[csglinux]

I would like to join in this fun experiment. But as of now, I don't have any equipment for measurement. What are some of the basic things required if I want to join in on the fun?

Welcome @Jitu13 - happy to have you on board! The more data points, the merrier

As @earfonia says, you can get into the measurement game without needing to spend too much money. I wrote a post specifically about that here: https://www.head-fi.org/threads/audio-measurements-on-a-headfi-budget.893084/

But you don't necessarily need to go down that rabbit hole to join in with this part of the project, because the mics are already inside this particular IEM and you probably already have all the equipment you'd need to record, i.e., a smartphone or tablet with a 3.5 mm mic input. We'll supply a small test track, you'd play it back into your ears at some comfortable volume level (or slightly higher, if you can tolerate it - it'll only be a few seconds long) and then you can send us back the recording(s) you make as wav or flac files.

Where are you based?

 

[Jitu13]

Welcome @Jitu13 - happy to have you on board! The more data points, the merrier

As @earfonia says, you can get into the measurement game without needing to spend too much money. I wrote a post specifically about that here: https://www.head-fi.org/threads/audio-measurements-on-a-headfi-budget.893084/

But you don't necessarily need to go down that rabbit hole to join in with this part of the project, because the mics are already inside this particular IEM and you probably already have all the equipment you'd need to record, i.e., a smartphone or tablet with a 3.5 mm mic input. We'll supply a small test track, you'd play it back into your ears at some comfortable volume level (or slightly higher, if you can tolerate it - it'll only be a few seconds long) and then you can send us back the recording(s) you make as wav or flac files.

Where are you based?

Good to know! I am in Tuscaloosa, AL, US.

 

[hakuzen]

I know that @castleofargh is now off on travels for a few months. @hakuzen - I wanted to check with you first as a courtesy. Since I've been working with @earfonia on this, would you mind if the entire tour package went first to Singapore?

thank you for the courtesy! i don't mind it at all, even i prefer it (still need time)

 

[csglinux]

thank you for the courtesy! i don't mind it at all, even i prefer it (still need time)

Thanks a lot @hakuzen We'll work the tour kit(s) towards you via the US and/or Singapore once we've figured out logistics.

 

[csglinux]

Here are some initial thoughts on establishing approximate individual and average preference targets for the various types of ear simulators: https://www.head-fi.org/threads/some-thoughts-on-the-harman-target.956923/post-16263972

 

[Blackwoof]

A possible drawback of testing at 94 dB SPL with some of these couplers is that the performance of the measurement mic can become a factor. When testing IEMs that can play back loud with really low distortion, it may come to a point where the measurement shows the mic’s distortion instead of the IEM’s.

I've been pointing that out a lot with Etymotic ER4 THD tests done at 94 ~ 100db. That the mic could be giving up and adding It own distortion to It. I've seen quite a few ER4SR tests that show it being 0.95% but when done again or use a better mic suddenly it under 0.3% from 20Hz ~ 16KHz?.

 

[earfonia]

I've been pointing that out a lot with Etymotic ER4 THD tests done at 94 ~ 100db. That the mic could be giving up and adding It own distortion to It. I've seen quite a few ER4SR tests that show it being 0.95% but when done again or use a better mic suddenly it under 0.3% from 20Hz ~ 16KHz?.

Exactly, the measurement mic play a very big role in distortion measurement. Better mic can measure lower distortion. And this is a parameter that cannot be calibrated. So there is no other way to properly measure THD other than to use a good mic.

 

[Blackwoof]

Exactly, the measurement mic play a very big role in distortion measurement. Better mic can measure lower distortion. And this is a parameter that cannot be calibrated. So there is no other way to properly measure THD other than to use a good mic.

Yup so many cheap out mic's and then blame the IEM. Since these chart's make the ER4 look worse than actually is, On another site had few posters remind me of a ER4SR at 1% THD while ignoring that the high 2nd order showed a stressed mic.

 

[earfonia]

Exactly right. This was why @earfonia suggested including the Blon BL-05 in the tour package (which we've now down). BL-05 is a very low-distortion IEM, and it's definitely a fun challenge trying to measure distortion on such IEMs

Thanks for including BL-05 in the tour package!

 

[earfonia]

80 dB test has it's own problem. For 0.1% harmonic distortion for example, that means the harmonic distortion is 60 dB below the signal. If the signal is at 80 dB SPL, that means the distortion is in the 20 dB SPL range. The problem with this measurement is that the room ambient noise where the IEM measurement is conducted has to be lower than 20 dB SPL. This is practically impossible for many of us. And some IEM like the BLON BL-05 and BL-05S, Beyerdynamic Xelento, and recently I measure TFZ Tx Bear Monica, they can have distortion down to less than 0.01 % in some area of the frequency range. That means 80 dB below the measurement signal. If we measure at 80 dB SPL, the harmonic distortion is at around 0 dB SPL. So the ambient noise around the test equipment should be less than 0 dB SPL. We need anechoic chamber to do the measurement properly. IMHO 94 dB SPL is just the right loudness for IEM measurement looking at all practical aspects and limitations. THD is usually correlated with the SPL anyway. I'm not so interested to see how low can it goes by lowering the signal SPL to 80 dB, but I'm more interested to see IEM that can maintain low THD in higher SPL. If an IEM can performs well in higher SPL, it will usually perform well in low SPL. So THD measurement in higher SPL is a better representation of the IEM performance.

For soundproofing my test setup, I modified a waterproof Pelican case and added 1 inch high density rubber mat inside it to improve soundproofing and added weight to the whole case to reduce low frequency vibration. The rubber (gym) mat is pasted to the case walls using double sided tape. With the soundproof case my setup can measure down to 0.05% THD without affected by room ambient noise from 20Hz - 20kHz, and some area after 1kHz can go as low as 0.005% before masked by room noise. The most difficult to block is the low frequency noise.

This is the ambient noise measured when the lid of the case closed:

The hard case for the measurement equipment:

 

[earfonia]

FYI, example of THD measurement of TFZ Tx Bear Monica at 80 dB SPL, 94 dB SPL, and 104 dB SPL. The grayed out parts on the 80 dB SPL measurement graph is due to the ambient noise is already higher than the measured harmonic distortion.

At 80 dB SPL (500 Hz reference point):

At 94 dB SPL (500 Hz reference point):

At 104 dB SPL (500 Hz reference point):

 

[earfonia]

A simple noise isolation test during noisy period with morning traffic noise from the roads (my flat happen to be at junction of 2 roads), very noisy crickets outside, and purposely turned ON a room fan whirring at around 100 Hz. To test the noise isolation of the Pelican case. I added window / door seal to it last night. So here is the result:

It seems started to effectively block noise from 80Hz onward. And totally shuts off the cricket noise

 

[castleofargh]

It's just not practical, imagine the Pelican cases I would need if I want to lock in all the crickets.

 

[earfonia]

I have received the ER2SE tour package, thanks to @csglinux !

4x IEMs:

First attempt on ER2SE measurement and to re-calibrate my IEC coupler (Model E610A SN:20229) to @csglinux GRAS RA0045. Just created a calibration file based on the ER2SE last night, the result looks pretty good:

Will probably take a few weeks to measure and make calibration file based on the 4 IEMs.

 

[aldarrin]

Is it possible to join this tour? Like in a couple months? I've got measuring gear being shipped and I'd like to use these to calibrate them.