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In Reply to: RE: Making Speakers Efficient/Non Effecient posted by AudioSoul on January 31, 2016 at 16:58:33
1. Size
2. Bass extension
3. Efficiency
Follow Ups:
There are a lot of technical approaches that shift the balance of the three variables, but they are always working for and against the designer.
I read this once, found it quite to the point and am merely passing this wisdom on.
Not quite correct. Ever hear of a Linkwitz Transform? Merlin did and so have many other manufactures. With this type of circuit you balance #1 and #2 for maximum SPL and low distortion at low frequencies.
Then there are self-amplified speakers.
You don't get better efficiency with a Linkwitz transform on a sealed enclosure. You will actually be throwing away 10 or so dB of signal somewhere in order to EQ the low end.
For example, if you put a 96dB sensitive speaker in a sealed box and intended to use a 4 Watt amplifier, with no EQ, you'll reach the desired 102dB of output.
If you put in a 10dB active equalizer ahead of the amplifier to flatten out the FR, the amp will clip at low frequencies long before it would have clipped with no EQ, and you might find that you can't get 96dB of output from your 96dB speakers with your 4 Watt amplifier.
For the sake of argument, I can't imagine anyone applying a LW transform to a speaker with 96db sensitivity. The tradeoff for practically zero bass output (for increased efficiency) has already been set by the choice of driver's T/S parameters.
Mike likes to talk about the Linkwitz speakers and the LXmini is a great example of the tradeoff between size and efficiency.
The recommended power for this little guy is four 80 watt amps!
Merlin did and so have many other manufactures
Is that why Merlin used the "BAM" active equalizer?
Self amplified speakers typically have high power.
> > Is that why Merlin used the "BAM" active equalizer?
Yes.
> > Self amplified speakers typically have high power.
Not necessarily. For example, a quad-amped speaker system will likely not need a high powered amp for tweeters. A competent designer will recognize this and likely use (or recommend) one that's appropriate for his design.
Small, efficient speakers typically require EQ on the low end to provide a flatter profile.
Merlin VSM
" The VSM is down 5 dB @ 37 cps, and 10 dB @ 32 cps. BAMed, the VSM is down 0 dB @ 37 cps, and down only 4.5 dB @ 30 cps "
Can follow this link .
that lacks first octave response. Witness the Bose 901 with its four inch drivers.
Equalization is merely a tool that can extend response.....within reason.
Speakers that are physically incapable of providing the necessary bass response can't magically do so with the use of equalization.
Dave.
You can get decent low end response if you EQ enough small drivers. The Bose 901 and Russell IDS-25 speakers are examples. Neither, however, would be considered efficient given the amount of low end boost applied to each.
My point to Mike is that you will not find small, efficient speakers with good first octave response. You'll have to trade off something.
If too much system efficiency is sacrificed to achieve the goal, then it's time to re-think the design approach. IMO. :)
Multiple drivers addresses the issue, but...
Equalizing "full-range" drivers/systems (like the Bose 901 or IDS-25) represents a worst-case scenario because every db of EQ applied to the lower octaves reduces the overall system sensitivity directly by a like amount. But, only if your program material contains much information in the lower octaves. (Trade-offs are everywhere.)
However, generally, drivers are equalized only with their passbands in mind in multi-way overall design. So, you don't sacrifice much from their "nominal" sensitivities.....relatively speaking.
Speaking of systems that sacrifice a large amount of sensitivity as a result of extreme equalization, this one springs immediately to mind:
http://www.adireaudio.com/Files/DDRDipoleDesign.pdf
Dave.
.
of course you meant Small Size, just clarifying
You can find small speakers with good low end extension, but they are necessarily not very efficient.
I'll choose 2 and 3 please.
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