Thank you Lojzek! Was on a phone and it felt like rearranging a room through a keyhole getting the picture to display.
Really consider hosting picture uploads Diyaudio. I love the site, but that would really be a huge improvement. Just put a cap on size and it shouldn't grow out of bounds.
And thank you Charlie2!
Do you have the search still open, so I can see your Googlefu in action?
I found nothing searching for "vintage coaxial oval paper driver" and the like, and going through hundreds of images.
Very funky cap by the way. The acrylic "grille" can't be good, and is sure to create cavity resonance, but is likely a stab at improving directivity.
Anyone seen anything like it before?
Really consider hosting picture uploads Diyaudio. I love the site, but that would really be a huge improvement. Just put a cap on size and it shouldn't grow out of bounds.
And thank you Charlie2!
Do you have the search still open, so I can see your Googlefu in action?
I found nothing searching for "vintage coaxial oval paper driver" and the like, and going through hundreds of images.
Very funky cap by the way. The acrylic "grille" can't be good, and is sure to create cavity resonance, but is likely a stab at improving directivity.
Anyone seen anything like it before?
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Not sure what you mean. We do host photos. Gazillions of them. When posting, go down to Manage Attachments and see if that helps.
Scored! At less than $30/£20 they where a pretty good deal. And in good nick too.
The cabs they came in did a good job at protecting them directly and acoustically, but they must have sounded awful.
A massive peice if acrylic with a few holes for grille, way too small a cab with no stuffing. Yuck!
I figure these really belong in the FR section, since they are essentially fullrangers with helper tweeters, so I’ll put impressions and build over there.
Again thanks to all who helped here.
The cabs they came in did a good job at protecting them directly and acoustically, but they must have sounded awful.
A massive peice if acrylic with a few holes for grille, way too small a cab with no stuffing. Yuck!
I figure these really belong in the FR section, since they are essentially fullrangers with helper tweeters, so I’ll put impressions and build over there.
Again thanks to all who helped here.
Attachments
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Yes, band pass holes are used in many multiple entrant driver systems currently, but the Isophon PH2132E is the oldest example I've seen, circa 1953-1965.
The four holes on the woofer create an acoustical low pass filter, which would reduce upper cone breakup output without requiring a complex coil/capacitor network and it's phase shifts, which would make the woofer lag behind the tweeter.
The single hole in the center of the tweeter is likely large enough to let the high frequencies coming from the cone center through largely "unscathed". The high frequencies up to the wavelength of the hole diameter would disperse widely by diffraction, while the small diameter hole also acoustically band-passing some of the objectionable breakup modes from the large diameter tweeter which also create off/axis peaks and nulls, and generally sound bad.
Knowing Isophone, the acrylic grid probably makes for a good sounding unit using "simple" components, resulting in a fairly flat frequency and phase response, I wouldn't dismiss it without some evaluation.
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I'm sorry might not have been clear, but this was clearly a home rolled box. And clearly done by someone with little understanding of the driver or speaker building in general.
Constricting a full ranger with a Qts of 0.9 in a hat box size small cab, and band passing it in that way is not sensible.
Constricting a full ranger with a Qts of 0.9 in a hat box size small cab, and band passing it in that way is not sensible.
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