There is lots of information on the net about measurement procedures and processes. There are also books on the subject.
Measurement can be one of the most daunting tasks because the room you do the measurement in can impact that measurement severely.
Most of us don't have an anechoic chamber to tests in, so there are some work arounds that you can try.
HolmImpulse is a free program that you can use your PC to generate the test sweeps and analyze the results. You need a microphone like the Behringer ECM8000 and enough room that you don't have reflections interfering with the results.
Typically. the mic is 2 meters away from the speaker, so you need a large room to do this in. It is best to get the speaker off the floor at head height.
HolmImpulse has a gating function to eliminate reflections of sound waves back to the mic, but there are limits and a room with walls and ceilings like an auditorium is needed to measure deep bass response. Basically, you need something like 1/2 wavelength of the lowest frequency you want to measure between the test speaker and any reflecting surface.
Some people do this outside and there are other tricks, too.
You should read up on something called 4π (PI) and 2π space (sometimes called full-space and half-space). This is the domain that the speaker radiates into. 2π is everything forward of the speaker baffle. 4π is in front and behind in all dimensions.
Polar plots are another valuable measurement. This tells you where the sound is going in a horizontal direction. Good polar responses help significantly with stereo imaging and the soundstage.
The whole process is very intense, but measurement is the only way you can be sure that any changes you make are doing the right thing.
Many expert speaker builders never listen to music on their speakers when dialing them in at all. The ears are way too subjective. Quantitative testing is the best way to do this. After the job is done they have a beer and put on some music.
There are tricks you can do to work around these problems, but it would take a small book to describe them and there is not enough room in the post to do that.
That makes things more difficult, but not impossible. There are different techniques that you can employ for the different bands of the frequency spectrum and you can "stitch" them together to make a full-frequency plot.
Joseph D'Appolito Testing Loudspeakers is a good book on the subject, even if it is a little old.
A rather late reply but do you think ATB PC Pro will do the job?
It suits my budget and has everything required in one package.
I've done a write-up about the dual-driver boxes on my site here:
Home (stevesstuffproject)
Might inspire others to give something similar a try.
Cheers,
Steve
It suits my budget and has everything required in one package.
I've done a write-up about the dual-driver boxes on my site here:
Home (stevesstuffproject)
Might inspire others to give something similar a try.
Cheers,
Steve
I find your (old) HI-FI shops very nice, and the audio-shows too. Interesting.
I have ATB, and it works. It compensates for room reflections, so you don't need to worry. Their measurements are some what different, but valid. It brings standard microphone, that it also compensates. One problem is German language (and bad CD-manual/website translations to English), people are nice (I don't know if they have website/forum already). Also the meter for LF I think (you pay) is extra, and I have one that didn't used yet (for more than one year now). There are some threads/information available but I don't have them on end. I find the CLIO type files, very useful between different softwares.
http://www.diyaudio.com/forums/mult...u-measure-drivers-what-works-doesnt-work.html
I have ATB, and it works. It compensates for room reflections, so you don't need to worry. Their measurements are some what different, but valid. It brings standard microphone, that it also compensates. One problem is German language (and bad CD-manual/website translations to English), people are nice (I don't know if they have website/forum already). Also the meter for LF I think (you pay) is extra, and I have one that didn't used yet (for more than one year now). There are some threads/information available but I don't have them on end. I find the CLIO type files, very useful between different softwares.
http://www.diyaudio.com/forums/multi-way/136500-speaker-testing-software-ones-actually-good.html
http://www.diyaudio.com/forums/mult...u-measure-drivers-what-works-doesnt-work.html
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Hi Inductor, thanks for the feedback on ATB PC Pro, very helpful especially regarding the compensation for room reflections. Would appear to be ideal for my purposes. Hopefully they've improved the German to English translations in later versions.
Looks like I'll be raiding the piggy bank for 150 euros.
Looks like I'll be raiding the piggy bank for 150 euros.
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