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Multi-Way Conventional loudspeakers with crossovers

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Old 10th June 2018, 04:52 PM   #1
Best Hi End is offline Best Hi End
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Default best 18 drivers that can go flat 20Hz

Hi Guys, I intend to build 4 way active horn speaker ,hopefully if possible something similar to OMA top of the line if I could get hold of plans for the conical horns. Otherwise I'd build 4 way Horn speaker on close enclosure with some matching wooden horns. I'd appreciate your advice concerning the bass which I'd like it to go down as possible to 20Hz.The options are AEspeakers TD-18H,BMS 18S430V2, ,Ciare 18SW,Beyma 18PWB1000FE,JBL 2245H,Mccauley 6174 ,however the cheapest driver is $400 and goes up to $800 per unit .On the other hand I saw a driver from Dayton Audio PA460 out ofwhich it's FR:26Hz-2kHz,97.8db,Fs-28.3Hz which merely cost $180 per pair ! Could someone let me know if the above Dayton is so inferior to the others or would I get 99% similar quality tight base without distortion ? I'd appreciate any solid recommendation even completely different ,since I haven't had the chance to hear any of the above drivers,hence am clueless which one will give me the best results !
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Old 10th June 2018, 08:09 PM   #2
John Busch is offline John Busch  United States
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The PE model PA460-8, with a QTS of .33 and FS of 28 Hz is not designed to play flat to 20 Hz. Few woofers can do that with any real volume output level. Even in a 10 cu. ft. ported box tuned lower than recommended, you are at F3 around 26 -28 Hz and are falling off rapidly below that (24db/octave). With room gain you will likely be down 8-12 db at 20 Hz. Doesn't mean the PA460 is a bad driver, it's great for the money, just not designed to do what you are asking for. And Xmax is a bit limited at 6 MM. Got to move a LOT of air to play loud at 20 Hz.

A better PE selection would be P/N 295-518 (UN18-22) Ultimax dual Voice coil 18". With an FS of 19.5 Hz, and an in box QTS around .55 or in a 120 liter stuffed box have an FS of 26 and rolls off at half the rate of the PA460. And the UN18 has an xmax of 22 MM, nearly 4 times that of the PA 460. So with the same room gain it should be close to flat at 20 Hz. Since you are planning an active crossover, the UN18 can be set up to work well up to 300 Hz or so. Just my $0.02 worth. But all this output in a small box comes at a price, $325.00 each!
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Old 10th June 2018, 10:52 PM   #3
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Dear John, Thanks for your illuminated reply.I read it's data and it's quite impressive apart from it's low SPL-only 88.6db which is disappointing factor as it diminishes it's quality. One guy on usspeakers reviewed it and said:" I have to give it 3 stars however due to my driver having an issue with upper and lower bass. With lower bass around 25hz and below the distortion was far more audible than the actual bass. I had to cross it over very low to avoid a muffled rattling sound on the upper bass. 80hz was a real issue and even with a 4th order active filter I had trouble finding any real usefulness for this subwoofer given the limited range of the one I recieved " that was the only negative review there. I checked all the drivers I mentioned earlier including BMS,Radian and AESpeakers TD-18H and it seems that this model of Dayton UM18-22 has better data than all the above mentioned -can it be or did I miss something ? Are there any better 18' drivers which can go flat 20Hz with better data and most importantly better performance at a reasonable price ?
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Old 11th June 2018, 12:35 AM   #4
John Busch is offline John Busch  United States
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That's the engineering challenge.... efficiency versus box size/efficiency. And, do you REALLY need to play flat at 20 Hz. To do it right at a reasonable sound level is an expensive proposition. Other than some pipe organ and or movie sound effects, there is not a lot of material down there. A good compromise is flat to 3 db down in room in the area of 32 Hz.

Then you get down to where this system is going to be used, big room, small room.... what are your priorities? How much are you willing to spend?

Not glamorous questions to be sure, but very important!
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Old 11th June 2018, 02:10 AM   #5
davewantsmoore is offline davewantsmoore  Australia
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Quote:
Originally Posted by Best Hi End View Post
Are there any better 18' drivers which can go flat 20Hz
No, but why do you need this in an active system?
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Old 11th June 2018, 03:05 AM   #6
friendly1uk is offline friendly1uk  United Kingdom
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Quote:
Originally Posted by John Busch View Post
That's the engineering challenge.... efficiency versus box size/efficiency. And, do you REALLY need to play flat at 20 Hz. To do it right at a reasonable sound level is an expensive proposition. Other than some pipe organ and or movie sound effects, there is not a lot of material down there. A good compromise is flat to 3 db down in room in the area of 32 Hz.

Then you get down to where this system is going to be used, big room, small room.... what are your priorities? How much are you willing to spend?

Not glamorous questions to be sure, but very important!
Might a HiFi build that can go this low, be well served by a car subwoofer for that last 10hz. Something disposable.. Car subs are for getting low with small boxes. Their compromised such that 200hz is about as far up as they can reach, but for this duty that's Okay.

I have $200US JBL 12s in 95L with a port tuned below 24hz. This was the box winisd gave me as optimum for the driver. It's flat at 30 but by 22 I'm 3db down. It's just drivers from a twin box I got used at $75US, Not specially chosen. You could surely stay flat to 20hz with a 15" or 18"

Nothing defined is going to happen at 20Hz. The HiFi speakers would do everything really, with the sub just there for the heavy lifting. Slinging vast amounts of air about. Giving reverence to your 18Hz pipe organ recordings.

I use mine to 100hz, in a FAST. I have always found JBL subs rather woolly in cars, but these add great weight. A real solidity. Even if not the tightest. Being a 12 in a 4" ported box.

It could be amusing to bottom one out. Even to blow it. It's cheap, and won't effect your main speakers. You might not even miss it, until you watch earthquake again.

Edit: You could power these effects speakers from a half kilowatt PA amp. Worth peanuts beside a hifi amp that can do that much work.

Last edited by friendly1uk; 11th June 2018 at 03:10 AM.
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Old 11th June 2018, 03:30 AM   #7
eriksquires is offline eriksquires  United States
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For the record, no woofer is flat in room to 20 Hz. You are going to need significant EQ with any speaker that plays that low. Depending on how the room works out, you could end up cutting output at 20 Hz, or just below, or just above, significantly.

Obviously worth calculating the excursion vs. output levels though.
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Old 11th June 2018, 09:25 AM   #8
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Thanks for all the responses.

John,based on what you say,if I make a compromise and pick a driver that goes down to around 32Hz-I could still pick the cheap Dayton PA460 which goes further down to 26Hz,although I must admit that UM18-22 have much better data and probably sounds better ,but it's lack of SPL frightens me a bit.Are there any other drivers with similar/better data and higher SPL ? I know that there are some prestigious brands such as Goto from Japan that couldn't care less for the formal data and their biggest drivers go down to 28Hz and still considered as one of the best(that is the rumor-I haven't had the chance to hear it).

Anyhow,had I not made any compromise up to let's say $750 per unit what driver that goes down to 20Hz would be the best one, bearing in mind I'm looking for beautiful tight bass down to 20Hz without any distortion on it's frequency spectrum whatsoever. My listening room is 3.5m*6.5m with 2.7m ceiling ? The reason for going active rather than passive is due to the possible "absolute" control with the way the whole set would sound including the low's of 20Hz.
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Old 11th June 2018, 10:32 AM   #9
KaffiMann is offline KaffiMann  Norway
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For low frequencies you can take that spl number (quite often given at 1khz which is very far away from 20hz), and just throw it out the window.
What you need to look at is: sd (surface displacement), and xmax (cone travel, either specified one way, or p-p/peak to peak), aside from the usual fs, qts, vas and so on, pending on your needs or wants.
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Old 11th June 2018, 03:08 PM   #10
John Busch is offline John Busch  United States
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KaffiMann's post is right on. The criteria you need to satisfy are how loud do you need to play cleanly at what frequency balancing box size and cost.

With active, taken to a bit of an extreme, you can force the PA460 to play down to 20 Hz. It would need to be in a stuffed sealed box and you would have to feed it with enough power to overcome the natural roll off that set up would have. Just guessing, it would require maybe 24-30 db of boost at 20 Hz. to do it depending on room gain. But once you do that, is it usable? The PA 460 has a clean one way volume of acoustic displacement of around 750 cc. The UM18 is around 2,700. Huge difference. So it is much easier for it (UM18) to play much louder. Also assuming a sealed box alignment. The UM18 would also require some boost, but no where near what the PA460 would require. The reason for the difference is the UN18 is designed for this kind of application, the PA460 is not. To get the most out of the UM18 is going to require 500-1,000 watts. That is because the UN18 design trades efficiency for the ability to play loud and low in a small sealed enclosure. The PA460 is designed to play loud from 40Hz up using the least amount of power in a medium sized ported box. You can go here and see how loud a woofer can potentially play at what frequency depending on the woofer size and Xmax.

Piston Excursion calculator

The UM will play ten times louder than the PA460.
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