Bose 901...really

More interesting findings about the Bose 901s.

I hooked up a Behringer DEQ2496 equalizer to see how they were doing. This equalization was in addition to the Bose equalizer supplied with the speakers. The frequency response was aweful! It was a big hump, with the peak at about 630 Hz. 10 dB down at 5K. 15 dB down at 10K. 25 dB down around 18K. On the low end, serious roll off started around 100 Hz. 12 dB down at 40 Hz. This was surprising to me because they really were sounding quite good in my pool room environment.

So I ran the automatic equalization process in the Behringer, and the result was even more surprising.
Perfectly flat from 30 Hz to 15 KHz. Like a different speaker.

Since the Bose 901 comes with its unique equalizer one wonders why they left the frequency response so bad. Most likely Bose engineers found out that the average guy likes that midrange emphasis. I did observe that when playing some music with a lot of bass really loud there was some obvious overload of the speakers. I will probably roll off the bass a bit to avoid this problem. The break around 100 Hz would play well into use of a subwoofer.

All in all I find these speakers near-ideal for the environment I am using them in.
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Eldartford, I think that your results reflect (excuse the pun)more your room than the overall response of the Bose. In my secondary system where I use the Bose 901s, I did not find the 630 peak nor the severe rool-off in the highs. I did find, however, a +6 db peak at 40 Hz and about a 6db/octave rolloff in the highs starting at about 8000 Hz.

My room is a typical 14 by 12 room with 10 ft ceiling, not the very 'special' room that you are running the Bose 901s. The larger the room, I think, the more the highs will be rolled off.

I am a bit surprised, however, at your comment on the loud bass. What makes you think that the bass is 'overloaded'?

Curious,

Bob P.

Inpepinnovations...The nature of these speakers (reflected sound) would surely make them more affected by the room than most speakers. The response that I observed (without the extra equalization) was a very broard "hump" across the entire audio range (like a Gaussian distribution curve) and had very little in the way of localized peaks and notches. My microphone position was at least 20 feet away from the speakers. I would try it again close mic'd, but how would you do that with these reflected sound speakers?

The bass overload (distortion) was due to the signal driving the speakers. The Bose equalizer boosts the bass, and I was adding another 15dB to get the flat response. The power amp I used for this test is good for 250 watts, so I doubt that it was the problem.

Eldartford, perhaps you are overloading the input to the pre-amp? can you increase the gain on your power amp so that you can reduce the signal necessary to drive the amp. Then the Bose equalizer need not output so much and you can reduce the output from the additional equalizer. But I am sure that you have thought of this and are worried about the noise that might be introduced by this solution.

Also, close mic readings are not want you want anyway. At any rate you seem to have 'tamed' that broad boost with the extra equaliser. Now you just ned to work on the Bose eualizer overloading distortion problem.

Salut, Bob p.

Inpepinnovations...The Bose equalizer comes before the Behringer, so the Bose doesn't have to put out anything extra. And the Behringer has LEDs indicating its input level, which, if anything, is a bit low. (The Behringer has balanced output to the amp).

I guess the 901's can play loud, or have extended bass, but not both at the same time. Hey, what can you expect from a bunch of 4" speakers.