Advantages to smaller speakers?

[yepimonfire]

lets say you have two options, a bookshelf speaker with a 6.5” woofer, or a floor standing speaker with two 4” woofers. I believe the total surface area of the two 4” woofers would be larger than a single 6.5”. It seems there would actually be benefits to this, at least in theory, no?

The theoretical pros and cons I’m thinking of are:
Wider dispersion of upper mids at the xover point, most 6.5” driver crossed over at the common 2.3khz tend to exhibit at least some narrowing directivity, while the wavelength in relation to a 4” driver is relatively large.

Higher breakup point. In addition to the stiffness and mechanical damping properties of the driver material, the greater the diameter, the lower the breakup mode begins.

An overall lighter driver, resulting in quicker impulse and decay times, resulting in a better transient response.

Cons I can think of:
Lower sensitivity, although this is mitigated by multiple drivers.

Reduced bass response, this one shouldn’t be a big issue when placed in a ported enclosure, one should easily be able to get a solid response to 70-80hz. The sub can take care of the rest.

am I incorrect in my thinking?


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[Johnny2Bad]

Smaller speakers (enclosure size) offer improved imaging and are inherently more rigid, which should reduce cabinet resonances. The ideal loudspeaker would be near-infinitely small, surrounded mostly by air.

The differences are most certainly audible even at current technology. The obvious drawback is low frequency response, which requires a subwoofer to mitigate. The 2 + 1 configuration can offer superior overall sound quality as Low Frequency (LF) information is not directional.

For floorstanders, or even bookshelf designs with larger LF drivers, there is the issue of cabinet width. Broadly speaking the narrower cabinet offers advantages over the larger cabinet, although very wide cabinets can offer their own benefits. It's when the cabinet is in between very narrow and very wide that you introduce issues.

These can be mitigated by advanced crossover design. The question then becomes, how well engineered is the crossover in the units you are considering. Financial constraints can affect this parameter.

You are correct to consider driver dimensions and construction in your assessment, I just wanted to point out there are other issues to consider as well.

 

[ski2xblack]

Seems you're on the right track. The smaller drivers should help with pattern matching at crossover frequencies. Floor speakers have the practicality of 'stands built in', but they'll be more vulnerable to cab resonances as J2B pointed out.

The sensitivity aspect you may be able to work with, as there are some smaller drivers that are still on the sensitive side. I'm thinking of the proposed design that TLS was pondering in another thread which would use dual MA Alpair drivers for the woofs and simple networks, which would most likely be more sensitive than a pair of Classix II or AA monitors (just using those as examples of two-ways with 6" woofs). Depending on radiation pattern and cone break-up, a higher crossover freq may be possible with those MA drivers as well, but that's a guess. I would like to see TLS' design and modeling, could be a worthy winter project.

 

[shadyJ]

One 6.5" woofer has a bit more surface area than two 4" woofers. You are correct about the pros and cons of 4"s vs a 6.5", higher breakup frequency, wider dispersion, narrower cabinet, etc.

The only thing I would add is that, all other things being equal, the 4"s will not be as adept at lower frequencies and will likely have a higher resonant frequency. They will probably have a smaller spider and narrower surround that will not permit as much travel, and so even two 4"s typically aren't going to do bass as well as a single 6.5". 4" is a good size of a midrange driver, not a bass driver. Two 4"s can make for a good midrange system.

 

[yepimonfire]

One 6.5" woofer has a bit more surface area than two 4" woofers. You are correct about the pros and cons of 4"s vs a 6.5", higher breakup frequency, wider dispersion, narrower cabinet, etc.

The only thing I would add is that, all other things being equal, the 4"s will not be as adept at lower frequencies and will likely have a higher resonant frequency. They will probably have a smaller spider and narrower surround that will not permit as much travel, and so even two 4"s typically aren't going to do bass as well as a single 6.5". 4" is a good size of a midrange driver, not a bass driver. Two 4"s can make for a good midrange system.

No, of course not, but I own both a pair of r-14m speakers and rb-10s, both have 4” woofers, one measures -3dB @70hz and the other 80hz. The still manage to blend well with a sub using an 80hz xover.


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[shadyJ]

No, of course not, but I own both a pair of r-14m speakers and rb-10s, both have 4” woofers, one measures -3dB @70hz and the other 80hz. The still manage to blend well with a sub using an 80hz xover.


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You can have a 4" extend deep, of course, but it will be very limited in output. I would not want a speaker with a 4" woofer attempt bass unless it were a near-field system like a desktop PC system.

 

[sholling]

You can have a 4" extend deep, of course, but it will be very limited in output. I would not want a speaker with a 4" woofer attempt bass unless it were a near-field system like a desktop PC system.

I agree. I have EMP 41-SE/B near field speakers on my desk and their little 4" mid-woofers would be lost at any distance and without a good subwoofer. BTW: I love these speakers on a desk! For mains in a full room system I prefer towers with woofers that will reach easily play down to 45-50hz to better blend with a subwoofer when the crossover to the sub is set for 60hz. It's probably overkill but it's my personal preference.

 

[AcuDefTechGuy]

IMO the monitor/bookshelf speaker can have the advantage as long as it isn't too small that it suffers sensitive and dynamics and as long as you have great subwoofers.



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