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Very Early Model One Crossover


rickrob2
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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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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?


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Maybe your early Model One is a prototype? I agree with your decision to use a later xo.

btw—any Cizek fan will get the extra credit question.

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4 hours ago, JKent said:

Maybe your early Model One is a prototype? I agree with your decision to use a later xo.

btw—any Cizek fan will get the extra credit question.

 

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.

 

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