From ches@qualcomm.com Mon Aug 27 14:27:32 2001
Subject:Re: KBR-M rotary driver failed, fixed

Jeff, there must have been something in the air this weekend.

Saturday night, got to my gig, got my V5/A-30/145 system set up, got the PA
set up, and was just sitting down to enjoy a pre-show beer when I noted a
problem with *my* treble rotor. It turns out that one of the three bolts
that hold the horn driver to the cabinet had worked itself loose, and
dropped off. The horn was hanging at a weird angle which prevented the
rotor from turning. I took the back off, and I have no idea what happened
to the missing bolt. It wasn't stuck to the speaker magnet, or up in the
spider, or stuck to the side of the motor. Weird. Fortunately, I made the
happy discovery that the bolts that hold the back of the Leslie in place
are the same thread pitch and size as the bolts that hold the treble driver
in place. It took 10 or 15 minutes of fuzting around but I finally got it
back together and was ready to go.

I took it all back apart yesterday, but I never did find the missing bolt.

Dave

At 09:13 PM 8/27/01 +0000, Jeff Conlin wrote:
>Hey all -
>
>Just wanted to drop a line and say hello, and pass on an interesting
>experience I had with my KBR-M this weekend.
>
>I joined the list last weekend at the last minute, trying to get some
>advice from you regarding an open diaphragm on the KBR-M... had to
>find replacement at the last minute. I put a few calls in to Motion
>Sound, but the guy I needed to talk to wasn't going to be in until
>2:30 their time (4:30 mine), and my gig was at 6.
>
>I wasn't able to get to "post" status in enough time here, so just
>took a chance anyway and spent 2 hours searching for anything that
>would work.
>
>I wound up getting an Eminence titanium replacement for a bit less
>than the Motion Sound OEM PD40. ($40, I think)
>
>On my way home, I finally got through to John Fisher (?) at Motion
>Sound and asked him if he thought my solution would work in a pinch.
>He said "it might - but not for long" (no big surprise), "The
>Eminence titanium drivers are designed for a 1200Hz crossover, and
>the KBR-M's is at 800Hz. The lower crossover could kill the driver
>pretty quickly."
>
>As a precaution, he recommended applying 1.2mL of self-leveling
>silicone around the edges of the driver to dampen the suspension
>resonance a little bit. I couldn't find any self-leveling silicone,
>so I just used regular gummy silicone, and I may have used a good bit
>more than 1.2mL. It was a pretty high paying gig and I just didn't
>want to risk anything.
>
>Put everything back together, and headed off to my gig. Hooked it up,
>and it sounded fine. With the silicone around there (I'm guessing
>that's the culprit), the KBR-M has a noticeably less shiny high end,
>which I really like. It sounds a bit more authentic and a bit
>warmer... more like a Leslie.
>
>While the KBR-M was open, I also tinkered with the acceleration pot
>of the rotary horn... I sped it up to almost full accelleration. My
>old 145 (admitted, it had the deflectors removed) was VERY quick to
>hit full speed and I enjoyed being able to tweak particular notes
>rather than wait for the ramp-up time. The KBR-M sounds good to me at
>these settings, but I'm going to continue to tinker with rotary speed
>and accelleration a bit more to find something I like. At full speed,
>it sounds a bit more choppy than my 145 or 860 ever did.
>
>I've got a Motion Sound PD40 now on standby when/IF this Eminence
>actually does get beat up by the 800Hz crossover. Looking at the PD40
>next to the Eminence titanium... I'm really skeptical about Motion
>Sound's claims... the Eminence looks to have far better construction
>and materials all around... but we'll see in time.
>
>Gig went well, I got paid ('course, I'm out a hundred for both
>drivers, but live and learn), and live rolls on.
>
>Thanks-
>Jeff Conlin
>Beltsville, MD
>XB-2/KBR-M C2/145 Wurlie140 Roland JX305
>
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