pitched female vocals sound just slightly off.

Again, EQ with a significant drop in those two regions makes these sound more accurate and softens a lot of the timbre issues. I think it behaves well to EQ luckily.