How to measure loudspeaker performance best?

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Hi,

my name is Daniel and I´m from Germany :)

I´d like to explore how I can capture the performance of speakers with measurements the best way, i.e. the most precise and complete way.

First of I hope to be in the most suitable category of this Form ^.^

Regarding the topic I feel like it would be the best to at first collect all possibilities to measure a speaker. (?)

Coming to my mind(edited):

- Frequency Response
- On Axis and on Angles
- Distortion
- Group Delay
- Waterfall
- Phase
- Maximum output SPL versus frequency
- SPL depending on inputvoltage (compression? distortion?)

The next step would be to get deeper insight in what this is exactly telling me.

For example I have good understanding of what the frequency response tells me but lack knowledge about different kind of distortion tests. (harmonic, intermodulation,...)

My current measurementequitment consist out of a calibrated ECM8000 + Interface and an Arta measurementbox.

I´d highly appreciate anyone who can give any Input.
(Interest himself, links to good articles,...)

Kind regarts :)
 
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Thank you mickeymoose. I´ll check the material later ;)

@arnyk: It´s not only a matter of finding a software that can do the measurements.
It is also important to know what they mean and how to do them correctly.
I knew REW and Arta, Holme Response however is new to me, I´ll check that! Tanks ;)

@Keruskerfuerst: Good point. Maximum SPL determined by? THD?
Also I´d like to now how to actually get absolute SPL ratings.
Is a simple SPL meter realy enough?

Greetings :)
 
Thank you mickeymoose. I´ll check the material later ;)

@arnyk: It´s not only a matter of finding a software that can do the measurements.
It is also important to know what they mean and how to do them correctly.
I knew REW and Arta, Holme Response however is new to me, I´ll check that! Tanks ;)

@Keruskerfuerst: Good point. Maximum SPL determined by? THD?
Also I´d like to now how to actually get absolute SPL ratings.
Is a simple SPL meter realy enough?

Greetings :)

There is a documentation or help file that is on the Holme website that has extensive tutorial content.
 
@Zoran: Frequency Response and Phase are already captured in the intro post. It seems quite obvious to me to optimise those parameters to your actual listeing enviroment if you can. (You can´t if you´re a developer for instance.)

I´d apreciate if you could give some insight in what you think Phase can tell us. Or: Why is it even important?

Also: What is our goal? Best combined response? Best response of 1 speaker at time? Whats up with Phase; whats our Goal? ;)

@Keruskerfuerst: I think I missunderstood you initially.
So you want to measure SPL with different inputvoltages?
Checking for? Distortion and compression?
Were is the difference in distortion limited and excursion limited SPL?
Istn´t overexcursioning causing distortion so it doesn´t matter? xD

@arnyk: I´ll check that :)

Im a bit in a hurry all the time, exams are coming ;) Will be better soon :D

Great Input so far! Thank you everyone! (I know why I asked here at DIY-Audio :D)
 
@arnyk: Good link. I googled for something linke this myself but I was to dumb, obviously -.-

Are they as acurate as claimed? +-0,5?

The price is sadly realy high compared to my actual mic, but it seems like the only option :D

@SY: I may should state that I´m already owning this book:

Lautsprecher-Messtechnik: PC-gestützte Analyse analoger Systeme: Amazon.de: Joseph D'Appolito: Bcher

Why are they sold at such hilarious prices :eek:

Anyway. Would it be still worth to get the book you linked?

Why shopuld I run? :eek:
 
@arnyk: Good link. I googled for something linke this myself but I was to dumb, obviously -.-

Are they as accurate as claimed? +-0,5?

Dunno, I have nothing to compare it to that would be a better standard.

It was recommended by someone who presented an AES paper about developing speakers.

The point of a mic calibrator is that they have inherently stable sensitivity, which the low cost electret mics that we commonly use don't always have.

For an example I have a number of Behringer ECM 8000 mics and some of them are 10 dB off from others.

Interestingly enough the frequency response is far more reliable, but its the acoustical sensitivity that wanders around.


The price is sadly realy high compared to my actual mic, but it seems like the only option :D

It is very easy to spend more, but very hard to spend less. Thing is, if you buy a precalibrated mic, you have no guarantee that it will keep its sensitivity. If you have a mic calibrator, its inherent stability is your guarantee.
 
take a well recorded drum track such as on Alan Parsons "Soundcheck" (horribly expensive) or Steve Clarke's "Solo Drums" (usually cheap), record the portion of interest on the device under test in a relatively dead room, then examine the original waveform vs recorded playback waveform for tracking - a little speaker might go "low" at low levels on a sine sweep but fall apart and severely compress on large drum toms.
 
@Michael Bean: Such a set looks pretty promising imho.
But I don´t think its the most reasonable purchase if you´re not starting from scratch.

@arnyk: I had my ECM8000 calibrated. (Response wise)
I think the fact the actual sensitivity varies more than response is interesting. At least it´s completly counterintuitive to me :D
My concerns are in deed 2: a) How do I know my ECM doen´t change it´s response? b)How do I know a calibrator doesn´t? Just the fact it is called a calibrator doesn´t seem a reason to reliable :eek: But if I knew it was reliable I think it would be worth the purchase...

@freddi: Seems like a resonable test. On the other hand I think we are propably testing macro dynamics here, which are captured by: Response over SPL and distortion measurements. What do you expact to get as additional information here?

Kind regarts
 
My concerns are indeed 2:

a) How do I know my ECM doen´t change it´s response?

IME their sensitivity is prone to spontaneously change very significantly, but at the same time their response does not seem to change nearly as much.

The probable failure mechanism is the well known propensity of electret mics to loose their charge. The polarizing voltage goes down and that predictably leads to a loss of sensitivity.

If you buy a more expensive electret mic, they can be very stable. It turns out that many of the B&K calibration mics are also electrets, but in this case you get what you pay for.

b)How do I know a calibrator doesn´t? Just the fact it is called a calibrator doesn´t seem a reason to reliable :eek: But if I knew it was reliable I think it would be worth the purchase...

The calibrator is designed not to change its sensitivity. It only operates at one frequency and one or two preset amplitude levels.
 
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