Hi Ray

to do one horn to cover 100hz to 2khz (single driver)is for me an no win plan

try this HD15 from 80/100hz to 180/220hz and MT102 180hz to 16khz

and you get one kick ass quad amp system but big and heavy

or you can get some turbo aspect tops(i dot know if they are ok or not)or some flood flash to be on the safe side

my take hope it helps

yours Vitor 

Hi

If you're planning to build some horns, I recomend 100 Hz straight horn (Quarterwave of course!) with a 15 inch driver with a QTS of 0.2 - 0.26

Having around four of them fed with some good power (800+) should really get the job done.

I'm currently using EAW KF 750's. But, I used to use some old 170 Hz straight horns. (4 of them) The total mouth of the combined four was 56 inches by 62 inches (2 high, 2 wide) They housed 18 inch drivers, but, I used the old EV Proline EVM 15L (no. 7.5%) instead. The low mids were very potent to say the least.

Best Regards,  

RayVaughn
Quarterwave - so the length of the horn needs to be more than 1/4 the wavelength? So 1m long is good?

Elliot Thompson

Yes. that will be fine.

RayVaughn
Why use a 15" driver though? There are some 2.5" and 3" voice coil 10" out there with good power handling (though not 800w continuous) and I'd be very worried about cone breakup at 1kHz with a 15".

Elliot Thompson

You said "Low Midrange", so, it should be cutoff at 1khz (Least efficient). The majority the work will be coming from 500 - 150Hz, and, cutoff at 120 or 100 Hz. (Whichever sounds better)  

RayVaughn
Here's the drivers I'm thinking of:
Precision devices PD107
18 Sound 10ND610
JBL 2012H

Elliot Thompson

When I think of midrange, I think 10 inch drivers. When I think of   Low Midrange/Midbass, 15 or 12 inch drivers comes to mind.

I just don't think a 10 inch can handle frequencies under 400 Hz very well without cone breakup.

Best Regards,

RayVaughn                                                                       I'm confused. For me 'cone break-up' is where the diaphragm stops acting as a piston and exhibits resonant modes across it. This is one reason why we use smaller diaphragms at higher frequencies.

Elliot Thompson

I agree. But, 1 Khz is midrange, and, anything below that is considered low midrange. If you want to go down to 150Hz cleanly, you're better off with a larger driver.

RayVaughn
The disadvantage with using smaller diaphragms for lower frequencies is less air being moved rather than break up - no?

Elliot Thompson

From my experience, smaller drivers will distort faster than larger drivers, when used in lower mid frequencies, under high spl use.

Since we are talking low midrange here, an not bass, your not going to find 10 inch drivers with 15 inch characteristics for midrange purposes. If you are so against 15 inch for low midrange, use a 12 inch instead.

RayVaughn
Also the diameter of a 15" speaker is approaching the wavelength at 1kHz which causes beaming in a direct radiating design. It's not clear to me how this influences behaviour in a compression design but my guess is it's not good.

Elliot Thompson

All speakers beam at a given frequency. The samething applies to horns. A Parametric will solve this problem.

RayVaughn
Thanks for the advice but the jury's still out on this i reckon...

Elliot Thompson

If you noticed, when I mentioned using 15's for low midrange, I mentioned, the EVM. The EVM is a speaker, not a woofer, and, offers a more fullrange sound. Today, you may not find a 15 that offers such  a response like the EVM 15. So, you might be better off going for a 12 inch for the design. 

I know the horn determines the frequency. But, I feel that a larger speaker is more efficient at 200 Hz, than a smaller one.

Best Regards,

To get that sort of bandwidth a phase plug is probably on the cards. I have been doing some planning myself for a 130Hz tactrix horn with the P.Audio SN-12B which models fantastically. The thing is that if you want to get low frequencies out of a Mid-horn, you need to move air and this means increasing the distance between the phasing plug and the driver cone. In my case Rog’s phase plug equation results in an upper cutoff of 1.6kHz for a 5mm clearance and I assume that this is an ideal case scenario for a multi-slit annular phase plug (I’d probably stay with one slit for my first try at a bass-mid horn)

A good phase plug evens out the arrival time of different parts of the cone to the horn throat (one wants a planar wavefront at the horn throat) and the directivity is governed by the horn mouth at lower frequencies and progressively by sections nearer to the throat as frequency increases. Could anyone post the speed of sound is through a paper cone? Rog?

My only concern with neo drivers is the small rear chamber which might cause the magnet to de-magnetize at the high temperatures, so perhaps an aluminium access plate is a good idea (the models favour around 3l rear chambers if one wants to keep excursion in check around fc)

My local P.Audio dealer told me that they’d be getting in the P-12N in their next shipment, so that might be a nice candidate for reverse-mounting the driver (doesn’t model as nicely as the SN-12B though). The magnet at the back of the driver is fairly big and has a suitable profile as a (botched) phase plug, but the compression chamber would limit upper bandwidth even with some tricks to reduce the volume and probably some funky molding on the horn throat (fibre-glass = evil). A German company Xmax uses an 18Sound 12MB1000 reverse mounted and with the phase plug stuck to the back of the driver crossed at 800 Hz to a DAS ND-10 (yummy, but at a price) on a big 60x40 horn and this top is said to sound very good and have very low compression.

If Rog’s 12” Mid-horn is not an option in the near future, perhaps you should ask Dirk Hahn from www.x-max.de about their horn and the 18Sound 12MB1000 to go with it. I don’t remember the price (wasn’t cheap) and it’s good from 140Hz, probably a bit lower in pairs. Pm me with your e-mail and I’ll forward measurements if you’re interested.

Martin

@ RayVaughn: How do you cover the range from 100-1000Hz now? And what tops are these, going only from 1000Hz up? Seems there is already a misunderstanding or misconception......

I agree with Pinheiro that you won't get this spectrum out of one box in a good way. Around 200-300Hz there is kind of a boundary for what speakers/horns can do, so you can design a horn that will be very good below 200Hz or you can do one that will be good above 200Hz. This is, of course, NOT a limitation coming from the diameter of the speaker, but the type of the horn. If you want real output around 150Hz and below you need to have the horn folded for getting it into a transportable shape. Above 200Hz you need a straight horn, because the mids won't play well in a folded design. Of course a folded horn will go even lower then 100Hz.... and a good 10" horn with phase plug will go above 1kHz...... but there is no good way to do it with one speaker in one box.....

As I said the output capabilities have nothing to do with the drivers diameter. The most amazing sub horns use 12" speakers.... Why? Simply because bigger drivers won't take the stress on the cone (bigger cone plus proportionally higher BL --> more stress). We have bass horns with 4 10" drivers per horn. They can do 40Hz (in a stack of four) to 250Hz real flat and really good sounding (flat doesn't mean that the timeline looks good too!) and they get very loud, so you see, the size doesn't matter in this case! Of course these are 10" drivers made for bass, not for mids.

15" drivers in horns should not be operated above 700Hz and even that doesn't sound really good.... and of course a horn of that type won't go below 130 or 150Hz (because it has to be straight and has to have a reasonable size)! So....

JD01 wrote: @ RayVaughn: How do you cover the range from 100-1000Hz now? And what tops are these, going only from 1000Hz up? Seems there is already a misunderstanding or misconception......

It's a 4 way system (per stack)
6 or 8 Fane 18" in short horns (a la TSW 118)  currently up to 175Hz
Array of 16 direct radiating 7" Kevlar mid-bass drivers 175Hz - 1KHz
4 direct radiating 6" surroundless Kevlars 1kHz - 7Khz
4 EV DH3 compression drivers on CD horns 7kHz up

Don't ask me about the kevlars, they're not available to the public - they're a favour from a friend. The 6" are most unusual as the effective radiating area of the diaphragm narrows with frequency as a result of having no surround. Nothing else sounds quite like them.

The  6"  are  fairly sensitive in the region we use them (100dB/w)  but will be the limiting factor  when i upgrade the lower mid. Thats ok. There's a price to pay for effortless clarity in vocals etc.

The 7" are not very sensitive and  despite the largish array  don't cut the mustard.  I could just replace them with a light coned 2" voice coil driver and throw more power in but a horn is clearly a better way to go.

JD01 wrote: I agree with Pinheiro that you won't get this spectrum out of one box in a good way. Around 200-300Hz there is kind of a boundary for what speakers/horns can do, so you can design a horn that will be very good below 200Hz or you can do one that will be good above 200Hz. This is, of course, NOT a limitation coming from the diameter of the speaker, but the type of the horn. If you want real output around 150Hz and below you need to have the horn folded for getting it into a transportable shape. Above 200Hz you need a straight horn, because the mids won't play well in a folded design. Of course a folded horn will go even lower then 100Hz.... and a good 10" horn with phase plug will go above 1kHz...... but there is no good way to do it with one speaker in one box.....

This makes sense. Maybe I need to be realistic and design for a 150Hz to 500Hz range.
I'm just not sure whether to try and design something where the roll-off is somewhat outside the range that will be used or match it exactly.

JD01 wrote: As I said the output capabilities have nothing to do with the drivers diameter. The most amazing sub horns use 12" speakers.... Why? Simply because bigger drivers won't take the stress on the cone (bigger cone plus proportionally higher BL --> more stress). We have bass horns with 4 10" drivers per horn. They can do 40Hz (in a stack of four) to 250Hz real flat and really good sounding (flat doesn't mean that the timeline looks good too!) and they get very loud, so you see, the size doesn't matter in this case! Of course these are 10" drivers made for bass, not for mids.

JD01 wrote: 15" drivers in horns should not be operated above 700Hz and even that doesn't sound really good.... and of course a horn of that type won't go below 130 or 150Hz (because it has to be straight and has to have a reasonable size)! So....

Timber_MG wrote: To get that sort of bandwidth a phase plug is probably on the cards. I have been doing some planning myself for a 130Hz tactrix horn with the P.Audio SN-12B which models fantastically. The thing is that if you want to get low frequencies out of a Mid-horn, you need to move air and this means increasing the distance between the phasing plug and the driver cone. In my case Rog’s phase plug equation results in an upper cutoff of 1.6kHz for a 5mm clearance and I assume that this is an ideal case scenario for a multi-slit annular phase plug (I’d probably stay with one slit for my first try at a bass-mid horn)   A good phase plug evens out the arrival time of different parts of the cone to the horn throat (one wants a planar wavefront at the horn throat) and the directivity is governed by the horn mouth at lower frequencies and progressively by sections nearer to the throat as frequency increases. Could anyone post the speed of sound is through a paper cone? Rog?   My only concern with neo drivers is the small rear chamber which might cause the magnet to de-magnetize at the high temperatures, so perhaps an aluminium access plate is a good idea (the models favour around 3l rear chambers if one wants to keep excursion in check around fc)

I've been experimenting in McBeans program with various drivers and horn flares. The best results have been with the TAD 1201 driver but I'm unhappy with it's low frequency performance.
The SN-12B has a relatively high moving mass which seems to diminish high frequency performance greatly.
I've also had a look at the Beyma 122ND which has a high BL and a very low moving mass.
I can only assume that these very light cone/coils will be more susceptible to break-up modes...

I too had assumed that a phase plug would be necessary but don't really know what I'm doing! Still, I'll have a look at the phase plug equations of Rogs that you're talking about.

Currently the models I've done in McBean are only exhibiting 2mm excursions even at 100Hz...

I see. So you want to go down to 500Hz with the 6" speakers then? Will they 'like' that?

How do you crossover? All active or some ways passive?

Adding up on the 6" seems to be a good idea...

Have you considered designing a passive crossover for the 6" to tweeter cross? So you could really do two horns... it's because I don't think that your existing basshorns could do better if crossed over at 100Hz or even slightly lower. I mean the rest of your system seems to be very audiophil, so why getting the 'slow' and heavy 18" above 100Hz?

My sims show the SN-12B to be very good up to around 800Hz regarding power response and if one looks at 0 to 30 degree performance,  I seem to be able to get the horn up to 1kHz and a little higher or there abouts until I get -6dB @ 30 degrees off axis (designing for a 60 degree cab). I presume the -6dB @ the angle I want to cross over in a horn top to be the highest I can push the horn before I get lobing, right? A 40 degree solution might allow one to cross higher.

The problem with McBean for HF horn design is that it doesn't accurately model the behaviour of a horn at high frequencies (David says so himself). Methinks this is where AJHorn, Speak, Akabak and what not come into their own, but Akabak is a tad too much for a student's budget. This is the bit where one just keeps the side-walls conical as far as possible and lets the phase plug make the horn contour and hopes for the best. The other approach is to make a phasing plug like a big compression driver and a couple it to a “normal” = “without nose” horn. The reverse mounting the driver seems a little risky, though it allows the horn to be shorter physically and lowers power compression.

For simplicity there is nothing like buying a working solution though.

Hi Ray,

Can you get me the other T/S specs, like Qts etc.

Found the specs,

Heres how my version of your horn looks.

Hi Ray,

The above plot is using your specs taken from Hornresp.

I've done some modifications and have come up with this.

Horn lenght 0.8 meters

mouth 66 x 66 cm

throat 350 sqcm

rear chamber 15 liters

front chamber 0.5 liters

here is the lot and the expansion details.

Dist     sqcm   width angle

0.000  350.00  5.30 10.56
0.016  350.52  5.31 10.56
0.032  352.10  5.33 10.59
0.048  354.73  5.37 10.63
0.064  358.44  5.43 10.68
0.080  363.24  5.50 10.75
0.096  369.17  5.59 10.84
0.112  376.27  5.70 10.94
0.128  384.56  5.83 11.06
0.144  394.11  5.97 11.20
0.160  404.98  6.14 11.35
0.176  417.21  6.32 11.52
0.192  430.90  6.53 11.71
0.208  446.12  6.76 11.92
0.224  462.95  7.01 12.14
0.240  481.52  7.30 12.38
0.256  501.91  7.60 12.64
0.272  524.26  7.94 12.92
0.288  548.70  8.31 13.22
0.304  575.38  8.72 13.53
0.320  604.45  9.16 13.87
0.336  636.09  9.64 14.23
0.352  670.48 10.16 14.61
0.368  707.85 10.72 15.01
0.384  748.39 11.34 15.43
0.400  792.37 12.01 15.88
0.416  840.05 12.73 16.35
0.432  891.70 13.51 16.85
0.448  947.63 14.36 17.37
0.464 1008.19 15.28 17.91
0.480 1073.74 16.27 18.49
0.496 1144.66 17.34 19.09
0.512 1221.38 18.51 19.72
0.528 1304.36 19.76 20.38
0.544 1394.10 21.12 21.07
0.560 1491.13 22.59 21.79
0.576 1596.03 24.18 22.54
0.592 1709.43 25.90 23.33
0.608 1832.01 27.76 24.15
0.624 1964.51 29.77 25.01
0.640 2107.71 31.93 25.90
0.656 2262.47 34.28 26.84
0.672 2429.72 36.81 27.81
0.688 2610.45 39.55 28.83
0.704 2805.76 42.51 29.88
0.720 3016.80 45.71 30.99
0.736 3244.85 49.16 32.14
0.752 3491.25 52.90 33.34
0.768 3757.50 56.93 34.58
0.784 4045.17 61.29 35.88
0.800 4356.00 66.00 37.24

Hi martin, sorry for the late reply, I have been so busy these days.

I've not used Ged Lees SPEAK, but I will try it now. I like AJ horn, for mid top its great and its predictions are good. So what you see is what it sounds like.

Hornresp is good for bass, but I'm not convinced for mid or top horns.

I also use Akabak with my own models of horns and chambers. This is the best way I have found yet. And no, I' can't send anyone the scrpits.

Rog.

Funny,

I can model 30 meter horns using my AJ horn.

What version have you got.

This is meaner.

Anyone fancy an 11 meter horn with a Void V18 driver in it.

Rog Mogale wrote: This is meaner. Anyone fancy an 11 meter horn with a Void V18 driver in it.

I'll go warm up the table saw....  Sort the plans out...