Bose 901 IV serie

[901Fixer]

I purchased the set of 901's I have a few years ago cheaply with the intent to use them just for the mid-range and add Woofer and Tweeter support to "fix" their deficiencies. Thus my screen name. I wanted to experience the magical surround sound effect too!

Having experimented many years ago with various subwoofer designs and types it makes me think he chose the 9 drivers he did because of how Spl increases in multiples. Two 10" woofers have more surface area than a 12", close to that of a 15" etc. A mid can stretch up and down in frequency range where a woofer can only go so high and a tweeter just so low. Since a mid will roll off with less Spl in the highs and lows just cut the Spl in the mid range to make it match the ends so to speak. Add wattage to bring the resultant "flat" level up.
....or he lost a bet or wanted to be talked about for years to come, could be any of the above.

[MCPete]

Are those two vents (ports) on the left and right sides in the 3rd photo posted by the OP in his first message? If so, I was wondering if the shape is just cosmetic to look cool, or did Bose at the time engineer a special kind of vent? If the two tubular shaped parts aren't vents, then what are they?

[River757]

^ yep they're vents, along with the smaller but identical version for the single front-mounted driver. The tapered rod located in the center of the vent is designed to decrease air turbulence at high volume levels. When I used to sell audio in the early 90s, I remember placing my hand near one of them while some bass-heavy music was turned up particularly loud and the air rushing out felt like a (heat-less) hair dryer.

[Inductor]

Originally Posted by River757

^ yep they're vents, along with the smaller but identical version for the single front-mounted driver. The tapered rod located in the center of the vent is designed to decrease air turbulence at high volume levels. When I used to sell audio in the early 90s, I remember placing my hand near one of them while some bass-heavy music was turned up particularly loud and the air rushing out felt like a (heat-less) hair dryer.

I guess no subs at the time (commercial gimmick like now) in the 70's & 80's, from what I remember, or LFE for the same effect.

[Inductor]

Originally Posted by 901Fixer

A mid can stretch up and down in frequency range where a woofer can only go so high and a tweeter just so low. Since a mid will roll off with less Spl in the highs and lows just cut the Spl in the mid range to make it match the ends so to speak. Add wattage to bring the resultant "flat" level up.

In part I agree... they are FR.

[River757]

If anyone's interested, in the near future an online audiophile magazine will be testing the current version of the 901. Read about it, and the audiophile indignation , here.

[daniloreyes]

Originally Posted by River757

If anyone's interested, in the near future an online audiophile magazine will be testing the current version of the 901. Read about it, and the audiophile indignation , here.

Which one? that would be interesting, a magazine that will not be afraid of being sued by Bose, that is.
Joke aside, it took me long time to get to a speaker that was good enough to replace them.

[River757]

^ tonepublications.com

[ctef]

The only test thet I know until now is this, in German HiFi magazine from 80's.

[ctef]

With the help of online translator, I understud more or less what they tolking about. But will be very grateful if somebody from Germany translate it for us. Not all, just the most essenial passages.
Here you are the same feature, but with digitalized from me text, for easy translation.