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rickrob2

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  1. It could be a prototype-- It's certainly the first time I have ever seen multi-conductor control cable used in a crossover. I'll open up the other cabinet soon. I'm expecting to find the same type of crossover in that one too The extra credit question was part of that post by Dick Pierce -- but it should be easy to answer.
  2. I found the story I read about the 50W resistor. It's still out there at this link. https://groups.google.com/g/rec.audio/c/RQhkcO0TgdM I posted it here in case the link goes away. Audio Anecdote of the <interval> Today's episode: Loose lips sink ships.. Back in the mid-70's, there was rumored to be a most amazing loudspeaker designer working out of the mid-west (Indianapolis) by the name of Roy Cizek. That he used some novel and questionable design techniques may be something of an understatement. For example, his solution to the problem of cone break-up (which is, essentially, standing wave patterns on the cone) was to slit the cone with a razor blade. Interesting, if not somewhat misguided. Well, one day, Roy Cizek shows up in the Boston area, and starts haunting our store, listening, asking questions, probing, and so forth. All in all, not a bad fellow, if not somewhat of a nuisance. It seems he's decided to design yet another loudspeaker. "Gee, Roy," we say, "that's nice." Several months later, we get a call from Roy. How would we like, he asks, to hear is new loudspeaker? Sure, why not, it's winter and nobody is coming into the store. Roy says he'll be right down. Maybe 15 minutes later, in ambles Roy, carrying his speakers. The first thing I do is rip off the grill cloth and comment, "But Roy, the cone is in one piece!" Roy was not amused. We sit down and listen to the speakers. Not bad, not great, but quite inoffensive. The one obvious drawback is that they have no bass. Trying to be as diplomatic as possible, we say, "Roy, your speakers have absolutely no bass." Roy, surprisingly, replies, "Yeah, I know, I can't quite figure out why. But they are reasonably efficient." That they were, and that was the obvious clue as to the problem. It seems that Roy had selected a woofer that was far to damped electro-magnetically for the enclosure he had designed. Thus, while the large magnet on the woofer contributed to a high-effciency, it also meant that the bass was far too tightly controlled. To me, the answer was obvious. If you wanted bass, and you have decided that you want a speaker of such and such a size using such and such a woofer, you got a choice, either low efficiency and bass, or efficiency and little bass. Opting for the former, my choice would have been to save money and order the woofer with a smaller magnet. Roy would hear none of that, however. No, he wanted a big magnet to properly control the woofer, which was exactly his problem. The discussion went on and on, Roy not wanting to hear anything about efficiency/bandwidth/power-handling trade-offs. Finally, in frustration, I said, "Well, Roy, why don't you just stick an 8 Ohm, 50 watt resistor in series with the whole damn speaker. That'll give you some bass!" Feeling even more bold, I said, "In fact, why don't you put a big switch in there, and convince customers they have a "Q" switch?" Well, everybody laughed, even Roy, just a little bit, though, and we closed up and went home. A year or so later, I was working at another store when in marches the sales rep for Cizek Loudspeakers. The speakers looked the same and, of course, had no bass. When that objection was raised, the rep said, "No problem, Cizek has developed this revolutionary new method for increasing bass response. They have added a "Q" control switch." He promptly threw the toggle switch on the back of the enclosure, and, obligingly, the efficiency dropped in half and the bass came back! I turned to the rep and the store manager and said, "I'll bet you $1000 that that switch is connected to an 8 ohm, 50 watt resistor." They looked at me incredulously. I just said to check it out. About half an hour later, the manager and the rep came running into my lab yelling "DICK! DICK! Look! You were right!" Sure enough, Roy had taken any advantage that his big magnet had and thrown it out the window with a big resistor. I figured at the time the retail price of the speaker could easily have been reduced by $100 a pair by not having the resistor and having the right sized magnet to begin with. And the speaker, in the "High-Q" position was not a bad loudspeaker, not a great one, but quite inoffensive. Although, it did have reasonable bass. Dick Pierce PS: Extra credit question: What is so ridiculous about the advertising propoganda from Cizek having a picture of Roy Cizek staring intently at a B&K real-time spectrum analyzer?
  3. And compared to a later model production crossover, it's like night and day. I'll be swapping out the early model for these newer ones, because I think they'll be much more reliable in the long run.
  4. I haven't visited here in a very long time... But though this might interest the Cizek fans. I have one last pair of Model One's that I'm restoring. When I opened up the cabinets, this is what I found for a crossover. Note the 50Watt resistor. I had read stories somewhere about someone listening to an early pair of Roy's Model 1's and suggesting (as a joke, I think) that Roy add a 50W resistor to the circuit , and then finding out that he actually did it. I guess that story might be true. And, one of the coils/inductors is made from multi-conductor cable with 7 conductors, with two of them being a larger gauge than the other five. There are wire nuts connecting those conductors up to the front switches/knobs so it is handing C1, C2, C3, C4, and Flat for the HFC control. I have no idea how early these Model One's are, but the date code on most of the crossover components is 1976. (7640, 7650) and the woofer's magnet is spot welded to the basket as well. I think they all were made that way, but these two are a rough job.
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