Suggestions regarding woofer placement on the baffle with multiple woofers

New 3-way project with dual Anarchy 6.5" woofers - in the early stages, boxes glued..

I'll be making a speaker with two 6.5" "Anarchy" woofers per enclosure.

In determining how high each is placed on the front baffle my primary concern is reduction of floor bounce cancellation, which of course, complicates things because the woofers will need to be crossover higher than ideal from a "localization" perspective, since the primary FBC node may be around 200Hz... The midrance will be located just above the dual woofer enclosure in it's own enclosure - so, say around 36" approximately.

The dimensions of the [already built] enclosures are:

33-3/8" Tall, 15-7/8" Deep, and, 8.5" Wide

The walls of the enclosure are 11/16" thick at this point, but I anticipate adding constrained layer damping inside, and, they will be well braced.

Any suggestions or comments?
 

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With a 200Hz crossover or baffle step boost from the woofers, 17" is the quarter wave limit for C-to-C mid-to-woofers. Most commercial TMWW speakers position the upper woofer just a few inches below the midrange in order to position the lower woofer "close to" a quarter wave. In order to move the floor bounce effect down lower in frequency, the lower woofer needs to be centered ~9" and that still puts the upper woofer center ~17.5" where it will push up the floor bounce frequency to about the same level as a 24" center upper woofer. Two stacked Anarchy woofers will have one woofer high enough up on the baffle to muck up the midrange.

With an 8.5" wide baffle, rear and side wall distances can have a larger effect on SPL.
 
Hi, the major error is making the boxes tall so you're tied to vertical positioning of the drivers.
What if...
The woofer ( two woofers >>must be horizontally aligned ) is set to equal distance from floor to ceiling.
So a radical rethinking of how the boxes are displaced in the room.
Another point is the position of the midrange and the tweeter.
Would they need to follow the progression WMT or maybe WTM or better MTW(W) as in this case ? Would they need to lay on the same plane or maybe arcuated ?
 
LineSource: I'm going to consider whether I need both woofers to extend all the way up to ~200Hz, I will not nesc. have both woofers extending as high. I don't think I want my midrange going much below 150Hz. The midrange will not need baffle correction, the baffle will only [significantly] affect the woofers - hopefully they will be operating at a low enough frequency range to not be strongly affected by baffle step (my next step will be to play with some baffle simulations, so sorry my view of this off the top of my head is not clear yet).

The midrange and tweeter will be above this box, the tweeter will be close to, but slightly below ear height of a seated listener.

pico: some of the best sounding speakers I've heard were the Madrigal Revel Salon Ultimas:

Revel Salon loudspeaker | Stereophile.com

IMO, based on years of listening to different speakers, but mostly based on my own personal testing, a vertical line of woofers gives the most pleasing sound at the listening position - at least in the rooms I have tested.

I would prefer more woofers, my reason for choosing only two is both to consider the over all cost of the speakers and the size of the enclosure while maintaining the option of a passive crossover.

I purchased a MiniDSP 2x4 HD and I intend to implement a DSP crossover/corrected system also, but I don't want to eliminate the option of a passive version yet (which would be the case if I put more woofers into a smaller box which required active correction to flatten/extend the low bass response).
 

Face

Member
2007-05-23 8:38 pm
With a baffle that narrow, BSC will effect higher than 200hz. Using a PE 1CF enclosure(9" wide), I had to cross from the Anarchy woofers to a SS10F around 450-500 to avoid the midrange needing any BSC. Plus, the size of the passive parts required for a 200hz crossover will be quite large.
 
No Matter How You Cut the Cookey ...

.... your are going to get 'crumbs'.

"I'll be making a speaker with two 6.5" "Anarchy" woofers per enclosure."

Not necessarily.

You can put each driver in its own (separate) enclosure; and then, you can arrange them any way you like based on what works best for the acoustics of your listening venue.

WHG
 
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whgeiger:

The dimensions for this particular set of towers are set - I could divide the enclosure internally to make it into two separate sub-enclosures in one cabinet, however, I'm planing on the design being ported with 1 3" Precision Port.

This is one of several test prototype speakers to evaluate various design criteria such as comparing a similar 2-way vs this one which will be a 3-way. I will attempt to have objectively similar frequency outputs between the designs with the goal of subjectively evaluating sound quality with the dedicated midrange vs a design with 2 woofers sans midrange, with one woofer playing full range and the lower woofer rolled off above 100 - 200 Hz depending how high I need to go to have effective FBCC [Floor Bounce Cancellation Cancellation ;) ].

Yes, I have considered "modules" where we can use 1 or more Anarchy "bass units" added under the TM "module" with a variety of TM modules from sealed going down to 80 Hz, sealed going down to ~150 or 200 Hz, to ported [somewhat] full range with extended bass (at a lower level)

But, my hope for this particular thread is to work out optimal placement of the two anarchy woofers on these particular cabinets :)
 
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The question of how to arrange two or more woofers on the front baffle to minimize or at least ameliorate the effect of floor bounce on the frequency response is a good one. I have not seen this studied anywhere. One extreme example would be the CBT, which has no floor bounce because of how the responses of its many woofers sum. With only a couple of drivers, you will get some interference and the better question might be: "How do I minimize these effects?".

You can look at the effect of floor bounce, one woofer at a time, using Jeff Bagby's Baffle Diffraction and Boundary Simulator. This will at least give you a general idea what each is doing. While the program can export responses as FRD files, they unfortunately do not include phase so you cannot model each driver separately and then sum them outside of the program.

If someone knows of a study of how multiple woofers can be arranged to reduce the peaks and dips of floor bounce, I would like to know about it.

Keep in mind that this is primarily a problem in the midbass to lower midrange, e.g. 200-800Hz. Also, the room response does fill in the dips somewhat... your ear/brain is used to listening to sources in reflective spaces and is not going to complain too much. But if you can reduce the problem this might result in a small improvement in some way.
 
Yes, at least one woofer will be close to the floor (but how close, I'm not sure yet), I already know this will help ameliorate the ~200 hz FBC dip and I have observed a noticeable improvement in sound quality. I'm trying to reach the best overall (practically) possible set of compromises which includes the low woofer filling in the FBC dip.

Yes, I will most likely have the port exit the bottom, with a base about one inch away.
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
If someone knows of a study of how multiple woofers can be arranged to reduce the peaks and dips of floor bounce, I would like to know about it.
You mentioned the CBT. If directivity is the method you are going to use then any theory be it line array theory, piston size vs beaming etc should help.

Then there's the 'Allison effect'. You can subtract the direct distance from the distance via reflection to find the frequencies.

Or am I missing something.
 
If someone knows of a study of how multiple woofers can be arranged to reduce the peaks and dips of floor bounce, I would like to know about it.
CharlieLaub, what do you make of Donald North's patented 'lazy x' array, as seen in DN Audio 'Sequence' loudspeaker? Do we have a name for this array? 'Double D'Appolito'? 'Lazy X'?
Here's the patent

from the patent:
"The geometric relationship between the woofers as shown in the embodiment 300 of FIG. 3 results in a sound field which maximizes the energy lobes directed toward the listener and minimizes the severity of the energy lobes directed towards reflecting surfaces and room boundaries. The embodiment reduces the severity of the magnitude of the side lobes through an advantageous arrangement of transducers, which minimizes the alignment of transducers along horizontal or vertical axes. Alignment of transducers along an axis results in severe standing wave interference of the sound waves from the transducers in alignment. As previously mentioned, a feature of the embodiment of 300 is that no two centers of the woofers align either horizontally or vertically."
 

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