I'm having some crazy thoughts about a large econowave type of 2-way with an 18" woofer and 15" SEOS horn, crossed over just below 1kHz. Although this uses the 18 at (high) frequencies where I would never think of using one, I want the woofer to be quite directional where it crosses over to the horn. The DI of the 18 seems a good match to the horn pattern, at least based on the directivity plots that I have seen for the SEOS-15.
I found a driver from P Audio, the P180/2242, that is not too expensive and might work for my application. Specs are available here:
http://www.paudiothailand.com/pdf/products/P180-22423.pdf
I'm not familiar with P Audio, so if anyone has experiences with them please post about it. Quality? Accuracy of TS specs?
What I like about the driver is the very low (for an 18) Le, and a combination of TS specs and sensitivity that, in a large box, would work well. We'll see if I can convince my wife about this... But especially since I want to use the driver to pretty high frequencies the low Le should help to keep distortion down when operating up there. Evidently there are a couple of demodulation rings that are responsible for the low inductance.
So, should I consider this driver or avoid it like the plague?
I found a driver from P Audio, the P180/2242, that is not too expensive and might work for my application. Specs are available here:
http://www.paudiothailand.com/pdf/products/P180-22423.pdf
I'm not familiar with P Audio, so if anyone has experiences with them please post about it. Quality? Accuracy of TS specs?
What I like about the driver is the very low (for an 18) Le, and a combination of TS specs and sensitivity that, in a large box, would work well. We'll see if I can convince my wife about this... But especially since I want to use the driver to pretty high frequencies the low Le should help to keep distortion down when operating up there. Evidently there are a couple of demodulation rings that are responsible for the low inductance.
So, should I consider this driver or avoid it like the plague?
Looks good but I have no experience with P-audio.
Duke LeJeune of Audiokinesis uses the Faital pro 18FH500 with a small 18 Sound waveguide in his high end line of m.i. boxes. Apparently sounds clean enough for live violin reproduction.
Duke LeJeune of Audiokinesis uses the Faital pro 18FH500 with a small 18 Sound waveguide in his high end line of m.i. boxes. Apparently sounds clean enough for live violin reproduction.
That's another driver I am looking at. Le is only 1.35mH, which is still pretty low for an 18 with a 4" voice coil, and it has an extended frequency response.
I have also looked into a couple of 18" drivers over at AE Speakers web site, but really there is only one model that would work and doesn't blow my budget. Their delivery time is usually a couple of months (which I can live with if the driver is right) so before I commit I am looking around for alternatives that I can get right away.
There are some P.Audio drivers that have been reviewed by the German loudspeaker magazines. TS-parameters and response curve published in the datasheet seem to be quite reasonable (not more off than those of many other manufacturers 🙂). But the impedance plot shown in the datasheet consistently is completely wrong and useless. I have no idea what P.Audio is doing there, but it's more likely a calculated response assuming an inductance loss angle of zero degree than a true measurement.
The review of the P180-2241 (unfortunately not the 2242) shows a slow decay of the upper resonance at 1.5 kHz in the waterfall diagram. The magazine attests a full 2-way capability when crossed at 700-800 Hz.
The review of the P180-2241 (unfortunately not the 2242) shows a slow decay of the upper resonance at 1.5 kHz in the waterfall diagram. The magazine attests a full 2-way capability when crossed at 700-800 Hz.
Thanks for pointing that out. I'm unabashedly a DSP user and am too stubbornly independent to build "proven" designs. 🙄 In this way I am forced to figure out everything on my own and as a result I learn something new from each project. I like that. Learning is one of the things I never want to stop doing, even if it comes as a result of failures.
My thinking here is that the directivity pattern of an 18 will match my horn's directivity at the crossover point (SEOS-15 at 1kHz). This assumption has been gleaned from looking at MFG data curves - I will have to measure the woofer's actual in-cabinet response to know for sure...
I very much appreciate this info - this gives me at least a little confidence in the brand. I wonder if the cones are similar between the P180/2241 and P180/2242. I was planning on crossing over with a pretty steep slope at 1kHz, but this is still allowing 1.5kHz through to some extent.
I think the various SEOS sizes were meant to be paired with woofers of the same size for best directivity, if anything I've seen suggestions for a size down (i.e. SEOS-18 with a 15" woofer, SEOS-15 with 12" woofer etc). Check out relevant threads on AVS.
Links to said relevant threads on AVS are appreciated...
Here is some support for my 18" 2-way concept. Horn is the SEOS-15 with the DNA-360 driver. Below is the off-axis directivity plot for the horn:
At 1kHz the pattern is starting to widen, but it still controlled to about +/-45-50 degrees. From what I can tell from the few manufacturer datasheets that show it, this is about the same directivity that (at least some) 18" drivers provide at this frequency. Thus a steep crossover will not result in a sharp transition in the directivity. Steep is needed because this is about as low for the horn+driver combo, and as high for the woofer (before you inevitably are listening to cone breakup), as one can go.
For instance, here is the response on axis (blue) and at 45 degrees (red) for a driver that could work (suggested above by ErnieM), the Faital Pro 18FH500:
45deg off axis is approximately -6dB below on-axis level at 1kHz.
What's not to like?
Found more measurements on the 18FH500 here:
just pulled a triger on a pair of FaitalPRO 18FH500 18"
There is a nearfield, waterfall, and distortion data posted at the link.
There is a resonance around 1.5kHz that I will need to avoid exciting. Hopefully it is a little higher, like in the MFG response plot (seems to be around 1.7kHz).
just pulled a triger on a pair of FaitalPRO 18FH500 18"
There is a nearfield, waterfall, and distortion data posted at the link.
There is a resonance around 1.5kHz that I will need to avoid exciting. Hopefully it is a little higher, like in the MFG response plot (seems to be around 1.7kHz).
I have a p-audio system in my living room: 15" coaxials + four additional 15" bass helpers. They are built very solidly and sound great. They do not match specs, though. I don't remember the exact numbers, but the spec sheets had an absurdly low qts, they measure as a more normal value (0.25 vs 0.4, something like that). These are old drivers, more than five years.
I used four of their poverty series (IMF) in an infinite baffle once. Cheap stamped frames, but did the job well.
More recently, I've been trialling their 4" full range drivers. I got four, and three were right on spec, one has a weak magnet. They sound good, build quality is good. The weak one has the sane FR plot as the others, but less efficient ( less than 2db variation
The 18 you nominated looks great for a sealed or aperiodic box. I want you to try it, because I've been speculating about it myself 🙂
I used four of their poverty series (IMF) in an infinite baffle once. Cheap stamped frames, but did the job well.
More recently, I've been trialling their 4" full range drivers. I got four, and three were right on spec, one has a weak magnet. They sound good, build quality is good. The weak one has the sane FR plot as the others, but less efficient ( less than 2db variation
The 18 you nominated looks great for a sealed or aperiodic box. I want you to try it, because I've been speculating about it myself 🙂
Links to said relevant threads on AVS are appreciated...
Here is some support for my 18" 2-way concept. Horn is the SEOS-15 with the DNA-360 driver. Below is the off-axis directivity plot for the horn:
At 1kHz the pattern is starting to widen, but it still controlled to about +/-45-50 degrees. From what I can tell from the few manufacturer datasheets that show it, this is about the same directivity that (at least some) 18" drivers provide at this frequency. Thus a steep crossover will not result in a sharp transition in the directivity. Steep is needed because this is about as low for the horn+driver combo, and as high for the woofer (before you inevitably are listening to cone breakup), as one can go.
For instance, here is the response on axis (blue) and at 45 degrees (red) for a driver that could work (suggested above by ErnieM), the Faital Pro 18FH500:
45deg off axis is approximately -6dB below on-axis level at 1kHz.
What's not to like?
Horizontal dispersion is only half the story. A good design would also place the vertical null (as given by the CtC spacing) at the angle where the vertical dispersion of the SEOS-15 falls off (-6dB) for uniformly collapsing directivity.
The closest center-to-center spacing you could achieve with the P180/2242 and the SEOS-15 is 33 cm. At 1,000 Hz xo frequency, the arc between the nulls would be 63 degrees. Increasing the CtC to 45 cm would reduce the arc to 45 degrees. 45-60 degrees would cover most WG but are you sure the SEOS-15 maintains its nominla vertical directivty as low as 1,000 Hz?
http://www.diyaudio.com/forums/group-buys/166312-waveguides-horns-60.html#post2603561
Hey guys...we need a little rallying here... - Page 59 - AVS Forum | Home Theater Discussions And Reviews
attitube: Beta- The ‘White Noise’ SEOS15 – constant directivity horn adventures
This is a vertical directivity plot for the SEOS-15 posted by Bill Waslo here a little more than halfway down the page:
The pattern is breaking down right at 1kHz. At 1kHz it's in that 45-to-60 degree range. I will have to live with that, but I think it will work out fine. With such a large woofer you get quite a break compared to point-source type spacing analyses.
Hi Charlie:
Where are you on the original question as to the P Audio 2242? I have an application in mind for a woofer that plays 400 to 500 Hz and the P Audio looks good for that if one can trust the data sheet. In the price range, its the lowest Le one can get by far, its got demod rings and its got (just) enough Xmax. Too bad there hasn't been more DIY use of the driver.
Ironically, the JBL 2242 has a highest recommended Xover of 1 Khz, an implicit endorsement of your approach.
The Faital Pro you are looking at seems nice, has a fairly low Le of 1 mH, but it doesn't have demod rings. How much of a difference does that make?
These are tough choices if you can't just go out a buy several woofers for evaluation.
Where are you on the original question as to the P Audio 2242? I have an application in mind for a woofer that plays 400 to 500 Hz and the P Audio looks good for that if one can trust the data sheet. In the price range, its the lowest Le one can get by far, its got demod rings and its got (just) enough Xmax. Too bad there hasn't been more DIY use of the driver.
Ironically, the JBL 2242 has a highest recommended Xover of 1 Khz, an implicit endorsement of your approach.
The Faital Pro you are looking at seems nice, has a fairly low Le of 1 mH, but it doesn't have demod rings. How much of a difference does that make?
These are tough choices if you can't just go out a buy several woofers for evaluation.
I also don't have the resources to just buy one of everything and then do a shoot out. As a result I have decided that the P Audio driver is a little too much of a question mark for me to pull the trigger on one despite the encouraging specs. Another mark against it is that, from the pics, it looks to have a dull lavender colored cone... 😱 At this point I am leaning towards the Faital Pro, although still considering a customized version of the AE IB18HT... I'm not sure the latter can be used up to 1kHz, however.
Regarding the Le, from what I understand you want to keep this low to minimize flux modulation distortion. But this also depends on how susceptible the magnet material is to modulation by the voice coil current, and it turns out that rare earth magnets like Nd alloys are much less susceptible by almost 20 times. Since the Faital Pro has a Neo magnet and has a relatively low Le even without demod rings, it's getting a nod in that department from me based on my current understanding of this kind of distortion mechanism.
Out of interest, where did you get the 4" fullrangers from ?
Interested myself in these.
cheers
blakkshepe
I met Earl Geddes at RMAF in 2005.
I really liked his speakers, but the prices were scary.
I attempted to 'clone' them using a paudio sn12mb and an 18Sound waveguide.
I never went anywhere with the project, and bought the Summas.
Geddes isn't a fan of paudios speakers, but I'm still using that woofer to this day, in a tapped horn.
I really liked his speakers, but the prices were scary.
I attempted to 'clone' them using a paudio sn12mb and an 18Sound waveguide.
I never went anywhere with the project, and bought the Summas.
Geddes isn't a fan of paudios speakers, but I'm still using that woofer to this day, in a tapped horn.
Hi Charlie:
Thanks for your post.
It inspired me to research flux modulation. I found an old thread on it and now understand the issues much better. We really want both NEO and demodulation rings, the latter for Le(x)...but that pushes the price up.
I never considered an IB 18 HT until you mentioned it. I simulated it in my box and was surprised how well it worked. I got a QTC of 1.7 which results in a peaked response that can easily be EQed flat. The TD18H+ works a little better in the application and with less EQ but costs $115 or so more. But both have the delivery risk so I'm still on the fence.
I keep plugging this series of drivers, but the Alpine Type R and Type S are hard to beat.
I have an Alpine Type S here that has a 15" cone, lower qts than the ubiquitous SI HT, and I paid a whopping $135 delivered to my door. Because these woofers are so common, it shipped from a store just ninety miles away and arrived in under two days.
Really nice build quality. The Type S is underhung and the Type R uses an aluminum demodulation ring.
I have an Alpine Type S here that has a 15" cone, lower qts than the ubiquitous SI HT, and I paid a whopping $135 delivered to my door. Because these woofers are so common, it shipped from a store just ninety miles away and arrived in under two days.
Really nice build quality. The Type S is underhung and the Type R uses an aluminum demodulation ring.
I found sections P and Q on this page to be useful for understanding Le(x) and Le(i):
Midrange distortion
There is also an IB18HT-PRO version of this driver. It has a lighter cone, which results in a lower Qts. Here are the TS parameters:
AE Speakers IB18HT
Fs 22.29
Re 5.60
Qms 4.73
Qes 0.52
Qts 0.47
Sd 1218.0
Vas 632.0
Xmax 18.00
Le 0.41
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