a simple question for 901 users

[SubSonic]

Hello, for those who own and use the Bose 901 speakers, im wondering if there are high frequencies coming out of the reflectant speakers- as in the 8 drivers facing the back/side walls. or are the high frequences coming only out of the direct and single driver in the front? All series welcome. I do not ask for any negativity on Bose or their products. please keep this peaceful. thank you!

[Snap]

I am not 100% sure, but the 901's have a HARD time with upper midrange, and high freq. That is just the design of the bose. I am 90% sure that the mid/high range is supposed to come out of the front. And the Low/mid range out the back driver.

But if I have my bose right, they do not have tweeters. They only have drivers, and this the problem with mid-high/high freq output.

[whoaru99]

I believe that all drivers in the 901's are "full range" drivers and that there is no crossover per sea.

[miner]

Yes, all are full range, not Xovers for per se. The reason for the extrernal eqaulizer, for boosting those freq that the full range speakers have a hard time reproducing.

Have you had to replace the surrounds on your drivers yet?

[SubSonic]

me?? i dont own them i was just curious.

[ac81017]

Hello, for those who own and use the Bose 901 speakers, im wondering if there are high frequencies coming out of the reflectant speakers- as in the 8 drivers facing the back/side walls. or are the high frequences coming only out of the direct and single driver in the front? All series welcome. I do not ask for any negativity on Bose or their products. please keep this peaceful. thank you!

They are ALL full range drivers!!

[TitaniumMan]

I do not own anything from Bose, but I have installed a few systems. The 901 EQ does affect all the drivers, so high frequencies are sent to both the front and rear of the 901. Back when Bose shared some of its technical information with the great unwashed, it was revealed that cone break-up was supposed to force the dust cap to act as the tweeter.

There are many other companies that rely on cone break-up including B&W, Lowther, Fostex, and almost every home-built speaker using a full-range driver. Some are even called "high end." I don't own those brands either.

[David Meek]

it was revealed that cone break-up was supposed to force the dust cap to act as the tweeter.

What? Could you (or someone) explain the reasons/principles behind that a bit more?

[AptosJeff]

What? Could you (or someone) explain the reasons/principles behind that a bit more?

There is much to read and say on this subject, but I'll offer a short version. Cone break up occurs when the freg becomes too high for the cone to act as a simple piston. There are radial and circumferential modes of deformation and it gets complicated as the freg gets higher. Parts of the cone are moving out of phase with other parts and this is generally bad. But another related effect is that as the freg gets higher, the outer sections of the cone start to decouple from the center. If this is done gracefully, as B&W and others claim (and not easy to do), it can be helpful in letting the cone act as if it gets smaller at higher frequencies, which reduces the bad effects of breakup and improves dispersion.

I'm guessing that Bose was saying that at high enough freqs the only effectively radiating part of the cone is the center, including the dust cap, esp if it is rigid.

[TitaniumMan]

What? Could you (or someone) explain the reasons/principles behind that a bit more?

I'll give it a shot. Of course, this will be just a vague generalization. There are plenty of exceptions and specifics I won't mention. As the frequency wavelength shortens to less than the diameter of the driven cone, the driver enters "break-up." It doesn't actually fall apart or anything like that. It merely stops acting as a piston, and various areas of the cone appear to move almost independently of the voice coil.

For instance, at one frequency I'll call X, the voice coil and the dust cap riding on top of it can move forward at the same time the edge of the cone is still trying to move back. I once saw a dust cap moving furiously in and out while the rest of the cone looked to be motionless. Needless to say, that was from a very large and flimsy cone.