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Audio measurement gear

c1ferrari

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Well, kudos for going that far then. :)

Are you renting or buying the R&S? If you have not done so yet, I would definitely start with the mic and REW software.

Oh, I own it along with other test & measurement gear! :D
 

c1ferrari

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By the way, for driver measurements, Kippel rules the world: https://www.klippel.de/

https://www.klippel.de/our-products/controlled-sound.html

Lots and lots of good info on their site and their AES papers.

They recently released a system that measures the 3-D radiation of a driver/speaker much like Harman does but without the need for anechoic chamber! They published a paper on it at the recent AES which I will at some point do a digest on.

I'll look into it...thanks. :cool:
 

DonH56

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REW plus a Cross Spectrum Labs UMIK-1 is a pretty good start for fun. The calibrated UMIK-1 I have from them is way easier to set up (and much cheaper than) than my Earthworks M30 and preamp and provides similar (almost identical) performance for typical measurements.
 

RayDunzl

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The calibrated UMIK-1 I have from them is way easier to set up (and much cheaper than) than my Earthworks M30 and preamp and provides similar (almost identical) performance for typical measurements.

That's good to know, since I stick my neck out posting measurements from time to time...

Wow. $699 or so...
 

c1ferrari

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REW plus a Cross Spectrum Labs UMIK-1 is a pretty good start for fun. The calibrated UMIK-1 I have from them is way easier to set up (and much cheaper than) than my Earthworks M30 and preamp and provides similar (almost identical) performance for typical measurements.

Thanks, Don, for making me aware of this measurement mic. I have a Gordon micamp that is pretty clean and thought it would probably do for this measurement activity.
 

DonH56

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To be clear, the UMIK-1 is about $100 USD from CSL with an individual calibration file. They do not provide the absolute reference, but you can get that by downloading the file for the mic from the miniDSP site (miniDSP sells them but does not individually calibrate them for on- and off-axis response that we typically use). See http://cross-spectrum.com/measurement/calibrated_umik.html Since it is USB it plugs right into a PC, no external preamp needed, and REW will pick it up.

The Earthworks M30 is a very nice mic but is not cheap as RayDunzl noted (~$700). I think Amir has an M50; he must be able to hear higher then I. ;) I had a couple of other measurement mics, a Sennheiser and B&K, that I wish I had kept but got rid of them decades ago. The Earthworks is a nice replacement. I also got rid of my measurement preamp but a cheap m-audio or similar is good enough for the vast majority of hobbyist measurements so that is what I am using these days. The Earthworks 1021 is a nice single-channel preamp but again pricey (~$2200 USD)... I bought mine (and a whole lot of other stuff over the years) from Sweetwater Sound.

Be sure to get a decent boom mic stand for your new toy.
 

c1ferrari

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Hi Don,

I've been perusing the REW and miniDSP w/s, along with Gearslutz and avsforum, and obtaining a nascent understanding of this test and measurement environment.
I presently have Schoeps mics with omni capsules, a Gordon mic amp, and a Korg MR-2000s (possible ADC?) that may work in an REW workflow -- but a USB mic is so
much more convenient! :)

Thanks for the info...I should have purchased the B&K 4007. :(

I like Sweetwater -- I purchased my Grace Design m905 through them. Grace design has some clean converters, but pricey, too -- this is tempting
http://www.gracedesign.com/products/m108/m108.htm ;)
 

amirm

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c1ferrari

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Oh, absolutely...I'll be studying it -- thanks, Amir! :D
 

DonH56

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I bought the CSL UMIK-1 and REW because I got tired of having to haul out a preamp, DAC, and power supply since my old notebook wouldn't power the USB preamp, and because REW is more user friendly (or, less user-hostile) than the professional SW I was using. The final straw was buying a prepro with Dirac Live; much easier to switch between measuring (REW) and programming (DL) when they use the same mic.

Be sure to download the massive REW user's and how-to guide from the guy over on AVS (forget who, sorry). However, I have not read Amir's version in some time (sorry Amir), so that may be a better starting place. Plus we can bug the author here... :)

I cannot remember the models of B&K and Sennheisers I had, and I do not think either of them makes high-end measurement mics anymore (? -- have not looked). I got them wholesale back then and they were still a fortune. I had access to audio spectrum analyzers and test gear through work but lost that access when I graduated and got a real job. I stupidly sold the mics along with a bunch of other gear.
 

amirm

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Be sure to download the massive REW user's and how-to guide from the guy over on AVS (forget who, sorry). However, I have not read Amir's version in some time (sorry Amir), so that may be a better starting place. Plus we can bug the author here... :)
Their guide is excellent for setup/configuration issues. Their acoustic advice though, is completely wrong and old school. I tried to explain that to them when that thread was created but there is a click there that created the thread and doc and they were absolutely resistant to anyone telling them otherwise.
 

c1ferrari

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Last night, I d/l and began reviewing the AVS document.
Amir, are you asserting the AVS' interpretation of the data is errant? o_O
 

c1ferrari

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Don,

I love reading about your experiences wrt test & measurement and enjoy metrology...of all sorts!
 

amirm

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Last night, I d/l and began reviewing the AVS document.
Amir, are you asserting the AVS' interpretation of the data is errant? o_O
I am saying if you follow their recommendations of what to look for in the graphs and act on them, you will get worse sound, not better. You will get prettier displays not prettier sound. The entire notion of time based analysis that they do with ETC is faulty. Both the values extracted from the graphs and what they say to do with them.
 

c1ferrari

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The entire notion of time based analysis that they do with ETC is faulty.
Fascinating and provocative position, Amir. Can you furnish the executive summary stating the case?
 

amirm

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Fascinating and provocative position, Amir. Can you furnish the executive summary stating the case?
This is the high level summary:

1. Measurements of reflection energy in such tools is spectrum blind. That is, you have one number and not what makes up that number (or value on the ETC graph). Two completely different reflection with very wildly different psychoacoustic effect will show up the same on ETC graphs. Here is an actual measurement from Dr. Toole's book:

i-sNvGjhR.png


The top row shows the spectrum of the reflection once high frequencies are filtered. We see just a 3 db reduction in overall energy. The bottom row shows the same thing in time domain that the AVS doc promotes. Notice that the exact same data shows a 30 db reduction in energy! Reason is that the ETC measure is much more sensitive to high frequency content.

2. Whether a reflection (as found in ETC time domain) is something good or bad depends on its direction. That direction is not in ETC graphs and can easily be found by just looking at the room. No measurement is necessary to know there is a side wall reflection versus front wall for example. Psychoacoustic research tells us which one of these reflections should be treated and which not. No measurement is needed or necessary. Indeed, rooms designed from scratch work exactly like this: we design them based on these principles as opposed to trial and error with ETC measurements.

This is going to be my part 3 of REW tutorial :). I can't tell you how many people have fought me tooth and nail on the above notions (while not being able to produce any listening test result that back what they advocate), only to spend months and years messing with their rooms to get rid of these reflections and winding up with worse sound. And then proceeding to take some out. It is the fastest way to build a dead room!
 

DonH56

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Their guide is excellent for setup/configuration issues. Their acoustic advice though, is completely wrong and old school. I tried to explain that to them when that thread was created but there is a click there that created the thread and doc and they were absolutely resistant to anyone telling them otherwise.

Here, hear...

I have a personal (family) emergency going on so am not able to do this justice. I will just say that I read the guide mainly for how to run REW, not really for acoustic advice. Frankly, I am not an expert on small-room (or large-room, for that matter) acoustics. I know just enough to know I don't know enough. It is a very tricky thing requiring IME a healthy dose of experience with in-depth knowledge of time- and frequency-domain analysis and knowledge of how/when to apply each. I do tend to place much more weight on time-domain response; frequency plots are easier for most to understand and interpret but all too often provide a woefully incomplete picture of what the system really sounds like. But, obsessing about time-domain tails and delayed impulses can also be counterproductive.

IME/IMO the tools have often outstripped the average user's knowledge base (in many areas). Giving a layman a scalpel will not make him a surgeon. Self-taught often means you've had a very poor teacher. Insert your favorite cliche here. That goes for me, too, and is why I tend to not comment beyond the basics or my direct experience on acoustic theory. Those grad classes were long ago...

IME, IMO, FWIWFM, YMMV, my 0.000001 cent (microcent), YMMV, etc. - Don

p.s. My room is very dead, intentionally, but is OK with me. Probably partly philosophy, a little taste, partly big panels provide a big sense of space, and partly experience in very dead recording studios ages ago means I can tolerate such a room just fine.
 

RayDunzl

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This is going to be my part 3 of REW tutorial

Will you be showing measurements of your own space as real-world examples?
 

c1ferrari

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Thank you, Amir. My intuition is well-served by such an argument (#57) rendered in lay terms.
 
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