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Multi-Way Conventional loudspeakers with crossovers

Subwoofer for an VOT A7
Subwoofer for an VOT A7
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Old 6th July 2020, 07:43 AM   #41
jakruby is offline jakruby  South Africa
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So seal the 416 into the "upper" compartment. Mount a woofer in the new "lower" compartment and all of said woofer's output will exit through the port. What kind of enclosure would that be? Surely you would want some direct sound from the woofer and use the port to augment lower end?
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Old 6th July 2020, 12:54 PM   #42
Pano is offline Pano  United States
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Subwoofer for an VOT A7
You're half way there.

Close off the woofer into it's own small box. Like putting a partition just below the woofer horn. Now you have the whole lower box (maybe 10 cubic feet) to use has your subwoofer enclosure. You replace the front baffle with a new baffle that has your subwoofer driver in it, along with the new ports you need for that subwoofer. Just like any normal bass reflex cabinet.

Your 825/828 cabinet now has two chambers. An upper chamber that contains the woofer and its horn, and a larger chamber that is your subwoofer.
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Old 6th July 2020, 02:18 PM   #43
Pano is offline Pano  United States
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Subwoofer for an VOT A7
This is where a picture might be worth its 1000 words.
You would add ports to the lower section if doing bass reflex.
Attached Images
File Type: png A7 with sub.png (15.4 KB, 72 views)
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Old 6th July 2020, 03:17 PM   #44
Pano is offline Pano  United States
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Subwoofer for an VOT A7
Here is a more accurate drawing and more to scale.
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File Type: png Altec-A7-with-sub.png (29.7 KB, 68 views)
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Old 7th July 2020, 02:49 AM   #45
GM is offline GM  United States
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Old 7th July 2020, 02:59 AM   #46
GM is offline GM  United States
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Quote:
Originally Posted by jakruby View Post
So seal off the front of the horn and just use the port?
I knew sure as I didn't post a link, someone would misunderstand.

Unfortunately, the original threads are MIA and some of these may be duplicates, just copied what I could quickly find doing a search of me [GM] and [2245] for the ones done using the JBL 2245H since at that time the Altec 411 I used was basically MIA since GPA couldn't do a proper recone even if a motor basket could be found, so in no particular order:

Getting more bass out of 825-828 cabs

would a 411 8A make a good speaker for a sub?

A7's with subs?

A Frenchman's version: Altec voix du Theatre A7/A5 anybody done this?

What to do with Altec A7 cabs..? | Audiokarma Home Audio Stereo Discussion Forums

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

http://www.hostboard.com/forums/f700...light=jbl+2245

Only picture I could find: https://www.hostboard.com/forums/att...l-2245-sub-jpg

GM
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Old 8th July 2020, 07:04 AM   #47
jakruby is offline jakruby  South Africa
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Excellent resources - thank you
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Old 8th July 2020, 09:14 PM   #48
freddi is offline freddi  United States
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Subwoofer for an VOT A7
Exemplar's solution to a subwoofer which "kept up" with their VOT-like horn/reflex speaker, was to use the old Karlson K15 cabinet with low fs Altec 515 and for original K15, make a port adapter using two 3 inch ID right angle "Street El" (I used regular PVC elbows)
K15's original port was 9 inches tall by 4.5" wide them narrowed in 1956 to 3.5" width so the port adapter is a perfect fit.

I can't understand what the front chamber involvement would be in the sub frequencies but it sure sounded really good and adept with my 4168Z and a 15 watt per channel JC Penny receiver on theatre organ recordings using a Behringer analog xover. (the high frequency speaker was a Karlson "12" with wimpy Knight coax (which had a pretty midrange - but impact was like a Nerf ball-bat against a feather pillow)


swivel those vents to so they are parallel with the shelf for better looks and clearance

some of the magic must be from the Altec having lower mass than many of today's speakers whose fs is in the 20's

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

Last edited by freddi; 8th July 2020 at 09:18 PM.
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Old 8th July 2020, 09:56 PM   #49
freddi is offline freddi  United States
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Subwoofer for an VOT A7
that is a cool idea to close off behind the woofer as a regular FLH then use the huge volume for a sub of sorts

Here's a 56 liter back chamber

Click the image to open in full size.
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Old 8th July 2020, 10:56 PM   #50
GM is offline GM  United States
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Quote:
Originally Posted by freddi View Post
I can't understand what the front chamber involvement would be in the sub frequencies.........

some of the magic must be from the Altec having lower mass than many of today's speakers whose fs is in the 20's
Well, my factory 515Bs had a near spot on 20 Hz Fs from the factory, ditto the two I had re-coned by the distributor when asked to match their specs.

Anyway, as you know these are only ~2 octave devices, so for 20 Hz it's down many dB by 80-100 Hz unless coupled to a ~matching impedance, so the front chamber sets a BP's HF response above its tuning, ergo reduce its net volume [Vb] if wanting to flatten it out or to a rising response out to its HF corner, which is a good thing when matching up to a compression horn, especially if corner loaded.

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