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Bose 901 Series VI Active Equalizer Measurements

Main differences are that an open baffle has the front and rear radiation which is of opposite polarity and of nominally equal amplitude front and back, whereas the 901s have all drivers of the same polarity and only 11% is to the front.

S.
"only 11% is to the front." Good thing because the original 901 could peel your eyelids off.
 
I loved my 901s, I had the Active EQ but didn't use it,I used a ten band per channel Pioneer EQ instead
Powered by my VSX D1S, Circa 1990, plenty of power for them,
Pretty good price for them in black or walnut at the BX
I may of liked my 601s a tad better though:)
I had the 601's, and although I may have been a less-sophisticated listener in 1981, I listened to a huge amount of classical, R&B, etc., and read as much Sterophile as I could, and still really enjoyed those speakers a decade later. Full orchestra sounded great and it had a version of the 901's direct/reflected sound, with a less-radical design than the 901 and healthy bass drivers to complement the 4 tweeters on each unit. (No electronic EQ required.)

Did anyone else have a good experience with 601's as Oldasdrt and I did, back in the day?

I put two satellite speakers in the rear with just out-of-phase signal (to convey ambience for acoustic source music) and got a very satisfying surround effect without modifying the source signal except to extract the unadulterated out-of-phase component. This helped to convey the reverberant acoustics of a concert hall with more than adequate delay even in my modest-sized living room. The front image was huge and convincing, and I missed it after I moved on.
 
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I had the 601's, and although I may have been a less-sophisticated listener in 1981, I listened to a huge amount of classical, R&B, etc., and read as much Sterophile as I could, and still really enjoyed those speakers a decade later. Full orchestra sounded great and it had a version of the 901's direct/reflected sound, with a less-radical design than the 901 and healthy bass drivers to complement the 4 tweeters on each unit. (No electronic EQ required.)

Did anyone else have a good experience with 601's as Oldasdrt and I did, back in the day?

I put two satellite speakers in the rear with just out-of-phase signal (to convey ambience for acoustic source music) and got a very satisfying surround effect without modifying the source signal except to extract the unadulterated out-of-phase component. This helped to convey the reverberant acoustics of a concert hall with more than adequate delay even in my modest-sized living room. The front image was huge and convincing, and I missed it after I moved on.
I also had the special edition 301s which were different than the normal 301s and also a Polk sub sat system that completely rocked and a Infinity bookshelf speaker for the center channel,
I'm sure I drove my neighbors nuts:)
 
In room Measurements of Series 1 vs Series 6
Thank you for the link to the measurements of different Bose901 versions. I hadn't known that they had 6 different iterations...:oops:

Boy, oh boy!
Now, I realize how complicated they really were to set-up in a room << almost impossible; especially without test-gear of today.
I mean, in the mid-70s, some of us had not even heard of "golden ears" or that one could even get their hearing tested.:facepalm:
You could move those speakers around just by a few inches (L/R/In/Out) and you knew something changed but did not know why and what!
 
Thank you for the link to the measurements of different Bose901 versions. I hadn't known that they had 6 different iterations...:oops:
There is actually Series VI and Series VI Version 2.0 so there are 7 official versions. Series VI uses foam surrounds. VI version 2 had the ribbed/waffle surrounds.

Now, I realize how complicated they really were to set-up in a room << almost impossible; especially without test-gear of today.
100%. Without the REW sweep, it’s trial and error. There are no detents for the equalizer sliders either, so mid positon is slightly different


You could move those speakers around just by a few inches (L/R/In/Out) and you knew something changed but did not know why and what!

Exactly, and there is also the dumbing down of the instruction manual over time.

Series 2 says that the 901’s were designed for 12” from the rear wall, ideally rigid and not glass. Then they give you a range of reasonable distances.

The later versions with ports only give you a range, which is greater. Is the design spec 12” still? Or is it further now?

No idea. With homebrew REW measurements, we can easily compare objectively. Without it? Who knows?
 
I found an original pair of 901's in a storage closet at work. They were free for the taking. That was a few years ago and I still have not listened to them since the eq box was not with them. The rubber on the drivers seems fine under inspection. Should I look for an eq box?
 
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Here is the Series VI version 2.0. This PSU is a bit nosier but may reflect electrical weather. The THD and noise are lower overall though.

I found an original pair of 901's in a storage closet at work. They were free for the taking. That was a few years ago and I still have not listened to them since the eq box was not with them. The rubber on the drivers seems fine under inspection. Should I look for an eq box?
You can just use Equalizer APO and REW and it’s probably better.
 
I miss my 901s, I bought them from an ex Bose employee who sold his home in Boise foothills and moved to Montana for retirement. I sold them for 400$ to a buffoon.

He had a story about how their store in Vermont had a hall with 4x901s, 2 from ceiling and 2 on the stands powered by Bose 1801 amplifiers. They played some classical music and his opinion was that he couldn't get to something like that ever again. BTW, apparently Dr Bose also was witness to that event.
 
While fun in the 70s don't understand why anyone wants to continue with these....
 
I also had the special edition 301s which were different than the normal 301s and also a Polk sub sat system that completely rocked and a Infinity bookshelf speaker for the center channel,
I'm sure I drove my neighbors nuts:)
I had heard 901's several times, and I saw the 601's as the fix to the 901's problems, as a more advanced design: every time I heard the 901's, I was intrigued by the imaging but always disliked the sound. The 601's had convincing bass as a two-way design (no strain on full range drivers or electronic EQ graft-on), and the direct/reflected image was stunning. They were not cheap or stripped down: each pair sported eight tweeters and four bass drivers, with more balance between direct and reflected sound, which gave a clearer, although still very large, stereo image.

I was always left cold by the 901's when I heard them, but always just liked the 601's. Nice, balanced sound, very satisfying bass; it made my small living room sound bigger. Classical just sounded like the real thing and rock rocked. I tried EQing them but found little to fix, since they just seemed to work well in my living room, and I ditched the EQ and experimented with room treatment a little. Maybe not super high-end, but they did everything pretty darn well, and I listened hard and long to their sound while also attending live concerts.

Weird side effect of the 601's: when I got them in 1981, I was NOT a fan of Neil Diamond ... but when my wife brought home a Diamond LP and put it on the 601's, I instead liked him, which I found really odd at the time. Maybe that's either a point in favor of or against the 601's, I'm not sure.

Over time, I picked up on the bias among audiophile opinion against Bose, but held onto my 601's until Los Angeles smog ruined the bass driver surrounds; I replaced the drivers, but they just didn't sound the same.
 
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While fun in the 70s don't understand why anyone wants to continue with these....
Because the unit in the 70’s is different from the later units.


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Because the unit in the 70’s is different from the later units.


View attachment 287485
Will check that out.
 
I am not sure if that tells me more about the actual sound of the speaker or your notions about bashing Bose as a company and name.;);)

I have heard them randomly over many years set up wrongly and so on and just very recently at a friends, and "Horrified" and "How bad" would never even come close to describing them.
They are not perfect for sure in regards to all ideals of "Audiophile Standards" and they have a huge, unusual at times, large soundstage for sure, but "Bad"??

They are relatively flat response, not annoying in the least, in fact relatively pleasant.
I feel if anything they lose some detail and clarity and so on, but nothing that would be even close to bad.

But, I have heard probably hundreds of speakers, rack systems, compact systems, cheap stereos, top of the line stuff...my standards of "Bad" may be different.
At high volume levels and with the 601s and Polk sub sat system, the 901s sounded fantastic, Id be happy to have the same system today, including the VSX D1S 2,
Back when Pioneer made good products
 
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I ran Dirac Live 3.0 with a Harman Curve with a +10 dB bass boost and compared the EQ against the Bose 901 Series VI Active Equalizer.

1) In general, you can see how the Bose EQ generally replicates the Harman Curve
2) Except for the 150-250 Hz room effect, you can see that Dirac Live's EQ actually isn't that far off from the Bose factory EQ. Impressive!

The 150-250 Hz may be from me taking the Dirac measurements while actually sitting in the listening positions.
 
At high volume levels and with the 601s and Polk sub sat system, the 901s sounded fantastic, Id be happy to have the same system today, including the VSX D1S 2,
Back when Pioneer made good products
Wow, I am amazed that I own something by 2 of those companies (& will own a 3rd, through no fault of my own): Klipsch desktop speakers & sub (Heritage series) & a set of ancient (but good) Sennheiser TS180 wireless headphones. And before next year I will own a car that has (not by choice) a Bose stereo system.
 
Besides the post right above comparing the EQ, I also ran measurements through Dirac's 9-point averaging.

Again, the Bose 901 closely matches a theoretical Harman Curve with an 8.5 dB bass boost and slight 2.5 dB downward slope!

Same images, one with the target curve shown and not shown.

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I personally don't like the roll-off of the high frequencies and I run a +10 dB bass boost and a flat target curve.

The correction with DIRAC alone doesn't boost the treble sufficiently, so you should run the Active EQ if you are sensitive to high frequencies or consider wiring a super tweeter if you are corrected exclusively with software.

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I gifted myself a pair of used but in excellent condition VIs for Xmas, this review was basically the tipping point (that is my excuse at least). After setting them up with a Minidsp Flex and Dirac (software crossover only) with the Dirac Autocurve (+4.0/-0.8db) i have to say they sound quite good. Quite happy with them so far, especially for the low budget involved.

My measured curve more or less stops at 8 khz, similar to the one above from GXAlan. I was thinking about adding a pair of ESS AMT Dipol Air Transformers, and a passive crossover 12db @7000Hz. Did anyone try such a setup yet, any dos/donts?

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