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Old 8th September 2010, 03:58 PM   #121
jbell is offline jbell  United States
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Quote:
Originally Posted by hellonwheels View Post
Thanks, I think there are valid counter arguements to this and they come to mind, but I would appreciate it if what I consider Very basic specs are given right away.
If I'm evaluating 10 designs and have to fill in hornresp for every one... that's some time.
Basically in my application theres nothing more important than max SPL at a given freq. Amps are light cheap and powerful. EQ works for low frequencies. If an efficent design runs out of excursion @ 12 watts, it won't serve my purposes.

Is this the latest version of the sub?
Yes, this is the latest and greatest, and last version of this sub I am going to work on. I'm happy with it. Actually, I'm very happy with it. It's the best sub I've designed to date.

In terms of the time required to put things into hornresp... it's the great equalizer. It at least gives you an apples to apples comparison, it's worth your time. What it doesn't show you is how port compression, etc... happen. Scott made an interesting comment... TH's 'bloom' where bass reflex 'wilt' at war volume.... and hornresp won't show you that.

As far as this particular cabinet in the above link? Hornresp says you'll get upper 120's per cabinet 40hz on up at 63v. A 40hz 48db/oct high pass makes this design PE limited, not xmax limited from 40hz on up.

I've personally run it up to about 125db with sine waves, so what I built vs. hornresp is on the money. The big difference between testing and hornresp specs are that I get a little more 40hz, and the notch at 170hz is a very narrow 2hz, 6db notch.
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Old 8th September 2010, 10:27 PM   #122
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Originally Posted by jbell View Post
Yes, this is the latest and greatest, and last version of this sub I am going to work on. I'm happy with it. Actually, I'm very happy with it. It's the best sub I've designed to date.

In terms of the time required to put things into hornresp... it's the great equalizer. It at least gives you an apples to apples comparison, it's worth your time. What it doesn't show you is how port compression, etc... happen. Scott made an interesting comment... TH's 'bloom' where bass reflex 'wilt' at war volume.... and hornresp won't show you that.

As far as this particular cabinet in the above link? Hornresp says you'll get upper 120's per cabinet 40hz on up at 63v. A 40hz 48db/oct high pass makes this design PE limited, not xmax limited from 40hz on up.

I've personally run it up to about 125db with sine waves, so what I built vs. hornresp is on the money. The big difference between testing and hornresp specs are that I get a little more 40hz, and the notch at 170hz is a very narrow 2hz, 6db notch.
I cant wait to build it! Just to be clear >125db up in 2pi is what the sim says and your staying within x-max. Because there it is more efficent theory says the Power handling should go up.. be nice to put 900w in reliably.
TY for your quick response.. and of course your design.
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Old 9th September 2010, 01:08 AM   #123
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Quote:
Originally Posted by AndrewT View Post
Hi all,
since I have had no response to a call for designs that offer lower frequency use from a 1.5 Board design, should I start a new thread for this challenge?
Hi, I made Jbell's 8x4 sheet a little bigger, it does a little lower but isn't quite so efficient, it's around 400litres which is approx 1.5 times the volume but I have no idea how much could it would take to build, but I'm guessing around one and a half sheets. They light grey line is the single sheet box so you can see the difference.
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Old 9th September 2010, 10:08 AM   #124
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by hellonwheels View Post
.. be nice to put 900w in reliably.
why is 900W chosen to be "nice"?
I could just as easily suggest that "nice" equates to 900mW or 9W or some other number plucked out of the air.
__________________
regards Andrew T.
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Old 9th September 2010, 12:26 PM   #125
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I think what we are gonna need here is an active DIY low cut filter. 24-48 db perhaps with the option of adding a switchable network to change the frequencies so you have a couple of choices. Perhaps 40hz and 35hz. Or a table with possible rc network vs freq so one could pick which cutoff they need. A variable pot like a crossover is nice but I strongly advise against it for reliability and unintended changing by small curious fingers.
On second thought a 12/24db 16khz low pass might be good to tack on as well
for the piezo crowd.
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Old 9th September 2010, 12:51 PM   #126
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Default ScreamerUSA's DIY low cut filter idea

Quote:
Originally Posted by screamersusa View Post
I think what we are gonna need here is an active DIY low cut filter. 24-48 db perhaps with the option of adding a switchable network to change the frequencies so you have a couple of choices. Perhaps 40hz and 35hz. Or a table with possible rc network vs freq so one could pick which cutoff they need. A variable pot like a crossover is nice but I strongly advise against it for reliability and unintended changing by small curious fingers.
On second thought a 12/24db 16khz low pass might be good to tack on as well
for the piezo crowd.
I love the idea. Pop it into the amp rack. Load and lock... Very useful. I'd want it as discrete as possible, to prevent DJs etc seeing it and bypassing it to make things louder

I know we can have rules and contracts, but idiot-proofing is the way to go in my case.

Google found this for me: http://focus.ti.com/docs/toolsw/fold...filterpro.html

Good stuff!

Regards, Ben
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Old 9th September 2010, 01:28 PM   #127
jbell is offline jbell  United States
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DIY highpass for making things idiot proof? That's what xti amps are for....
Crown XTi-1000 Stereo Power Amp

Ben/Scott, I appreciate the thought, and I've even considered a 500uf passive or other type of active protection for my subs... but I just can't beat the simple setup of the xti.


$329 for full '3yr no fault' warranty b-stock... delay, dsp, eq, highpass, limiter, amp... all in a password protected, front panel lock out, 17lb all digital chassis.... Runs a pair of tops and a pair of subs beautifully. And limits out WAY before 900 watts per driver is possible. Using the internal 'Y' so that there is only a single audio input, and a single volume control even keeps peoples hands off of the sub/top volume ratio, so things always sound the way you want them to sound. To top it off -- 2 channel speakon cables even prevent mis-wiring on setup.... just chain all the speakers together.. Start on the side/top, go to the 2 center clustered subs, and then on over to the other side top.... beautiful.

I've been using nothing else for my school installs.... which have to be idiot proof....

Last edited by jbell; 9th September 2010 at 01:45 PM.
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Old 9th September 2010, 01:42 PM   #128
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Default Jbell

I completely agree. Next time I have a wad of cash and can start from scratch I will do so with Crown XLI or XLS! (or maybe Peavey IPR 1600 dsp?)

However, currently I am sitting on a bunch of heavy old iron. I have a variety of soldering irons and tools and I like ScreamerUSA's idea.

But maybe I ought to grow up and sell the old iron...

Regards, Ben

P.S. over here it's €525 - so approx a very evil 666 US Dollars http://www.thomann.de/de/crown_xti_1000.htm

Last edited by salzburgsoundsystem; 9th September 2010 at 01:45 PM.
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Old 9th September 2010, 02:39 PM   #129
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Yamaha's P series has a low pass filter, making them ideal for powering subs. Yamies are cheap too.

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Old 9th September 2010, 03:20 PM   #130
jbell is offline jbell  United States
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Quote:
Originally Posted by Lee in Montreal View Post
Yamaha's P series has a low pass filter, making them ideal for powering subs. Yamies are cheap too.
P7000S, P5000S, P3500S, P2500S | Power Amplifiers | Products | Yamaha Pro Audio

12db/oct... I wouldn't... nope, no way. 24db/oct minimum if you are going to set it at 40hz on this sub. And the yammy filter can be EITHER low cut or low pass... the xti allows you to HP butterworth 40hz@48db/oct, LP 95hz@24db/oct linkwitz riley, and then also use 24db/oct HP for your tops if you choose to run tops on channel 1, and subs on channel 2.

For a loud cheap DJ proof setup that fits in a corolla... I haven't found a setup that beats a pair of the half sheet beta12a tops, a pair of the single sheet subs and an xti.
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