CSS FR125 Bipole revisited.. - Page 2 - diyAudio
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Old 7th March 2008, 10:25 PM   #11
Bukem is offline Bukem  Belgium
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Hi Cal,

That clears things up a bit.

Presuming it can be an all FR125 system then this is a serious contender. I have a few thoughts about how I could possibly rearrange the horn mouth so I get a smaller enclosure. I love your design but I don't think my wife is quite so sensitive to the benefits....

If you imagine the two horn mouths which are now situated at the top and bottom and place one on the left hand side and the other one on the right hand side you'd slash 2/3 rd of the height and triple the width of the enclosure. Provided the volumes etc of the cavities is respected do you reckon something like that might work?

I'll be away the whole day tomorrow so I won't be able to explain further until sunday. I'll try if necessary to draw what I mean in cad.


As another contender I would still like to explore the possibility of a front to back bipole with possibly another two units as a "Q-tune-able passive radiator".

Does anybody else have some further thoughts on this? I somehow feel that we need to think a bit further then just slap a driver into an enclosure. People also tend to avoid using two drivers in a tandem arrangement with a small sealed cavity in between to reduce box Vb. It also evens out non-linearities. I'm just trying to get the best type of sound instead of being driven by expenditure.

Regards,

Bukem
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Old 7th March 2008, 10:40 PM   #12
chrisb is offline chrisb  Canada
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Quote:
Originally posted by Cal Weldon


I believe our dear friend is indeed referring to these:

precisely, yes

Bukem - I had a chance to hear these a few weeks back, and I can't remember what woofer Cal might have been using, but the net results was quite fine ; can Jimmy Buffet sound bad on anything?
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Old 7th March 2008, 10:45 PM   #13
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Quote:
Originally posted by chrisb
and I can't remember what woofer Cal might have been using
Um...woofer?
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Old 7th March 2008, 11:12 PM   #14
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Hi Bukem,

Reason for shape - convenience, but worked well.

No measurements, only listening.

FR125 is not going to do much bass without LF displacement garbling the rest, so why not let other drivers come in near floor level and help at LF where otherwise the FR125s would be rolling off.
I don't mean woofers, but maybe more widerangers or mid-bass with a choke in series.

If as you suggest other drivers are used passively as 'resonant phase changers' the main drivers will still be the only drive source at LF.
Additional parallel connected drivers at LF need not rely upon cabinet or passive resonance.

Cheers ....... Graham.
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Old 9th March 2008, 11:30 AM   #15
Bukem is offline Bukem  Belgium
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Graham,

My intention is not to use another "active" bass driver. The reason why I kept going on about using the FR125 as a passive is just to explore another type of "loading".

People have explored different types, from sealed to horn, from aperiodic to bass reflex but never ever do people to experiment with using a fully working driver as a "passive" unit. Furthermore, by doing so you have the opportunity to play with the resistor values to alter the behavior of the "passive" unit.

There are a few of my original questions in this topic which have been left unanswered. Hopefully somebody manages to explain to me.

1) BIPOLE - What's best and why: Narrow and deep baffle OR Wide and shallow baffle OR Wide+deep OR Narrow+shallow......

2) Consensus seems that the rear or side driver should be run full range - possibly with a cap to pad the highest frequencies. However, I would like to find out why this is. General comments are that "the life is sucked out"...surely the objective MUST be to fill in the baffle step "gap" left by the front driver?


Quote:
I cannot see any advantage for giving each driver its own cabinet; reflection paths to the rear of each driver would be shorter, whereas some damping material or reflectors could be used between sharing drivers
Why wouldn't there be an advantage. The mechanical vibrations passed on to the enclosure are the same for the front and rear driver. Wether there's a shared volume or not. The only thing that happens by dividing the volume into two, is that the one driver has no possibility to alter the other drivers' cone movement - surely that must be a HUGE advantage?

Cal,

Do you have any thoughts about sticking the mouth to the left and right of the driver? Or even to the side? (reducing the height of the enclosure by 2/3rd) ...More or less the idea like in the attached drawing. In this case I have positioned the 2nd driver at the back although a design with the driver on the side could be done as well. It's not a very good "copy" as for the length and path of the cavities but this can be done. I just want to know whether a reworked design like this might work.


Many thanks,

Bukem
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Old 9th March 2008, 04:19 PM   #16
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Hi Bukem, I'm not the expert here. I rely on others knowledge and I do the subjective listening part.

If i were to do it, I would consider cutting the box in half rather than thirds. That way the construction would be easier as the exit from the compression chamber is in the center as it sits now and you basically be just folding it in two. If you were to try it your way, you'd need others to guide you through that.
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Old 9th March 2008, 04:49 PM   #17
Bukem is offline Bukem  Belgium
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The way I look at the current enclosure style is that it's a partial bass reflex enclosure + a horn. The slot + the channels running up to the horn throat look like a traditional vent to me. Perhaps it even mimics an aperiodic type of vent.

At the end of the vent is the horn. I presume the slope angle and width/depth of the horn is fixed.

So basically, what I would like to know, can I shape the vent part in any way I like and stick the horn bit at the end of it? If that's the case then I'll do a few proper designs.

Can't wait to find out !

Bukem
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Old 9th March 2008, 04:55 PM   #18
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I would imagine you could reconfigure it as you wish. My thought was that the exit from the compression chamber is in the middle now so it would be rather easy to construct a side by side Calhoun. I wonder if the figure you posted might end up being a bit boxy?

Here's the shot again of the boards laid out before construction.
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Old 9th March 2008, 05:10 PM   #19
Bukem is offline Bukem  Belgium
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I'll have a think about a different design layout and see if I can come up with something sexy!

Cheers,

Bukem
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