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Loudspeaker Analysis Graphs

truevis

truevis

Well-Known Member
Recently did some measuring in my apartment of some of my speakers. All have original crossovers, etc. Room resonances obviously affect the results. Some graphs have smoother parameters applied to them than others. However, I think the results are edifying.

Boston Acoustics A200: -- woofers refoamed.
A200+in+room.png


Cambridge SoundWorks Ambience:
CSW+Ambianc+off+axis.png


Cambridge SoundWorks TheSurround II -- bipole in green and dipole in orange:
CSW+thesurroundII+in+Bi+Green+and+Di+Orange.png


KLH 22:
KLH+22+without+woofer.png


KLH 38:
KLH+38.png


Boston Acoustics Micro 80W (woofer):
Micro+80W.png


Mission M71:
Mission+M71.png


NAD 20:
NAD+20.png
 
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frperdurabo said:
Hm. Interesting. Thanks for posting. Care to comment on correlation between the measurements and perceived sound quality?
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Except for the Boston Acoustics 80W woofer, they all sound good. The different amounts of bass make the biggest difference in their sound. Boston Acoustics A200 is my favorite.
 
Thanks for sharing that. I would be interested in measuring the response in my room like you did. Does anybody have recommendations for a low cost way of doing so? I don't want to have to spend a gob of money to satisfy my curiosity, but if I'm going to spend anything, I'd like to make sure it yields accurate results. I've seen ipad apps, but I'm pretty skeptical about their abilities. What's needed, in terms of software and hardware, and what is simple enough for a low tech guy to get his head around?

Thanks in advance.
 
R.E.W. room equalizer wizard. It's free Google it.

The klh 38 and micro had best tweeter response. However, the Micro woofer was over compensated!

The surround II response was unimpressive.
 
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spkrdtr said:
How do you like your WTpro?
I have one also.

Not sure about your measuring issue vs stereophile.
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I reckon that there were multiple version of all of the CSW speakers. Perhaps Stereophile's and my ($15 used in 2012) units were of different generations.

The WT Pro was borrowed from a mad scientist friend.

PS: Gotta dissolve the sticky black coating off of those Ambiances one of these days.
 
Stereophile's graphs may have different smoothing.

There is some information in the References sticky in the top section of this forum about measurement, the gear, and software used for it. It's totally possible to get setup for less than a few hundred. I use a crappy laptop, a DBX measuring mic, an Maudio direct box with phantom power, and the sundry cables and stands. Iuse REW, primarily since I'm still in infancy on measuring. Holm Impulse is another Freeware product.

Also, RayW clued me in to the iphone app, RTA lte, it is actually pretty cool. I used it to dial in levels on a couple of speakers and it seemed worthy.
 
truevis said:
It's curious that my graph of the Cambridge SoundWorks Ambiance does not look anything like Stereophile's 1990 measurements ... Can anyone explain?
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As far as I can tell, they are pretty close. You can see similar treble behavior, where it starts falling off pretty good at 8kHz, peaks in the top octave, and is over 10dB down by 20k. Overall, it has way too much reflected sound in it to look for the other features in the Stereophile measurement (like the peak between 1-2k).

The reflections will trump everything else in large part, but while I'm at it ;): You didn't mention what mic you were using, which is kind of a big deal. Also, distance from the speaker and the measurement axis is critical, if you want to compare to others' measurements.

Freds.Bands said:
Woofer tester graph shows PHASE. Stereophile's graph is Amplitude. Like comparing apples and volkswagens.
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No it doesn't.
 
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P.S. Looks like you can window the impulse to remove reflections in your software if you want, like the red lines are doing in this shot:

InAirAcousticResponse.gif
 
Pandovski said:
Did the KLH 22 sound the best to the OP?
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Boston Acoustics A200 is still my my favorite.

I believe all of those charts are amplitude at different frequencies.

dumptruck said:
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The reflections will trump everything else in large part, but while I'm at it ;): You didn't mention what mic you were using, which is kind of a big deal. Also, distance from the speaker and the measurement axis is critical, if you want to compare to others' measurements...
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The mic was a Berenger test unit at around a meter from the speakers. Yes, certainly the room makes a big difference.

I see the Ambiance resemblance now.
 
dumptruck said:
...

Originally Posted by Freds.Bands
Woofer tester graph shows PHASE. Stereophile's graph is Amplitude. Like comparing apples and volkswagens.
Click to expand...


No it doesn't.
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Then perhaps you can explain the labeling if the vertical axis. I am confused by your comment and the graphs, and I know how to read scientific graphs. If it is in dB, then why does the Boston Acoustic Micro 80W amplitude rise to almost 160 dB at 70-80 Hz?
 
Freds.Bands said:
Then perhaps you can explain the labeling if the vertical axis. I am confused by your comment and the graphs, and I know how to read scientific graphs. If it is in dB, then why does the Boston Acoustic Micro 80W amplitude rise to almost 160 dB at 70-80 Hz?
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Yes, notice that it says "Phase OFF" and then look at scale the other side, which is response amplitude in dB (and also consider it's an in-room measurement of a small "subwoofer", and appears to be banging into a noise floor around -52dB).
 
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Freds.Bands said:
Yes, it was confusing. Thanks for the help; I haven't used that software. What SPL does 0dB correspond to?
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I don't know, I haven't used that software either. Probably just the 0dB point in the digital data, but it doesn't really matter unless the setup is calibrated for real SPL and the measurement distance is provided.
 
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