816 flare vs 825 flare

[MERDY]

hi all and Hny
in process of rebuilding and making about 16 flares of the 816 cab i noticed the dimensions to be not the same as the 825 flare ,the 825 which has a sloping side is about 3 in larger which makes the 816 a 200hz flare and the 825 a 150 hz flare, of course its documented on some old lit i saw on the lansing heritage site

i apologize to any one if i have said it was the same,

this week i have been listining to all kraftwerk remasters , they sound greaty on the altecs

[Audio_by_Goodwill]

hi all and Hny
in process of rebuilding and making about 16 flares of the 816 cab i noticed the dimensions to be not the same as the 825 flare ,the 825 which has a sloping side is about 3 in larger which makes the 816 a 200hz flare and the 825 a 150 hz flare, of course its documented on some old lit i saw on the lansing heritage site

I didn't think the height mattered so much? I've compared the 825/828 flare to my 816VIX, and the 816 is a bit wider. I've never had access to an earlier 816, Though. Depth was eqaul......14 inches, I think.

[MERDY]

i wonder how many versions of the 816 were evolved over the years can folks who have them get the measuring tape out
altec owners have huge measuring tapes dont they?

music for today sade new album to be realesed in feb
its disco

[Audio_by_Goodwill]

i wonder how many versions of the 816 were evolved over the years can folks who have them get the measuring tape out
altec owners have huge measuring tapes dont they?

A, B, C (I think), and VI/VIX

[GM]

I didn't think the height mattered so much?

Every horn dim matters. The throat area sets its HF corner and its mouth area combined with its end correction sets its LF corner with the length + end correction setting its 1/4 WL cut-off and last, but not least, its flare sets the shape of its pass-band response.

So from this we see that for a given driver the 825/828 with its exponential flare to a larger mouth will have a wider, flatter gain BW than the parallel wall 816 of the same width which is clearly shown here: http://www.lansingheritage.org/image...515g/page3.jpg

GM

[Audio_by_Goodwill]

Every horn dim matters. The throat area sets its HF corner and its mouth area combined with its end correction sets its LF corner with the length + end correction setting its 1/4 WL cut-off and last, but not least, its flare sets the shape of its pass-band response.

So that would mean that a split 210 won't go as low as a unmodified 210, even if the reflex issue is ignored, correct?

[GM]

Correct, it will have the same cut-off, but a higher F3, ergo a lower Q roll off, same as the 816 Vs 825/828 does and since its throat is smaller it will have more HF gain BW. Both of these things makes it a better choice over the 210 for a typical HIFI/HT app since the former tends to blend better to the room's gain curve and the latter combined with the higher frequency eigenmodes (standing waves) that its narrower parallel walls cause yields a smoother/flatter response when >500 Hz XOs are used.

The 210 OTOH was designed for a 300 Hz XO, so unless the woofer is designed to fill in between where the horn rolls off and the driver's break-modes BW has ramped up enough to extend its HF BW there will be a dip in its response, which again, is clearly shown in the 210's 'swayback' response between ~300-500 Hz since the 515-8G has been optimized for the smaller 'bass' horns.

GM

[MERDY]

Thanks GM just the answers i was lookin for on the 816, and on the split 210 i still use ,its f3 is about 70 hz sealed and maybe 50 hz in br,estimated volume about 12 cubic foot
the 210 on its own is a completly different animal ,i use the split horiziontally on 4 inch pedstel with a 300hz horn at 500hz crossover
in both cases the getting the transition from lf to hf is key in the box flares
some old measurements and will find some more between my very old laptops etc
so much to learn

favourite new cd Fever Ray from the sweedish band the knife