I've made them from plaster, epoxy, aircraft aluminium, wood (both with the grain and translam), fibreglass, acrylic plexiglass, rubber, cardboard, flexible plywood.
I have built several 15" 2 way systems as kind of an experiment to find the best solution. In my experience, you will want a large horn and a 1.5"-2" compression driver, and cross as low as possible. I wanted a 1" driver to work, for better treble, but it's a stretch to find something that will work at ~1khz crossover and sound right.
A ~200L vented cab and a K402 replica horn have consistently been the best choices for me, with various woofers and compression drivers, but i have not tried sealed yet
A ~200L vented cab and a K402 replica horn have consistently been the best choices for me, with various woofers and compression drivers, but i have not tried sealed yet
I take my 1" B&C drivers down to about 800 Hz with no problem at all (Home Theater.) Going above 1" almost always requires another HF driver and crossover. Not worth the trouble and is actually a worse way to go.
I'm glad Mr. Gedlee can hear 15000 to 20000 hz reproducable only by 1" compression drivers. I, along with most ex-military vets, can't hear above 14000 hz. Not since ROTC camp 1969. So 2" (1.4" throat) compression horns are fine with me. Actually I'm better than almost all of my friends that are not professional musicians with no service experience. Hunting, motor boats, motorcycles,, chainsaws, fireworks destroy most US male HF hearing before age 20.
As for crossover point, the choice in a two-way is to a certain extent determined by the max wattage of the tweeter, plus the maximum wattage the speaker is rated at on pink noise. Peavey used the same 2" driver rated 70 w in early SP2 crossed at 800 hz rated at 175 watts. Then the SP2-XT crossed at 1200 hz with a 300 watt rating. Then the SP2(2004) crossed at 2000 hz with a 500 w rating. Obviously, getting most of the vocal range, 800-4000 hz, into one low distortion driver (the tweeter) is an advantage. However 175 w speakers don't sell very well to the bar band market. I've heard Peavey's PV15 1" compression driver product, and was not impressed by the inaccuracy. No JBL, Gedlee, magnaplanar, tannoy or other high end products are stocked or demonstrated in this flyover city of only 2 million pop.
As for crossover point, the choice in a two-way is to a certain extent determined by the max wattage of the tweeter, plus the maximum wattage the speaker is rated at on pink noise. Peavey used the same 2" driver rated 70 w in early SP2 crossed at 800 hz rated at 175 watts. Then the SP2-XT crossed at 1200 hz with a 300 watt rating. Then the SP2(2004) crossed at 2000 hz with a 500 w rating. Obviously, getting most of the vocal range, 800-4000 hz, into one low distortion driver (the tweeter) is an advantage. However 175 w speakers don't sell very well to the bar band market. I've heard Peavey's PV15 1" compression driver product, and was not impressed by the inaccuracy. No JBL, Gedlee, magnaplanar, tannoy or other high end products are stocked or demonstrated in this flyover city of only 2 million pop.
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I think I'm set on a sealed 80-100L bass bin with the Faital 15fh520.
After reading a million threads, the goal is to cross as low as possible with a 1.4 or 2" CD, between 500 and 750hz.
The horn/waveguide is a difficult choice. It's still not clear to me how to determine how low I can use the horn/waveguide. In my domestic environment, (<105dB) I don't think I need 'loading' from the horn, so the parameter I'm looking at should be: where does the waveguide start losing control of directivity.
Is that correct or do I have it wrong? Does the low cross over point mean I have to use a large horn? Then why?
After reading a million threads, the goal is to cross as low as possible with a 1.4 or 2" CD, between 500 and 750hz.
The horn/waveguide is a difficult choice. It's still not clear to me how to determine how low I can use the horn/waveguide. In my domestic environment, (<105dB) I don't think I need 'loading' from the horn, so the parameter I'm looking at should be: where does the waveguide start losing control of directivity.
Is that correct or do I have it wrong? Does the low cross over point mean I have to use a large horn? Then why?
No and Yes.
First you must decide on what directivity you want. In general, the wider it is the more spacious the sound will be and the narrower the more detailed the imaging will be, - your choice, but both optimized simultaneoulsy is virtually impossible. (Small rooms assumed here, of course.)
Next, the narrower the coverage the larger the waveguide must be to hold control to a lower frequency. Once you know the coverage angle then you must choose the woofer directivity, which will determine where the crossover has to be to match the waveguide coverage angle. That frequency will then set the width of the waveguide.
And now you have a simple process - it's just very hard to hold and the compromises will make all the difference.
PS. A nice clean 105 dB is a good target even at home, mine is a lot greater than that, but that's just personal choice. To get even the lower number you would need a CD, which then easily gets you a higher number should you ever wish.
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Faital 15fh520 seems to do pretty good up to 2k / 3k
But yes as you know beaming will be lower off axis around 700 to 800 Hz
You could get away with a higher crossover around 1k
which will reduce the size of the horn.
But yes I have always wanted the same, a large midrange horn.
You typically want to be at least 100 Hz above the min frequency of the horn.
and many can go a octave above for low distortion.
So if you wanted a 600 Hz crossover you would want a 300 Hz horn
or at minimum a 500 Hz horn
JBL did various Bi Radials that go down to 300/400 Hz
JBL 2360A
JBL 2365A
JBL 2366A
More realistic approach probable be 400 to 500Hz horns like
JBL 2380A
JBL 2382A
JBL 2385A
JBL 2386A
all depends what coverage angle you want
The studio monitors with 15" drivers
often used the
JBL 2344A
typically crossed around 1 to 1.2K
but could be pushed to 800 Hz
But yes as you know beaming will be lower off axis around 700 to 800 Hz
You could get away with a higher crossover around 1k
which will reduce the size of the horn.
But yes I have always wanted the same, a large midrange horn.
You typically want to be at least 100 Hz above the min frequency of the horn.
and many can go a octave above for low distortion.
So if you wanted a 600 Hz crossover you would want a 300 Hz horn
or at minimum a 500 Hz horn
JBL did various Bi Radials that go down to 300/400 Hz
JBL 2360A
JBL 2365A
JBL 2366A
More realistic approach probable be 400 to 500Hz horns like
JBL 2380A
JBL 2382A
JBL 2385A
JBL 2386A
all depends what coverage angle you want
The studio monitors with 15" drivers
often used the
JBL 2344A
typically crossed around 1 to 1.2K
but could be pushed to 800 Hz
Thanks for these very helpful comments. Things are slowly starting to make sense 🙂
What confuses me is "choose the woofer directivity". What does that mean, how do you choose woofer directivity?
From the attached chart, the woofer starts being directional around 650-750. Let's say I have a waveguide that holds a 90° pattern down to 500hz. How do you know if the woof matches directivity at that freq? Take measurements? Or can it be calculated?
What confuses me is "choose the woofer directivity". What does that mean, how do you choose woofer directivity?
From the attached chart, the woofer starts being directional around 650-750. Let's say I have a waveguide that holds a 90° pattern down to 500hz. How do you know if the woof matches directivity at that freq? Take measurements? Or can it be calculated?
Attachments
I assume it's good enough if the polar map of the horn and the woofer are overlaping around the crossover frequency between axial response to 45° off axis ? the width of the horn should be near than the diameter of the woofer (?) to reduce problems. Faital drivers seem flat enough at least to 30° in the frequencies advised for a cut-off with a 1.4"/2" cd/horn combo (the 2" compressions will beam like a laser in the highs... not good sweet spote I assume ! Certainly easier to acheive with a higher slope, like LR24 I surmise ?!
As any commercial avaliable horn are able of controlled directivity from 500 hz but very expensive autotech horns copies -while made in their low cost country (so very big margin= fool customers)-, your best bet is a Yuchi bi-radial horn made of wood in Europe (Athos, ALG, etc-even thoses are not cheap) : circa 290mm width. XO around 600 hz or more with electronic EQ; maybe even better with a 12".
Too much hassle and expensive for me. Waiting to jump of the PA driver, a good horn enough that doesn't exist yet at Faital, 18ThSound, B&C... Many hobbysts are saying you need minimum 90° horizontal dispersion and often they report a better result when it goes till 110° horizontal. Such a horn for controlled directivity on the shelf doesn't exist yet. It will need a throat between 1" to 1.5" to match the newest compression driver that have a very wild power response (HF1440 and so on) and EQ... A no go for me, I admire people like Earls or folks of unity horn system that are able to propose something feasable with a passive crossover w/o complex electronic EQ.
Ok it's not state of the art with very low controlled directivity from 600 hz or less but such old bi-radial horn proved to have good sound enough (TAD style...)
just my two cents as I would like to jump on the train but indeed not easy progress made at democratic price from 30 years and more!
As any commercial avaliable horn are able of controlled directivity from 500 hz but very expensive autotech horns copies -while made in their low cost country (so very big margin= fool customers)-, your best bet is a Yuchi bi-radial horn made of wood in Europe (Athos, ALG, etc-even thoses are not cheap) : circa 290mm width. XO around 600 hz or more with electronic EQ; maybe even better with a 12".
Too much hassle and expensive for me. Waiting to jump of the PA driver, a good horn enough that doesn't exist yet at Faital, 18ThSound, B&C... Many hobbysts are saying you need minimum 90° horizontal dispersion and often they report a better result when it goes till 110° horizontal. Such a horn for controlled directivity on the shelf doesn't exist yet. It will need a throat between 1" to 1.5" to match the newest compression driver that have a very wild power response (HF1440 and so on) and EQ... A no go for me, I admire people like Earls or folks of unity horn system that are able to propose something feasable with a passive crossover w/o complex electronic EQ.
Ok it's not state of the art with very low controlled directivity from 600 hz or less but such old bi-radial horn proved to have good sound enough (TAD style...)
just my two cents as I would like to jump on the train but indeed not easy progress made at democratic price from 30 years and more!
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Isn't Yuichi a radial horn (not bi-radial)? It allocates its compromise away from vertical directivity and in return, favours loading.
I "choose" the woofer such that it matches the waveguide at the crossover I want. For woofers the diameter is generally good at predicting the polar response, except that deep cones tend to be a little wider than a flat disk calculation will predict. But let's face it, without measurements you are really guessing. A 90° pattern, 45° +-, will need a 15" woofer to work at 600-700 Hz. and a waveguide about 15" across to hold the pattern down to that point.
If you had chosen 120°, then a smaller driver would be needed, or a lower crossover creating a need for a larger waveguide to go lower.
As someone suggested, I use polar maps of the two drivers in order to determine where the crossover should be.