Ya know I thought about this a long time and refused to believe there wasn't an easy way
that would not harm the horns and that would take less than 2 hours...
anyway that's how I am..
I'd rather take two years to figure out how to do it in a few hours.
I was on the right track but didn't think it through.
The pipe foam in Lowe's/Home Depot is okay.
Here's what I did:
1) take a dowel with foam and first cut a slice to use as a base...
this was what I finally figured out
http://www.steevee.com/images/foam1.jpg
http://www.steevee.com/images/foam2.jpg
2) apply it to the edge...
http://www.steevee.com/images/foam3.jpg
3) cut/shape attach the pipe foam to the edge plus the additional foam edge
http://www.steevee.com/images/foam4.jpg
http://www.steevee.com/images/foam5.jpg
The effect is appreciable...sounds like horn blare diminished. It sounds MUCH better.
This'll cost ya 10-20 bucks...hope someone finds this helpful!
hey steve...
thats sweet , think it'll work for multicells? i understand the theory and you've done a nice clean job. looks like a lil' pink left from the smoothing of the bores.. i was wondering if you did a before and after measurement? love your system..i say go big or go home
"those sounds to which no definite pitch can be assigned are usually classified as noise"<br />harvey fletcher-1928
The thing is...because it's reversible and because it takes a coupla hours...Originally Posted by valhallax
I say go ahead and experiment with the multi-cells. If it reduces any disturbance
at the lip it should help. Just make sure you do not overlap the lip.
I say that because I foolishly attempted this with bad result.
The shinny closed cell foam does not have acoustic properties like open cell foam.
Just thinking out loud............................
closed
Armacell 1/2 in. x 6 ft. Tubolit Foam Pipe Insulation - OEP05838 at The Home Depot
open
Thermwell Products Co. Inc. 1-1/4 in. x 3-1/2 ft. Foam Air Conditioner Weatherstrip - AC42H at The Home Depot
It's shiny...not shinnyThe shinny closed cell foam does not have acoustic properties like open cell foam.
Just thinking out loud............................
closed
Armacell 1/2 in. x 6 ft. Tubolit Foam Pipe Insulation - OEP05838 at The Home Depot
open
Thermwell Products Co. Inc. 1-1/4 in. x 3-1/2 ft. Foam Air Conditioner Weatherstrip - AC42H at The Home Depot
Anyway...
a) don't believe it's an issue if it extends the flare
b) no data to support that whatever type open cell foam used is "too open"
c) no data to support that whatever type closed cell foam used is "too closed"
But an easy technique for application would make it possible to experiment with
variants of pipe foam(not sure what to do with air conditioner seal) if they
could be sourced... And that keeps the hacker alive and the expense down.
Not shine-e ?
I never could write or spell correctly anyways and the spell checker lets me down too.
I didn't know if the objective is to increase the flair or to dampen turbulent edges.
I keep open cell foam in my Rube Goldberg box of parts for various damping needs.....
Well...this is good because I just thought of something that happened whenNot shine-e ?
I never could write or spell correctly anyways and the spell checker lets me down too.
I didn't know if the objective is to increase the flair or to dampen turbulent edges.
I keep open cell foam in my Rube Goldberg box of parts for various damping needs.....
I was applying the foam...there was a bar code price sticker and when I pulled
it off...the finish was pulled off and it was no longer shinny...shiney...shiny...shawnee.
...maybe I'll give that a try!
Just caught this...no I didn't. When I got the horns and saw how rough the insides
were I just decided to not bother even mounting a driver to them until they were cleaned up.
Depends on the desired performance goal(s). Way back when on the old basslist, me and Lee T. Niedow use to expound on the audible benefits of the < zero WAF tweak of adding foam horn extenders (to 'deaf' and/or derisive 'ears' IIRC), i.e. wrapping 'Trailpad' or similar open cell foam mattress pads around horns to damp mouth reflections back to the throat and roll off any spurious HF 'scatter'. In short, a much more extreme/aggressive variant of the M19's HF horn foam insert.
More recently, I've periodically suggested a slightly more WAF version using a large panel of it with a slightly undersized cutout for the mouth bonded to something very lossy such as insulation board to create a highly damped flat baffle horn extension, but to date I don't recall anyone other than me actually experimenting with such tweaks.
Then there's Dr. Geddes extensive research on waveguide (WG) foam inserts, choosing 30 ppi open cell foam such as used for fish tank filters for his products, though he starts with what he considers a theoretically 'perfect' WG profile, so doesn't need a lot of damping compared to the highly 'colorful' diffraction horns we know and love.
WRT multi-cell and sectoral horns, ideally they need a foam lens with undersized cutouts for each 'cell'. Just how 'undersized' and what density/thickness remains to be discovered AFAIK. Historically, higher end manufacturers spec'd grill design and cover properties to deal with the worst of it and provide the end user with adjustable HF to compensate somewhat for the HF loss incurred.
If dense enough for the BW, closed cell foam OTOH will in theory increase the horn's acoustic mouth size, increasing acoustic damping and controlling the horn's directivity to a lower frequency, but I don't see it doing much in the way of quelling mouth reflections/diffraction, so layering open cell on top of closed might be worth spending some quality time on experimentation. IIRC there's some products like this designed for mobile audio already on the market, though quite pricey IIRC.
All that said, most vintage spec 'hornies' prefer theirs out in the open with nothing obscuring their output, so I imagine well damped units though more 'accurate', will sound too 'dry' for most. Indeed, many folks who own or at least have auditioned Dr. Geddes designs describe his WG as being neutral to the point of transparency like a good ribbon or electrostat. Quite an accomplishment to my way of thinking. Not many 'free lunches' in audio though, so efficiency is no better than a CD compression horn EQ'd flat out to 20 kHz.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
In terms of experimentation...this is what I was most excited about.
A reversible...fast way to extend the flare...and that to date I have seen nowhere.
The thing I like about these forums and altec is that we can still build hot rods for
a fraction of what the walnut veneer experts charge.
One idea I'm considering is close to what you are saying here and I'm just throwing
it out to get opinions or experience. Now that the horn lip has been curled,
perhaps picking up some plush, black fabric.
1) Cover the edges of the vertical vanes an inch? or so
2) Cover the foam lip extenders with this fabric too...overlap an inch?
One thing I do notice with the foam lip extenders is that my ears detect less irritation/distortion.
...but not wanting to say too much without a good long period of experimentation.
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