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In Reply to: RE: Masochists ? posted by claudej1@aol.com on May 19, 2023 at 07:16:31
Yep, the acoustics are the same but modern drivers can be very different.
I did have to close off the large port opening and change to 4x 4 inch dia port tubes to tune lower. I also reinforced the woofer flare as they had a resonance around 350 if i recall.
The octave added at each end is the difference in drivers and the "flat" without the normal phase shift is a computer aided crossover design.
Best,
Tom
Follow Ups:
Co-incidentally, I have a pair of JBL 2226 drivers from Ebay to be delivered in the next hour. But it's for refurbishing some 2-way JBL PA speakers whose horns with 2447 drivers and xovers are intact (too much power for FOH operators who ignore power meters and Limiters). The guy needed the space so I bought the lot as an investment. Most of the woofers were blown and he needed the storage space, so, solde them to me for a song (pun intended).Those 2226's can take a lot of power in pairs, but any device can be overdriven to the point where it will fail. This is why I like your speakers so much for HiFi because they will never see more than 10% rated power for home application, even during a "demo" for friends (some of who have been scared out of the room by the BT7 and TH50 running LFE).
He told me he had to sell off the "flying bananas" (really like that expression) during Covid he had subsequently purchased as replacements for the blown driver ones in storage. Live music was nowhere to be booked then, as you well know.
Still, I got some very solid late 90's tech. no longer made but the drivers are available used from other boxes that are pieced out.
The boxes I have have twin 12's and twin 15's with very well built cabs that get down to 40 hz.
I hope to make my modernized BT-7 become part of a package eventually since I got a local "steal deal" from a drummer who didn't need the JBL BR 18" Sub designed for theaters (same Motor Tech as the 2226). Using it in the rear, firing against the back wall and waiting for help to move the BT7 into the shop for permanent driver upgrade we discussed. Thanks for all your help, as always.
Even your improved version of the VOT, whose size would not work in my living room with LCR "miniature" SH-50's with Subs asking as working "speaker stands." I like to make every cubic foot count in my small room, which is 11.5 x 16.5 x 8 with full 11 channel Atmos with 2.2 at the touch of a button for music.
Back to the OP. While Bill F's and your curves clearly show I was right about the limited response I experienced in a small, cheap local theater with the unmodified versions (6 years ago), the improvement shows what can be done with better drivers, crossovers, and optimized tuning, using the right tools. Applied Science wins again.
Edits: 05/19/23 05/19/23 05/19/23
The improvement also shows that the needs when the VOTT was invented aren't the same as those today. It was very much an empirical seat of the pants design, made to sound as good as possible with the audio content of 1940s movies, driven with 25 watt amplifiers. One should no more expect them to perform to today's standards than one would a 1947 Ford.
Absolutely right!
There were so many things that were the build / listen /modify loop with very few acoustic measurements.
It was the TEF machine that allowed one to measure the loudspeaker's phase and that didn't happen until the late 70's and become practical in the 80's.
I heard an old WE driver from a theater speaker and it sounded great. looking at the insides, except for materials, it was a modern compression driver = there was very little that could be improved in the acoustic part in many decades since. That was something to think about, the process that lead to that driver design.
Tom
Jim Hunter, Klipsch Historian, retired Chief Engineer showed me a WE 555 unit the he says the Atlas driver was based on and he was amazed at how good it measured. Pretty impressive those Engineers were almost 100 years ago!
I agree fully! the ones that got it, really got it and left little to improve other than new materials mostly and to a degree computer modeling neither of which they had.
I don't remember which theater driver it was i heard but it sounded just fine to me.
At a trade show a person asked why the old drivers didn't have power compression?
Good question but the answer is the glue that was available for the voice coils let go at around 150C and so the wire never got hot enough to suffer from that.
I agree with your historical statement, Bill.
They were good in their time. Just like Altec Drivers, which can be bettered in every regard by modern drivers, like an Eminence Deltalite 3015 in the right box.
Altecs were my favorite back in the day. I preferred them over JBL and EV. By the same token while I loved my BMW 2002 in 1972 I wouldn't want one today over my 328iX GT. They both have 2000cc engines, but that's where the resemblance ends.
" I loved my BMW 2002 in 1972"
Oh man my Mom had one of those maybe a year or two earlier, a blue one (Dad had a 1960 R-60 bmw) that I got to drive. It was a fun car at a time and place when there weren't that many sports cars.
What i do remember was it was "cold blooded" like the Honda motorcycle i had and needed to warm up for a bit in the winter.
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