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https://www.hostboard.com/forums/hbm.../2021/04/7.jpg
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with grille cloths(marshall bluesbreaker gray)
https://www.hostboard.com/forums/hbm.../2021/04/8.jpg
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I’m witholding judgement until the system gets moved to its new home later this year but:
-it sounds great
-i wonder what larger altec sectoral horn would get me safely down to 300hz...
329A or 311-90
Thanks, will these horns properly couple the 288 down to 350hz?Quote:
Originally Posted by Old Guy
Would I still need to consider a higher filter than 12db?
Didn?t you have a pair of the 311-90s? :)
It depends on the max power it will likely 'feel' since these horns at a ~220 Hz cutoff are way too short for true 300 Hz loading and barely long enough for their 500 Hz measured ratings [1 WL effective path-length]. Ditto 300 Hz multi-cells.
In short, the 300 Hz rating is about pattern control [polar response] over a wider bandwidth [BW] to a lower frequency [Fc].
Edit: My [failing] memory caught me out. :( Went back and pieced together the [assembled] dims and all the [3] suffix multi-cell horns have sufficiently long path-lengths for the claimed 300 Hz rating.
Spot on that you will lose some pattern control. 24 Db/octave helps. The octave down is 150 Hz, should be around 12 Db down at 220.Quote:
Originally Posted by GM
Another option is the one I PM'd awhile back, i.e. a horn baffle large enough to support 300 Hz that combined with reduced power should suffice.
thanks gm...Quote:
Originally Posted by GM
How high the moon...err how big the baffle. :)
I would be okay baffling left and right to the edge of this design but how high above the 511e?
...depends on the xo freq and the xo slope and how hard it’s driven...in general not a fan of steep xo points but willing to try
OK, how wide is the mids box?
outside dimension width = 36”(3 ft)Quote:
Originally Posted by GM
Well, we're basically dealing with a 1 WL of 300 Hz/4 = 75 Hz = ~58" dia. wave, so ~29" from the horn centerline down will drape over the mids and part of the subs, so ideally need to square them up and use closed cell foam insulation or similar to seal the joints, then a 36" w x 36" rounded up and seal the horn/baffle joint.
This might be sufficient, but it's now going to reinforce some part of the sub's, mid's output, so it ideally needs to be well braced, recommending 'boxing' the horn in [open back] to the depth of the mids cab and placing concrete bricks or similar on the bottom plate to mass load it. Better still, Velcro one or two to the horn.
Reinforce the back perimeter, toss in enough damping to mute any hollow sound and the sum total will for sure load to < 75 Hz, which would need to be measured, but a basic pipe end correction would be ~29" x 0.613 = ~17.8"+ ~181 = ~198.8" = ~13543/198.8 = ~68 Hz, so pretty confident it will load at least this low as the sides of the mid/tweet cab will contribute some also even though at 90 deg.
I have read this through a few times and understand what you are saying...thank you...great info!Quote:
Originally Posted by GM
Stepping back a minute there’s a fellow who makes what ha calls 300hz horns...markus horns.
This one I liked...
https://www.hostboard.com/forums/hbm.../2021/04/9.jpg
https://www.hostboard.com/forums/hbm...2021/04/10.jpg
this has fewer cells:
https://www.hostboard.com/forums/hbm...2021/04/11.jpg
You're welcome!
No dims, but just eyeball scaling using the driver sure makes them look like 500 Hz to me and of course the baffle will work with it too, just need more work to seal it up. Beautiful workmanship for sure!
I wanna say the 1st pics are 805B’s ?Quote:
Originally Posted by GM
Facsimiles, not Altec built.Quote:
Originally Posted by Steve Mac
I see what theyve done....the Fc is 300 HzQuote:
Originally Posted by GM
I thought about something @GM said about the machining at the throat...Quote:
Originally Posted by bowtie427ss
In the examples shown I could see no pics at the throats of those wood horns and that’s what is most concerning about the design. Maybe it’s great, but I have no idea...
In particular, his words i remember most are in reference to, and the importance of the entry of each cell and the partition between cells being free of acoustically reflective surfaces, also a classic Emerson, Lake, & Palmer tune...Quote:
Knife Edge.
https://www.youtube.com/watch?v=TQQdYokbp4E
Right, as critical as it is to seamlessly line up a 511/811 throat to the driver for max [smooth] HF extension, just think about a bunch of round/square/whatever throats dumping into a collector [low pass filter] that in turn adapts to the driver!
Once I learned from experience just how critical it is, I had a much greater appreciation that these huge horns/drivers could top 12 kHz at high SPL at a time when 8-9 kHz was the max available signal.
Wish I still had the pics of the super rare Jensen [32] cell/500 Hz horn; talk about attention to detail! Must have been made by pocket watch and/or 'sailing ship in bottle' craftsmen.
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One thing I've noticed is that all these [installed] wood horns have super tweeters [not to mention they are typically offered by said wood horn manufacturers as a set], so assume the throats, etc., quality are more typical of large PA horns [~ 8 kHz upper limit].Quote:
Originally Posted by Steve Mac
I’ll take two please. :)Quote:
Originally Posted by Old Guy