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Old 5th April 2013, 08:43 AM   #1941
djk is offline djk
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733
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Old 30th April 2013, 08:24 AM   #1942
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Quote:
Originally Posted by AndrewT View Post
where does this take you?
Single sheet TH challenge
To the top of page 15 at first, then goes to page 74, post #733
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Old 30th April 2013, 08:34 AM   #1943
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Quote:
Originally Posted by YogiNC View Post
Anyway, I am curious about the HS12 tops but it has been a much more difficult message string to find. If someone would kindly point me in the right direction I'd be so ever thankful.
Google

The ones that say "Page 26," "building jbell's hs12," and "JBell PA Top" have all the info you should need.
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Old 10th July 2013, 06:04 AM   #1944
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Another of JBells single sheet designs has been gathering some acclaim on the SAC Forum (Software Audio Console). This design is based on the Dayton PA460-8 18" driver. I built 2 of these, ran some sweeps with REW, and asked him in PM if he'd like the data posted anywhere...he suggested this thread.

His design allowed the cabs to be deployed standing upright or laying down, mine will be permanently mounted standing upright, so I did use additional ply to close off the portion of the mouth that is blocked by the floor in that orientation.

My cabs are 3/4" birch ply, latex painted internally, and coated with Line-X externally for continuous outdoor life. I used 1/2" expanded steel as a grill, with grillcloth behind to keep rain splatter from reaching the driver easily.

Testing method:
Outdoor measurements in a park, no buildings within 100 yards
Amp output set to 28.3V at 100Hz with no load other than the meter.
DBX reference mic 1' off ground at 10 meters distance from cabinet.
Allen & Heath mixwizard used as Ref mic Preamp. REW loopback also passed through A&H
SmaartLive and REW both calibrated to match Radio Shack SPL meter at same position as reference mic
Results of 4 sweeps 20-1KHz on each cabinet averaged as single trace.
Tested: Both JBell SS18, Dayton 460-8, red/orange traces
2 Cerwin-Vega T36-750 as a 'control', blue/green traces
Frequency Response and Phase plots attached

Further data from single SS18 (Though I don't honestly know if these following plots have any validity when performed on distant measurement methods...they're still pretty)
Group Delay, Decay, Waterfall

BTW: a great sounding cab, based off of a wonderfully inexpensive driver, and one of the simplest I've ever built.
Attached Images
File Type: jpg jbell vs t36 fr.jpg (91.4 KB, 428 views)
File Type: jpg jbell vs t36 phase.jpg (98.8 KB, 411 views)
File Type: jpg jbell ss18 dayton pa460-8 gd.jpg (62.1 KB, 369 views)
File Type: jpg jbell ss18 dayton pa460-8 decay.jpg (148.8 KB, 368 views)
File Type: jpg jbell ss18 dayton pa460-8 waterfall.jpg (151.6 KB, 366 views)

Last edited by Trackzilla; 10th July 2013 at 06:14 AM.
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Old 10th July 2013, 06:52 AM   #1945
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Hi Zilla,
Could you clarify a bit,,,
  • This is two cabs at a time or one?
  • Are there any filters or EQ?
SPL seems way low IMO.
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Old 10th July 2013, 08:16 AM   #1946
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Each trace is a single cab.

There is no EQ, no filters, no nuttin 'cept signal, power amp, speaker, mic.

I suspect my calibration may have been off by a couple of dB as I was using a borrowed Rat shack meter (couldn't find mine) and repeated previous tests with the CVs as reference show the peak between 90 & 100 Hz to be in the 108-110 range they advertised for those cabs rather than the 104ish I got here...So I bet we can safely assume that I'm slightly under the actual performance.

Last edited by Trackzilla; 10th July 2013 at 08:21 AM. Reason: checked previous t36 data
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Old 10th July 2013, 12:42 PM   #1947
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thanks for posting measurements -- appreciate it.

BTW -- for anyone wondering, no this is not an 18" driver stuffed in the typical ss15 cab.

The request for this cabinet design was cheapest/simplest/most output possible. (emphasis on cheapest) It's basically an up/back singlesheet TH with a dayton driver. Better drivers give more output, however I think this driver/cabinet hits the original target quite well. (hey it hangs with a T36-750 without the T36's rising response you have to eq flat)

Last edited by jbell; 10th July 2013 at 12:51 PM.
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Old 10th July 2013, 04:43 PM   #1948
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need layout and cut sheet please for the ss18..
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Old 10th July 2013, 04:45 PM   #1949
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Where can we see the plans? Thanks
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Old 11th July 2013, 12:53 AM   #1950
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second the request for a plan (and cutsheet - if there's one available) for the SS18 - one sheet cabs are perfect things
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