DIY PA Project, Multiple Entry Horns + Subs

Hello,
i purchased a bunch of PA drivers in the winter and finally started my build a few days ago.

my goal is to build a PA for small/medium clubs and small/medium open airs.

after some research i settled on the following setup as a first try:

2x 2-way Midtops : Conical Multiple Entry Horns with 2x Eminence KappaPro 10A and 1x BMS 4552 ND

2x Subwoofer: a custom design 4,2m folded horn/reflex hybrid with 1x 18" PD1850/2 driver

i will use a Behringer DCX2496 Ultradrive Pro and some cheap thomann t.amps for a first test phase, then hopefully switch to passive crossovers and decent amps later...

here are some pics of the first midtop being built:

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i've never worked with wood before, so don't be too hard on me please.

the stupid virus will now delay the build a bit, hard to guess when i will be able to finish this project, but ofc i'll update with some more pics and measurements once i get a chance.

please feel free to drop some advice or feedback...

cheers, lisette
 
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To an extent its a bit genre dependent but I would go with 4 of the subs. Other than that the plan looks good.

1) Is the multiple entry horn going to have a secondary flare? it reduces the midrange pattern narrowing phenomenon.
2) what are the intended crossover points?
3) I would stick with DSP crossover, limiting will not be very effective or you will have to run drivers far under rating with a passive crossover. Furthermore for the price of all the high power crossover components you will need you can buy a second hand higher end free form DSP like QSC, Symetrix etc.
4) Whats the specifics of the throat transition?
5) whats the intended coverage angle of the multiple entry horn?
 
thx for the feedback!

i think you are correct that another 2 subs will probably be needed... i am a bit concerned about the weight of the entire system (2tops+4subs+amprack ~ 900kg) but i guess thats my own fault for designing huge enclosures^^ ill decide on the sub count once i can hear and measure the 2 subs...

i think i'm fine without the secondary horn flare, hornresp puts out a nice curve, i really hope the measurements will be close to the prediction...

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my hornresp simulation runs with a x-over at 1.4k, i'll have to see if that is realistic... the lower x-over maybe~180, no idea how the subs will sound in this region...

sticking with dsp is definitely an option, i have not really researched high power crossovers yet...

the throat transition is a 3d printed part. it has the same conical flare as the rest of the horn but its shape is a transition from rectangle to 1" round, here's a sketchup screenshot of the part without screwholes

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heres a short vid during printing:

https://i.imgur.com/jcSkY8v.mp4

the intended coverage angle is ~ 60° x 40°

cheers
 
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The secondary flare is for pattern control, without it the coverage will narrow in the mid-range. See this paper:
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1975-05 AES Preprint) - Whats So Sacred Exp Horns.pdf

I didn't spot that your subs are huge FLH, whats the expected output? any more info on these?

If your amp rack is heavy that's an area where a lot of weight can be lost using switch mode amps. Keep an eye out on the second hand market a lot of clubs and venues will be going out of business at the moment. From my experience Powersoft or Lab gruppen are good if you can get them.

1.4kHz sounds high, i only managed 1.27kHz with my multiple entry horns (see sig) and this is higher than the SynTripP design that uses 10" drivers (800Hz). If you have to go down to 800 Hz your going to have to use a large format compression driver and 1.4" or 2" throat.
 
+1 keep the DSP.

The DCX2496 will take your system a long way until it's a limiting factor. After that, you may get small sonic benefits from moving to a unit such as a db-Mark.

I would say try to not skimp too much on the amps for the mid-hi. Keep it SMPS AB if possible. As mentioned second hand lab gruppen / other big name would be great.

Something like this Behringer thing will do two FLH just fine for bass.
 
I finally had a chance to continue my build today... so here are some updates:

i installed a backwall and performed a quick first measurement. with a crossover at 1.2k and -8.5db on the tweeter i got a pretty flat response from 100Hz to 10kHz without any other filters. from 10k to 20k theres a pretty linear drop to -20db i did not perform any off-axis measurements yet, so i have no idea if i have bad pattern control like kipman725 suggested...

heres a short clip of a random song playing, recorded with an old cellphone:

YouTube

i have a microphone recording i can post later...

the backchamber is still empty, havent ordered my polyfill yet, so i guess the sound quality might improve after i stuff them, but i did enjoy the sound (room has terrible acoustics)

when starting the assembly of the second midtop i unfortunately realized that one of the 10" mids i hadn't unpacked yet has the acoustic sealing tape glued right on to the front of the cone XD now i have to get a replacement, which will probably set me back at least week :/

in the meantime i will start building my woofers... they will be huge:

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inside is a 420cm offset driver folded horn with a 200 liter reflex chamber. I hope they sound as good as my simulations suggest...

concerning amps: i know mine are trash, but i intend to sell/rent out the speakers without amps and i have acess to some highend amps i can test them with, so im happy with what i have for the moment (t.amp TSA 4-1300, t.amp proline 3000 )

i'll have more details and some curves in my next update!

cheers, lisette
 
updates from my build:

the replacement driver was delivered quickly and i was able to complete the second midtop.

i also managed to finish one of the subs, heres some pics:

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measurements showed -3db ~28Hz, with some nasty dips at ~100Hz, which i suspect were due to room acoustics, ill have to wait for a decent outdoor measurement to know if i have a design problem here...

the soundcheck was jawdropping... heres a short clip of a cellphone camera trying to cope with the bass vibrations (rolling shutter effect from floor vibrations) :) : YouTube

i left the laptop with measurement curves in the workshop, so i cant show any of those now :/

unfortunately i will be travelling for 2 weeks now... when im back, ill finish the second bass, finetune the system and take it outdoors for some reliable measurements...

cheers, lisette
 
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crikey I haven't seen that before! PD sub driver? looks like the ventilation will be very good for the back chamber which will reduce long term compression.

when you do the outdoor measurements you should do power compression tests like those on data-bass for comparison with other sub designs. Its also good for working out where to set limiters.
 
update

heres's an update on my PA build:

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i finished building and most of the paintjob. the paint i ordered for the horns was terrible, so horns are still untreated... black paint is warnex. also i did not have time to measure & dsp yet, hopefully later this week...

heres another soundcheck video, this time with steadycam ;)

stereo soundcheck mono recording

the sound was incredibly good, i am very pleased with the result so far... first gig will be in august!

cheers, lisette
 
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those slots do compress the drivers significantly, however the compression is more of a side effect... the geometry is needed so that all the drivers act as a single point source. i am not sure about the physics behind it, i rely completely on simulation tools...


in the coming weeks the system will play on a festival floor. i will set it up a day early and finally do some nice outdoor measurements. any tips on what measurements i should do (i have never done any of this :F) ?


current plan is:


frequency response
impedance
power compression
directivity(polar&sonogram)


cheers lisette
 
i rely completely on simulation tools...

Hi, Lisette!
Please, let me know what a tool you used for high-freq driver simulating? Yes, for midband we can use famous Hornresp, but how you join/link HF and MF responses?

any tips on what measurements i should do

Ouch!
1. Bands phase at a crossing freqs, LF to MF and MF to HF. Do your bands are summed correctly.
2. Crossing point shift per volume increasing (yes, you will add subs volume more than MF/HF and this will anyway impact crossing points due to settled filters slope)
3. Response at different distance, say 10, 20, 50 meters. (yes, long-throw will loose LF due to MF/HF directivity)
4. Response at different height, say standing/sitting listener (yes, they will vary)
5. Waterfall for avoiding insystem intrinsic resonances (yes, using modern digital crossovers you can cut very narrow freqs and more or less resolve the problem)
6. Long-term heating of drivers (yes, being rear-chambered drivers will anyway have a lack of ventilation/heat exchange)
7. Phase lag between stacks through listening area (yes, 2 stack stereo system will anyway have some kind of beaming through all freq range)
 
a small update:
Please, let me know what a tool you used for high-freq driver simulating?
i used several tools, but mosty hornresp. the "multiple entry horn" tool lets you combine the responses (Hornresp)

i still have no measurements to show, but a nice festival gig on sep 11-13. i will setup 2 days early and finally measure... in the meantime here are some pics of the gold leaf horns (fotos by www.sophiereuter.com):

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cheers lisette
 
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hello,

long time no update but thats because i dont have much to show...
the festival was awesome, but my soundcheck time was extremely limited, so still no measurements...
the feedback on the soundsystem was incredible. one DJ came upt o me and said it was the first soundsystem hes heard thats in the same league as funktion1. i also got a couple follow-up gigs for october and november. at one point a naked 50+ year old, covered in glitter, tried to climb in the midtop horn, good thing the speakers were strapped down :F some pics&vids were made, but i wont have access to them for another 2 weeks or so.
here's a shitty screenshot from a cellphone vid, kaspar krug & pabel hitting the decks:
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here's the set they played: Pabel & Kaspar Krug @ Sarasvati's Bretterbude, Praerie Festival 2020 by Pabel | Free Listening on SoundCloud


cheers, lisette