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Multi-Way Conventional loudspeakers with crossovers

3-way how would you do it?
3-way how would you do it?
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Old 15th April 2019, 12:31 PM   #11
Cousin Billy is offline Cousin Billy  Canada
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The best 3-way is a 4-way. I wish more people would realize this. It's all but ignored at diy websites. I know it's more money, but we're already saving a bundle on store bought.
We used to have a few real guru's here. The law's of physics where often discussed. A 6" midrange can't be paired with a 1" tweeter, but everyone does it. Let's try to be different.

-tweeter
-2" - 4" midrange
-6" - 10" midwoofer
-15"+ woofer

or

-tweeter
-2" - 4" midrange
-multiple 6" - 10" midwoofer (ported, transmission line etc.)

Someones going to respond; it's more difficult to design a 4-way than a 2-way. I would counter; if you chose your drivers carefully, no out of band peaks/dips/breakups will need to be heavily addressed, making the crossover easier? (that's a stretch, it's still hard).
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Old 15th April 2019, 02:07 PM   #12
Cask05 is offline Cask05  United States
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Quote:
Originally Posted by arivel View Post
...Thinking of a 3 way, if one day you felt like doing it, how would you do it?
What would be the things to think about before choosing the 3 drivers that make it up and start designing? below I write what comes to mind:
  • ...considerations is that of the best quality / price ratio without spending too much (thinking of a possible replacement in the future)...
  • ...how to...to divide the frequencies according to the chosen drivers or to choose the drivers based on the chosen frequencies?...which technology to choose for each single frequency band? As for the low frequencies I believe that the choice is precluded to the magnetodynamic drivers
  • ...for the rest of the medium and high frequencies, which ones to choose? ...to do this: which technology best expresses the medium frequencies? And which one for the high ones?
  • ...the 3 drivers must be well blended, there must be a fusion between them and a synergy. They have to work well together without one of them prevailing over the others.
  • Crossower: as simple as possible, slope? Active or passive ? you say.
  • Requirements for placement in the environment and format of the boxes: the dimensions have their importance and since many people have small to medium rectangular or square rooms including mine, I think that the best choice is a tower leaning against the wall.
  • Sensitivity and pairing with the amplifier: on this I let you say.
  • ...as for the choice of technologies, personally I would do it like this: magnetodynamic loaded to TL for the low ones, CD to compression for the middle ones, for the high ones I am still uncertain, maybe a tape? For now, it is not specific which drivers I would choose because I do not have clear ideas, I let you say which ones are better.
One observation that you might have made already by reading the responses is that there are many entry points to the cycle of designing and implementing any loudspeaker.

If you start with a set of performance requirements in some sort of hierarchical order, then you add your particular design constraints to use some sort of technology while using those hierarchical performance requirements, you will increase the chances of a successful outcome. I strongly recommend writing down your requirements, and then assigning precedence to the importance of each requirement relative to the others. This is where most loudspeaker designers (DIY or commercial) tend to make the most mistakes: they fail to realize that they haven't properly balanced the requirements and they end up with something that doesn't survive the test of time.

I think that when you look at successful loudspeaker designs and the kind of person that buys each of them and their specific proclivities for the sound they seek and total ownership experience, i.e., the degree of "exclusivity" and image attached with whatever they build--sort of like the Pygmalion effect--which seems to be a big part of the incoming requirements, you will begin to see why the answers that you get from others in this thread may not be as useful as you had intended. When you write down all that stuff mentioned just above and arrange it in a hierarchical list (irrespective of the specific technologies or arbitrary design constraints chosen), I think that you'll go a long way toward answering your own questions.

Don't forget to include your room size/acoustics in the performance requirements of your 3-way loudspeaker, and any specific requirements to the type of sound reproduced based on specific music genres that you might intend to listen to more than others. In my experience, when you do add this operational view to your design problem, the design usually changes.
_____________________________________________
For me, I would not consider direct radiating acoustic drivers. The reasons for this come from my overall requirements for full range directivity control and the space that I intend to put the resulting loudspeakers into. There are psychoacoustics reasons (i.e., how the human hearing system works) that are the source requirements for this design decision.

Chris

Last edited by Cask05; 15th April 2019 at 02:34 PM.
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Old 15th April 2019, 04:06 PM   #13
planet10 is offline planet10  Canada
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3-way how would you do it?
For a 3-way i’d first choose a good midTweeter. I’d cross that at 200-500 Hz to a midBass coupler, with multiple subwoofers (with DSP to minimize any room modes).

dave
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Old 15th April 2019, 04:33 PM   #14
nipper1 is offline nipper1  United States
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I like the midrange to be as wide as possible; usually this means staying in the 3 inch to 5 inch size. Ideally; what I am doing most of these days is a fullrange or near fullrange with super-tweeter and woofer (adding a sub-woofer completes the package). So, for me, I try to choose a fullrange that can do 100 Hz to 10 KHz ideally, usable from say 200 Hz to maybe 8 KHz; 300 Hz to 6 KHz is good and I rarely ever choose a mid or full range that can't do at least 400 Hz to 4 Khz. Of course; there are many different views and "schools of thought" on how to best approach a new design. two 6 in or 7 in or 8 in woofers in parallel I think overall have a better quality sound than say one 10 in or one 12 in woofer just because of a quicker transient response if nothing else. Do you have a price range in mind yet? What room size? What types of music? Many different questions. I'll stop here; read up on the many successful designs out there already. One more thing; I have done designs based on starting with a known woofer I wanted very much to try and built around that. I have also done the same with a known mid or fullrange. I have also done the same with a known tweeter. This is a never ending hobby for me; once bitten by the DIY bug; it's like a disease or something that never seems to ever completely go away. I often think about what I might try next...have fun!
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Old 15th April 2019, 04:53 PM   #15
conanski is offline conanski  Canada
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Quote:
Originally Posted by marco_gea View Post
I like the old-school approach of having crossover frequencies at approximately 500-700Hz & 5k-7kHz
(instead of the 200-300Hz & 2k-3kHz that are more common nowadays).

+1, this keeps crossovers and the phase muck they create outside the range of frequencies where we are most sensitive to it. Of course the application the system is designed for will impact this, for home listening at a single position off axis response can be sacrificed with widely spaced crossovers but if broad listening coverage is required then all drivers need to be crossed well below where beaming begins.
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Old 15th April 2019, 08:01 PM   #16
nipper1 is offline nipper1  United States
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Quote:
Originally Posted by conanski View Post
+1, this keeps crossovers and the phase muck they create outside the range of frequencies where we are most sensitive to it. Of course the application the system is designed for will impact this, for home listening at a single position off axis response can be sacrificed with widely spaced crossovers but if broad listening coverage is required then all drivers need to be crossed well below where beaming begins.
Agree; I think that beaming is the least important parameter. Of course, most of my critical listening is just me or maybe one other person. The Fletcher-Munson curve shows us our most sensitive range and I also try to avoid any crossovers there. Also; if one were to look where the top fundamental frequencies (highest notes) of some musical instruments are, you would see the piano for instance has its range past 4100 Hz! This is why I rarely cross-over a 3-way mid to tweeter below 4 KHz; 5 or 6 KHz are preferred. The REAL magic to me is getting the tweeter and mid to blend "seamlessly" so that the very important overtones, harmonics, etc. of these higher notes all arrive at my ears with the original harmonic structure intact. People like me that are (or were at one time) musicians get really picky about these things; this is what really makes a great loudspeaker stand out from a good or mediocre design! Call it phase purity if you will. I will add that I try to use 1st order X/O's whenever I can get away with it for the exact same reasons I just gave above.
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Old 15th April 2019, 08:14 PM   #17
mbrennwa is offline mbrennwa  Switzerland
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Quote:
Originally Posted by arivel View Post
how to split cut frequencies?
This and many other questions depend on what you want to achieve. Assuming you're designing a speaker with a passive x-over, the first thing to ask yourself is how big the speaker is allowed to be, how efficient it needs to be, and how deep the bass needs to go.

These points will guide the choice of the woofer. With a larger woofer, the woofer/mid x-over will end up at a lower frequency than with a smaller woofer. For example, a 15" woofer will work well up to maybe 200-400 Hz, whereas an 8" may be okay up to 800 Hz or so.

Once the woofer and it's x-over cut off is set, choose a midrange that fits with this x-over. A tiny 2" midrange might struggle to go deep and loud, so choosing a large woofer will also require a relatively larg midrange (or midwoofer).

When choosing the tweeter, I'd try to keep an eye on matching the dispersion of the midrange.
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Old 15th April 2019, 11:49 PM   #18
Brett is offline Brett
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Quote:
Originally Posted by Charles Darwin View Post
Talking old school if you are placing them close to a backwall I'd go for a wide and shallow cab rather than deep and narrow. No need to bother with baffle step 'correction'.


Also start off active and stay that way.
This (cab dimension choice is what I chose for my surrounds).

A 15 or 18 for the MB, an 8 for the MR and a TPL150H for the HF. Where the actual xovers are would depend on the specific drivers, but they would be active and steep.
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Old 15th April 2019, 11:51 PM   #19
Brett is offline Brett
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Quote:
Originally Posted by Cousin Billy View Post
The best 3-way is a 4-way. I wish more people would realize this. It's all but ignored at diy websites.
I agree completely, but it wasn't what was asked.
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Old 16th April 2019, 11:46 AM   #20
nipper1 is offline nipper1  United States
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How about these drivers as a "starter" set? Inexpensive but all around good reviews. I'm just looking at different sites thinking about what combinations of drivers I might like to try in the future. (at various price points)

Your Madisound Cart

In case the link won't open; the drivers are:

Fostex FF85WK

Seas 22TAF/G

SB20PFC30-8

All low cost but very good performance.
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