I've got an Idea for a good front horn design. I would start with the fostex FF125k in a front horn loaded down to about 300hz. I think this is a good choice for a front horn because the response starts rising drastically after about 1500 to 2000 hz. Then I would place a super tweeter crossed over at 10khz above it, probably the FT17H. Underneath the horn I would have about 8 6" woofers in an isobaric bass reflex cabinet crossed over at 300hz. That should give me an f3 of about 26hz with the woofers I have in mind and a cabinet of aproximatly 2.5 cubic feet. With 8 drivers it should match the sensitivity of the horn.
I would like to do a round front horn but a square horn seems to be a much easier option. I'm not quite sure of what the difference would be as far a sound quality is concerned. If the difference is significant and some one knows a relitively easy way to build a round horn any suggestions would be appreciated.
let me know what you think of my idea.
I would like to do a round front horn but a square horn seems to be a much easier option. I'm not quite sure of what the difference would be as far a sound quality is concerned. If the difference is significant and some one knows a relitively easy way to build a round horn any suggestions would be appreciated.
let me know what you think of my idea.
You've just closely described the newest speaker project I'm working on that I have a working prototype of in my living room now of the mid horns sitting on a couple of 12" BR boxes I had around just to try the idea. In my rough prototype plan the woofers are 8" and there are not as many as I only have a total of eight in stock. I haven't built the bass boxes yet because i just cannot get high enough efficiency out of 4 woofers to matchg my HF horn and may just wait until I can afford it and order more 8" woofers. This is not attractive though in what was hoped could be a commercially viable design and components costs have to be minimized. I use completely different drivers than you propose and am operating without a tweeter since my mid driver goes high enough. My target application is very high efficiency for use on low power SET or tube amps in general.
As such I'd have to give your idea my blessing to proceed with encouragement. Good luck. Horn loading the largest portion of the midrange as low as 100-300 Hz really rocks.
I looked at the FT17H and almost purchased a set until someone else on this board said they weren't all that great. For what you are making, for a high tweeter I think you definitely want great.
As such I'd have to give your idea my blessing to proceed with encouragement. Good luck. Horn loading the largest portion of the midrange as low as 100-300 Hz really rocks.
I looked at the FT17H and almost purchased a set until someone else on this board said they weren't all that great. For what you are making, for a high tweeter I think you definitely want great.
The FR horn driver is a 6" FR no-name unit from Taiwan with a paper cone, treated paper accordion surround and ceramic magnet. I bought the entire stock from a company (almost 400 pcs.) when I discovered how smooth and extended these were. 2nd and 3rd order HD is very low. I'm also using them very successfully in some prototype open baffle arrays with some modification. They are very efficient, and I just discovered much to my delight, love to be horn loaded with an open back.
For woofers I was going with the Dayton 8" woofer PN 295-310 from PE since I have 8 NIB in stock. Getting these from the US is a real pain though because of killer shipping and border expenses.
Here are the FR horns presently on the 12" BR cabs in test configuration.
For woofers I was going with the Dayton 8" woofer PN 295-310 from PE since I have 8 NIB in stock. Getting these from the US is a real pain though because of killer shipping and border expenses.
Here are the FR horns presently on the 12" BR cabs in test configuration.
I'm curious about a couple of points. What 6" driver will give you an f3 of 26 Hz, and how do you plan to get horn style sensitivity with an isobaric configuration? Isobaric pairing halves the required cabinet size but does not increase sensitivity,and I'm not aware of any 6s with the requisite Fs and Qts to achieve a 26 Hz F3.
I've used those woofers, # 55-1170; the specs are inaccurate. F3 of45 Hz is about all you'll get. Don't expect miracles for ten bucks.
You'll also want to consider the Xmax; even if the box could get to the suggested F3 the small Xmax is going to result in blown suspensions with any appreciable power input below 60 Hz or so in an isobaric alignment. Isobaric pairings lower the required box size but the acoustic output capability remains the product of the cone area x Xmax of only the driver(s) that is actually exposed to the air.
You'll also want to consider the Xmax; even if the box could get to the suggested F3 the small Xmax is going to result in blown suspensions with any appreciable power input below 60 Hz or so in an isobaric alignment. Isobaric pairings lower the required box size but the acoustic output capability remains the product of the cone area x Xmax of only the driver(s) that is actually exposed to the air.
well I also have used them I haven't measured them or any thing but the bass from just one in a .5 cubic ' box sounded decent thats less than half the optimal size so 8 of them in a box of correct size should give me decent output I think. I'm not looking to shake the foudation or anything. I'm gonna try it if they suck I let you rub it in and say I told you so. To tell you the truth I was pleasently suprised at the quality of these woofer for $10 they may not be as good as there specs indicate but I think they are a lot better than there price indicates.
I don't know the xMax off hand but do know that in a vented box you'll exceed it if you give them more than about ten watts below 60Hz. They really need to be mounted in sealed boxes of no more than .7 cu ft so that they don't blow the surround and spider. Model one in that configuration and you'll see why they aren't real woofer material. Isobaric mounting, which doubles the stress on the suspensions with every doubling of drivers, is guaranteed to be the doom of the outboard unit. A sealed box with all 8 drivers as direct radiators wouldn't help F3 at all and would require a good 4 cu ft to work properly but at least it would work.
If I've got 8 of them how often are each of them gonna get more than 10 watts anyway? like I said I'm not looking to shake the foundations I really am looking for a high efficiency design do go with a low power tube amp. probably an SET. If the eight of them would give me the sensitivity I'm looking for I'll probably be happy with 45hz. My goal is to design as close to a full range system as possible that could be powered by such an amp.
brsanko said:
I'm still in the experimental stages on these horns so there isn't much to say yet. I don't wish to sell any of my 6" driver inventory as I hope to use it in a product. If this changes I'll be happy to sell them all and will place notice here.
Thank you for the complement on the horns.
I'm making a mold to cast a ~20" diameter round horn for a 4" diameter cone driver that could use plaster or cement, impregnated with metal mesh. These unfinished horns could be offered as a component for the DIY community down the road but don't expect anything soon.
Using the listed specs (at least for now), your net Vb implies that you're planning on series/paralleling four sets of isobaric pairs, ergo the sensitivity will increase ~9dB. The 92dB eff. rating must be a midbass peak due to a high Le since the calc'd eff. is somewhere around 84.3dB, so once the Le is halved due to lowering the system to a nominal 4ohms, I imagine the sensitivity around 300Hz will only be ~93.3dB/2.83V/m or a little higher, not enough to blend well with the horn so best to rethink the bottom end IMO.
WRT your horn, your description is a bit too sketchy to really comment on it beyond the round Vs square issue. Square works well as long as you make the sides the same width as its equivalent diameter rather than the more common equivalent CSA, make a nice mouth flare to reduce reflections back to the throat like on a round horn, and use wood putty/Bondo/whatever to round the throat somewhat. IOW, using 1500Hz as an example, make a mounting baffle with a ~13560/pi/1500 = ~2.875" dia. hole in it for the throat and use it as a guide to taper from round to square over ~an octave. A butter knife works for me. Just make sure the surface is clean/coarse enough to ensure a good bond, don't want it cracking or falling out. Mildly rounding the seams all the way to the mouth doesn't hurt either. Last, but not least, make sure the horn's interior is well sealed/smooth for best performance. Folks tend to forget that air is vibrating at ~13560"/sec against it.
A bit of work, but still less of a hassle than a round horn and in this BW I've found the difference to be inaudible. Where square/rectangular get a bad rep is folks tend not to bother with the details that makes round ones the ideal.
GM
WRT your horn, your description is a bit too sketchy to really comment on it beyond the round Vs square issue. Square works well as long as you make the sides the same width as its equivalent diameter rather than the more common equivalent CSA, make a nice mouth flare to reduce reflections back to the throat like on a round horn, and use wood putty/Bondo/whatever to round the throat somewhat. IOW, using 1500Hz as an example, make a mounting baffle with a ~13560/pi/1500 = ~2.875" dia. hole in it for the throat and use it as a guide to taper from round to square over ~an octave. A butter knife works for me. Just make sure the surface is clean/coarse enough to ensure a good bond, don't want it cracking or falling out. Mildly rounding the seams all the way to the mouth doesn't hurt either. Last, but not least, make sure the horn's interior is well sealed/smooth for best performance. Folks tend to forget that air is vibrating at ~13560"/sec against it.
A bit of work, but still less of a hassle than a round horn and in this BW I've found the difference to be inaudible. Where square/rectangular get a bad rep is folks tend not to bother with the details that makes round ones the ideal.
GM
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