Hey all,
I've been running through some scenario's in my mind and i was hoping to get some input from the crowd on here,
I've been diving into the operating principles of the Bose 901,
How you all think the reflected sound would be affected if using larger full ranger drivers, say 2 x 12inch full rangers vs the 8 x 4inchers on the back face?
Or ditch the full range entirely and use a combination of mid-woofers and two horn loaded CD's on the back face?
Just curious if people have thoughts on this.
I've been running through some scenario's in my mind and i was hoping to get some input from the crowd on here,
I've been diving into the operating principles of the Bose 901,
How you all think the reflected sound would be affected if using larger full ranger drivers, say 2 x 12inch full rangers vs the 8 x 4inchers on the back face?
Or ditch the full range entirely and use a combination of mid-woofers and two horn loaded CD's on the back face?
Just curious if people have thoughts on this.
I have wondered if 9 2 inch full range woofers would sound good in that configuration.
Adapters would need to be made.
3 sets of 3 woofers equals 8 ohms.
Adapters would need to be made.
3 sets of 3 woofers equals 8 ohms.
Did you ever listen to a technical intact 901 with the equalizer box in front of the amp? Don't judge a speaker system by descriptions some people post on the web.
The 901 is special, as for optimum performance it used an active frequency correction, that expanded it's range. Without the thing in the chain they sounded very different.
The other point was that it could take enormous amounts of power. Even as a single chassis was quite weak, the power distributed over all of them was very high. It is not really made for weak valve amps, as any electronically corrected speaker. Today one would use a DSP to get a similar or better result.
You can build any direct/reflecting loudspeaker with any chassis size you like, but the main point about a 901 clone is the form of the cabinet and the number and size of chassis. At least you should look for the function and idea of the construction. Like many BOSE constructions it was quite special and in general it is questionable to use so many identical chassis.
I may get burned for this, but imo at Bose they were quite good in combining construction mistakes that canceled each other out. Some say they use any trick in the book to make candy from dirt... I question that you will have the time and funds to do the same with some 12" full rangers.
There are a zillion ways to build a different or better speaker, but that has nothing to do with a 901 anymore.
A huge improvement would come from the use of a large passiv radiator, driven by the summ of the 4". Maybe on the underside. You could get some nice, deep bass for free.
The 901 is special, as for optimum performance it used an active frequency correction, that expanded it's range. Without the thing in the chain they sounded very different.
The other point was that it could take enormous amounts of power. Even as a single chassis was quite weak, the power distributed over all of them was very high. It is not really made for weak valve amps, as any electronically corrected speaker. Today one would use a DSP to get a similar or better result.
You can build any direct/reflecting loudspeaker with any chassis size you like, but the main point about a 901 clone is the form of the cabinet and the number and size of chassis. At least you should look for the function and idea of the construction. Like many BOSE constructions it was quite special and in general it is questionable to use so many identical chassis.
I may get burned for this, but imo at Bose they were quite good in combining construction mistakes that canceled each other out. Some say they use any trick in the book to make candy from dirt... I question that you will have the time and funds to do the same with some 12" full rangers.
There are a zillion ways to build a different or better speaker, but that has nothing to do with a 901 anymore.
A huge improvement would come from the use of a large passiv radiator, driven by the summ of the 4". Maybe on the underside. You could get some nice, deep bass for free.
The large drivers are going to be more directional at lower frequencies requiring a different equalisation to produce a reasonable tonal balance at the listening position. 2 sources rather than 8 is going to be more coherent at the listening position with possibly more significant comb filtering (Carlsson used multiple tweeters to address this issue with his earlier speakers and in his later speakers largely avoided reflections off the front wall). It is unlikely to be as effective as multiple smaller drivers but to what extent is hard to say.
901 design is quite special concerning amount of direct sound (1driver) vs 8 at the back side.
With bigger drivers this relation is changed.
But principally it would work with two 12 inch on the back side and one 12 inch at the front.
If made active you could control the loudness of the two on the backside separately from the one on the front. So you can experiment how much indirect sound you want, even from music title to music title if adjustment can easily be made.
I wanted to build a 901 copy with 12 inchers but never found the time to do that.
With bigger drivers this relation is changed.
But principally it would work with two 12 inch on the back side and one 12 inch at the front.
If made active you could control the loudness of the two on the backside separately from the one on the front. So you can experiment how much indirect sound you want, even from music title to music title if adjustment can easily be made.
I wanted to build a 901 copy with 12 inchers but never found the time to do that.
Crucial is placement in the room. You certainly need space for having some distance to back and side walls
If one designs a speaker with the objective of increasing a sense of spaciousness (at the expensive of imaging precision) by increasing the level of indirect sound relative to the direct sound then the quality of the indirect sound is going to increase in importance. At higher frequencies this indirect sound needs to be significantly diffuse rather than coherent to minimise interference issues. This is very likely why the Bose used multiple smaller drivers rather than one or two larger ones which likely would have been cheaper and more efficient. I am not familiar with Bose publications but can anyone confirm?
Having a go with one or two large drivers for the indirect sound seems like a fun project and I would certainly be interested in the results as it would seem would one or two others. So not wishing to be discouraging just pointing out there will be cons as well as pros compared to the original Bose speaker.
Having a go with one or two large drivers for the indirect sound seems like a fun project and I would certainly be interested in the results as it would seem would one or two others. So not wishing to be discouraging just pointing out there will be cons as well as pros compared to the original Bose speaker.
Not sure diffusion of that kind will be of great benefit compared to multiple sources with different path lengths but it may do something positive. Well worth putting on the list of things to try.
Flawed. The best improvement i made to a BOSE 901 system was to rotate them 180° so the 8 drivers faced forward.
I would look to an omni if you want lotsa room.
dave
The 901s throw a large soundstage but don't have much imaging ability IME. If that's not important, and a corner placement for the speakers is possible, I'd sooner consider a Decca corner horn. Much cheaper to construct, more efficient, with a large, spacious sound that doesn't need equalization.
I read that they use light bulbs to protect the drivers - is that true?
It's not a bad thing, necessarily... it's just the the power it actually uses - is limited.
OP don't take too much notice of the detractors. Here is a thread on blind listening tests involving a Linkwitz Orion open baffle speaker, a modest Behringer studio monitor and a cheap Bose 901(ish) clone using radio shack drivers. Guess which came out on top?
They do use light bulbs in the XOs to act as compressors, and help protect the drivers. A good move to lose them.
dave
dave
Wouldn't the 301 be a better starting point to play with reflected sound?
I have to say I've never heard them, but I'm curious as to how well they work.
I have to say I've never heard them, but I'm curious as to how well they work.
Funny, the one and only time I heard 901s was with the rear side facing forward, in my high school auditorium. I don't remember anything about the presentation, just the speakers. They did a good job filling the large space with sound. That was a long time ago, graduated in '77. I once coveted the 901s but couldn't afford them at the time. I've since moved on.
As a PA speaker, that would be the way to do it. Pretty sure I've been in a disco with 901's, but that was a long time ago and my memory isn't improving.
jeff
Typically it would be Bose 802's in a PA system. Similar size and shape as 901's, but only the 8 drivers facing forward.
https://reverb.com/en-fi/item/77379072-bose-speaker-802-series-2-w-case-used
https://reverb.com/en-fi/item/77379072-bose-speaker-802-series-2-w-case-used
Last edited: