Are these L400 prototypes?

[4313B]

Nice! I need to find the photo of my pair. That was so long ago.

[3dbdown]

Tom !!

Hey, Swimmer!! Long time, no talk to...I remember when you built those puppies!

Also remember the rides with Gordy and Carol! Had dinner with GT a few weeks back, and he says Howard Durbin is still around somewhere.

Welcome to the Forum....

Rick Horn
(JBL #12)

[SMKSoundPro]

Well! This thread has become SO very cool!!

I am a gog! Thank you Mr. Swem for joining!

Scotty.

ps. I learn so much here!

[Ian Mackenzie]

Nice! I need to find the photo of my pair. That was so long ago.

Bring it on!

[4313B]

Bring it on!

Ok, I just replaced the broken HP with a Brother of dubious background and these are the first scans I tried. These photos are really old and I've always been a bad photographer.

Bi-amp only mirror imaged 4315 variant. 2231H, 2108H, 2105H, 077, modified 3114A. Mark Gander graciously answered any questions I had.

That "large scale" L96 variant in the second picture was built before there was a JBL L96. LE10H, LE5H, 044, 3113B. Those 044's were a gift off the desk of a certain someone at JBL, they were unavailable as raw drivers way back then.

[4313B]

if I remember right he was very much into bass reflex enclosure design

Yes, he did substantial follow up to Thiele and Small. I heard that he and Small both work for Harman Becker now.

GT got to JBL a year or so before me and Mark got there after me. JBL moved to Balboa (the old RCA facility) from Cacitas just after I left in 1976.

Oh, it looks like Don didn't make it to JBL until 1977. I didn't realize that he was at Klipsch between EV and JBL.

Had dinner with GT a few weeks back, and he says Howard Durbin is still around somewhere.

I wonder what he is doing these days.

[scott fitlin]

Ok, I just replaced the broken HP with a Brother of dubious background and these are the first scans I tried. These photos are really old and I've always been a bad photographer.

Bi-amp only mirror imaged 4315 variant. 2231H, 2108H, 2105H, 077, modified 3114A. Mark Gander graciously answered any questions I had.

That "large scale" L96 variant in the second picture was built before there was a JBL L96. LE10H, LE5H, 044, 3113B. Those 044's were a gift off the desk of a certain someone at JBL, they were unavailable as raw drivers way back then.

That's ALOT of McJBL you got there!

Your almost as bad as me!

[4313B]

That's ALOT of McJBL you got there!

Your almost as bad as me!

That was 30 years ago Scott. All that stuff is long gone now. My junior high school woodshop teacher got me started on building boxes.

[scott fitlin]

That was 30 years ago Scott. All that stuff is long gone now. My junior high school woodshop teacher got me started on building boxes.

Still, great to know Im not the only JBL- A- Holic!

[DavidF]

That was 30 years ago Scott. All that stuff is long gone now. My junior high school woodshop teacher got me started on building boxes.

Do schools still have "shop"? Simple things I learned in shop back then carry huge benefits still today.

How did you work up the volume of the enclosures? Appear like they are set up for max. damping on the woofs.

Not gonna ask about that carpet...does match with the JBL blue, though.

Thanks for the look back.

[4313B]

How did you work up the volume of the enclosures?

With a bunch of formulas from D.B. Keele, parameters from Mark Gander and crunching numbers using the contraption below.

At that time I had a big old HP VT oscillator and VTVM to measure tuning frequencies with.

I distinctly remember that the 10-inch 3-way box was built on the 1.62:1.00:0.62 golden ratio and it didn't sound so good. It probably would have sounded better if I'd used the 0.62 side panels as the baffles since deep boxes with narrow baffles tend to sound better than shallow boxes with wider baffles. The components and networks themselves were perfectly sound, so, "bad" boxes.

Speaking of Mark, here's an article from 2003. - Sound Profiles: Ready For The Next Challenge

[Mr. Widget]

With a bunch of formulas from D.B. Keele, parameters from Mark Gander and crunching numbers using the contraption below.

Oh, that takes me back!

Parallel Universe... I still have my HP 25C with my own box formula lost in it's tiny brain... unfortunately the battery died years ago and since it was proprietary the otherwise perfectly good calculator became a useless brick.


Widget

[tsslo1]

Hi Rick....where are gordon and Carol now?? Say Hi to Greg for me and if you get up to SLO, give me a call...

[Hoerninger]

... HP25C ... since it was proprietary the otherwise perfectly good calculator became a useless brick.

Irreversible? The HP25 containes two 1,25 V cells:
My HP75 has a proprietary batterie pack with 3,6 V. I carefully opened the plastic box with a cutter knife. It contained three mignon cells - replaceable and still running (but not in use).
( And I have four more programmable pocket calculators by HP. US made at its best!)
___________
Peter

[Chas]

That was 30 years ago Scott.

Man, you ditched the fog horns that long ago?

But seriously, nice to see you share a part of your history. It's likely appreciated by more of us than just me.