ALTEC 815 cab mod

[leifchristensen]

hello
I?m playing with the thought of having built a pair of 815 bass horns
I have an experienced cnc equipped speaker builder,who can make them in 24mm Birch Plywood with laminated horn flares
BUT I?d like to make them as small as possible
when scrutinizing the drawings in top view, it looks as if the 2 square areas in the back corners of the cabs are "blinds", and just a function of the rectangular box, and that they?re not a part of the back chamber for the horn drivers
if so, I?d like to omit them and just "stretch the sides of the rear chamber forward til they meet the back side of the curved horn
thus the whole box in top view would look more like a horn shape and it would require less space
any opinions?
best
Leif

http://www.altecpro.com/pdfs/vintage...net%20Plan.pdf

[bowtie427ss]

815 isn't really what i'd call a bass horn, more of a mid-bass horn. 815's output from 100hz to 1000hz is impressive("acoustic sledgehammer" comes to mind) and will challenge a user to fill the octaves above and below with equipment that can dynamically track the 815's output.

I think a trapezoid shaped box would be more practical in terms of weight and packing volume, it also provides support for additional bracing behind the horn flares(needed). Beyond that, i think there's little to be saved or gained by altering the original design. Some folks are likely want to experiment with coupling that unused internal volume, or portions of it to the woofer chamber.

In terms of H, W, and D, they're large and are a challenge to get thru many standard doorways.

Depending on your end goal, there might be better ways to employ the quantity of material required to build a pair of 815.

Just my .02..................

[leifchristensen]

hello
thxs for answer
the midbass horn of the Trio is 95cm in dia and not much smaller but in my room it start to roll off at 140hz and not the claimed 100
a better way to stack those materials...like how?
best
Leif

[valhallax]

leif... double your subwoofer order and go with the 815. its mid bass heaven and an altec design. bowtie summed it up perfectly, and i'll agree on the standard door part, my 210's almost need grease to get through a 3'0" door

[leifchristensen]

hello
my woofers are solid as is:
4 x 15 inch BD-15 in 2x 380 liters vented enclosures per side
efficiency 103db@25hz
ETA Norway before Easter
hope I don?t break any rules here:
Forum at BD-Design - Less is more...

best
Leif

[Old Guy]

The only issue I can see is the driver box isn't as wide as the horn so the sides will be angled. Not a problem for an experienced cabinet builder.

Don't truncate the with of the horn it will hurt the sound.

[leifchristensen]

could the 815 be split like the 210 and what would the implications be?
standing up with only one 15 incher? the original is marginally too wide...maybe?
or does anyone have a cabinet/horn plan for fronthorn w/o refleks for single or dual 15 416B/515-G that?s narrower in the rear(and wider in the front if necessary)
best
Leif

[valhallax]

dont quote me but i think the 815 is a 210 with out the reflex portion of the cab. in our search area lokk up mid bass horns. there was a nice build there about a yr ago, one of our members did. other than those, one would have to retro a 815 or 210 cabs, about a weeks work, letting the glue and paint dry sufficiently

[GM]

4 x 15 inch BD-15 in 2x 380 liters vented enclosures per side
efficiency 103db@25hz

This assumes a lot more room gain than is typically measured............

GM

[leifchristensen]

I don?t think the 815 equals 210 w/o the ports
: the 815 is 111cm high and 210 w/o ports would be 172cm,besides the 210is 100cm deep and the 815 is 82cm,so 210 must have a wider and longer flare, or did I miss something?
I think he gets more output by having the drivers so close and the stuffing makes the cabs seem bigger to the drivers.the cabs are filled with sheets of stuffing
his previous design was very good and I lived happily with it for several years,but wanted more output,so no of drivers and amps are doubled
best
Leif