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My Brother in Law brought over his old Bose 901's from Storage in his basement Thought I'd get the up and balanced in the system. You see the graphs - the EQ system adds 16dB @ 31 Hz. It starts below 100Hz, and is going strong in the low frequencies. Remember this is lower efficiency sealed box version of the 901's. I also plotted the high Frequency settings labeled flat, 4& 5.
These are at the 7.5 foot distance in my listening room. The obvious sonic characteristic the the honky 200-500Hz boosted area. The sound stage is wide, the dynamics pretty good - Can't wait to do some DSP EQ on these.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Follow Ups:
This is why Bose speakers sounded good with crappy, tizzy '80s CD players.
Yep! That solo guitar is twenty feet across. :)
I've got them (front drivers) about 6 feet apart (I almost said "tweeters") and slightly toed in the mono center is about 4 feet wide! With my MMG's pushed out now to almost 9 feet between tweeters (tweeters in) the mono center is only 2 ft or so... Amazing difference. I can't wait to DSP this weekend on the 901's and see if I can "Dial them in"
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I own a pair of 901 series IV and apart from a few cones coming un-glued after 30 years they work well with Live Concert DVD's.
“The bitterness of poor quality remains long after the sweetness of low price is forgotten”
...the mono center is about 4 feet wide
What exactly is the criteria for determining "mono center width"?
When you play a mono band limited pink noise signal - how wide does my brain think the imaginary center source is.
FYI - I've dinked around with the positioning of the 901's and with the faces parallel to the rear wall about 2-3 feet away the center image has shrunk to an acceptable size. The high frequency level has suffered a bit for that move - since the listening position is now 30 degrees off axis.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Well to me a speaker that has produced the narrowest image - width and height would be the most resolving. For me, stereo is too confusing - so dependent on source material. Sure - I have a test tone that moves from left to right based on a pan - and another signal that moves the phase of one channel relative to the other. One of these days I'm going to make a good M-S recoding of a single loudspeaker in an anechoic environment and create a series of image placement positions based on level and phase.
I always start in mono when evaluating loudspeakers. Or other devices. In fact I'll listen to just one loudspeaker playing music way before I switch to mono through stereo - I get a far better idea of the way the timber is carried through and how directive the loudspeaker is.
Good thing I have a good relationship with a couple of my retailers near me. I even get to do real ($$$) work for them now and then.
Happy listening....
FYI teaching Seminars in MLPS this spring. I think I'd enjoy getting together.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I've always approached it from the opposite end. How realistic is the stereo image?
The high frequency level has suffered a bit for that move
Which was poor to begin with using midrange drivers!
Well, have fun with your experiments.
I'm reflecting n the design of the EQ unit a bit. I think in 1972 or so when these speakers were built, we were not as obsessed with high frequency detail, there were a lot of speakers that, by design,did not attempt to go above 16kHz and we had scratch filters to eliminate the intrusiveness or surface noise from our vinyl playback. And we also listed to a lot of radio, and there was hiss and other unwanted "birdies" as part of that experience. We were willing to do away with the high frequencies to "protect" our listening experience from noise.
In the Boss 901 -2 EQ the 1-2-"Flat" settings had that obvious roll off... in addition there was a Hi frequency filter switch that, when enabled, took all the high end boost away.
The bad thing about listening to modern equipment now-a days is that once you consistently listen to solid high frequency content - when the content is gone - the experience is dulled as well.
This EQ also has a Bass "Contour" switch that appears to be valuable if the 901's were place near a wall - it drops the low frequencies about 6dB with the role off starting at 250-300Hz.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I think in 1972 or so when these speakers were built, we were not as obsessed with high frequency detail...
The bad thing about listening to modern equipment now-a days is that once you consistently listen to solid high frequency content - when the content is gone - the experience is dulled as well.
I wouldn't call myself "obsessed" then or now, but have always enjoyed hearing the natural extension of cymbals, brushes, shakers, bell trees, triangles, etc. In 1972, I owned Large Advents which were definitely shy in the top octave. I supplemented them with Microstatic tweeters, intended to improve range and dispersion for many speakers of that day.
I also learned the role that the electronics played around that time. By '74, I was using an HK Citation 11 with a Crown D150 amp to drive them. A dealer friend loaned me his Audio Research SP3a for a weekend. What a difference that made at the top! I can still remember how much more natural the shakers that open Steely Dan's Do It Again sounded.
When these came out, the company had an aim to produce an array as good as the JansZen I30 at a greatly reduced cost. While the quality was nowhere near that of the JansZen it was so much more inexpensive it made sense to add them to speakers like the Advents and ARs. Sadly, they killed the JansZen as a viable product but it was a rapidly shrinking market so it was only a matter of time before the I30 was a dead product. It was sad as this was Art's cash cow, so to speak and not mixed up in all the licensing messes he had.
Don Brian Levy, J.D.
Toronto ON Canada
I wish I could have heard the Janszen tweeters with the Advents. I recall the 130 was originally paired with AR-1s to great success.
It wasn't until '76 that I heard Dayton-Wrights and became an instant fan of electrostats...
Didn't those use the Peerless cone tweeters?
They employed cones of two different diameters, but I don't know the manufacturer. While the dispersion of each tweeter wasn't impressive, the four driver angled array offset that issue.
It still didn't have the clarity of the soft dome tweeter in the Braun LV1020 that replaced it.
Looks very much like the Peerless, which was avail. in at least
two diameters. I think the largest was 3" frame. They all used very thin
aluminum domes which allowed them to have upper extension. I have some
in AA ads with pics, if you want to compare them. Mine are alnico with
black frame also.
They sure do look like yours.
of their speakers. You might have to lawyer up.
Hopefully they will head the warning from the tragic tail of Monster Cable!
Dave
I had the Series I that later was replaced with the series IV. I loved the open/surround sound of these speakers- but obviously they were heavily midranged, without much extension to top and bottom and lacked imaging among other weaknesses. Still, this set the stage for a company that has become a household word for mid-fi
jrb
Here you see the response of the MMG's - about 6dB less efficient - much more extended highs - the MMG is a completely no eq response and this one is setting outboard the Right 901 I tested. This causes most of the aggravated up and downs 160-200Hz and the peak at 630 in my room.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Interesting! What are you using to measure the room response?
Dave
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