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901Fixer 8th July 2009 01:16 PM

Bose 901 design
The much debated 901 has been criticized for its lack of quality components, over touted marketing hype, lack of bass and treble but what about its design? Does the design for reflecting sound add to the audio experience in a way other speakers can/do not? What other speakers utilize reflection?

I consider the 901 to be like a full range speaker which lacks both high and low extension. Some music this is fine but bass and tweeter support can easily be added.

Would it be worth while to design and build a speaker similar to the 901 but using superior components? Maybe just 3 drivers, two on the angled rear baffles and one on the front, padded to achieve the 88:11 ratio of reflected:direct sound. Use either full range or just a mid and forget about trying to achieve below 150hz and above whatever the natural ability is of the driver, no EQ to compensate. This enclosure could be half as tall as a 901.

Ok, I'm ready, flame away. :hot:

wwenze 8th July 2009 01:42 PM

Nice nick btw

(puts up flame shield)

IMO the key of Bose designs lies in reflected sound. The 801 is the 901 without the forward woofer but all woofers pointing towards the listener, the 301 has 2 tweeters - one pointing forward and one pointing backward.

Sony actually has a speaker with 100% reflected sound also.

Reflected sound seems to boost the feeling of space at a huge expense of everything else. But given certain situations, this may be critical. I actually have my bookshelves pointing backwards angled outwards due to lack of space on my table, or more specifically, the computer chassis.

In the case of 901 the massive time smearing resulting from drivers pointing in all directions probably gives the same effect as a large hall.

(puts down flame shield)

But that's about it for the reflection part. Even for those without drivers pointing backwards, Bose speakers have characteristic Bose sound which you already mentioned. I'm interested in knowing how they produce that kind of sound also.

I've seen before an Audax speaker following the 301 design (can't be sure if it can be considered a clone of one of the series's)... so there might be slight chance that a 901 clone exists.

But still, why would you want that kind of sound if you can do better. I wouldn't call your designed anywhere near a 901 as it is. I'm also partial to having reflecting tweeters than woofers.

And what this person said might be useful:

Bose 901's are all 9*.8 ohm speakers wired in series. They use the active equalizer for matching the drivers to the cabinets. Each active crossover is special to the series, although they all show simular results on the scope. It is posible to use the 901 without the active eq if you have a plain eq and configure it in a V (boost the base and the treble) to about 12-15db.

planet10 8th July 2009 03:35 PM

Fred Toole has a lot to say about the importance of reflections for home audio Ir makes one start to think that the idea of the 901 isn't as far off as many think. (i'm only to Chapter 9, and i have the feeling that he is going to push surround speakers with the "reflections" synthesized in the recording).

But i've heard a few 901s, and i think there is too much reflection. A bipole or omnipole , i'm guessing, provide a better balance.

If you use 3 drivers, 2 rear wired in series, in parallel with one on the front, gives equal level front & back with a more diffuse sound than a single rear-firing driver.


Cal Weldon 8th July 2009 04:15 PM

Back when I was fooling around with the idea, I found that 4 - 8 ohm drivers wired series/parallel with one on the front and three on the back worked pretty well.

901Fixer 9th July 2009 12:43 AM


Originally posted by Cal Weldon
Back when I was fooling around with the idea, I found that 4 - 8 ohm drivers wires series/parallel with one on the front and three on the back worked pretty well.
What did the enclousure look like? Were the rear baffles angled etc. ?

The large woofer enclosures I'm working on are also stands for the 901's I have. If I'm not happy with the 901's at some point I will replace them with a better full range or multiples of full range drivers. This is for a large room, 25' x 25' with 10' ceilings and I listen to it not while sitting but rather doing other stuff and in other rooms sometimes.

Does a rear firing woofer about 12" from the back wall need a deflector on the wall or does <300hz not matter so much?

el`Ol 9th July 2009 11:25 AM

Here are three threads about indirectly firing fullrange concepts:

An interesting driver for rear firing in a 901-like speaker would be the Ciare HX160 which has a high sensitivity (rising up to 100 dB towards the top) which has a strange dispersion pattern and images much better when rear firing compared to front firing. The front driver could be something with lower sensitivity like a little Jordan/Bandor/Mark Audio.
For the enclosure one could think about two really large bamboo bowls mounted to a UFO-like structure like Manger once did for their bipole.

bear 9th July 2009 01:34 PM

Back in 1973 I built a "better version" of the 901.

I used a twin line of drivers, in a vertical array in the rear. Built both 2 x 8 and 2 x 10 in the rear, two drivers on the front, wired in series parallel, iirc 3 in series then paralleled.

The idea was to improve the horizontal dispersion by making a better polar response, due to the double wide line array.

At the time I used the Ted Jordan designed Maximus woofer, an alnico magnet driver with a 1" VC and a 3" cone with a 1/2" surround, total mounting hole was 4.5" size, iirc.

I also added a mylar dome tweeter to the array, one on each rear line.

This made a taller, thinner box. The bass was EQ'd, the highs not.

Worked quite nicely back in the day... sweet midrange with that driver.

Today Tang Ban seems to have a number of candidate drivers for such a project, as well as some other companies... I think I'd experiment a bit with low cost drivers before committing big $ to a Bose 901 redo...

I'd rather listen to a real line source than a reflecting speaker today... or actually even in 1976, when I went to a direct radiating line source. You can see an image of that in the Archives section of my website - latest version Firefox users will have to go into prefereces and make an "exception" to unblock my site, it is free of malware now, they will take their time unblocking it.


myhrrhleine 9th July 2009 10:29 PM

look into LEDE studio design
and chip davis

Cal Weldon 10th July 2009 12:41 AM


Originally posted by 901Fixer

What did the enclousure look like? Were the rear baffles angled etc. ?

Yes, if looked at it from the top they were the shape of home plate in baseball (from the pitcher's perspective) with two drivers on one part of the back, one on the other and one driver on the front. Nothing on the sides. It gave you the opportunity to switch them around depending on how wide you placed them and what kind of "imaging" you wanted. Like most of those projects from long ago, I made one, it was a rough plywood box and I found better things to do with the drivers in the long run. It deserves revisiting as I am considering a new livingroom speaker and am considering the fostex FF85 driver for the mids in a similar if not the same configuration. Hard to say, I have two OB mid speakers now and it might be hard to go back to a box.


planet10 10th July 2009 02:04 AM


Originally posted by Cal Weldon
It deserves revisiting as I am considering a new livingroom speaker...

After our exchanges earlier, that immediatley popped into my head when i read the thread title in my mail...


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