Generic Disclaimer: All measurements on this page are provided for informational use only. I'm not going to say that XXXX brand sucks, don't ask me that question. Different people like different things, I like to learn about speakers and that's why I do this.
Speakers I've looked at so far:
Infinity Reference 2000.3
Sony SS-TL1
Bose AM-3
I recently had a chance to measure a pair of PSB 400s and a Polk RT4000 tower speakers.
The on and off axis frequency response of the PSB 400s
The on and off axis frequency response of the Polk RT4000
(white 15 degrees, yellow 30 degrees)
For comparison, since these speakers both sell for ~$400 a pair, depending on where you buy them I thought I'd put up these two plots. The red trace is the PSB 400's and the white is the Polk speakers.
Polk and PSB off axis (30 degrees) response
Infinity Reference 2000.3, in room response.
The memory trace (red) is the semi anechoic response, the white trace is the speaker placed on the floor behind a big fluffy green chair. The normal placement for a lot of homes...for goodness sakes, you just spent a lot of money, do the system justice. Get them out from behind the high-frequency killing furniture. Also the added bumps in the bass region show that room boundry effects cause a lot more wiggles in response than any bad engineering.
Note the dip in the anechoic response at 2.5-4.5 kHz. That is most likely due to a mistuned crossover, or possibly a reversed polarity tweeter. I lived with these speakers for about a year, I thought they sounded great, It just goes to show how forgiving your ear actually is. The right speaker still has a small dip, but only 1-3 dB in magnitude.
Bose AM-3 System, in room response.
I borrowed one of these systems, and thought I'd run it through it's paces. The waterfall plots don't look to good, but I'm still not sure if it's my measurement method yet. As far as frequency response, I'm pretty confident in those.
The first plot shows the Bose running full range, compared to my Infinity Reference 2000.3 bookshelfs. At this price range, all speaker systems will have there problems, these two are no exception. The Infinity speakers show a dip in the 2.5-4.5 kHz range. That's a pretty broad dip for a ~10dB drop. Note: The plot shown is for the left speaker, therefore the statement above applies. The Bose system was normalized to 0dB by Lauds easy scripts. It's actually pretty flat from 6 kHz to 500Hz or so. Above 6 kHz the speaker starts to show some pretty series resonance problems, which show up as long decays in the waterfall plot. Below 500Hz, the 2.5" driver can't keep up with the bass module, so you see the response falling off. The Infinity speaker is shown in white, Bose in red.
Bose AM-3 vs. Infinity Reference 2000.3 anechoic response.
The second plot shows the nearfield response of the AM-3 bandpass bass module. Again, I compare it with my Infinity Reference 2000.3 speakers. As you can see the Bose module has pretty flat response from 60-200Hz. Lower usable limit is about 50-55 Hz. Notice the jagged response above 300 Hz, this is caused by port turbulance, common in bandpass modules. This shows up pretty clearly in the distortion plots, which I will put up at a later date.
The Infinity speakers sacrifice flat response for deep bass extension, notice that the Infinity speakers are 20dB higher between 30 and 40 Hz. That is a factor of 100.
Again the Infinity speakers are in white and the Bose in red.
Bose AM-3 vs Infinity Reference 2000.3 nearfield bass response.
Soon I will add some waterfall plots, as well as impedance and impulse response measurements, on the Infinity, Sony and other speakers as well.
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