My open baffle dipole with Beyma TPL-150

[StigErik]

Originally Posted by mige0

LOL
(you don't have to use rubber - no good!)

Oh yes, there are situations where rubber is no good.

[Rudolf]

Another example of a stringed WOB (WithOut Baffle )

Xovers are at 100Hz and 1500Hz with 24dB/oct. Bass EQ is 20 dB total from 100-15 Hz. Mid EQ is 15 dB total from 450-100 Hz.

The builder reported that there is almost no movement of the Kilomax when hung from the ceiling.

[CLS]

Wow! that's a quick action, and wonderful, too!

In such 'suspension', I found the compliance in the tensional direction is not necessary. By the relatively low mass and low rigidity, the vibration energy can not pass through the suspension effectively. So any string/wire/cable can be used if only the tensional strength is enough. (I myself use stranded steel wire with clips for hanging my mid-high horns)

[mige0]

Originally Posted by CLS

Wow! that's a quick action, and wonderful, too!
...I myself use stranded steel wire ...

Me too - I found it the best sounding, cheap and most reliable solution.

I recommend to pay attention to some details - there is some reward of.
Make sure you have well defined points where the most part of movement (bending) occurs - meaning - avoid any rubbing there (the internal friction is already something we can not avoid).


Michael

[StigErik]

I am very tempted to try the same with the woofer as well. I am a bit unsure whether such a heavy woofer (370 grams cone) with large Xmax will stay in place without any support. Just have to test it I guess. Will need a much heavier frame than I have now, but we'll see.

[CLS]

I got a center OB sub which the construction is very shallow, accommondating 2 18" with 130g Mms (total 260g). When playing, its vibration is quite obvious by touch.

OTOH, my main baffle is more rigidly braced and with deeper base board. And with only one woofer (same as above), it's much calmer by comparison.

I think, baffle-less or not, these heavy woofers would better be braced/supported rigidly to obtain better dynamic and output. Suspended freely, there'd be inevitably opposite motion (or some forms of delayed and irregular motions... ) on the whole driver related to the cone.

[StigErik]

CLS,
Like I suspected... thanks.

Think I'll go for a heavy bracket or something for the woofer.

[mige0]

Originally Posted by CLS

Suspended freely, there'd be inevitably opposite motion (or some forms of delayed and irregular motions... ) on the whole driver related to the cone.

Regarding irregular motion - that's what I too thought before I dived into the topic – but actually quite the contrary is true. Try and you well see - aahhh - you will hear


If you read through my paper (math is pretty simple) you can see that "movement in disorder" only happens with the common approach eg. trying to keep speakers rigidly in place – whereas suspending a speaker freely results in absolute predictable movement of veeeeery low amount.
http://members.aon.at/kinotechnik/di...ducing_CIC.htm

The net benefit is that there is *no* resonance whatsoever (except the veeeery low fundamental of the pendulum) when speakers are hung – well - for the overall movement we are talking of here.

Seen from a more philosophically point of view my arguments outlined in the paper directly relate on the concept of "local mass" – which can be seen as an equivalent to "acoustically small dimensions".

Michael

[Rudolf]

Originally Posted by mige0

The net benefit is that there is *no* resonance whatsoever (except the veeeery low fundamental of the pendulum) when speakers are hung – well - for the overall movement we are talking of here.

Thats what the user of that Kilomax reported: There was NEVER a visible motion of the woofer basket and magnet.
Regardless it helps to make the pendulum as long as possible.

[CLS]

Hmmm.... can't imagine now, but I'll try to understand. Thanks a lot

For those drivers already installed on the baffle, what can be done? It seems all gaskets/spacers are not compliant enough. And it's hard to 'float' the whole assmebled baffle