I bet that sounds great Chops.
Yes! Or some foam! or maybe even Bud's Enable process!
Chops, I can't agree with Pano more. Killing the edge reflection on the Altec horn is the best improvement I've made so far. I'm still experimenting but this is where I'm at right now. It's just regular egg crate foam....
Yes! Or some foam! or maybe even Bud's Enable process!
Chops, I can't agree with Pano more. Killing the edge reflection on the Altec horn is the best improvement I've made so far. I'm still experimenting but this is where I'm at right now. It's just regular egg crate foam....
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badman said:
Yes, I realise all of that, as I said in the last paragraph in my last post. I already have the full 1/24 octave version of TrueRTA, but it does not run on a 64-bit operating system. Until they make a version that does, or until I buy the Behringer, I can only tune by ear. The only other option I have is using the sweep tone generator on an old Azden 10-band EQ I have and my RS SPL meter.
Also, like I said in the first paragraph, if I had known that I was going to build OBs with the Usher drivers, I would have gone with the 15PA's instead. However, as these drivers are breaking in more and more each day, they are getting better and better sounding as well as their bass extending a little more.
mpmarino said:
Do you think you're getting most of that "edge reflection" from the top of your folded horn (La Scala ??) below the horn and piece of wood above the horn?
The reason I ask is because I never had this issue while running the Klipsch Cornwall bas bin, even when I measured with TrueRTA.
chops said:
You might try synRTA. I find it quite handy, easy to use - and it's free! I run it on Windoze 2K just fine - don't know how it runs on other OS.
I do suggest you try the old towel trick. It's fast, easy and cheap to do. Or use foam, if you want. I was surprised at the difference it made, both to the ear and to the measurements. The horn edge and how it couples to the open air is important.
Don't think you have to worry about your Usher drivers much. Looks like they are doing a fine job.
Hi Chops & panomaniac,
I'm awed and inspired by your comments and knowledge and it (along with Lynn's thread) has spurred
me into wanting to do an OB using a compression driver and horn. The problem I keep coming up with is all of the specifications I look at for the drivers makes them look as if they beam HF (>8Khz) like a laser (even with the horn) which sort of defeats the point of going OB. 
What's the trick to getting wide dispersion for HF?
I'm awed and inspired by your comments and knowledge and it (along with Lynn's thread) has spurred
me into wanting to do an OB using a compression driver and horn. The problem I keep coming up with is all of the specifications I look at for the drivers makes them look as if they beam HF (>8Khz) like a laser (even with the horn) which sort of defeats the point of going OB. What's the trick to getting wide dispersion for HF?
I don't think so. I was running the horn without the top hat and tried poking it forward past the frame - didn't seem to make a difference. The altec horn/902 sounded good, but not as good as I had hoped. A bit shouty in 'my' opinion. I started out by draping laundry around the horn - some of it dirty
. What a difference! My wife didn't like the dirty socks draped all over the place, so I had to do something!
Oh yessss - the "Right Horn". Sort of reminds me of a movie title.
I'm thinking (low budget) about:
Selenium D210Ti 1" Titanium Horn Driver http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-235
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-312
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-312
with a pair of these Selenium 12PW3-SLF 12" Driver
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-334
Just not sure if these horns will get the job done.
I also have a pair of AMT1's I could slap in for HF tho -
Just noticed these for some bottom end - http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-386
I'm thinking (low budget) about:
Selenium D210Ti 1" Titanium Horn Driver http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-235
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-312
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-312
with a pair of these Selenium 12PW3-SLF 12" Driver
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-334
Just not sure if these horns will get the job done.
I also have a pair of AMT1's I could slap in for HF tho -
Just noticed these for some bottom end - http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-386
That's an awe inspiring system Chops. You should ping Dennis Bohn at Rane, I know he would love to see what you are up to.
All of you want to be very careful with EnABL and horns. They get very very fast and so very hard edged. Not ugly, as with more odd order distortion to provide edge, but with power. Big EnABL'd horns can hurt you, physically, so please approach anything like these stadium power beasts with respect.
Now, those 15's would be another story entirely. You could make them just as wicked fast as the stock horn. Probably remove any refractions where energy from the bass drivers is being forced out into the listening area from the joint with the horn. A pattern line on the outside of the horn mouth, top and bottom, should then make the drivers mate in speed seamlessly.
Your back wall depth will be potentially infinite, your comprehension of space, due to subtle bass cues, will be complete and with everything capable of the same dynamic rise time...well, plan on getting scared a few times.
And then to top them off, Mamboni the cone backsides to get the back wave to couple with the room even more effectively. C2C has this technique down cold by the way.
All done, you would have stupendous power released from an already awesome system, with delicate grace and complete transparency, right to the corners of the back of the venue, top to bottom.
Hope my enthusiasm isn't out of line here, but the potential already realized and just waiting to be unlocked is just so tantalizing.
Bud
All of you want to be very careful with EnABL and horns. They get very very fast and so very hard edged. Not ugly, as with more odd order distortion to provide edge, but with power. Big EnABL'd horns can hurt you, physically, so please approach anything like these stadium power beasts with respect.
Now, those 15's would be another story entirely. You could make them just as wicked fast as the stock horn. Probably remove any refractions where energy from the bass drivers is being forced out into the listening area from the joint with the horn. A pattern line on the outside of the horn mouth, top and bottom, should then make the drivers mate in speed seamlessly.
Your back wall depth will be potentially infinite, your comprehension of space, due to subtle bass cues, will be complete and with everything capable of the same dynamic rise time...well, plan on getting scared a few times.
And then to top them off, Mamboni the cone backsides to get the back wave to couple with the room even more effectively. C2C has this technique down cold by the way.
All done, you would have stupendous power released from an already awesome system, with delicate grace and complete transparency, right to the corners of the back of the venue, top to bottom.
Hope my enthusiasm isn't out of line here, but the potential already realized and just waiting to be unlocked is just so tantalizing.
Bud
c2cthomas said:
Not a bad little driver, especially for the price. The Altecs are in another league, of course. But the D210Ti does OK, as long as you keep out of its resonance range. I almost bought a set of those 12" waveguides myself.
Funny! Those Goldwood look like an 18" version of the famous OB darlings - the Alpha 15s. Dude! Where's my magnet?
Put two of those per side on a Chops size baffle and you'll really move some air! Parallel 2 of them for 4 ohms is nice, too. Easier for a passive crossover.
Hi Zen Mod,
I haven't actually used them yet, but I was a little disappointed when I got them. I expected a more-less conical flare from the picture, but they're anything but conical. Hard to say exactly what they are, but if you're looking for something close to a Geddes style waveguide, these aren't them. I'll have some screw-on drivers within a week to try them out, but my experience with WGs and horns is practically nil. Don't know what I'll be able to report.
I haven't actually used them yet, but I was a little disappointed when I got them. I expected a more-less conical flare from the picture, but they're anything but conical. Hard to say exactly what they are, but if you're looking for something close to a Geddes style waveguide, these aren't them. I'll have some screw-on drivers within a week to try them out, but my experience with WGs and horns is practically nil. Don't know what I'll be able to report.
m0tion said:
I won't get technical as when I do I mess it up, so here goes:
Q is a measure of the lack of damping. The higher the number, the less damping. (often caused by a weak motor) Damping is the motors ability to return the cone to rest after an impulse. Low damping allows the cone to flop around a bit after the impulse. This translates to a warmer and richer sound and is especially useful when there is little baffle to interrupt the flow of air from the front to back of the cone and vice versa. This back and forth causes cancellation of the waves which is why we use baffles in the first place. To overcome or reduce the need for baffling, we use floppy woofers.
Hope that helps.
AndrewT said:
Here are some sensible parameters for OB woofers
Diameter 15" or above
Qts: 0.6 - 1.3 Most woofers below this (without EQ) will sound thin, anything above might sound underdamped.
Fs: 25-35Hz Much below might be too low, anything above will roll off a bit quickly
Efficiency is good, preferably 96dB or above (Think large PA woofers)
Xmax is a tricky one. Huge Xmax values are usually associated with low efficiency HT / car woofers and despite being able to move more air, may sound less musical than low xmax PA woofers.
A lot of people find they barely even see the woofers moving anyway, so a huge xmax is not always needed.
A bigger baffle will require less EQ. The bigger you go the less bass cancellation you get and thus higher efficiency the lower you go. U-Frame baffles are a good way to "cheat" slightly, since one unit of deepness equals two units of width on a normal flat baffle, but drawbacks include resonances (which can be damped) and a not a perfect dipole radiation pattern.
Have asked but will ask here also...
I posted on Magnetar's thread but got no response.
What about a "W" style or "Ripole woofer section? This would allow a suitable driver with higher Qt to yield lower bass response without EQ, providing it has suitable xmax. I know that the BW is not great with this style of loading however the size cannot be beat. If you were to use two inexpensive 15 -18 inch drivers for the bass per chanel then a 12 or 10 inch unit for mid bass (since the Ripole does not go too high) you could then finish off with a 4 - 8 inch coax unit for the top.
The Ripole style loaded bass drivers get a lot of extra control over cone motion and could be run lower without EQ than the same drivers on an OB could you might even get away without a sub. A possible issue would be that of efficiency with the Ripole loaded bass drivers but that might be well worth the size offset that the design privides. Any thoughts? Am enjoying all the OB threads here.
I posted on Magnetar's thread but got no response.
What about a "W" style or "Ripole woofer section? This would allow a suitable driver with higher Qt to yield lower bass response without EQ, providing it has suitable xmax. I know that the BW is not great with this style of loading however the size cannot be beat. If you were to use two inexpensive 15 -18 inch drivers for the bass per chanel then a 12 or 10 inch unit for mid bass (since the Ripole does not go too high) you could then finish off with a 4 - 8 inch coax unit for the top.
The Ripole style loaded bass drivers get a lot of extra control over cone motion and could be run lower without EQ than the same drivers on an OB could you might even get away without a sub. A possible issue would be that of efficiency with the Ripole loaded bass drivers but that might be well worth the size offset that the design privides. Any thoughts? Am enjoying all the OB threads here.
Hi Moray! Good to see ya poking around here!
zobsky has an interesting thread about his efforts with a ripole design http://www.diyaudio.com/forums/showthread.php?postid=1316979#post1316979 looks like it would take more power than I have to spare.
Chops design has some aspects that interest me - primarily his placement of his OB's near the walls.
I'm thinking that I might go with my ESS AMT1's above 3.5 kHz and use the Pioneer 10 inch http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-088 from my Walsh 5 Remakes (using two per side) and add the Goldwood http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-386 driven from a second amp in a MTMW configuration. Large baffle as per chops design with the woofer down low for floor coupling.
zobsky has an interesting thread about his efforts with a ripole design http://www.diyaudio.com/forums/showthread.php?postid=1316979#post1316979 looks like it would take more power than I have to spare.
Chops design has some aspects that interest me - primarily his placement of his OB's near the walls.
I'm thinking that I might go with my ESS AMT1's above 3.5 kHz and use the Pioneer 10 inch http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-088 from my Walsh 5 Remakes (using two per side) and add the Goldwood http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-386 driven from a second amp in a MTMW configuration. Large baffle as per chops design with the woofer down low for floor coupling.
Yeah, generally, the higher the Q, lower the Fs and larger the baffle, the more bass you'll get without resorting to EQ.
Also, the more efficient the driver is, the less you have to worry about Xmax as it will take little power to get loud.
As it stands, I have watched several bass-heavy movies with my dipoles. I have seen a max input of roughly 10-12 watts on the peaks and sustained peaks of about 4-5 watts. The sound is very loud, ultra clear and the cones are just barely moving at all. Very hard to see with the naked eye. And that's even with all the +10dB of EQ boost I have from 40Hz on down to 20Hz!
Also, the more efficient the driver is, the less you have to worry about Xmax as it will take little power to get loud.
As it stands, I have watched several bass-heavy movies with my dipoles. I have seen a max input of roughly 10-12 watts on the peaks and sustained peaks of about 4-5 watts. The sound is very loud, ultra clear and the cones are just barely moving at all. Very hard to see with the naked eye. And that's even with all the +10dB of EQ boost I have from 40Hz on down to 20Hz!
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