Well IB is definately different from OB, so I'm not too sure if the Pyles would be good for IB or not. Since you're only getting sound from one side of the driver with IB, you might need considerably more Xmax. I don't know for sure though, and I don't even know if that has anything to do with anything.
Chops noted what I think is the only big problem with the Alpha 15As; the higher Fs. Even modeling it with wide 36" baffles they drop at least 16 to 20 dB from 40 Hz down to 20 Hz (depending on distance to the back wall). I have them in baffles that are 19.5 x 35" wide but haven't tried measuring them outdoors. The in-room response measurements are complicated by by room nodes but seems to mirror the modeled response.
[Incidently MJ King in his Project 7 measured the Fs for the Alpha 15A to be a little bit lower than the Eminence published spec at 38.9 Hz and the Qts came out to 1.19.]
The Pyle Pro PPA15 looks to be a very good OB driver. It's cheaper than the Alpha but its about 5 dB less sensitive at 40 Hz. Even though it has double the advertised Xmax of an Alpha 15A at 6 mm, they will both exceed their Xmax at low bass frequencies at levels around 100 dB. However, due to its lower Fs, the PPA15 response doesn't rapidly drop off until lower than 30 Hz.
Unfortunately I haven't been able to find a site that provides all the TS parameters needed to model the PPA15. But with short look at it, it may be a better choice than the Alpha 15A.
Based on the various emerald physics prototypes, it does seem possible to go flat to 20Hz with alphas. Then again, there's more than one and these are active/eq'd.
http://www.emeraldphysics.com/
http://www.emeraldphysics.com/
Flat to 20hz with Alpha15A ? with room gain and all you might do it at low level, BUT at higher level you will have to consider the relative short Xmax - but as you say, with multiple woofers its a different matter, on the other hand I dont think its recommendable to force a high Q driver that low
Well, xbaffle sims don't remotely back up any claims being made here. John K's excellent article about dipole behavior below the room fundamental doesn't supports any of these claims.
I wonder why it is, that there are never any measurements to back up the internet claims made about these cheap pro woofers, etc.?
Perhaps all that is needed for (dipole) output to 20hz and below is a computer keyboard and an internet connection?
cheers,
AJ
I wonder why it is, that there are never any measurements to back up the internet claims made about these cheap pro woofers, etc.?
Perhaps all that is needed for (dipole) output to 20hz and below is a computer keyboard and an internet connection?
cheers,
AJ
for what it's worth, another review of an alpha based system
http://www.sonicflare.com/archives/vegas07-vision-of-the-future-emerald-audio.php
http://www.sonicflare.com/archives/vegas07-vision-of-the-future-emerald-audio.php
I agree with Tinitus. The other issue with pushing an Alpha 15A that low would be the high levels of distortion at frequencies below Fs at even moderate sound levels.
I looked at the Emerld Physics website but couldn't find mention of what drivers they were using. Do they note this anywhere?
I looked at the Emerld Physics website but couldn't find mention of what drivers they were using. Do they note this anywhere?
AJinFLA said:
Gee, why do I have the distinct feeling that you're referring to me? Maybe because you pulled the same type of thing with me before in my own thread and other related threads? I would think you would get bored of doing this everytime, especially over what, 3+ years now?!
You fail to remember... I didn't build my dipoles to be small and compact like everyone else does. Nor did I use drivers with the wrong T/S parameters for dipole use just so I could have a large Xmax. No, not at all. Mine stood 4' tall, were 2' square and used drivers who's T/S parameters were darn near perfect for dipole use. With the amount of baffle I had along with the low Fs of the "cheap pro woofers" as you so put it, is precisely why they were able to go so low without any EQ help.
But you know what, I'm not going to sit here and get ticked off and argue with you. Some people are just too stinkin' pig-headed and closed-minded to accept anything other than measurements and what they "think" is right.
For some people to pretend that they are smart, all they need is a "computer keyboard and an internet connection", right? LOL
You know, instead of trying to pick fights all the time, why don't you just try building the exact same dipoles I had? It wouldn't cost anymore than about $150 for the drivers and wood and would finally prove to you what they are actually capable of. That would be a small price to pay to finally shut you up for a while.
At any rate, have a nice day.
chops said:
Paranoia? Self doubt? I would consult with your psychiatrist. I concede to their expertise in these areas.
chops said:
chops said:
Perhaps, like many tales, they have "grown" taller with age?
chops said:
If you claim so.
chops said:
That's not a good indication that 16hz was measured. Or anything else.
It would be much cheaper and less time consuming for me, if you were to get help, get the measurement software you own working and post some measurements on your image hosting site. No?
Then we could all see that 16hz response from the no eq 26hz Fs dipole drivers eh. As you claim.
cheers,
AJ
AJinFLA said:
No, no paranoia or self doubt. I just know how you are. And so what, I forgot exactly how tall they were. Wow. But I was right, they WERE 24" square. LOL
And as for the TrueRTA software, that was on my old laptop, and for whatever reason, it didn't want to work right. Maybe it was some kind of conflict with the onboard soundcard. Who knows, who cares. The thing is, it DID work on my server PC just fine once I got the cabling, mic preamp and everything run into the other room, and whether you believe it or not, that 16Hz was the measured results. I never posted it because the thread had pretty much died at that point and I was sick of dealing with you on it every single time. Also one of the reasons I left this site for nearly a year.
"It would be much cheaper and less time consuming for me".. Yeah, like I care about what's easier for you. LOL
I have no reason what so ever to lie, knowing darn well anyone on this board could easily go out, buy these same drivers, build the same baffles and come up with very similar results as room modes would have very little impact on the final results. Anyone is more than welcome to prove me wrong, and not be out a lot of money in the process. I even spoke to Seigfried Linkwitz on a number of occations about these dipoles and even he was quite positive about them.
Much like most other "normal" people, I don't get tied up in software and mathematical predictions. If you want to find out if something is going to work, you just have to build the darn thing and see what happens, which is exactly what I did. You on the other hand just get all moody because my "claims" don't jive with your calculations. Tough, too bad.
If you don't like it, then prove me wrong and build those dipoles. Unless you're affraid to because you'll find out the same results I got and realize that you've been wrong all these years. But knowing you, you'd probably alter the results to try and prove me wrong anyway.
Looks like you've got some work to do, so get crackin'! LOL
Chops, I may be all wet but my thinking was that in IB there would be no cancellation. My theory is that with cancellation more cone movement would be needed for the same output so in theory it would seem that IB would need less excursion for the same output. It is possible of course that the reflected backwave reinforcement may be a factor.
mike
mike
mashaffer said:
Hey Mike,
I too am kinda "wet" when it comes to IB's. What I was thinking though is that because there is nearly no air resistance with IB (meaning a spring of air like a small sealed enclosure would have), the controlled motion of the cone is entirely up to the motor and suspension. So when the driver approaches and/or exceeds its Fs, it could start to "flop" out of control similar to a driver going below the tuning point of a ported enclosure.
Of course, I am only guessing at all of this as I haven't really done any research on IB's, so don't go by everything I say until someone with some real knowledge can shed some light on the subject.
Then again, the same is true for OB's as well, but I never had that problem with my dipole subs because the Audio Control Richter Scale xover I was using had a subsonic filter built into it @ 20Hz, which would explain why I never had that problem.
One thing I'm wondering is the following:
Since high Qts is at least helpful for getting bass out of OB designs without EQ, in comparing drivers lines, the one with a larger magnet (more expensive) basically always has a lower qts, so is that bass you get from the high qts designs really accurate bass?
I'm thinking of
goldwood 15", qts .63, $45
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-345
vs
goldwood 15", qts 1.95, $29
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-384
for instance, but this seems to hold for any manufacturer.
Since high Qts is at least helpful for getting bass out of OB designs without EQ, in comparing drivers lines, the one with a larger magnet (more expensive) basically always has a lower qts, so is that bass you get from the high qts designs really accurate bass?
I'm thinking of
goldwood 15", qts .63, $45
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-345
vs
goldwood 15", qts 1.95, $29
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-384
for instance, but this seems to hold for any manufacturer.
OTMOPO3OK said:
Fishy? Better not tell Meyer Sound, who used Ciare drivers in their early models, when they were making their name.
http://www.meyersound.com/
Ang said:
This would be true if you were installing the drivers in an enclosure. It's also somewhat true I suppose for OB, but nowhere near as bad. With an OB, there's no resistance on the driver. The only thing the motor has to do is take care of the cone movement. It doesn't have to fight with the air pressure inside a cabinet.
Think of it like flapping your arms in the air vs flapping them under water. The water creates a lot more resistance and you can't move your arms as fast as you can in air.
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