Double 10 and Horn
- Thread starter Peter Morris
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What is the effect of tilting the 10" in opposite directions like Jaroslav Mikyska did? How will it affect directivity?
Jaroslav, maybe you can elaborate a little about the performance of your build?
Jaroslav, maybe you can elaborate a little about the performance of your build?
Hi, I chose the loudspeakers only to reduce the size of the box. I would say that the directionality does not have an effect, but it has a great impact on the sound color. it has a big gain around 300Hz and it has to be solved by using PEQ in the sound processor. I do not measure the directionality of the boxes so that I did not have to measure it, but when using such a low dividing frequency (600Hz) the directionality is already quite negligible.
Thank you for your answer, Jaroslav!
I started cutting wood some days ago for the PM90, but after reading this I got inspired. For many years I have been wanting to build the ultimate battery powered portable speaker, and now I am hoping that I can combine this pa top build with my old dream. I plan to make a MTM 12" version, but bass reflex. I plan to use them as tops for my subs in pa situations, but also as a battery powered boom box for sunny days, so I need them to extend quite low on their own. I have settled for the B&C 12NDL76 because of the nice price, nice LF excursion and high sensitivity. But when used on their own, I want to lay them down sideways. Will I be able to do this and maintain 90 degree pattern control, or do I need to turn the horn 90 degrees around everytime I do sideways use? I would appreciate some thoughts on this.
I started cutting wood some days ago for the PM90, but after reading this I got inspired. For many years I have been wanting to build the ultimate battery powered portable speaker, and now I am hoping that I can combine this pa top build with my old dream. I plan to make a MTM 12" version, but bass reflex. I plan to use them as tops for my subs in pa situations, but also as a battery powered boom box for sunny days, so I need them to extend quite low on their own. I have settled for the B&C 12NDL76 because of the nice price, nice LF excursion and high sensitivity. But when used on their own, I want to lay them down sideways. Will I be able to do this and maintain 90 degree pattern control, or do I need to turn the horn 90 degrees around everytime I do sideways use? I would appreciate some thoughts on this.
If you turn the box sideway with the two 12" or 10" drivers either side of the horn, and cross to the BMS 4594/HF950 horn at around 630Hz the pattern at this point will collapse (as a best guess) to round 40 - 50 degrees. This is why the double 10 like Jaroslav's design looks great, it controls the vertical pattern of the 10" drivers to match the horn's nominal vertical pattern of 50 degrees at the crossover point.
@ Jaroslav ... that gain you get around 300Hz and EQ-ed out will actually translate more SPL
Below (excuse the cat) is a box I built which is some what similar to yours (its on its side in the picture). The 2 slots and chamber in front of the 2 x 14" drivers produces a peak around 400Hz which is EQ-ed out. The spacing of the slots either side of the horn form a dipole and hence control LF directivity. If you get it correct (the spacing and crossover frequency/slope) you can get an almost perfect off axis frequency response through the crossover point in both the horizontal and vertical plane.
@ Jaroslav ... that gain you get around 300Hz and EQ-ed out will actually translate more SPL
Below (excuse the cat) is a box I built which is some what similar to yours (its on its side in the picture). The 2 slots and chamber in front of the 2 x 14" drivers produces a peak around 400Hz which is EQ-ed out. The spacing of the slots either side of the horn form a dipole and hence control LF directivity. If you get it correct (the spacing and crossover frequency/slope) you can get an almost perfect off axis frequency response through the crossover point in both the horizontal and vertical plane.
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Nice Cat ?If you turn the box sideway with the two 12" or 10" drivers either side of the horn, and cross to the BMS 4594/HF950 horn at around 630Hz the pattern at this point will collapse (as a best guess) to round 40 - 50 degrees. This is why the double 10 like Jaroslav's design looks great, it controls the vertical pattern of the 10" drivers to match the horn's nominal vertical pattern of 50 degrees at the crossover point.
@ Jaroslov ... that gain you get around 300Hz and EQ-ed out will actually translate more SPL
Below (excuse the cat) is a box I built which is some what similar to yours (its on its side in the picture). The 2 slots and chamber in front of the 2 x 14" drivers produces a peak around 400Hz which is EQ-ed out. The spacing of the slots either side of the horn form a dipole and hence control LF directivity. If you get it correct (the spacing and crossover frequency/slope) you can get an almost perfect off axis frequency response through the crossover point in both the horizontal and vertical plane.
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Thank you for this answer!
Okok, let me see.. .I dont quite get why turning mtm speaker on the side changes pattern relationsip between woofers and horn, could you explain a little more?
So exciting , some other questions have been piling up as well,
Horn will still be able to control directivity of 60x90 degrees down to 630hz?
Can I turn horn 90 degrees around to make up for turning sideways?
Jaroslav tilted his woofers outwards and you in towards horn, is there a particular reason?
Do you have ports inside the slots on your speaker? If no why not?
And a final one, I have been looking for a driver with good LFR, and I wanted to ask you opinion on the 18Sound 12NW530. They seem to be able to do FB 47hz at 70 liters. Do you find them suitable?
Okok, let me see.. .I dont quite get why turning mtm speaker on the side changes pattern relationsip between woofers and horn, could you explain a little more?
So exciting , some other questions have been piling up as well,
Horn will still be able to control directivity of 60x90 degrees down to 630hz?
Can I turn horn 90 degrees around to make up for turning sideways?
Jaroslav tilted his woofers outwards and you in towards horn, is there a particular reason?
Do you have ports inside the slots on your speaker? If no why not?
And a final one, I have been looking for a driver with good LFR, and I wanted to ask you opinion on the 18Sound 12NW530. They seem to be able to do FB 47hz at 70 liters. Do you find them suitable?
By turning it on it side I assumed you would be rotating the horn - sooo at the crossover of (say) 630Hz you have 3 sources of sound and the directivity is determined by the width/spacing of these three sources. As the frequency increases the pattern will tend to that of the horn and as it decreases it will tend towards the pattern created by the dipole of the 10" or 12" drivers.
For a horn the size of the HF950 as you approach the cut off frequency of 400Hz the pattern becomes very wide, much wider than 90 degrees and tends to be controlled by the width of the horn not the angle of the horn walls at these frequencies.
Have a look at this horn, the 60 degree horn used in the PM60 ... its 100 degrees at 600Hz http://www.eighteensound.com/en/products/horn/1-4/0/XT1464.pdf
Getting it all to work together is a lot more compliacted than just selecting nice components.
I suspect the 12NW530 is a very nice speaker but I have never used any.
For a horn the size of the HF950 as you approach the cut off frequency of 400Hz the pattern becomes very wide, much wider than 90 degrees and tends to be controlled by the width of the horn not the angle of the horn walls at these frequencies.
Have a look at this horn, the 60 degree horn used in the PM60 ... its 100 degrees at 600Hz http://www.eighteensound.com/en/products/horn/1-4/0/XT1464.pdf
Getting it all to work together is a lot more compliacted than just selecting nice components.
I suspect the 12NW530 is a very nice speaker but I have never used any.
Just for the sake of interest. I built 12 "bass boxes to small 2x10 boxes according to the construction instructions from 18Sound, I am very pleased with them.
Photo from the building here.
Photo from the building here.
Attachments
Aaaahyes. Im sorry, I may have over complicated things a little bit in my mind. My technical understanding is still... erhm.. under development, but I'm getting there, slowly slowly.
So when the speaker is standing up straight, and horn is radiating 90 degrees horizontally, the speaker is still limited to woofers horizontal directivity (approx 50 degrees)? That means that only half the FR has 90 degrees angle control?
So if I turn the speaker sideways (AND rotating the horn), and mount the speakers dipole, I'm coming closer to the horns now horizontal spread? hope I got it this time...
So when the speaker is standing up straight, and horn is radiating 90 degrees horizontally, the speaker is still limited to woofers horizontal directivity (approx 50 degrees)? That means that only half the FR has 90 degrees angle control?
So if I turn the speaker sideways (AND rotating the horn), and mount the speakers dipole, I'm coming closer to the horns now horizontal spread? hope I got it this time...
Jaroslav, that rig is the most aethetically pleasing set up I have seen for a very long time. If sounds half as good as it looks, then gratulations
Hi Kristoffer - with the box standing up the horizontal pattern of the low frequency drivers will be wider than their vertical pattern; from my computer simulation about 45 degrees vertically at 630Hz gradually getting wider as the frequency goes lower.
This will match in very well with HF horn which in nominally 90 x 50.
Horizontally at 630Hz the HF horn will have lost a bit of its pattern control and will actually be wider than 90 degrees. The pattern at this frequency will be determined mostly by the width of the horn; because the width of the low frequency section is the same as the horn the pattern of the low and high sections will be about the same horizontally at the crossover point, which is exactly what we want.
Vertically the HF horn at 630Hz will have also lost its pattern control and instead of being 50 degrees it will be more like 100 degrees … but because all the drivers, the 2 x 10” and the horn are all working together at this frequency the pattern will be a result of how all 3 sum together. If we are lucky it will be reduced back close to 50 degree.
If you rotate the horn the low frequency pattern will not match the high frequency. If you just have a single 12” + horn then you can rotate the horn without issue, but with MTM designs it won’t work so well.
@ Jaroslav - yes the 18sound designs are great - BTW how is this little system go for you.
This will match in very well with HF horn which in nominally 90 x 50.
Horizontally at 630Hz the HF horn will have lost a bit of its pattern control and will actually be wider than 90 degrees. The pattern at this frequency will be determined mostly by the width of the horn; because the width of the low frequency section is the same as the horn the pattern of the low and high sections will be about the same horizontally at the crossover point, which is exactly what we want.
Vertically the HF horn at 630Hz will have also lost its pattern control and instead of being 50 degrees it will be more like 100 degrees … but because all the drivers, the 2 x 10” and the horn are all working together at this frequency the pattern will be a result of how all 3 sum together. If we are lucky it will be reduced back close to 50 degree.
If you rotate the horn the low frequency pattern will not match the high frequency. If you just have a single 12” + horn then you can rotate the horn without issue, but with MTM designs it won’t work so well.
@ Jaroslav - yes the 18sound designs are great - BTW how is this little system go for you.
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Kristoffer:
Thanks for the praise. ?
Peter:
I am so excited about the mini bass boxes that I decided to build 12 pieces and use them for larger events. I needed to try out this mini system with 4pcs of bass boxes, so I used it to sound the student event in the square. At a distance of 20 m, the sound was still incredibly loud and clear, the bass was massive due to the size of the entire PA system. With the BMS driver and the HF90 horn, this micro box has excellent recitation and incredible volume potential. For such a small system, the driver may have an unnecessarily large margin, but that's good. One soundman colleague was listening to it and came to me during the event and said I had to build the four bass boxes for him as well, he liked the first listening. Their size is incredibly low.
Photos from the event are here.
Thanks for the praise. ?
Peter:
I am so excited about the mini bass boxes that I decided to build 12 pieces and use them for larger events. I needed to try out this mini system with 4pcs of bass boxes, so I used it to sound the student event in the square. At a distance of 20 m, the sound was still incredibly loud and clear, the bass was massive due to the size of the entire PA system. With the BMS driver and the HF90 horn, this micro box has excellent recitation and incredible volume potential. For such a small system, the driver may have an unnecessarily large margin, but that's good.
One soundman colleague was listening to it and came to me during the event and said I had to build the four bass boxes for him as well, he liked the first listening. Their size is incredibly low.Photos from the event are here.
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This makes sense, finally I understand! Thank you very much for you patient explanation, I will make sure to pay it forward when the time arrives. Do you know approximately how many liters is occupied by horn, bms driver and bracing inside the box?
What volume the horn and driver have, I don't know. I have basreflex ports inside the box, diameter 50mm, length 80mm. This is indicated by dashed lines on the drawing.
Okay, thanks! what are tuning frq for your speakers? and where did you find those fancy speakergrills? Been looking for something like that.
I haven't measured the tuning yet, basreflexes are only tuned in order to keep the box as low as possible. Because the box in fulrange mode is used only exceptionally and at low power, there is basically no need for it. With standard use of compact boxes with subwoofers at crossover frequency of 115Hz, the basfflex in the compact box no longer applies.
Protective grill is made to order on the Trumatic punching machine.
I see. Thanks!
I have decided to do things a bit differently, and go for 10", I find the formfactor really applicable. I need some help to decide woofers. It comes down to 18Sound-10nw650 vs B&C-10NDL64. Can anyone point me in the right direction for what parameters to look for that gives an indication about low frequency performance? I need them to go down to 60 hz with authority.
Ps: Thanks for the pictures Peter. I've downloaded rayend and been trying it out for my self. Now I have got the point.
I have decided to do things a bit differently, and go for 10", I find the formfactor really applicable. I need some help to decide woofers. It comes down to 18Sound-10nw650 vs B&C-10NDL64. Can anyone point me in the right direction for what parameters to look for that gives an indication about low frequency performance? I need them to go down to 60 hz with authority.
Ps: Thanks for the pictures Peter. I've downloaded rayend and been trying it out for my self. Now I have got the point.