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In Reply to: Yet another bose 901 post posted by zman on April 2, 2007 at 11:58:44:
The series IV was a ported system and so needs less bass boost than the earlier sealed ones. The EQ is designed specifically for the specific series of 901, so you need a series IV EQ. The bass end is the trick part. I'm pretty sure, it's a sixth order low end, with bass boost and a rolloff at specific frequencies. A graphic EQ and a subsonic filter can come close. Your SAE parametric might also work well.Comparing the DQ-10 and the 901 is really interesting. The reflected sound of the 901 gives a live quality, but it's not really clear, like being in a live performance but viewing it through a smoke filled room. The DQ-10 will be like looking at a perfectly focused Kodacolor print. You know it's not live, but it's exquisitely clear.
The 901's (all versions) need a lot of clear open wall space for the rear reflective drivers to work properly. Most real rooms have doors and furniture that subvert the reflective sound. A way around that is to use slings and hang them from the ceiling so they are above the furniture and have access to a clear wall. You really need about 3' of clear wall space on both sides of each speaker.
You also need a good 100 watts per channel minimum because of the bass and treble boost. 200-250 is better.
If you get them set up well, the impression of a live performance is quite profound and they do best on large scale classical works that are miked with a more distant perspective.
When I had the room to place them, I didn't have the $$$. Now I have the $$$, but no place to put them.
As an alternative to high end boost, consider blending in a good dome tweeter (actually 3 good dome tweeters per channel).
These are not high definition speakers. The theory was to duplicate the percentage of direct and reflected sound in a large concert hall, and Bose made his measurements at Symphony Hall in Boston. Bose also showed in the 60's that a collection of equalized full range speakers could perfectly reproduce an impulse sound. The 901 is the commercialization of that research work. One of the key differences between a pair of 901's in your living room and Symphony hall is that the reflected sound is delayed a lot more than in your home. You need DSP to do that in your home.
It's a noble adventure. Look at it as a learning experience. Go for it!
Follow Ups:
...in that I've always felt that what the 901's and to a large degree the original 501's represented a quite legitimate way of looking at the problem of recreating a live concert hall in the living room.
The whole idea of recreating a live concert hall performance in one's home is completely contrived to begin with, unless one envisions actually building a home concert hall.The various proponents of East Coast acoustic suspension designs believed that the key was in designing a speaker capable of playing deep bass with as flat a flat response through the treble as the budget would permit. Recall all those "live versus reproduced" experiments AR did in the early 70s. They were generally content to try this using at most a small group of musicians and never quite got to the point of asking the listeners whether they were hearing an actual full orchestra playing in the concert hall versus a bunch of AR 3a speakers sitting on the stage with the musicians only acting as if they were playing. But even if they had done this you still had the problem that no one could actually bring a pair of AR 3a's home to their own personal concert hall.
Amar Bose, on the other hand, tended to think more radically about the whole problem and generally believed that there was no way a conventional speaker with two or three forward-facing drivers had a chance of ever coming close to recreating the experience of sitting in a prime seat in a great concert hall. Acoustically, the great concert halls are tricky places, and the really good ones do not all approach the problem in the same manner either--witness all the discussion relating to the recent rennovation of the Mormon Tabernacle. Locally in my church we just got through rejecting what would have been a gift of money for pew cushions because an experiment done believe it or not with borrowed pew cushions revealed that the reverberation of the pipe organ was significantly adversely affected, never mind that singers came through with improved clarity with cushions in place because the reverberation in the largely hard-surfaced interior was lessened ever so slightly. I thought the church with the pew cushions in place sounded more nearly like a church nearly filled with people, and without the cushions the church was overly reverberant but my view clearly (or perhaps not so clearly) did not prevail. And this is just one horizontal surface in an otherwise quite reflective space (hard-surface tile floor, high pine ceiling at about 45 degrees, oak pews) with lots of non-parallel surfaces.
Anyhow, Bose did offer one option (or two options of you count the 501 or three if you count the 301) he thought came closer than the standard forward-facing setup for recreating this concert hall acoustic at home. We could debate how successful he was till the cows come home, but that is what he was trying to do, a serious legitimate effort, [and this has nothing to do with the currently fashionable game some guys are into to bash Bose the company for pricing products with too high gross margins--never mid that Bose continues to be profitable whereas the vast majority of other speaker builders and Bose competitors from the 70s went bankrupt].
My church acoustics experience tells me that if you get a small group of people together who all think they are pretty good at hearing nuances in room acoustics, you still will have a lot of disagreement as to what is right or not right. For starters, the pipe organ players have one criterion (generally more reverberance is preferred to less at least to a point) the vocalists and vocal conductors often a dramatically different view (more clarity and ease in understanding what singers are singing is preferred to less clarity and more mud). Given all of this is it any shock that fans of reproduced sound get into these same sorts of disagreements as well?
Meanwhile, here I am with all these conventional systems employing foward-facing two- and three-way speakers, one set of speakers I built that aim the sound upward at an angle to the ceiling much like the old epi 101 and 201 did. and a 6.1 home theater system not surrounded by side walls but sitting out in a much larger room with a fairly high wood ceiling and a very hard ceramic brick floor.
As I have indicated in other posts, somehow I don't spend much time listening to the vintage gear any more. I think after going at this for 40 years I'm a bit bored with the sound of conventional forward-facing speakers in rectangular boxes. The 6.1 HT setup, on the other hand, is not very listenable so far as conventional stereo music is concerned, but it comes alive on movie soundtracks and the sound is tremendously realistic in that world, so I couldn't be happier. So far as music is concerned right now, the home-built speakers with the angled drivers I built as an experiment win the day. The odd thing is that in theory at least these aren't supposed to have any bass below about 50 Hz, but since they push sound off of back and side walls given the configuration, I don't even notice--indeed the bass seems as strong or stronger than a lot of my big-forward facing vintage speakers have.
Go figure!
D
David,Nice post!
I'd like to add a couple of points.
First, AR did do a live Vs recorded demo in Carnegie hall with a full orchestra, and I believe KEF did one in London using their 105 speaker. Recording those performances in a way to achieve that must have been quite a task. The normal procedure was to record the instruments anechoically for playback in the demo.
Second, you forgot the Bose 601, which was much less demanding of open wall space than the 501 or 901 and which had one of it's two 8" mid-woofers mounted to a slanted top surface.
There was a fad back in the late 60's/early 70's to place a full range speaker on it's back against the wall. Julian Hirsch was a proponent of this technique and he mentioned it in a couple of his test articles. My guess would be that it helped ameliorate the beaminess of the tweeters of that era and also gave a "bigger" sound.
Your experience with the church is interesting. With people sitting on the cushions, they would have no acoustical effect. People are quite good absorbers, and it's customary to put fiberglass wedges in the seats to simulate people when asessing the acoustics of a concert hall. Of course, if you don't regularly fill the church, then the cushions would be exposed and the church would have the acoustics of a fuller church. Too bad, the cushions would have been nice for long sermons.
The AR (and other's) live vs recorded demos were interesting. They did show that conventional cone and dome drivers were good enough 40 years ago to accurately reproduce the tonality of instruments. This basically confirmed Bose's research from the early 60's. The fallacy in this, is that it proves nothing about the ability to reproduce a live performance in the home from commercial recordings. This is particularly true in stereo, where formation of a virtual image is a critical part of the process. The live Vs recorded demos were all multi-track mono and imaging was not a part of the process. (a live performance isn't in stereo either, and has no virtual image)
This all gets us back to what a wise person once said (I'm paraphrasing, and I wish I could remember who said it) "Since it is impossible to reproduce a live performance in the home, the best we can do is to achieve the aesthetic equivalent".
The nice part about that philosophical approach is that you are the arbitor of what is the aesthetic equivalent in your home.
Altec 19's driven by a Soundcraftsmen MA5002A. Actually, two pair of 19 in a big garage. The neighbors cried "uncle".
Bose just don't sound so good. Decent, yeah, but there are many better choices.
The seamlessness and coherency of using full range drivers. A gaggle of midranges, however, doesn't cut it at the extremes.
ears. To create a larger soundspace
In my experience (and seating preference), I would reverse the 11% direct to 89% reflected radiation of the 901s. I find some controlled reflected content desirable for a realistic presentation, but beyond a certain point, one simply gets vague and bloated images.
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