if auplater can make them accurately which seems to be easily done
with his technique, then they can be quite thin as it should be very easy apply a thick coat of bitumin, polyester or epoxy resin, that water based roofing stuff, that "rigid foam in a can" used in construction to seal cracks, or put them in a box of sand, there are many options and they don't have to be precise if they are applied on the outside...
gedlee said:
I've tried three different set ups with the Summas in two different rooms. Yesterday I stumbled upon an arrangement which sounds dramatically better than my second setup, and marginally better than my first.
Setup #1 - This was in the basement of a brick house I own. Basically a cramped home theater. I wasn't expecting much from the Summas in such a small room, but they worked really well. Even though they were way too close to the walls, the imaging was amazing. I used an off-center approach espoused over on decware.com. The Summas were cross-fired, as recommended in the PDF file from gedlee.com.
Setup #2 - I tried replicating setup #1 in my new house. The sound wasn't nearly as good. I believe much of this was due to the fact that the new house has very tall ceilings, and hardwood floors. This is the trend in new manufacturing, and it doesn't sound very good. I'm not saying the Summas sound bad (they sound great.) But the room is terrible.
Setup #3 - In this setup I've basically followed the set up instructions from gedlee.com to the letter. The speakers are five feet from any wall, they're toed in, and I'm seated twelve feet away. This setup is definitely the best by far. There's an enormous sound stage and better coherence. The treble also seems to sound "mellower." This could be due to the rug that I added to the room on Sunday though. All in all, it sounds great.
loopguru said:
I don't have the exact URLs handy, but I've posted reviews of the Summa.
After hearing it at the RMAF in 2004, I bought one of the last pairs earlier this year.
I've had it set up at two different houses (one is a 50yo brick house, the other was built in 2007 and is typical of new construction.)
The reviews were posted about 3 months ago on diyaudio iirc.
horn - ey
From that wiki place
"In the basic electroforming process, an electrolytic bath is used to deposit nickel or other electroplatable metal onto a conductive patterned surface, such as glass or stainless steel. Once the plated material has been built up to the desired thickness, the electroformed part is stripped off the master substrate. This process allows high-quality duplication of the master and therefore permits quality production--at low unit costs with high repeatability and excellent process control.
Compared to other basic metal forming processes (casting, forging, stamping, deep drawing, machining and fabricating) electroforming is very effective when requirements call for extreme tolerances, complexity or light weight.
A wide variety of shapes and sizes can be made by electroforming, the principal limitation being the need to strip the product from the mandrel. Since the fabrication of a product requires only a single pattern or mandrel, low production quantities can be made economically."
http://en.wikipedia.org/wiki/Electroforming
looks like I'll be ordering a cheap horn for "show & tell"..
just as I get my last youngin' out of the house and off to college...
me and my big mouth....
John L.
Variac said:
From that wiki place
"In the basic electroforming process, an electrolytic bath is used to deposit nickel or other electroplatable metal onto a conductive patterned surface, such as glass or stainless steel. Once the plated material has been built up to the desired thickness, the electroformed part is stripped off the master substrate. This process allows high-quality duplication of the master and therefore permits quality production--at low unit costs with high repeatability and excellent process control.
Compared to other basic metal forming processes (casting, forging, stamping, deep drawing, machining and fabricating) electroforming is very effective when requirements call for extreme tolerances, complexity or light weight.
A wide variety of shapes and sizes can be made by electroforming, the principal limitation being the need to strip the product from the mandrel. Since the fabrication of a product requires only a single pattern or mandrel, low production quantities can be made economically."
http://en.wikipedia.org/wiki/Electroforming
looks like I'll be ordering a cheap horn for "show & tell"..
just as I get my last youngin' out of the house and off to college...
me and my big mouth....
John L.
ShinOBIWAN said:
Dr Geddes could make a hell of a lot more money doing audio work as a full time employee. As DIY'ers, we're VERY LUCKY that guys like Geddes and Danley post on here. Some of the old timers might remember guys like Dan Wiggins, who was also very generous with his time.
Sooner or later they all lose a ton of money on the DIY market, throw in the towel, and get a day job.
I read a post from Dan Wiggins where he said that he can make a lot more money designing a speaker for a speakerphone than for the hifi market. He was basically saying there are companies out there that will buy 10,000 speakers for a phone, but finding a hundred people to buy a loudspeaker is tough.
Didn't the owner of Lambda Audio end up selling insurance a few years back, after losing too much money on his DIY business?
More ro the electroforming wiki:
"The advantage of the electroforming process is that it reproduces the form or mandrel to within one micrometre without the shrinkage and distortion associated with other metal forming techniques such as casting, stamping or drawing. And, since the mandrel is machined as an outside surface, close dimensional tolerances and high surface finishes can be held and maintained on complex interior configurations."
"The advantage of the electroforming process is that it reproduces the form or mandrel to within one micrometre without the shrinkage and distortion associated with other metal forming techniques such as casting, stamping or drawing. And, since the mandrel is machined as an outside surface, close dimensional tolerances and high surface finishes can be held and maintained on complex interior configurations."
badman said:
This isn't true since the patent on the foam plug is still "pending" and I have every expectation of issue - just with what wording. In any case it will cover the plug as currently used. Thus, perhaps you can get a cheaper waveguide made in metal (although I would never use metal) there is still the foam plug to contend with. There is simply no way that waveguides like I sell will ever appear at a cost less than what I sell them at. Thats what patents are for.
It's long, but the idea is simple:
#1 - take your regular room setup
#2 - rotate the ENTIRE THING a few degrees. Like fifteen degrees.
#3 - now that the whole room has been rotated, reflections off the walls won't happen simultaneously in *time.*
For example, if you have the typical setup, with two speakers spaced the same distance from the side walls, firing ahead, there will be an equal reflection off the side walls which occurs at the same time for BOTH speakers.
When you rotate the room, the reflection still occurs, but they occur at different frequencies and at different times for the two speakers.
http://www.decware.com/paper14.htm
In my experience, this works particularly well for small rooms.
#1 - take your regular room setup
#2 - rotate the ENTIRE THING a few degrees. Like fifteen degrees.
#3 - now that the whole room has been rotated, reflections off the walls won't happen simultaneously in *time.*
For example, if you have the typical setup, with two speakers spaced the same distance from the side walls, firing ahead, there will be an equal reflection off the side walls which occurs at the same time for BOTH speakers.
When you rotate the room, the reflection still occurs, but they occur at different frequencies and at different times for the two speakers.
http://www.decware.com/paper14.htm
In my experience, this works particularly well for small rooms.
markus76 said:
Earl, are there any papers in JAES or similar publications? I have easy access to that and always love to learn something new.
And yes, there'll be definitely a new thread called "Placing the Nathan 10"
Best, Markus
Markus
Lidia and my paper was never submitted for publication, but I think that its on my web site.
The data in AES is sparse and not directly applicable, but you can glean some important information from the works of Brian Moore in the audibility of group delay. Pay particular attention to the point he makes about how this form of signal distortion would be absolute level dependent. This is a key point, but one that he only mentions in passing and doesn't seem to put together the relavence. Because virtually all of the subjective work in loudspeakers is done at fairly low SPL levels, the diffraction, which is a group delayed signal, might never show up at those levels. But at some level it will and at even higher levels it will be the limiting factor in sound quality. John Vanommen has posted several times, and many others have noted, how loud the Summas play without fatigue, compression or coloration. I attribute this to two things; the thermal perfomance, which is virtually never considered in hih-fi speakers, and diffraction which is virtually never considered at all.
The hard data is sparse, but all available data points to exactly what I am saying.
markus76 said:
Personally, electroforming is a dead end.
I've built more of these devices than you could possibly imagine and I am perfectly comfortable with my approach. When others quote costs they are only quoting materials, not tooling, time, etc. OK, the material cost for one of my baffles is about $15. The rest is labor, tooling amoritization and IP. When are these costs going to be factored into these outrageous claims?
And I'm not talking about refections but diffraction.
Or are you refering to the decorrelation comment? If so, then yes a decorrelated reflection would be an advantage to imaging, just as elliminating the early reflections would be even better. But such things are not possible, reflections are coherent and ever present. Decorrelation only occurs after multiple reflections, many ms. after the initial arrival and the early reflections.
Or are you refering to the decorrelation comment? If so, then yes a decorrelated reflection would be an advantage to imaging, just as elliminating the early reflections would be even better. But such things are not possible, reflections are coherent and ever present. Decorrelation only occurs after multiple reflections, many ms. after the initial arrival and the early reflections.
Patrick Bateman said:
Supplying quality product and a business failing in a limited market are two different things. I don't see a correlation. Supplying a poor product and a business failing are definitely related though.
Businesses go under everyday and yes its horrible for those involved. However I think it goes without saying that if the product isn't up to standard then this will only become an inevitability and that company won't be missed. Harsh but true.
Regardless of how generous folks are with their time, the minute they sell something, there's a certain level of quality to be reached - enough to satisfy the customer.
You see I could setup a shop front with a humble OAP at the desk dealing with customers. Folks would never be rude to that guy, well reasonable folks wouldn't. My point? I could supply substandard product and should anyone shout down to the old man on the desk, others would rightly flock to save him. Does it make it right though? Depends at who and what your looking at.
The moral of the story here? Geddes is an OAP
BTW Wiggins failed not because of the DIY market but because some of his partners ran off with a load of money and he made a bad call switching production to overseas. He also, at times, provided shoddy aftersales service.
Folks were and still are screaming out for his drivers so the demand is and was there.
Behind every failed business there's usually either bad decisions involved or bad products.
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