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Panasonic RP-TCM125 Review (Budget IEM)


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
This is a review and detailed measurements of the Panasonic RP-TCM-125-A in-ear monitor. I purchased this from Amazon and costs US $15.10 including prime shipping (retail $19.99). I picked this because it was used in Olive et al. research (see below). Yes, folks, we are getting into measurements of IEMs! :) I have a bunch which have come for review and I constantly get offers to test more. So I finally allocated a bit of time to see how my GRAS 45CA fixture can measure them and to my delight, it was dead easy, far more than any headphone I have measured! Time will tell however as I measure more whether this is typical or not.

To that end, this is also an introductory thread on IEM measurements. So go ahead and say your peace now and here instead of polluting future review threads.

One "problem" with IEMs is how to take pictures of them so I apologize for the crappy nature of this one:

Panasonic RP-TCM125-A Reviewed IEM in-ear monitor headphone.jpg

The dual panther rating means no-EQ on the left, and with EQ on the right.

Panasonic RP-TCM-125 Measurements
Good bit of work was involved in creating the target for IEMs which is different than over or on ear headphones I have tested before. So do note this as you look at the frequency response graph:

Panasonic RP-TCM125 Frequency Response Measurements.png

Synchronization point of the measurement and preferred reference is around 425 Hz as usual. I was puzzled by this response thinking I was doing something wrong seeing how the bass response is well above reference and the rest well below. Fortunately as mentioned, the non-A revision of this headphone was part of the research from Harman. They don't associate the graphs with the headphones in the paper but man, did I get close to the IEM indicated as "HP4:"

Panasonic RP-TCM125 AES Paper Measurements.png

The top graph shows the deviation. Compare that to mine:

Panasonic RP-TCM125 Relative Frequency Response Measurements.png

Darn close to about 10 kHz, yes?

Distortion is very low at 94 and 104 dBSPL:

Panasonic RP-TCM125 Distortion Measurements.png

The only point to note is something around 2 to 3 kHz:

Panasonic RP-TCM125 THD Distortion Measurements.png

The fact that we already have plenty of bass and indeed, will be turn down some of that in EQ, we should be in excellent shape with respect to distortion, outperforming many headphones and just about any speaker!

Group delay is almost perfect:

Panasonic RP-TCM125 Group Delay Measurements.png

There is a kink between 200 and 300 Hz which also shows up in frequency response measurements. I found the same in another IEM I measured. This may be a measurement artifact so ignore that for now.

Impedance is very low by headphone standards at 16 ohm:
Panasonic RP-TCM125 Impedance Measurements.png

Fortunately most phones and portable headphone dongles are deficient in voltage and not as much current so they should be able to drive this IEM easily. Here is its sensitivity:

most sensitive IEM review.png

As I get more IEMs tested, I will create a bar graph dedicated to them.

Panasonic RP-TCM-125 Listening Tests
For measurements I had used the middle sized silicone tip that came preinstalled. They fit perfectly in the measurement fixture. On my ears though, even though they stayed put, there was no bass at all. In that regard, it didn't sound too horrible. Since I usually wear larger tips, I swapped out the larger size. Oh man, I was not prepared for how horrid these sounded now! Bass became overwhelming like I have not heard before. The rest of the spectrum almost got buried. As much as I like bass, this was just wrong on many levels. So out came the EQ tool in Roon player I use:
Panasonic RP-TCM125-A equalization EQ.png

The errors are large so I eyeballed pretty large corrections. The transformation was incredible! I am listening to them as I type this. The sound is so detailed, clean and with incredible sub-bass capability that puts a smile on my face on every track! On the ones with high dynamics, the result is startling on tracks like Games from Hans Zimmer Wonder Woman 1984 soundtrack:

It is stunning what fidelity you get! More fine tuning is needed to tame a bit of brightness that exists post EQ but man, what is there is so satisfying I can't wipe off the smile from my face!

Yes, there is no spatial qualities like you get with some headphones. And bass is not tactile like it is on speaker. But high fidelity it is. This bodes well for overall correctness of the target response.

So we enter a new chapter in ASR by testing IEMs. I use mine for a few hours in bed to watch youtube videos in bed so they are essential component to test and review. With respect to this Panasonic, clearly this is tuned to go after bass which they think sells. Maybe this is because they know most people wear these loose so need that extra punch. Result is quite bad given the deficiency above 500 Hz. But apply equalization and this thing pretties up like nobody's business. I look forward to testing more IEMs but for now, I can't stop being impressed with the sound I am getting out of this $15 IEM!

Without EQ, you want to avoid this headphone at all cost. With EQ, the Panasonic RP-TCM125 easily lands in my recommended list.

As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/


  • Panasonic RP-TCM125-A Frequency Response.zip
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Major Contributor
The Curator
Nov 29, 2019
BC, Canada
To import this PEQ profile into 'Equalizer APO', use:
Preamp: -11.6 dB
Filter 1: ON PK Fc 160 Hz Gain -3.4 dB Q 1.0
Filter 2: ON PK Fc 2500 Hz Gain 5.5 dB Q 0.5
Filter 3: ON PK Fc 4618 Hz Gain -3.0 dB Q 5.0
Filter 4: ON PK Fc 7500 Hz Gain 10.0 dB Q 4.0
Otherwise, see my PEQ guide.
For those who don't have PEQ-capable app, and want to use GEQs instead.
Preamp: -5.0db
32 -2.2
64 -1.3
125 -4.4
250 -3.2
500 -1.0
1000 0.1
2000 3.7
4000 0.4
8000 4.8
16000 -2.8
Preamp: -7.4db
20 -1.2
25 -1.0
32 -1.4
40 -1.5
50 -1.6
63 -1.9
80 -2.0
100 -2.4
125 -3.6
160 -4.3
200 -3.3
250 -2.4
315 -1.9
400 -1.4
500 -1.1
630 -0.8
800 -0.2
1000 0.2
1250 1.0
1600 1.9
2000 2.4
2500 2.7
3150 2.8
4000 1.0
5000 -1.2
6300 4.1
8000 6.7
10000 -0.3
12500 -1.3
16000 -2.2
20000 -6.4
If you want to import into "Wavelet" (Android App):
GraphicEQ: 20 -9.6; 21 -9.6; 22 -9.6; 23 -9.6; 24 -9.6; 26 -9.6; 27 -9.6; 29 -9.6; 30 -9.6; 32 -9.6; 34 -9.7; 36 -9.7; 38 -9.7; 40 -9.7; 43 -9.8; 45 -9.8; 48 -9.8; 50 -9.9; 53 -9.9; 56 -10.0; 59 -10.0; 63 -10.1; 66 -10.2; 70 -10.3; 74 -10.4; 78 -10.5; 83 -10.6; 87 -10.8; 92 -10.9; 97 -11.1; 103 -11.3; 109 -11.6; 115 -11.8; 121 -12.0; 128 -12.3; 136 -12.5; 143 -12.7; 151 -12.8; 160 -12.8; 169 -12.8; 178 -12.6; 188 -12.4; 199 -12.2; 210 -11.9; 222 -11.7; 235 -11.4; 248 -11.1; 262 -10.9; 277 -10.7; 292 -10.5; 309 -10.3; 326 -10.1; 345 -10.0; 364 -9.8; 385 -9.7; 406 -9.5; 429 -9.4; 453 -9.3; 479 -9.1; 506 -9.0; 534 -8.9; 565 -8.8; 596 -8.6; 630 -8.5; 665 -8.3; 703 -8.2; 743 -8.0; 784 -7.8; 829 -7.7; 875 -7.5; 924 -7.3; 977 -7.1; 1032 -6.9; 1090 -6.6; 1151 -6.4; 1216 -6.2; 1284 -5.9; 1357 -5.7; 1433 -5.5; 1514 -5.2; 1599 -5.0; 1689 -4.8; 1784 -4.6; 1885 -4.4; 1991 -4.3; 2103 -4.2; 2221 -4.1; 2347 -4.0; 2479 -4.0; 2618 -4.0; 2766 -4.0; 2921 -4.1; 3086 -4.3; 3260 -4.4; 3443 -4.6; 3637 -4.9; 3842 -5.3; 4058 -5.9; 4287 -6.8; 4528 -7.9; 4783 -7.7; 5052 -6.8; 5337 -6.0; 5637 -5.4; 5955 -4.8; 6290 -3.9; 6644 -2.5; 7018 -1.0; 7414 -0.2; 7831 -1.4; 8272 -2.8; 8738 -4.2; 9230 -5.5; 9749 -6.5; 10298 -7.1; 10878 -7.5; 11490 -7.8; 12137 -8.1; 12821 -8.3; 13543 -8.5; 14305 -8.6; 15110 -8.7; 15961 -8.8; 16860 -8.9; 17809 -9.0; 18812 -9.7; 19871 -11.4
Otherwise, see my GEQ guide.
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Major Contributor
Forum Donor
Mar 18, 2019
Somerville, MA
Amir, first of all, this is a very cool direction to go in. I don't like IEMs but they are an interesting and important transducer category. Second, how did you select 425hz? It seems like with wildly nonlinear devices choosing the reference point for comparison is a difficult task. What is your process for that?


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
Second, how did you select 425hz?
It came from looking at the research papers and seeing where they picked the intersection. And also, where you most likely are in the accurate zone of the fixture. It actually makes no difference from technical point of view what we pick but visually, changing the reference point completely colors one's idea of whether a match is there or not.

When the above impression becomes extreme, or the area around 425 Hz becomes variable, I do deviate from it. But most of the time it is a good value.


Nov 19, 2020
Amir, thank you so much for bringing detailed IEM measurements to us!

So you chose the Harman preference curve again for FR target, will this affect your ratings on Etymotic Research IEMs that tries to simulate human perception of flat frequency response from an ideal studio monitor? Their curve is "bass light" and treble recessed, yet IMHO a different approach towards accurate sound reproduction.

Ron Texas

Major Contributor
Jun 10, 2018
A mysterious place with no name.
This is a whole new world of measurements. If one has a lot of wax in their ears, it makes a mess of IEM's. I actually have trouble seeing how these tiny things could work. Thank you @amirm for starting a new chapter in measurements and impressions. I'm surprised EQ makes the difference between broken and OK, but anything goes.


Forum Donor
Aug 3, 2019
Seattle Area
Some of the more expensive IEMs sound excellent. I have an inexpensive pair of Shure EC2s that are quite good sounding. IME (no pun intended), the seal to the ear is even more important with IEMs than standard headphones.

Blumlein 88

Grand Contributor
Forum Donor
Feb 23, 2016
Since iem phones eliminate the pinna what does that do to the head stage? Seems they might be better for binaural recordings.


Senior Member
Jul 10, 2018
To avoid sweaty earphones outdoors in south Florida, where I lived for over 30 years, I resorted to IEMs. They were mostly pretty horrid. Then I discovered Etymōtic ER (extended range, ie slightly elevated bass, not “basshead bass”) and they were life-changing. They became my reference standard against speakers and headphones for neutrality and low distortion. They achieve noise isolation through a very, very snug fit which takes some getting used to.


Master Contributor
Mar 1, 2018
Gold Coast, Queensland, Australia
So it will be the same for all the studio monitors reviewed on this site to be referred as speakers in our living rooms then? :p

Absolutely. ;)

Actual industry reference standard speakers referred to as studio monitors I have no problem with. But with every little powered 2 way fiasco-in-a-box having " studio monitor" printed on it these days, the term is bastardized beyond any meaning.

It started a long time ago, for sure. "Reference/Monitor" used to mean the absolute top model or range, not tacked on anything to make people buying cheap junk believe it was something special.

Plenty of JBL speakers were and are studio monitors. Several Yamaha speakers have been studio monitors. Several AKG headphones are/were industry monitor cans. As for IEMs, surely that is a professional designation for those things they wear on stage, not $14.99 Panasonic earphones for music on the go?

Amir's Salon 2s are not studio monitors and yet they are a TOTL speaker. They are a reference speaker.


Major Contributor
Forum Donor
Jul 19, 2018
Midwest, USA
Aren't IEMs in ear monitors for professional musicians playing on stage? What is "monitor" about them?

These things are just earphones to me.

If part of it goes inside your ear canal it's an IEM.

If it just rests in your outer ear it's an earbud.

"Monitor" is just left over from where the style was originally popularized.
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