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Author Topic: Splitting a heavy sub in half  (Read 19762 times)

Art Welter

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Re: Splitting a heavy sub in half
« Reply #90 on: November 11, 2016, 11:07:02 am »

Art, very informative, helpful, funny and exciting.
I built two 18" bass reflex subs back in the mid 90s, perfect copies of Apogee AE SB models (AE5 companions) except I never put the Gauss drivers  that came originally with the AE-SBs. Instead I used RCF drivers, so they never sounded as  good as they could, but using the original Apogee analogue P5 processor, they sounded just OK

EDIT: From what I found out, Ken DeLoria from Apogee Sound designed 21 filters, that would  align frequency phase response; interestingly, since those responses are a moving target as you increase  or decrease the volume,  they are much harder to design in the digital domain and so many of us prefer the analogue processor.
 
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I find it really interesting that epoxy impregnated foam core would give close measurements and a lighter weight. That is the core of this thread.
Just like an aeroplane, a strong bracing skeleton and lighter material may reduce flexing, ie increase stiffness and rigidity to acceptable levels.

I would not be surprised if you can reduce the sub's weight in half and lose only 3dB.
John,

If a lightweight, multi-section (BR, TH or FLH) sub is made properly, it's response will be within 1/2 dB of the same enclosed volume, the 1/2 dB loss due to the "non-productive" area lost to fasteners. The overall truck space can be reduced by 66% or more. Cost to produce such a cabinet will be approximately 6dB (four times) more than a standard single heavy box.

My Keystone Sub design is lighter than the multi-part "Collapsible Cruncher", has response that extends an octave lower, and has around 6 dB more output potential with lower distortion, but uses more than 6 dB more power to achieve that output.
In inflation adjusted dollars, the Keystone sub using a single B&C18TBW100-4 and the 3000 watts of power it receives actually costs considerably less per dB SPL than what I paid in 1978.

When I have been forced to go up stairs alone with something heavier than I can lift, I used a stair climbing dolly and rigged a winch to it.

Decent winches with remote control are available at Harbor Freight for less cost than a stagehand would want for a couple gigs.

The winch I used was a makeshift rig using an electric drill, it would not pass an OSHA inspection, but I was the only person that would have been maimed by it's use- "kids, don't try this at home" ;^) .

Art


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Ivan Beaver

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Re: Splitting a heavy sub in half
« Reply #91 on: November 11, 2016, 11:17:39 am »


The winch I used was a makeshift rig using an electric drill, it would not pass an OSHA inspection, but I was the only person that would have been maimed by it's use- "kids, don't try this at home" ;^) .

Art
Most of us have done-adn still do (often many times) things that are not safe or correct.

But they get the job done.

If everything was done "by the book" and "safe" and "proper", it would never get done :)

Sometimes you just "gotta chance it".

I look back at the things I did and "constructed" over the years.
 
I'm just glad camera phones didn't exist back then :)
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Art Welter

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Re: Splitting a heavy sub in half
« Reply #92 on: November 11, 2016, 01:49:49 pm »

Most of us have done-adn still do (often many times) things that are not safe or correct.

But they get the job done.

If everything was done "by the book" and "safe" and "proper", it would never get done :)

Sometimes you just "gotta chance it".

I look back at the things I did and "constructed" over the years.
 
I'm just glad camera phones didn't exist back then :)
Ivan,
Those antics would have made us good fodder for the "Darwin Awards", we could be famous on the interwebs if photographed..

Since I sold my house/studio/shop of 20 years, had to "lighten the load" for the cross country move. Sold my bench belt sander, along with a ton or so of other tools.

The other day I was using my heavy-duty hand-held belt sander on it's side to "machine" some small aluminum parts. Although I had my shirt tucked in, lost enough weight during and after the move (</>120 degree heat index here in Florida for over a month) that it was loose, the shirt got caught in the belt, slamming the sander in to my stomach and tightened the shirt up like a foot wide ratchet strap before I could shut the thing off, humming away, getting tighter by the millisecond.

Had to cut the shirt off, loosen the belt, and use a big wrench to get the shirt remnants out of the machine. I had replaced the worn drive belt which had been slipping just a week  before...

I will make sure I stand on the opposite side of the hand sander the next time I use it for a bench sander.

Good news is I should be closing on a house/studio/shop shortly, and won't have to "make do" with the minimum amount of tools I can fit in a single carport rental house any more, hopefully no more carport accidents before then  :-[.

Art

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John Ferreira

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Re: Splitting a heavy sub in half
« Reply #93 on: November 11, 2016, 02:47:03 pm »

Obviously the next best option is to go modular, and carry smaller subs, just more of them.

Ivan talking about pictures of questionable moves, I once (in 1990) bought a whole bunch of Bose 802s and as many subs (6 per side), thinking I could EQ any sound that would come out if it. I could not. It could not be done with EQ. The sound was so bad all 6 pairs were sold within days.

It completely shattered my "modular" small speaker approach.
On the bright side, I really enjoyed carrying the six pairs onto the club, I was singing and happy until I heard them.

My small sound system evolution 1980 to 1990
My previous speakers were designed by George Krampara, now KV Audio, Elite PM1000 (in 1982), and the subs were built and tuned by him right in front of me, no name at the time, but later named EX1000 (not sure anymore). This is when George was working for Long & McQuade, and he designed the Elite series.

This was the first time we were looking at trapezoid boxes and analogue sound processors designed for the particular speakers. The EV 1152 were another example of quite successful (for the time) early adopters of similar design.

I had at the time, big scoop subs made by JBL with 2205 drivers, I can't even remember what they were called anymore. I remember the 2205 drivers because I blew a couple. For Mids and Highs I was using Martin horns. The very first time I made a comparison between the JBL Subs with Martin horns and the single box Elite PM1000, I never again performed with The JBL/Martin. The volume, the bass and overall quality on the Elite PM1000 was way better.
« Last Edit: November 11, 2016, 11:50:10 pm by John Ferreira »
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John Ferreira

ProSoundWeb Community

Re: Splitting a heavy sub in half
« Reply #93 on: November 11, 2016, 02:47:03 pm »


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