I’m thinking of creating over-engineered loudspeakers. They might be something such as the 3.5 ways floor-standing with 4 active drivers and 2 passive drivers, i.e.,
If compared with a conventional 3-way system, will it be better than the 3-way? Assume all the crossover design is performed with the same techniques, by the same designer.
It’s just like comparing a multi-link suspension with a semi-trailing arm suspension.
Is it worth it?
- A 1” tweeter at the top of the front baffle
- A 2” dome midrange below the tweeter
- Two 10” woofers below the mid-dome in which the upper woofer is responsible for lower midrange and bass, and the lower woofer is for only bass
- Two 10” passive radiators for deep bass at the bottom and on both sides of the cabinet, e.g., Acoustic Research AR-9/ AR-90 series.
If compared with a conventional 3-way system, will it be better than the 3-way? Assume all the crossover design is performed with the same techniques, by the same designer.
It’s just like comparing a multi-link suspension with a semi-trailing arm suspension.
Is it worth it?
The answer would be 'it depends' ;-)
Say, we have the same baffle width and geometry around the tweeter and mid and the same XOs for tweeter--mid and mid--(low-mid)woofer, then the difference would only be in the bass section.
The .5 way effectively makes it 4-way wrt to phase response as both woofers must be in phase at all frequencies, the lower one just reducing amplitude for low mids. The timbre and perceived speed may be different from the straight 3-way (assuming the same bass alignment with a PR).
Undistorted bass output will be about 6dB higher and low-mid-IMD will be lower as the upper woofer runs at lower excursion in the bass compared to the single.
So, IMHO it all depends on the levels at low frequencies, and listening levels in general that you want to achieve.
Say, we have the same baffle width and geometry around the tweeter and mid and the same XOs for tweeter--mid and mid--(low-mid)woofer, then the difference would only be in the bass section.
The .5 way effectively makes it 4-way wrt to phase response as both woofers must be in phase at all frequencies, the lower one just reducing amplitude for low mids. The timbre and perceived speed may be different from the straight 3-way (assuming the same bass alignment with a PR).
Undistorted bass output will be about 6dB higher and low-mid-IMD will be lower as the upper woofer runs at lower excursion in the bass compared to the single.
So, IMHO it all depends on the levels at low frequencies, and listening levels in general that you want to achieve.
It's hard to make a blanket statement about one approach being better than another, since so many different techniques and drivers can be used.
Answering the question as stated and without nuance, I think the answer would be: no, there's not much benefit to the added complexity over a standard 3-way design. That's why you don't see this approach much anymore.
But if you just want to build something for yourself and you like dome mids, that's a different scenario. Build whatever makes you happy or helps you learn.
From a general design standpoint, I think the advice for your proposed setup would be to do something about the transition from the 2" dome to the 10" woofer. That's a tough jump to make well. It's not impossible, but is it optimal? Or the best use of money? If you want to stick with the two 10" woofers, you may want want to use two different drivers. One for the upper range (like a large midrange), and one that's built more like a subwoofer.
The more typical approach for the range below the dome mid would be to add a small fast cone midrange. Something like a 4-6" that will get down to around 200-400 Hz without strain. But once you've done that, the question is why bother with the dome mid at all. I know some are enamored with them, but they aren't used that often in mainstream designs anymore because they don't have the volume displacement to do much at lower frequencies, so you basically get about an octave of extension from them compared to just using a good dome tweeter in a typical speaker design. There are some unicorn dome mids that go down lower, but again the question is whether that money is better spent on the other drivers in the system.
If you're looking for high output, that changes things some, since that might lead you to use a higher cross point on the tweeter. The dome mid might get you a couple octaves of extension in that case, but you still have the transition from 10" to 2" that's not going to be easy to do seamlessly.
It gets hard to draw a line at too much complexity or too many drivers in a design like this. If a 3.5-way, why not 4-way? If 4-way, why not 5-way?
For typical speakers, 3-way is a pretty good break point. Beyond that you should probably have good reasons for adding complexity. "I want a really big, impressive looking speaker" can be a valid reason too, though.
Answering the question as stated and without nuance, I think the answer would be: no, there's not much benefit to the added complexity over a standard 3-way design. That's why you don't see this approach much anymore.
But if you just want to build something for yourself and you like dome mids, that's a different scenario. Build whatever makes you happy or helps you learn.
From a general design standpoint, I think the advice for your proposed setup would be to do something about the transition from the 2" dome to the 10" woofer. That's a tough jump to make well. It's not impossible, but is it optimal? Or the best use of money? If you want to stick with the two 10" woofers, you may want want to use two different drivers. One for the upper range (like a large midrange), and one that's built more like a subwoofer.
The more typical approach for the range below the dome mid would be to add a small fast cone midrange. Something like a 4-6" that will get down to around 200-400 Hz without strain. But once you've done that, the question is why bother with the dome mid at all. I know some are enamored with them, but they aren't used that often in mainstream designs anymore because they don't have the volume displacement to do much at lower frequencies, so you basically get about an octave of extension from them compared to just using a good dome tweeter in a typical speaker design. There are some unicorn dome mids that go down lower, but again the question is whether that money is better spent on the other drivers in the system.
If you're looking for high output, that changes things some, since that might lead you to use a higher cross point on the tweeter. The dome mid might get you a couple octaves of extension in that case, but you still have the transition from 10" to 2" that's not going to be easy to do seamlessly.
It gets hard to draw a line at too much complexity or too many drivers in a design like this. If a 3.5-way, why not 4-way? If 4-way, why not 5-way?
For typical speakers, 3-way is a pretty good break point. Beyond that you should probably have good reasons for adding complexity. "I want a really big, impressive looking speaker" can be a valid reason too, though.
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You've proposed a solution to unknown goals.
If you want PA SPL levels, then this might be under-engineered (depending on pro / home driver choice that is).
So the usual suspect questions:
1. What peak SPL are you after? and What amplification have you got? (our sensitivity starting point)
2. Do you have any size constraints?
3. Are you going to be using subwoofer(s)?
4. Any other constraints? e.g. I hate ported bass, I don't like open baffle, I want a thin speaker etc....
If you want PA SPL levels, then this might be under-engineered (depending on pro / home driver choice that is).
So the usual suspect questions:
1. What peak SPL are you after? and What amplification have you got? (our sensitivity starting point)
2. Do you have any size constraints?
3. Are you going to be using subwoofer(s)?
4. Any other constraints? e.g. I hate ported bass, I don't like open baffle, I want a thin speaker etc....
Actually, this over-engineering idea is generated from the need of making an improved version of some commercial speakers. I own Braun LS200 speakers and, yes, I love them. However, as a daily user, I know there’s something that if it’s fixed, it will bring them to the flawless design.
First, the originally large sealed box with relatively low-Q for dual 10” woofers yields best transient for bass, but have quite low sensitivity as well. I’ve been confirmed this by some users in the owner’s group. Some users prefer using the Loudness button on his amplifier, some just use subwoofers. But, I don’t totally agree with them because I think we already have four 10” bass units. They should produce bass in a satisfactory level if optimally redesigned. Yet, I personally don’t prefer a hole for port on the speakers, thus, passive radiators are interested. Two PRs might be enough for the two 10” bass I guess. And placing them at the closest to the floor, on both side of the cabinet, might be a good option as well. But, if the two PRs aren’t sufficient for two woofers, I’m thinking to add a dividing plate between two woofers making the lower woofer as a subwoofer with two PRs, while the upper woofer is sealed system. I’m not sure if they would work fine together.
Second, the two 10” woofers are responsible for some lower midrange duty because their crossover point is at about 450Hz. Some people may find, like me, excessive mid-bass where some recognized it as the cabinet resonance. I proved it myself that tweaking Q of the woofer’s crossover helps it a lot. So, instead of letting two drivers play mid-bass, only one is enough, I think.
First, the originally large sealed box with relatively low-Q for dual 10” woofers yields best transient for bass, but have quite low sensitivity as well. I’ve been confirmed this by some users in the owner’s group. Some users prefer using the Loudness button on his amplifier, some just use subwoofers. But, I don’t totally agree with them because I think we already have four 10” bass units. They should produce bass in a satisfactory level if optimally redesigned. Yet, I personally don’t prefer a hole for port on the speakers, thus, passive radiators are interested. Two PRs might be enough for the two 10” bass I guess. And placing them at the closest to the floor, on both side of the cabinet, might be a good option as well. But, if the two PRs aren’t sufficient for two woofers, I’m thinking to add a dividing plate between two woofers making the lower woofer as a subwoofer with two PRs, while the upper woofer is sealed system. I’m not sure if they would work fine together.
Second, the two 10” woofers are responsible for some lower midrange duty because their crossover point is at about 450Hz. Some people may find, like me, excessive mid-bass where some recognized it as the cabinet resonance. I proved it myself that tweaking Q of the woofer’s crossover helps it a lot. So, instead of letting two drivers play mid-bass, only one is enough, I think.
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