Do you have a particular reason for using a low-power amp (a favorite tube or class-A amp maybe?).
Not that it makes a huge amount of difference. Sound level is logarithmic in nature, so doubling power only gets you a 3dB increase, and using speakers 10 dB more efficient will cut your power requirement to one-tenth.
The problem with high efficiency drivers is to get that you need either horn loading (a whole different set of design problems there) or plenty of cone area or very light cone materials or both. Large cone area results in poor dispersion at high frequencies, and light materials tend to flex and "break up". "Pro sound" drivers require high efficiency to keep amplifier power reasonable for large spaces, but few of them have flat frequency response. This is the result of breakup and beaming issues.
For increased efficiency consider using an array. Early VMPS designs (from the late Brian Cheney) used a combination of multiway/multidriver arrays to get efficiency and sufficient cone area without using large drivers except for bass frequencies. A 2-by-2 (4 drivers total , 2 in series paralleled) gains you 6dB of sensitivity, and you can keep adding more in other combinations for further gains. This can allow you to use a driver of lower than desired sensitivity. Line arrays make use of this too, and can be augmented with a supertweeter and subwoofer if desired.
Many good points touched upon already. One of the first things that I learned is that the speaker design should take into account the room size. I have the 5" TB in a small box with a small sub and this system sounds pretty good in a small room - think hotel room or small bedroom. But if you are designing a 4-way (ambitious), I would consider going active and looking at the miniDSP 2x8 (4x10) or Behringer DCX2496. Each set of drivers would get its own amp and you can address the problem of the bass running out of steam with a low powered system. You don't have to spend a ton of money if you spend time workin' Ebay.
Yeah, I don't have the time or budget to make a powerful version of my amp any time soon. The efficiency is low even for class A but damn does it sound good.
Yeah that's what I was going to do anyway.
4 way system, each driver gets its own amp.
I have a bunch of leftover PCBs for my low powered amp available to build more without too much trouble.
There are many good high efficiency designs based on 'ordinary' pro components. Kits are a good place to start, e.g:
pi speakers
Denovo Audio Titan-615LX
Cornscala? | Critesspeakers.com
Hello all. I'm thinking of using a couple of driver types I already have here, Mark Audio Alpair 7P and Revelator 15W/8530K 01 in a small sealed cabinet, about 0.23ft3 after drivers displacement.
I like the Mark Audios, (faint praise) but want a little more heft, so am thinking of using the Scanspeaks up to about 450 hertz. I will be highpassing these at my amplifier at around 100 Hz. Given that, and not playing all that loud with a 10 watt amplifier, should I bother with a separate enclosure to avoid the blowout I've read about?
I just prefer the sound of a lower crossover point over most regular tweeter/woofer combinations, and steeper crossovers.
I'll be using a cabinet I also already have at hand. Only a spare baffle needs to be holed.
I like the Mark Audios, (faint praise) but want a little more heft, so am thinking of using the Scanspeaks up to about 450 hertz. I will be highpassing these at my amplifier at around 100 Hz. Given that, and not playing all that loud with a 10 watt amplifier, should I bother with a separate enclosure to avoid the blowout I've read about?
I just prefer the sound of a lower crossover point over most regular tweeter/woofer combinations, and steeper crossovers.
I'll be using a cabinet I also already have at hand. Only a spare baffle needs to be holed.
I have been looking into this issue. There are any number of tweeters that are up to the task so no issues there. The bass is also not terribly difficult. One or two pro 15" woofers in a transmission line or even conventional ported enclosure should be able to handle the bass. Even a pair of Eminence Beta 15s or Delta 15s in a sealed enclosure could work in a room with reasonable room gain.
The trick seems to be the midrange. The best possibility I could find so far that isn't a very expensive horn loaded CD is this one
FaitalPRO M5N8-80 5" Neodymium Professional Midrange 8 Ohm
If you could find a very efficient full range it would not be at all unreasonable to use it as a wide band midrange.
Another possibility is a 15" Pro coax (CD fires through the center of the woofer magnet structure) or a 10 or 12" version with a larger pro helper woofer.
P.S. I don't think a 4 way is the best approach for a SET due to the complexity of the crossover.
It is an interesting task but I think it is worth pursuing. Would love to see what you end up with.
The trick seems to be the midrange. The best possibility I could find so far that isn't a very expensive horn loaded CD is this one
FaitalPRO M5N8-80 5" Neodymium Professional Midrange 8 Ohm
If you could find a very efficient full range it would not be at all unreasonable to use it as a wide band midrange.
Another possibility is a 15" Pro coax (CD fires through the center of the woofer magnet structure) or a 10 or 12" version with a larger pro helper woofer.
P.S. I don't think a 4 way is the best approach for a SET due to the complexity of the crossover.
It is an interesting task but I think it is worth pursuing. Would love to see what you end up with.
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