While recordings from the 80s may have been recorded poorly, they certainly don't suffer nearly as much from compression. Nothing like a waveform that looks like a zipper...Patrick Bateman said:
Patrick Bateman said:
John
This is actually hilarious to me. Thats because I have long believed that people would be very disappointed to find the "Holy Grail of Audio" because then the "search" would be over. If its the search that is of interest and not really the end result then finding the "answer" is only going to be a disappointment.
You are a case in point of my concern. Now that you've found it, there is no longer any interest in pursuing it. BUT, you find the greatest pleasure in the end result and so you are satisfied. But that can only occur if in fact it IS the music that is the main driver and not the pursuit itself.
But what you say is exactly what I have found too. Newer recording are so much better. And thats unfortunate in many ways, but a blessing in others.
The one point that I do make over and over and over again, but it just does not seem to get through, is that its not JUST the waveguide contour that makes such a big difference its also the foam plug. People seem to be obsessing about the contours and missing what is just as important and that is the foam. Just changing the contour is not going to be a huge effect when one is going from say a LeCleach horn with large mouth radius to an OS without the use of the foam plug. However, going from an old fashioned diffraction horn to a waveguide with foam is going to be huge.
But at any rate go back to your listening and enjoy. Try some Diana Krall - she seems to have a very good producer - excellent recordings.
My personal experience is that the old recordings sound much better when the playback polarity is inversed. Especially those mono recordings.Patrick Bateman said:
Earl
i have made some research here in brazil, but the companies that make this kind of foam, are not interested to sell a small quantity. i have read however somewhere people made direct comparisons with and without the foam, and the difference was reported to be very very slight or even not perceptible. So i really don't know....
Angelo
No one here will sell a small quantity either. I have to buy about $1000 worth at a time. The material is very expensive - and then it has to be cut, which is no small feat.
I can only say that I have only ever read where people have reported a big difference, which agrees with my experince. What your reporting I have never seen anyone say.
I can only say that I have only ever read where people have reported a big difference, which agrees with my experince. What your reporting I have never seen anyone say.
angeloitacare said:
I have a Unity horn system. To my ears it had a slight "horn" character. Not much, certainly not to an objectionable extent. That is to say, that it didn't stop me from enjoying the speakers, but on certain passages it was there - that slight echo kind of quality. If I fill a little more than half the depth of the waveguide with the foam (that I bought from Dr. Geddes), it completely goes away.
Maybe some are more sensitive to this effect than others. However, I'm no golden ears listener. I build my own amps and speakers and I can't hear differences between most caps I've tried, or most tubes - though I can measure differences between individual tubes and I pick the ones with the least measurable distortion.
Now if your horn has low HOM's to begin with, maybe the difference would not be so audible. But I would certainly try it.
Sheldon
Is there anything particular about the foam that cannot be replicated with some carefully-cut-and-folded fiberglass insulation?
angeloitacare said:
Please post the URLs. AFAIK, I am the only person who's ever done an A-B comparison of a horn WITH and WITHOUT the foam besides Sheldon, and posted the results.
I did this back in 2005 on Richard Clark's forum.
The differences I heard were DRAMATIC, and eventually led me to invest in a pair of Summas.
Keep in mind that the ONLY proper comparison is done with a re-designed crossover. If you don't redesign the crossover, the comparison is meaningless, as the frequency response is affected by the foam.
i made this research several month back. I posted here about my interest to try out the foam , and got also some advice where to find it in the u.s. I dropped however the idea. And knowing, that some crossover tweak is needed, makes it even less interesting.... If Dr.Geddes sells freely to the public the foam, and maiby give advice in regard of the crossover, then it might be interesting to try it out.
Angelo
I'll sell foam, but most people are surprised by its cost. The stuff is very expensive. And cutting it, well thats your problem if you buy a solid chunk from me and don't use my waveguides - the foam is precisely fit to my waveguides and won't fit other designs that are different. As to crossover mods, well those are all going to be different and there is no "rule of thumb" that I can give. The foam drops the high end about 2-3 dB.
Foam reduces HOM but it also reduces internal reflections whcih ALL horns and waveguides have. There is no way to distinguish between the two so I seldom mention it. Hence, any horn or waveguide would benefit by the foam, but to varying degrees.
Foam reduces HOM but it also reduces internal reflections whcih ALL horns and waveguides have. There is no way to distinguish between the two so I seldom mention it. Hence, any horn or waveguide would benefit by the foam, but to varying degrees.
454Casull said:
I use the foam because it is quite porous - unlike fiberglass. Its probably four times less dense than fiberglass. And fiberglass is not well controlled, being denser in spots etc. I've never tried fiberglass, but I wouldn't think that it would work too well. The foam is ideal since its highly controlled and comes in various densities etc.
To fit into a waveguide - no! That takes a custom cutting tool and apparatus that I had to design and build. Sure there are companies who would do that but they need about $10,000 in orders to make it worth their time and effort.
Patrick Bateman said:
To get an apples to apples comparison, yes. But my HF hearing is poor, so I don't hear much of a difference in frequency response. But I do hear the change in horn character. Still, my system is frequency corrected with a DEQX, because I use it for my crossovers anyway.
I'd wager that even without the correction, most horns/waveguides will sound better with the foam. I find it fairly easy to adjust to small changes in frequency response, less so to horn artifacts.
Angeloitocare, if you post your crossover, we could probably recommend simple mods that would get you close.
Sheldon
Sheldon
I think that you are quite correct here and there is data to support it. The foam will be a very gradual smooth (nothing resonant) roll-off of the high end and almost nothing below about 6-7 kHz. Its major effect will be on waves that pass through the foam several times, like reflections, and waves that travel longer distances, like HOMs. This is why it works so well. Its effect upon the main wave is minimal, but its effect on the aberations (distortions if you like) will be major. A real nice net improvement overall.
I early subjective tests of the foam (with no EQ), some, like myself, liked the change, but others didn't like the HF loss. When I corrected the HF loss with EQ everyone liked the effect.
I think that you are quite correct here and there is data to support it. The foam will be a very gradual smooth (nothing resonant) roll-off of the high end and almost nothing below about 6-7 kHz. Its major effect will be on waves that pass through the foam several times, like reflections, and waves that travel longer distances, like HOMs. This is why it works so well. Its effect upon the main wave is minimal, but its effect on the aberations (distortions if you like) will be major. A real nice net improvement overall.
I early subjective tests of the foam (with no EQ), some, like myself, liked the change, but others didn't like the HF loss. When I corrected the HF loss with EQ everyone liked the effect.
hi Sheldon
i use a simple 6db first order crossover.
first i made a lowpass for the midbass horn at 700hz/6db, and used a 5,9mF cap for the midrange. The midrange channel is however too strong that way.
Now i don't use any lowpass on the midbass horn, and for the midrange i use a 3,7mF cap.
I have the feeling, that i can improve integration, making the midrange horn bigger. But the distance of the two sources , midbass, and midrange, will remain the same. Bringing them closer, would be another way to go. Voices sound sligthly colored, and i want to adress this too.
Angelo
i use a simple 6db first order crossover.
first i made a lowpass for the midbass horn at 700hz/6db, and used a 5,9mF cap for the midrange. The midrange channel is however too strong that way.
Now i don't use any lowpass on the midbass horn, and for the midrange i use a 3,7mF cap.
I have the feeling, that i can improve integration, making the midrange horn bigger. But the distance of the two sources , midbass, and midrange, will remain the same. Bringing them closer, would be another way to go. Voices sound sligthly colored, and i want to adress this too.
Angelo
angeloitacare said:
Obviously you have to work more with your xo
It have been concluded over and over again that 6db slopes doesnt exist in reality, well maybe only in rare cases...so the question is "what is it then, what can I obtain, and how can I effectuate the possible"...is continuity the right word ?
454Casull said:
I know that Dr. Geddes addressed this question, and I would tend to agree with his answer. Given his methods, I would guess that he tried a variety of materials until he found one that achieved the best compromise of form, uniformity, and response. That said, there is nothing magic about it and nothing to say that other materials couldn't achieve similar results.
The point about uniformity is probably an important one, and not easy to achieve with many materials. And I would think that different materials will have a different frequency response distribution. Neither issue prevents you from finding alternative materials, but be prepared to do a good amount of experimentation and measurement.
Sheldon