Patrick Bateman said:
It's not so easy to get some of the right foam around here - so I did some experiments with way to heavy absorbing stuff.
I have to adimt that it works - somehow - but at least with the not really optimal foam (roughly three times the 6dB / 10kHz I think Earl is doing) I lost a lot of the "thrill".
Would you mid to share your measurements with and without foam?
Did you correct / equalize for the dampening of higher freqeuencies and how much roughly have you been down by the foam at 10kHz?
Michael
doug20 said:
The sound of HOMs is the sound of horns.
Here's an example. When I listen to my Summas, they basically sound like a two-way dynamic speaker. They don't sound like horns. You wouldn't even know they used a compression driver if you walked into the room and listened.
I also treated a pair of tractrix horns with the foam. Without the foam, they were exciting and dynamic. But I would often turn them up for a few minutes at a time, because they grew fatiguing at high volumes.
So I'd find myself constantly fiddling with the volume knob, to enjoy a particular track, then turning them back down to a reasonable level.
With the foam, I don't fiddle with the volume know any more. They're not fatiguing like they used to be.
The tractrix horns also use a very nice driver. A JBL 2470 alnico compression driver, with a radian aluminum diaphragm to replace the dreadful fiberglass diaphragm that they normally use. I've personally matched them. It's a very good compression driver, made better with the foam.
"The sound of HOMs is the sound of horns."
Not in my experience. I have and have heard some really "good" horns that do not sound bad at realistic listening levels. Saying it's the sound of horns means nothing as harshness is not unigue to Horns as SPL increases.
"I also treated a pair of tractrix horns with the foam. Without the foam, they were exciting and dynamic. But I would often turn them up for a few minutes at a time, because they grew fatiguing at high volumes."
Did you change the EQ to compensate for the LP filtering of the foam???
Rob🙂
Not in my experience. I have and have heard some really "good" horns that do not sound bad at realistic listening levels. Saying it's the sound of horns means nothing as harshness is not unigue to Horns as SPL increases.
"I also treated a pair of tractrix horns with the foam. Without the foam, they were exciting and dynamic. But I would often turn them up for a few minutes at a time, because they grew fatiguing at high volumes."
Did you change the EQ to compensate for the LP filtering of the foam???
Rob🙂
Patrick Bateman said:
I agree that things like putting in foam and rounding the mouth of a horn are good ideas and can improve the sound and the measurements. But what it's improving may not be HOM at all. It could be 'horn honk' from the mouth. As Michael points out, HOM is a specific subset of reflection and diffraction effects and separating that specific one from all the others is tough. Personally, I'm going to stop using the term HOM and just call it reflection/diffraction. I don't really care about the specific mechanism, just the audible and measurable results.
For those who missed it, Jack Bouska's explanation of horn honk and his experiment with the rolled up magazine and the towel are a good read.
http://audioheritage.org/vbulletin/showthread.php?t=12967
Robh3606 said:
I am just trying to describe what a hom-less device sounds like. I've been living with them for quite a while now, so I'm fairly well qualified to describe what it sounds like.
A hom-less device sounds like a good dynamic speaker. It doesn't sound like a horn.
As for the tractrix horn, of course, I modified the crossover to compensate for the rolloff. It's fairly easy to do, because the rolloff is linear.
Honestly, I'd love to see someone put this foam into their big tractrix or Le'Cleach horns. Based on my understanding of how it works, the biggest improvement will be found in horns, not waveguides.
I am going to post plans for a foam plug for the 18 Sound XT1086 this week. Stay tuned.
Well, you see, that's just it, you have an opinion whereas he has some evidence which may correct your opinion.
Geddes didn't say folk loved his speakers, (although some apparently do). He said folk can describe, contrary to your opinion*, the sound of low HOM speakers such as his own and provided some evidence.
*This is what you said:
Now this:
This is your rhetorical flourish and is not what he was answering, is it?
Look, in cases such as discussed in this forum, if someone cannot provide a subjective description, there is no reason to measure anything, there is no reason for making theory, and in fact, (as opposed to opinion), there is no reason to do science or engineering, or even mess around in the basement trying to build a better speaker.
"To the extent that the breakup modes are above about 10kHz, the foam would attenuate them. But it won't attenuate them selectively. Since the typical application is to equalize the system after the foam is applied, then output from breakup modes would not see any net relative reduction. "
Actually I was thinking of application to cone drivers.
Actually I was thinking of application to cone drivers.
noah katz said:
My Unity thread over on diymobileaudio.com has measurements of an OS waveguide with the foam plug, driven by midranges. Polar response even!
Hello,
The foam is not there to reduce HOM, but to reduce the ping-pong waves from mouth back difraction (throat-mouth-throat-... oo)
- Elias
The foam is not there to reduce HOM, but to reduce the ping-pong waves from mouth back difraction (throat-mouth-throat-... oo)
- Elias
FrankWW said:
No rhetoric from me (Im not selling anything), Im just posting that after reading all the threads there is no definition to what an HOM sounds like. That is my opinion still.
Geddes replies with a simply statement "Im wrong to form that opinion because People say hist speakers sound great" with all due respect " speakers sound great" isnt even subjective proof of what HOM sounds like so Im not sure what you aggressive in defending Geddes's statement and going after my simple observation.
Im simply saying HOM sound has not be defined.
Is it less Distortion?
Is it a HONKless sound?
Does HOM need to have a distinct and defined sound?
ZilchLab said:
lol, that was my exact thought 😀
Its obvious there is big interest/confusion on all the HOM mystery....several threads are beating the same topic to death.
Thanks Catapult! Im with you on stopping the whole HOM madness and calling it a reflection/driffraction issue. Doing that just makes it have normal meanings to it.
"I am just trying to describe what a hom-less device sounds like. I've been living with them for quite a while now, so I'm fairly well qualified to describe what it sounds like."
Hello Patrick
OK I will give you that however you are making a rather gross charaterization that all horns sound like horns. I don't think that is so and is not my personal experience. It depends on how they are used and their SPL levels.
I don't have an issue with you saying that Earls waveguides are the best thing since sliced bread or that they sound better than any horns you have used. It's the all horns sound like horns I take issue with. It is just too broad a brush IMHO.
I look forward to your foam no foam measurements.
Rob 🙂
Hello Patrick
OK I will give you that however you are making a rather gross charaterization that all horns sound like horns. I don't think that is so and is not my personal experience. It depends on how they are used and their SPL levels.
I don't have an issue with you saying that Earls waveguides are the best thing since sliced bread or that they sound better than any horns you have used. It's the all horns sound like horns I take issue with. It is just too broad a brush IMHO.
I look forward to your foam no foam measurements.
Rob 🙂
Hello,
Look at the Makarski's papers posted earlier. He defines HOM as higher order modes in the driver membrane i.e. break up resonances. He also presents the set up for measurement the sound field where HOM is detectable.
Now, because HOM is a driver break up resonance, HOM must sound like a driver break up resonance!
- Elias
Look at the Makarski's papers posted earlier. He defines HOM as higher order modes in the driver membrane i.e. break up resonances. He also presents the set up for measurement the sound field where HOM is detectable.
Now, because HOM is a driver break up resonance, HOM must sound like a driver break up resonance!
- Elias
doug20 said:
Elias said:
I don't see anywhere in that reference where he confines HOM exclusively to break up resonances. Because HOM can be generated by membrane break up, doesn't mean that they cannot be generated by other means.
Sheldon
Robh3606 said:
Actually I never said Earl's waveguides sound better than any horns that I've ever used. I said that they don't sound like horns.
It's an important distinction, because it's the easiest way for me to describe the sound of a hom-less device. It's not that it sounds sweeter, or smoother, or that I'm more involved in the music. The difference is that there's something in the sound of all horns, that I don't hear in this speaker.
Subjectively, it's easy to describe a speaker that has a certain sound, but it's challenging to describe the sound of something when it's absent.
Honestly, I'm doing my best to put this into words, but it's not easy. That's why it's frustrating to read these threads, because I know what distortion sounds like, and the absence of HOMs isn't the absence of distortion. It's the absence of a certain character which I've heard to one extent or another in all horns. Some horns have more, and some horns have less, but they all seem to have it.
Here's another stab at describing it. A few years back I was at an audio show, and a vendor was selling a set of full-range back loaded horns. He was playing them with a small SET amp, to thunderous levels. They were exhilirating, with incredible impact and clarity. But after two or three minutes, I couldn't bear to listen any more. Was that HOMs?
Maybe. All I know was that I liked it at first, and then I wanted to run out of the room after just minutes of listening.
On the flip side, I've found that Emerald Physics sells speakers which are completely the opposite. While they're very dynamic, they don't grate on my nerves. Was that a lack of HOMs?
Maybe.
doug20 said:
HOMs are apparently indefinite, but another modus is clearly in evidence:
gedlee said:
http://www.diyaudio.com/forums/showthread.php?s=&postid=1845882&highlight=#post1845882
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