Compression driver and horn selection

Hi all,
I am going to build a PA speaker set to complement my 4 12" subs (fEarFul from greenboy).
I am thinking of a column speaker that will look like (and hopefully sound like) the RCF nlx 24-a
So a beaming speaker featuring 4 8 inch woofers (dayton audio mb820-8 probably). They sound nice and have pretty high efficiency of 94db.
I will use biamping for this set, so filtering is no problem. I would like to cross over around 1.5khz.
I have some trouble selecting a good sounding tweeter and Horn (CD, 90×60)
There are so many models and brands!
My goal is hifi sounding highs, smooth and brilliant with smooth roll off to the sides. It does not have to hit 20kHz, up to 18 is fine.
Colouration should be minimal.
I have qcs rmx amps to drive both woofers and tweeters
I don't have a big budget, I am thinking of something in the 100-200 euro price range per side.

Any tips welcome (also for alternatives for the daytons)!
 
I am thinking of a column speaker that will look like (and hopefully sound like) the RCF nlx 24-a
So a beaming speaker featuring 4 8 inch woofers (dayton audio mb820-8 probably). They sound nice and have pretty high efficiency of 94db.
I will use biamping for this set, so filtering is no problem. I would like to cross over around 1.5khz.
No sorry... you need a 1.4" exit CD and a low crossover(800hz) like the NLX24.
 
@MrKlinky
wat kind of radian driver were you going to suggest? Is that a bit higher than my budget or way over budget?
I know the highs and mid highs for sparkling vocals are more important than spending $$$ on woofers, so if the radian is much better than the suggested B&C than I might consider that...
I see on the plot of the B&C 610 that is has a considerable bump around 1kHz and a dip around 4kHz. Not nice and flat?
 
Hi all,
I am going to build a PA speaker set to complement my 4 12" subs (fEarFul from greenboy).
I am thinking of a column speaker that will look like (and hopefully sound like) the RCF nlx 24-a
So a beaming speaker featuring 4 8 inch woofers (dayton audio mb820-8 probably). They sound nice and have pretty high efficiency of 94db.
I will use biamping for this set, so filtering is no problem. I would like to cross over around 1.5khz.
I have some trouble selecting a good sounding tweeter and Horn (CD, 90×60)
There are so many models and brands!
My goal is hifi sounding highs, smooth and brilliant with smooth roll off to the sides. It does not have to hit 20kHz, up to 18 is fine.
Colouration should be minimal.
I have qcs rmx amps to drive both woofers and tweeters
I don't have a big budget, I am thinking of something in the 100-200 euro price range per side.

Any tips welcome (also for alternatives for the daytons)!

Some notes here:

  • A total of four 12" subwoofers (two per side?) will be out-run by main speakers with 4x 8" midbass drivers
  • The RCF NX24A has an 800Hz crossover point for a good reason: above that, the column of 6" drivers have undesirable directivity characteristics. 4x 8" drivers will be worse.
  • I'd try to pick some nicer 8" drivers, and use two per side. Cheap drivers tend to run into power compression problems, resulting in reduced output. They also often sound "dirty" and "compressed" when you put any real power in.
  • 1.5kHz should be just about possible with 2x 8" drivers
  • The HF compression drivers which get up to 18-20kHz tend to be expensive, and limited in output below 3kHz. Even if they can get up to 20kHz, a lot of that will be absorbed at typical PA listening distances: https://www.doctorproaudio.com/cont...ption-attenuation-with-humidity-and-frequency
  • Colouration is mostly the frequency response. Do you have any measurement equipment?
  • Is your stated budget for all of the drivers, or just the tweeters?


My recommendation here would be to cut down to 2x 8"s, use better drivers, and a 1.4" HF driver with a ~1.2kHz crossover.


Chris
 
Thanks for the suggestions. @conanski: Why the low cross over point of 800hz?
At frequencies where the wavelength of sound is smaller than the driver diameter the polar pattern narrows to a beam, so to achieve a wide coverage pattern with consistent spectral balance the crossover has to be set low... which requires better quality large diaphram compression drivers. The lower crossover point with the large format CD also changes the character of the speaker system in ways that don't show up on the spec sheet, with the vast majority of the vocals spectrum coming from a single driver the coherence and projection are much better.
You can build these speakers with a 1" CD and they will sound fine on axis but won't come anywhere close to delivering the the overall performance of the RCF boxes.
 
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A bit more info about my idea for this.
I now have 2 12" subs per side (96db/m each, so about 101 db/m coupled), and above that per side 1 Ecler Awak 208 with 2 8" woofers and a 1" horn tweeter in a d'Appolito setup with a sensitivity of 96 db/m.
The awaks sounds really nice, even though they cross at 4,5kHz 😀. But they are outrun by a lot by the subs. And I'd like to be able to play a little bit louder/have some overhead on big venues with my band.
Hence my idea to add some extra woofers in a new cabinet. I have read a lot about line arrays, but that's a whole other store (and price category). But I like the beaming characteristics of the array speakers and as I understood, a column speaker with several woofers above one another, with a good compression driver on top does have a narrower beam. And in difficult rooms or outside, that is desirable.
A horizontal coverage of 90 degr. Would be nice, and a vertical of 50 or 60 degrees.
The choice of diy is (besides the fact that I like to build speakers) a limited budget. So the whole set should be cheaper that a comparable set in the shop. Or differently said: the result of the set hould be better than a similar set (pricewise) in the shops :)

Are there any users here that have build a 4x6' plus high PA speaker?
I read the RCf uses a 3inch high CD.
Anyone knows the sound of the DS18 PRO-DRN2? That is inside my budget.
 
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A bit more info about my idea for this.
I now have 2 12" subs per side (96db/m each, so about 101 db/m coupled), and above that per side 1 Ecler Awak 208 with 2 8" woofers and a 1" horn tweeter in a d'Appolito setup with a sensitivity of 96 db/m.
The awaks sounds really nice, even though they cross at 4,5kHz 😀.
You need to do an honest evaluation of those with respect to spectral balance horizontally across the coverage pattern, if you really look at them scientifically I think you will find the range from 1khz to 4khz has pretty narrow coverage. A crossover that high also suggests the CD is quite small... more of a super tweeter and not really capable of handling midrange frequencies.

But they are outrun by a lot by the subs. And I'd like to be able to play a little bit louder/have some overhead on big venues with my band.
Hence my idea to add some extra woofers in a new cabinet.
OK I see where you are going... add 2 more 8's and change the CD to something better. That can work well and has been done before. What speaker brands do you have access to? There are quite a few 1.4" CD options from B&C, Radian, Celestion, Eminence, and others. Also note that DSP processing is not really optional if you want to get the very best from this setup, the raw published driver resonse is almost irrelevent because it can and often does change a lot once it is mounted on the horn you will want to use.
 
The Awaks have a smallish 1" driver, and a 4x4 horn. It is indeed uncapable of crossing low.
I have done some further investigation and found the exact drivers that are used in the RCF nlx24a :)
The woofers are 6":
https://shop.ampman.co.uk/rcf-nxl24-a-6-bass-woofer-2683-p.asp - > 70 pounds from the UK

The mid/high driver is a RCF ND640, 8 ohm, 1.4 inch crossed at 800hz -> around 220 euro

I was already planning on bi-amping, and I am using a digital processor with 6 band eq, phase and delay possibilities, so thats no issue :)
I am using open sound meter with a calibrated mic to measure the speaker (done outside, because I dont have an an echoic room)

Then all i need to find out is the horn that is used... to diy the speaker hahaha.
 
The RCF NXL24 horn is most likely a custom part. 100 x 30 deg dispersion and it looks asymmetric to me. I am not aware of any 100 x 30 deg horn on the market.

While you can buy a line array waveguide to set the vertical directivity and add a 100 deg horizontal flare yourself, these waveguides tend to limit the vertical dispersion to 15 deg or lower.
 
I built a nightclub sound and light system and was the DJ for a few years. Honestly, you do not want high SPL flat from 20 to 20k.
The midrange is the absolute worst for long term listening, as listening fatigue sets in really fast.
In the club, I used the typical smiley face eq setup, and that reduced crowd turnover significantly. Meaning I couldn't cheap out and repeat songs because of crowd turnover but had to actually work, using some real oldies and hopefully not clearing the dancefloor playing them..:(. At 5 minutes per song, you'd be surprised how quickly you need to decide what to play next while still pleasing the crowd.
For mobile, I used 15's (formerly 18's but gravity kept increasing) in reflex cabs, and eminence delta pro 12's mid bass to 3k, third order 5K hipass to Selenium D205TI's with a 40 by 40 degree horn flare.
The 1k to 4k region is fatigue city, so I gave my customers a break, less ringing of ears at the end of the night, and a better ability to talk to others (translation, hooking up) while the music was playing. For emphasis during specific song points, I jammed the mids up to pretend there was real power, I don't think anybody was wise to my 200 watt goose of the mid horns given the 2kilowatt bass setup (yah, not much by today's standards.)

I prefer bass I can feel down to 20 hz, but most of the drunk patrons only understand the punch of a system that has a resonant peak at 50 hz for the gut hit. Not my cup of tea, but plays well with the drinking crowd.

Now, I'm thinking of a single X-1 from speakerplans (Rog Mogale) with an old Eminence 18 sitting on my shelf. Just not sure if it will fit easily in my Subaru Impreza. Rog has an 15 inch horn cab (HD 15) which is pretty much just 50 hz punch (100 db 1w/meter at 50, peak at 110, 100dbspl 1/1 at 300 hz). I of course would have to eq the daylights outta it, but who cares. I might just do that and the X10, just using the X10 when I really want to.

Oddly enough, this site used to have an eminence 18 (sigma pro or omega pro, not sure) listed in the approved drivers. Whatever I have, mine was in the list. No matter, I'll never drive the speaker beyond its rms listing. And never overdrive it below tuning frequency.

John
 
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