Mentally, I tend to segregate my audio stuff into two bins:
- The first bin is the system that I rely on to listen to music and movies. I am using a set of your speakers. As I see it, the speaker is a bit like a Honda Accord. There's nothing exotic about a Honda Accord, it's simply a well-engineered car that's been refined to a knife's edge over the years. While there are other cars/speakers which are similar, I am not aware of any that are superior.
- The second bin is my DIY projects. Generally these tend to be zanier. A lot of tapped horns and Unity horns. Basically I invest my time in these projects because I'm more curious to see how they work, which is why I frequently don't finish them. The journey is more important than the goal.
Basically, if one's goal is to have fun with a DIY project, messing around with waveguides is fun. But if one's goal is to listen to something that's been refined to a knife's edge, a DIY project makes about as much sense as trying to build your own Honda Accord. The exception to this rule is a clone or a kit; and it's the reason that many of my projects are clones of existing designs.
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Thanks for the comfirmation. I have that waveguide with and without Foam and I couldn't really see big differences in measurements and I definitely couldn't hear much difference.
What is that Curve called? I never figured it out, it doesnt look OS to me. Is that what we call "exponential"?
If you couldn't see a few dB loss of sensitivity on axis from the foam then it probably wasn't doing anything. Too porous, troo small, something like that. I see a 2-3 dB loss at 10 kHz. from the foam.
Its the black 30 ppi choice from swisstropics.com
Poret Pricelist
Maybe I should source it from somewhere else then.
In my tests, it took as much foam as I could get into the device to be effective. Small amounts had small to negligable effects. I fill my waveguides as much as possible because anything less is just not as effective.
Seems like the throat would be where it's most critical, as I'd expect the incidence frequency (how often the HOM has to pass through the foam) to be highest- once you get into the conical section any HOM would seem to tend to be diffracted in a forward direction, and no longer encounter it multiple times. I won't know as I've built very similar devices to yours and am taking care not to infringe upon your patent. They're OS and use reticulated throat foam, but not the level of fill that you have patent coverage on.
I'm not Doug, but I do have some of Nick Mickenny's original Unities. And I got some foam from Earl. I'm using TAD 2001's and my foam plug goes all the way to the driver phase plug. I only fill about half the depth of the waveguide. So it's around 5cm in the driver and about 15 or so in the guide, for a total depth of about 20-21cm. To fill the guide out to the mouth, takes about 15cm more. I have tried the guided completely full, and couldn't hear a difference between that and the smaller fill. But there was a clear difference with no foam. YMMV, particularly if your hearing is better than mine.
Sheldon
I cut the poret foam to fit the QSC-152i waveguide from throat to mouth. I think I did a decent job. It fills the waveguide 99%, I didnt get coverage on the last 1/2" of the mouth sides that is all.
Ed, here are some pictures from Augerpro's foam experiments.
Waveguide Horn Study :: Picture004.jpg picture by augerpro - Photobucket
His NQ builds (HPR-152i clones) can be found here, He has foam inserts in them.
HTGuide Forum - Can you smell what Brando's cooking!?
Waveguide Horn Study :: Picture004.jpg picture by augerpro - Photobucket
His NQ builds (HPR-152i clones) can be found here, He has foam inserts in them.
HTGuide Forum - Can you smell what Brando's cooking!?
This is an old thread, but today I did some measurements with and without foam for an 18 sound waveguide. Surprisingly the foam does not create a huge attenuation, 2db that is fairly consistent and around 3db in the top octave. You could get away with trying this even with a passive xo, perhaps just changing the Lpad. The foam is a pest to cut.
The difference is all that Earl and Patrick have described. When I first tried it, there was a moment when my jaw dropped at the imaging. It works.
My experience has been that if you follow what Earl suggests, things like multi subs, waveguides, foam, oblate spheroid waveguides, you get results.
Based on my experience with it so far, I'd say using a waveguide without the foam is a pretty big disadvantage. The foam takes away the most obvious sonic differences between a nice sounding hifi dome tweeter and a compression driver in a horn/waveguide. Then you are left with all the advantages - efficiency, output, directivity control, dynamics and that effortless sound.
The difference is all that Earl and Patrick have described. When I first tried it, there was a moment when my jaw dropped at the imaging. It works.
My experience has been that if you follow what Earl suggests, things like multi subs, waveguides, foam, oblate spheroid waveguides, you get results.
Based on my experience with it so far, I'd say using a waveguide without the foam is a pretty big disadvantage. The foam takes away the most obvious sonic differences between a nice sounding hifi dome tweeter and a compression driver in a horn/waveguide. Then you are left with all the advantages - efficiency, output, directivity control, dynamics and that effortless sound.
HI Paul
Yea, there is very little broadband lose from the foam, but a lot of audible effect.
This goes to a fundamental principle of mine and that is to fix the biggest problems first. Thats why I don't worry about things electronic - they make such small differences when compared to loudspeakers and rooms - or "nonlinear distortion", its audible in only a very small set of circumstances. I find it bafling how audiophiles can spend endless energy on things that are marginially audible at best and usually arguable that they are audible at all. The real problems are blantantly obvious - early reflections, poor power responses, etc. etc., but these get ignored for the most part. Concentrate on the big effects and solve thaose and "you get results."
It's really too bad that there are none of my speaker designs in Aus. (too expensive to ship.) If you heard those you'd just go buy a pair and spend the rest of the time just listening. A chance to quite "chasing the Holy Grail."
Yea, there is very little broadband lose from the foam, but a lot of audible effect.
This goes to a fundamental principle of mine and that is to fix the biggest problems first. Thats why I don't worry about things electronic - they make such small differences when compared to loudspeakers and rooms - or "nonlinear distortion", its audible in only a very small set of circumstances. I find it bafling how audiophiles can spend endless energy on things that are marginially audible at best and usually arguable that they are audible at all. The real problems are blantantly obvious - early reflections, poor power responses, etc. etc., but these get ignored for the most part. Concentrate on the big effects and solve thaose and "you get results."
It's really too bad that there are none of my speaker designs in Aus. (too expensive to ship.) If you heard those you'd just go buy a pair and spend the rest of the time just listening. A chance to quite "chasing the Holy Grail."
I agree with what Paul has stated above. About two years back Patrick let me listen to his car system with his OS Mini-Unity horns and it was the best car audio system I'd ever heard. At one point he removed the foam plugs and the magic just went out the window. Big difference! Much more than I would have expected and it certainly converted me.
Patrick also had brought his pair of Summa speakers and they were truly wonderful.
Best Regards,
TerryO
Patrick also had brought his pair of Summa speakers and they were truly wonderful.
Best Regards,
TerryO
This is often met with comments like "yes but if you have a crap source, you can't fix it with room treatment and speakers." Some people like to major on the minor issues. The part I find hard to understand is how they can't see that's what they are doing.
And let you have all my fun?! I think not! I'm one of the ones who is far too invested in the pleasure of designing and creating something. Learning is also a passion, and there is nothing like "hands on" learning. And in that process, I also have more that I can share with others ... again another passion of mine. In fact, there isn't too much that goes into creating a speaker that I don't find incredibly interesting.
I agree though that it's a shame none of your speakers have made it downunder. I'm a little surprised that there aren't any at all. They are unfamiliar and that is a difficult obstacle. Perhaps they also appear too good to be true - Aussies are wary of that. There is also the common belief that you should always audition first and choose "whatever sounds best to you." Many won't even buy a single component without doing that first.
I have just ditched a reasonable Marantz amp I was using for a nice 10W bipolar SE I built and I have to say, the difference is uninspiring. I also notice it nowadays with little things, like component quality. The difference is just not there like it used to be for me.
Perhaps a little 2nd order HD will partially mask some other less desirable distortions but some 2nd over a clean signal will not be that noticeable. My point is, though, that when you think you're on a good thing, you may get sidetracked.
There is something mysterious about the summa concept and I cant quite put my finger on it. I will say that audiophiles like to build speakers and they like to build amps, but few seem to have any interest in acoustics. Pity.
Lidia, my wife, who has been arround this stuff for as long as she has known me, said it well. People can't do what they should - room acoustics and speaker design - so they do what they can - new amps, cables etc. They assume the hard stuff, rooms and speakers, to be fixed and focus on the stuff that they can readily change. This process elevates the lessor components to a level way out of proportion in the "big picture" of total sound because it focuses attention on ever smaller effects.
