Hi doug it is an aussie product it was called soundsorber barrier when I purchased it a few years ago, but now it is called something else I think... I also have a small amount of polyester fill in the cabinet as well. Link to the page here Soundsorber Barrier technical data
It was a bit of a gamble as I couldn't find anyone who had used the product for speakers, and the manufacturers didn't know of anyone using it for that purpose either (and it isn't exactly cheap) but it worked very nicely 🙂
Below are a couple of pics of the stuff.
Back on topic, I did nearfield measurements with eggcrate foam, carpet underlay, packing foam, acoustic tiles and bare, all had differing effectiveness (interestingly the acoustic tiles were the worst!!) The soundsorber was by far the best. The only thing that came close was two layers of eggcrate foam combined with excessivly dense fill, which measured well (in that the reflections were gone) but sounded horrible.
Tony.
It was a bit of a gamble as I couldn't find anyone who had used the product for speakers, and the manufacturers didn't know of anyone using it for that purpose either (and it isn't exactly cheap) but it worked very nicely 🙂
Below are a couple of pics of the stuff.
Back on topic, I did nearfield measurements with eggcrate foam, carpet underlay, packing foam, acoustic tiles and bare, all had differing effectiveness (interestingly the acoustic tiles were the worst!!) The soundsorber was by far the best. The only thing that came close was two layers of eggcrate foam combined with excessivly dense fill, which measured well (in that the reflections were gone) but sounded horrible.
Tony.
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Thanks, I will try to source some locally. I wonder if Parts Express, Madisound or even Elemental designs Carry similar products.
I do have the PE foam that they sell with their speaker designs and I also use carpet pad but Im always willing to try something new and your measurement is insanely flat from the that soundsorber.
I do have the PE foam that they sell with their speaker designs and I also use carpet pad but Im always willing to try something new and your measurement is insanely flat from the that soundsorber.
In my opinion quite good results can be achieved with dipoles:
An externally hosted image should be here but it was not working when we last tested it.
These are measurements of my own dipoles. With a few small changes it could even be improved. Pretty much Constant Directivity from the low bass up to about 7 khz. There are others on this forum who have had similar results with their designs.
I agree Constant Directivity is very important to get good sound quality. Non-CD speakers all have issues. However, there are several concepts that could meet that requirement and there is not one concept that rules out all the others. CD-horns, dipoles or monopoles (omni) are equally valid, if done right. Although many aspects of sound quality are independent of the 'taste' of the listener, I believe there is still a great deal of preference involved with when it comes to which type of CD speaker you should choose.
EDIT: While reading the last few pages of this thread it seems my point has already been addressed.
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Let me know if you find a source. I did not see anything in the US in a quick search.
Im thinking something like Elemental Designs
brushed on all walls then just using PEs foam on top of it might do some great things??
Parts-Express.com:Sonic Barrier 1-1/4" 3-Layer Damping Material w/PSA 18 x 24" | acoustic damping foam black hole sonic barrier acoustic foam damping foam damping sonic impact sonic110408 cabinet_damping
Im going to create a thread for this discussion because its OT now.
My technique work with any number of off axis curves and spacing, but clearly the more data there is the more accurate the representation. One curve on axis and one at 45 degrees is not going to be very useful. But I appreciate the offer and will look forward to getting some data.
In your response to Catapult you focussed only on the comparison of the curve of the uncorrelated power average and the 15 degree curve. Have you not noticed the similarity in all the curves? All curves are pretty much parallel to each other. I would call this Constant Directivity, as you'll get practically the same spectral balance at all angles. My dipole design has dipole radiation from the bass up to about 7 khz. If you read 'constant' as 'unchanging in value', my dipole is actually more CD than the Summa, as the off-axis response of the Summa drops more at higher frequencies.
The problem with the brush on materials is vapor out gassing. Many have volatiles that could attack the driver's glues and suspension (i.e., foams, etc.).
The PE foam looks interesting, but very, very expensive.
I will be running some experiments with a test box and an accelerometer using a number of different materials, including a constrained layer with green glue, which I think will be the best choice in the end.
We see the data differently and if plotted in comparable ways you would see that as well.
I certainly do not agree with your position, but that's not new I guess. I've tried all the technologies and one stands out head and shoulders above the rest. There are better and worse examples of the rest, but none of them is as effective as a waveguide (for the HFs, but thats all you showed data for anyways). By this I mean that, at best, a dipole could compare with a waveguide for directivlty and frequency response, but then what about dynamics and power compression? The technology simply cannot be efficient and this will always be an Achiles heel.
We certainly do not see the data in the same way. Maybe that's because they are not done the same way, but I see things the exact opposite of what you see.
Fiberglass insulation. I think it was just like an R15 and it was fairly tight but with plenty of space for the woofer.
Dan
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The measurements are gated, so yes, they don't show any bass. The curves shown are accurate from about 500 hz. I don't understand why you keep stressing to all use your polar graph. The way I see it, it shows the exact same information as the frequency amplitude graph. Therefore I honestly don't see why the data can not be compared.
The weather is getting better here, so when I've got a bit of time and the sun is shining I'll take the system in the garden where I'm able to measure down to about 100 hz. I'll make sure to set all angles accurately and I'll save all measuring data. Then I'll also represent the data in a polar graph and I'll post it.
I don't agree with your criticisms with respect to the off-axis behavior of a well executed dipole, but you are of course right when you say it has ridiculously low efficiency. This means you need more drivers and power, which cost money. Nevertheless my speaker goes loud enough for my tastes.
Alright, it does indeed not drop so much at higher frequencies. The curves for the ESP15 are quite smooth and flat from 1.5k and up. The step around the crossover is visually more obtrusive, but you claim that not to be audible - of which I have no possibility to verify.
Because you keep posting data what I believe proves my point but then you see the opposite. Obviously there is some problem somewhere. I believe that if the two data sets were done in identical ways that the real answer would be obvious. You seem to be afraid of that.
There is more to "dynamics" than simple SPL level.
Those plots are five years old now (Ai has been out of business for several years now), better graphics and newer data are on my web site.
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Do you mean the narrowing of the directivity below the crossover? (The woofer) Otherwise I don't know what you mean.
Yes, a LF dipole would allow for a shallower transition of the directivity from 100 Hz - 800 Hz, but not without a price in terms of performance and dollars. I haven't found this tradeoff to be worthwhile and I have looked at it in some detail.
Unfortunately as you know CSDs have never been demonstrated to have any real impact on SQ. Improving on the throat of the PE WG/Selenium is exactly what I was talking about. I can see where the way I wrote it my point was less than obvious.
By your standards, the Celestion 1425 is the best of the bunch judging by Brandon's measurements. There's nothing there on the 10" PE WG, the similar Celestion WG (but it's pictured), or the Selenium's ability to load a WG(something that matters). You have nothing but a CSD and 2 tone IMD measurements that have little if anything (nothing I know of demonstrated), especially in the frequency range we're talking about, to do with audible SQ. I'm saying show me some measurements that demonstrate the audible superiority of the devices in question. They very well may be better--I don't completely doubt it--but until there's some evidence, it's just a fruitless discussion about nothing. I know I've said this before. IOW, we can go around and around about this, but until you do, there's nothing to go around and around about. There's no reason to discuss what we cannot show. You want to show that they are better, show me a smoother polar response than what I've got. Dr. Geddes has shown that 30%THD was inaudible in CDs! So by your standards you should go back to that cheap Celestion. What I'm concerned about is how the CD loads the WG and the pattern the WG puts out. That's what's been shown to matter.
I have a pair of speakers with a good CSD plot and they do not sound better than my good dispersion speakers. Not even close.
This is courtesy of http://www.zaphaudio.com/smalltest/compare.html:
Those same speakers do very well in the HD graph as well, but those graphs don't tell use much at all. I've made that mistake already.
Oh, and I can state AGAIN that I don't like the screw on CDs. It doesn't help your cause--only evidence of the results does. We don't need Dr. Geddes to tell us what's obvious and what we agree on. No need to waste his time as well.
I find this useless back and forth just that--useless. Hopefully someone is getting something from it. I gotta say, it seems you like to argue without an argument. I don't, but I won't let you do it either. I know you don't like when others do it as evidenced by your posts in the cable thread. Give me a good argument and I'll believe you whole heartedly. Until then, I'd rather not waste time. I'm only planning on living once.😉
Dan
Please excuse me, but then what is your point exactly? Do you dispute the dipole has CD behavior?
Agreed. It doesn't sound compressed at higher volume levels, but then again, that could hardly pass for evidence.
Yes, it's this 'step' in the frequency response I mean.
If measurements and listening tests is not good enough evidence for the you then there is nothing else that will remotely convince you, that is your choice. You need to spend $$$ to figure this out.
Im not here to convince you of anything, you are going to defend the D220 because its in your build. You are going to ignore measurements using the lame "its not audible" because its your build. I choose to not only want a great sound speaker but I want measurements that show it to be superior design. Note: I am not using the Celestions because they are also below my standards. Im currently using the BMS4550 and I have Radian 475 ordered. I also use TD12Ms instead of the other common choices.
I find CSDs usefull, I find Proper distortion measurements useful and you can hear distortion!! Many expert Speaker builders find them useful too. Geddes is one speaker builder, I tend to look at all experts to get a overall rounded opinion. Geddes is wrong about somethings sometimes, Like everyone else he isnt perfect you know 😉
I find if funny you are using Geddes theories but you do not even realize that he does not consider that PE 10" waveuide to be a proper waveguide and he would never use a screw on CD. If you are going to post that you are following in everything Geddes does then you might want to realize you have choosen the wrong horn/CD
If you actually do care about waveguides then you should actually buy one instead of buying what everyone considers a horn 😉
This is only a back and forth because you choose to banter, you choose to comment on the QSCs without any knowledge. You choose to ignore the facts about your current horn/CD.
You choose to argue even when data is posted. Im find with any debate but you keep choosing to keep going with statements that are inaccurate.
Im not here to convince you of anything, you are going to defend the D220 because its in your build. You are going to ignore measurements using the lame "its not audible" because its your build. I choose to not only want a great sound speaker but I want measurements that show it to be superior design. Note: I am not using the Celestions because they are also below my standards. Im currently using the BMS4550 and I have Radian 475 ordered. I also use TD12Ms instead of the other common choices.
I find CSDs usefull, I find Proper distortion measurements useful and you can hear distortion!! Many expert Speaker builders find them useful too. Geddes is one speaker builder, I tend to look at all experts to get a overall rounded opinion. Geddes is wrong about somethings sometimes, Like everyone else he isnt perfect you know 😉
I find if funny you are using Geddes theories but you do not even realize that he does not consider that PE 10" waveuide to be a proper waveguide and he would never use a screw on CD. If you are going to post that you are following in everything Geddes does then you might want to realize you have choosen the wrong horn/CD
If you actually do care about waveguides then you should actually buy one instead of buying what everyone considers a horn 😉
This is only a back and forth because you choose to banter, you choose to comment on the QSCs without any knowledge. You choose to ignore the facts about your current horn/CD.
You choose to argue even when data is posted. Im find with any debate but you keep choosing to keep going with statements that are inaccurate.
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I'm sure I haven't done as extensive of experimentation, but I have come to the same conclusion after what I consider to be a lot of work. That said, I still prefer the sound of OB bass/midbass. I don't have a good reason why other than maybe the way OB excites room modes. For deep bass (below 70Hz or so) OB is too much of a pain, or rather too expensive for me. I'm cheap. That said, I think the thing that has killed my OB experiments is actually the midrange. All the ipsilateral reflection and possibly baffle diffraction seem to have a negative effect on image though it does give an interesting sense of space that I'm ambivalent about my preference for. IOW, my OB/UB experiments just don't image as well as my Box/WG combo and has stopped my desire for more OB experimentation dead in its tracks. I have never had an OB that I could toe in sharply and have a good tonal balance. The exception being a very small baffle experiment that required EQ, was very inefficient, and ran out of gas too easily. That's been a problem with all my OB experiments except the Hawthorne Audio PSI. It was efficient and could be run off anything in a U baffle. The U baffle has some audible resonance that seemed to muddy up the MR(but that could have been a dip in the off axis MR response as well). It's hard to have a win/win situation with OB and the cost doesn't seem worth it to me. Maybe if I had a larger room to reduce the amplitude of the front wall reflections or perhaps foam behind the speaker to absorb the MR but leave the bass intact plus an absorptive front wall and the desire to have a cost no object with massive amounts of experimentation, I'd think OB does have some serious potential to beat out a box. Of course that's hypothetical as I can't prove it. The foam behind the woofer may end up making it a pseudo cardioid response that requires more workarounds. I'll leave HiFi OB to John K, Stig, and SL to figure out as I've lost enough hair in the effort. There is certainly some merit in it. Call me lazy and cheap b/c I am. Even doing a Box/WG combo was a lot of work for me and it still doesn't measure up to some similar designs.
OK, enough of my labyrinthian diatribe. You get my point,
Dan
Since CD means whatever anybody wants it to mean, yours question is simply a matter or opinion. But I will say that the data that I have seen does not hold the polar pattern as well, and as narrow, as I expect in that frequency region where it matters most. Is it CD? I've seen people call beaming horns "CD" - a monopole is CD. It's a tag that seems to have lost all meaning. Maybe I should say CNC (controlled narrow coverage).
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