Measurements: Charts, Graphs, Software & Methods

Bear in mind that using REW, which is what the instructions that come with EARS will walk you through the setup with, the compensations are separate from the measurement. This means that you can do the measurement pass(es), and apply different compensations after the fact.

Thus one measurement can be portrayed using multiple different compensations.

That said, if you want any kind of accuracy - you’ll need to use compensations that take into account the microphone calibration of your EARS. The standard compensation files for your specific EARS will do so. And to use the SBAF compensations you’ll be creating a copy of your HEQ profile and adjusting it by the amounts specified in the SBAF data - done properly that’ll preserve the microphone calibration for your SBAF-adjusted compensations also.

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Thanks @Torq, that makes sense.

I guess it’s a case, as with any software, of starting to use REW and seeing where I get stuck. For our audio installs we use SMAART but I have only really been a bystander as it is the engineers that perform the final room tuning. My measuring experience is (very) limited to playing around with Audiotools on Android.

Thank you all for having so.much patience for all my questions!!

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For IEMs, I much prefer my IMM-6 cheapo setup with vinyl tubing over my E.A.R.S. just because the ear canals in the EARS are too short to simulate a realistic insertion depth and so narrow that they often pinch the IEM tips, yielding weird results.

I do quite like my E.A.R.S. for over ears though!

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In the thread on SBAF, one person mentioned using a piece of drinking straw to make the insertion tube longer. Do you think adding a small piece of vinyl tubing would be benefitial to the EARS for IEMs?

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Never tried it, but it’s worth a shot!

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Making the “insertion” longer will basically eliminate the ability to accurately use the compensation curve though. It was designed to be used at the depth of the EARS. I could be mistaken though.

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I have spent a few hours playing with the EARS (I found it strange that it actually says HEARS on the product) with REW and I seem to have got the hang of the FR measurements at least. Well, I have for the over ear anyway, I haven’t even started with IEMs.

A quick question regarding distortion, are the distortion graphs shown in REW relative?

Also, do you think that I need to come up with a compensation calibration file for the output (Topping D10 into JDS Labs)?

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You shouldn’t need to.

I don’t know anyone else that does using the EARS.

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Just how easy is the E.A.R.S to use and get measurements with. How easy is the REW software to use as well? Do you have previous experience with measurement rigs?

I am looking at this being a measurement virgin myself and how easy it would be to get a setup running myself. Thanks.

Please note that so far I have only tried with over ear headphones.

The EARS are plug and play, even on Windows 7, so not much to go wrong there. I did loosen the screws a little to get the headphones seated.

As far as REW, I would say it is pretty simple for an acoustic measurement app. In the past I have only really played around with AudioTools on Android but I would say that REW is simpler to get the basics out of, or at least it seems that way to me. At work we use SMAART but I have only been a bystander so I can’t really compare the two.

As I say, I found REW relatively easy to get started although I still have plenty more to learn before I can say I know my way around. I will point out though that, while not measurement software, I have been using audio production software for many years (I started with Acid around 2001) so maybe that helps.

The excellent part is that REW is free and you could use what you already have on your PC to give it a go and learn if you like the idea or not. You can simply use any output and input to make measurements and find your way around. You could even use something like the microphone from a cheap set of IEMs and your motherboard in/out to test it. Obviously these measurements wouldn’t be accurate but they would let you play around with REW.

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Thank you very much for you insight. It seems straight forward enough. I may or may not pick one up in the future.

One might be nice to tinker with, it wouldn’t be for reviewing purposes as I aren’t a big reviewer. Many better qualified folks out there to do this. Thanks anyway for the heads up @SenyorC.

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A question for those of you that have more experience with the EARS…

I started out by using the settings recommended in the EARS manual, running the sweep at -20dBFS. The first day I ran a few measurements on the DT1990 getting pretty consistent results. However, I did not save these.

When I set up yesterday to repeat the measurements (and save them this time) the first measurement on the L channel went fine, but when swapping to the R channel it gave a distortion error. I tested some other HP and it gave the problem on both channels. When switching back to the DT1990 again, this now gave the distortion error on both channels.

After playing around with setting for a while, I found that to be able to run the tests I had to recalibrate to -40dBFS in order to not get the errors. The resulting tests seem very similar to what I got the other day (although I am going by memory as I didn’t save them).

My biggest concern is the difference between channels. Here are the measurements I got from the DT1990 and the Sundara. These are the the averages of 5 measurements each side, then smoothed with 1/12

Do these look normal to you or am I doing something completely wrong and missing something?

I did repeat the tests a few times and got the same results.

Each time you measure a headphone, you need to make sure you’ve set the proper output level on your amp/source, such that their output level is consistent with that used for other measurements. The level required on your amp/source for a given volume level with be different for every headphone.

You can ensure this by firing up the Signal Generator, setting it to the same values you used to calibrate with initially (Sine Wave, 300 Hz, -20 dBFS), and then starting the SPL Meter and adjusting the volume on your amp/source so that you get the same SPL reading as you did when you initially did calibration (the default is -40, which is then adjusted by the number for your “sensitive side”, so in my case 39.1).

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Thanks Torq. Yes I was doing the calibration each time (as you mention, with the sine wave @300Hz etc.) but to -20 not -40.

I am not sure what you mean by adjusting my “sensitive side”. Is that the part that cries when I watch a sad movie? :smile:

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Re-reading your post again, I think I know what I was doing wrong!

I understood that the SPL Meter reading was to match the same dBFS as the Sine Wave.

So, I was setting “Sine Wave, 300 Hz, -20 dBFS” and then calibrating to -20dBFS on the SPL meter (so turning up output until it hit -20dBFS) rather than -40dBFS.

Am I correct in assuming that this is where I was going wrong?

Also, as long as I always calibrate to the same dBFS (so -40dBFS in this case) with all DUTs I should be able to trust they match?

(And thanks again for your help here!)

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Yes, that’s where you were going wrong.

As long as you don’t fiddle with the other settings in the Signal Generator, yep.

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Thank you @Torq, I highly appreciate your patience!

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30hddp

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I couldn’t resist… I’m…sorry? :thinking::smirk::stuck_out_tongue_winking_eye:

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Very fitting you should choose a red and gold theme for the photo…

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