DizRotus

D-Man, What is it?

My complaint with Bose is the same expressed by many others. Bose markets image/form over performance/subtance. Sure people can enjoy music from their Bose--whatever--, but they do so at a price that is IMHO inflated. This comes from someone who owned and loved 901s prior to getting four Speakerlab SKs in the 70s. Bose reminds me of "House Brand" speakers. When I got married in 1982 my wife brought to the mariage a stereo system that she'd purchased ten years earlier from Pacific Stereo in Chicago, and which she'd enjoyed without reservation. It was a modest Scott receiver and Garrard turntable--not high end audio by any stretch of the imagination, but WAY better than the "House Brand" speakers. included in the package. Most clock radios have better speakers. The enclosures were a joke, the crossover from the cheap 6" woofer to the crummy cone "tweer" was a single cheap capacitor. Even mediocre speakers would have sounded much better, but that would have cut into Pacific Stereo's margin. IMHO Bose is similarly overpriced, but I will fight to the death to preserve every American's right to pay too much to enjoy their music on the equipment of their choice.

During the 70s, when I used four Speakerlab SKs in a mobile DJ business, they always--and often--traveled standing up. Of course, I was not worried about the finish on the raw birch plywood enclosures painted a lovely shade of flat black. Nevertheless, the four were crammed so tightly, along with the other gear, into a 5 x 10 U-Haul trailer that they could not shift in transit. If well padded and anchored, standing up is fine. I never had a problem with the components inside the cabinets shifting or coming loose.

---------------- On 7/27/2005 2:34:27 AM TBrennan wrote: In short I think rear horn-loading of this class of drivers is a waste of time and wood. ---------------- Tom-<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> I respect your experience and dont disagree with what you said except the last part quoted above. How can a DIY horn person call this experiment, a waste of time (recreation) and wood (free available underlayment)? Its a hobby, not a business. The enjoyment for me is in the process as much as the result. I enjoy the pleasure of watching the reactions from people who cant believe theyre listening to 4 Radio Shack speakers in homemade particle board enclosures; total cost $0.00, instead of the giant Klipsch Cornwalls.

I really like the sound of the RS 40-1197s. Now I'm tempted to modify them as described in a few DIY sites. If I could score another pair I'd chance it, but I don't want to risk the two that were so generously provided by Klipschguy. I'd be interested in hearing about any other single driver rear horn projects that any forum members have conducted. Craig, I should bring these up to see how they sound when powered by VRDs?

They've been sold to a Forum member. They'll soon be on their way back to Arkansas.

Two Forum members have expressed interest. While the pending discussions are concluded (in the order in which they contacted me) the speakers are no longer available. If neither of them elects to complete the purchase, the speakers will again be available, but they will be for local pickup or local (within 50 miles) delivery only.

Thanks for the articles. I've only had an opportunity to scan one, but it looks very interesting and useful to DIY types like your's truly.

The following (in blue) is excerpted from an email I sent to a forum member who expressed interest in the speakers. The same delivery terms would be available to anyone within 200 miles of <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Detroit. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> In a nutshell, the speakers are $475 if the buyer picks them up here and $500 if delivered, subject to $50 non-refundable delivery charge once they leave Detroit. (Your city) is within 200 miles of Detroit, so free delivery is an option. There are some conditions to "free" delivery, which are as follows: It must be on a Sunday; and You must send $500 prior to delivery. You could make payment by check or through PayPal. The speakers are as represented (they look better in person than they do in the photos) and they play flawlessly. You would be able to play the speakers to confirm their operability prior to unloading them from my van. At the time of the free delivery, if you change your mind, $450 would be refunded to you. I would retain $50 for the time and cost to allow you to audition the speakers. If the foregoing conditions are satisfactory to you, you will end up with a great pair of Cornwalls delivered free to (Your city) for $500. If you are uncomfortable with the arrangement described, you could make arrangements to drive to Birmingham, MI (approximately 3 hours) and collect the speakers for only $475. You would be able to audition them (in a better setting than the back of a van) prior to making payment. If youre still interested, please reply to this email. At that time we can exchange pertinent information to facilitate the transaction. Regards, Neil

Michael- Yes 1985. The last year not labled II, I believe. As the photo shows they have EV T-35 tweeters; CW IIs do not. I'm too lazy to remove the backs again. They do not have the Atlas squawker compression driver that my Heresies have and Speakerlab SKs had. They look like the drivers referred to in the following thread: cornwall k-51-v mid range driver. original ?? The above photo is from the other thread. This is not a photo of one of the drivers, although they look identical. Indy's not so far. I'll meet you halfway, Niles, Dowagiac, or how about Buchanan? We could visit the former site of Electro Voice on Cecil St. in Buchanan, MI. Regards,

A blown tweeter is NBD. It can be fixed for less than $30. Do a search.

Bump to show price reduction.

Bump to show price reduction.

My subjective impression is that the RS 40-1197s clearly sound better than the rest of the drivers, especially the highs. Nevertheless, in very limited blind comparisons, I was unable to distinguish between the RS 40-1197s and the Pioneers (not the 49 centers). Oh bother.

---------------- On 7/11/2005 10:40:12 PM DrWho wrote: http://www.adireaudio.com/Files/TechPapers/RDOOperation.pdf Kinda like this but on a passive radiator? ---------------- Not kinda, exactly! Assuming the author of the above tech paper is correct,, it's as I originally specualted; efficiency is one of the first casualties. Using a separate driver as the "passive" should eliminate the problems caused by the proximity of the VCs in a dual VC driver. I'm not planning on trying this, it just occurred to me that it might work and could create some interesting possibilities.

Bruce understands what I was trying to describe. His description accurately describes what I was suggesting. Drivers A and B are not connected to each other electrically. Driver A is conected to the amp, while driver B is not connected to the amp, but has its VC shorted by a resistor, which should cause driver B to resist being moved by the changing air pressure caused by the excursions of driver A. If Driver B had an open VC it would move more freely, similar to an unloaded generator.

In that year we lost Jimmie Smith. So now who is the king or queen of the B3?

I guess I was recalling the Nestorovic design. Speakerlab sold a version. It was that concept that caused me to wonder about doing something similar on a simpler scale, such as a variable load across the voice coil of a passive active radiator. By variable, I mean adjustable, not constantly variable during use.

---------------- On 7/9/2005 10:41:12 PM William F. Gil McDermott wrote: The resonant frequency Fs is set by the compliance (spring) of the surround and spider and by the mass. So the resonant frequency can be tuned by the mass. I've read about screw on weights. There is little to be done about the compliance. The Qms (mechanical system) or peakyness of the system is set by the mechanical resistance in the surrond and spider. It is usually fairly low. This is why woofers have high Qms compared to Qes (electrical system). The overall resistance could be adjusted by the voice coil load as you point out. But I think the Fs is the thing most designers would like to fool with. It is not going to be changed by the electrical load. Gil ---------------- Either I'm totally off base, or failing to make myself clear, or both. It seems to me that putting an adjustable load (independent of the signal going to the "active" driver) across the voice coil of the "passive" driver would alter the compliance of the unit, just like adding mass, decreasing enclosurure volume, etc, i.e., the Fs would change as the increasing load across the voice coil caused the passive driver to increasingly resist being moved by the change in pressure inside the enclosure. There would be no direct electrical connection of the passive driver to the other driver or the amplifier. EDIT: Gil, I think I now understand why the Fs would not be changed by a load across the voice coil of the passive driver. The Fs is determined in free air, is it not?

---------------- On 7/9/2005 10:33:50 PM johnyholiday wrote: just my 2 cents, i would think the counter EMF would be the highest with no resistance, an lowered by resistance ---------------- I believe you have that backward. If the voice coil on the "passive" radiator were open it would not generate an "EMF." With a load, it would be forced to do work. Try turning a generator (dynamo) with no load; it's easy. Now put a large wattage bulb in the circuit and it gets hard to turn.

I've seen some that are not rectangular.

Are those enclosures rectangular? From the picture it appears to be triangular when viewed from above.

I'm aware that most passive radiators have no voice coil. My question concerns the ability to use an active radiator as a passive radiator and tune it by varying the load across its voice coil.

I seem to recall a system (perhaps Speakerlab) many years ago that used two dynamic drivers, but one was not powered. Instead, it had a resistor across the contacts. When the motion of the active driver caused the passive dynamic driver to move, the current it generated was sent through the resistor. Wouldnt it be possible to get more elaborate than a simple resistor, e.g., an L-pad or something even more sophisticated to tune the passive dynamic driver? Intuitively, it seems the first penalty would be inefficiency.

If were checking spelling, he also misspelled probably and diaphragm. At least he put a C in Klipsch.