That type of omni speaker were common in the 60's with a number of DIY articles and a few commercial versions seen. The July 1961 and June 1962 Popular Electronics featured similar systems designed by David Weems. One loaded into a ten inch clay sewer pipe. Eico had a Hageman designed commercial system loaded into a transmission line. Collectors still pay top dollars for those systems. If you don't care about exact imaging,they offer an interesting design to experiment with. A good project for a full range fan.
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If the diameter of the base of the conic-reflector is for example 13 inches (33 cm), then it is pointless to radiate sound of a frequency less than 1 kHz towards the cone. At 1 kHz ( wavelength = 33 cm) and lower frequencies, the cone is more of an obstacle than a reflector, so sound in that frequency range is only marginally reflected.
What is usually stated about the reflection of sound is that the dimensions of the reflector must be several times the wavelength of the sound. So far I haven't discovered a more precise statement about it, like the percentage of reflection that occurs for a given ratio of size of the reflector to wavelength.
What is usually stated about the reflection of sound is that the dimensions of the reflector must be several times the wavelength of the sound. So far I haven't discovered a more precise statement about it, like the percentage of reflection that occurs for a given ratio of size of the reflector to wavelength.
I'm sure that having an omni in a dorm room had nothing to do with it
Or maybe it did)
Very little if anything to do with it. I had plenty of other opportunities to hear them in other situations, as I worked for a Zenith dealer part time later in college. There were awful, IMO, period. Do you really think that some cheesy speakers that are included with a $250 late 60's Zenith mid fi stereo system with a VM changer and a ceramic cartridge are going to be anything but marginal at best? You could probably find a set on Craigslist for 10 bucks or so to check out yourself. Otherwise, you'll just have to take my word for it. Or not.
A generalization that is easy to find a counter-example of: The FE103A that came in the similar Admirals systems are quite fine.
The examples that i have had thru here had drivers ranging from trash to quite decent... sometime in the same model but different production runs.
dave
You only gave the dorm room example so that's what I addressed- certainly suboptimal environs for an omni system. I'm not an omni kinda guy, though I guess they have their place, it's just not for me. I want "you are there" not "they are here".
There were some unique consumer products produced in the 60's stereo wars and the Zenith omnis are just one example. The goal was low production cost stereo sound, with the emphasis mostly in the mid-range area. Bass was usually limited at 100 Hz and , if present, was boomy. The public went for them by the millions much like today's ear bud MP3 crowd.
Well look at what this guy came up with for midrange dispersion. I have some air conditioner filter foam that should work for this, the dispersion improvement graphs are dramatic.
Now, how abut that tweeter ? Maybe a metal screen version, if it works. My mic is not calibrated, but can show axial ratios. Gonna duit.
Looks like for other sized drivers, you cut the hole a bit smaller than the dust cap.
Speaker Directivity Modifier :: TGP Webzine
Now, how abut that tweeter ? Maybe a metal screen version, if it works. My mic is not calibrated, but can show axial ratios. Gonna duit.
Looks like for other sized drivers, you cut the hole a bit smaller than the dust cap.
Speaker Directivity Modifier :: TGP Webzine
That treatment would be great for making a bi-polar speaker system even closer to being fully omnidirectional. Going that route I think makes a lot more sense than the conical reflector.
-cT
Looks like the Fresnel of the audio world. I'm wondering if it may be better to look at a concentric gang of tuned delay tubes. It may be possible to stage them to reconstruct the wavefront for better dispersion. I'm not far enough along to reliably determine wave physics.
I tried the doughnut yesterday, it only muffled the midrange. I may have made the wrong mask dimensions. Air conditioner filter foam did not seem to attenuate in a full mask over the ear, but on the cone with a hole, it did.
I tried the doughnut yesterday, it only muffled the midrange. I may have made the wrong mask dimensions. Air conditioner filter foam did not seem to attenuate in a full mask over the ear, but on the cone with a hole, it did.
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