How to install a foam lip on a 511

[Steve Mac]

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

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.

[GM]

You just missed them. Not to diminish your inventiveness, but pipe foam or similar horn 'lips' experimentation has been posted about on various forums for over a decade with quite a bit done after Charlie Hughes (Peavey, ex-Altec?) 'invented' the foam terminated 'quadratic throat waveguide' around 2000, then more recently when 'Patrick Bateman' and/or one of his several aliases re-invented it for some very interesting DIY horn designs for his Honda using soft rubber terminations IIRC. I assume a Google search will find them all.

Really, all these are functionally just variants of Henry Kloss's felt ring around the AR speaker's tweeter and to a lesser extent, the offsetting of drivers on a baffle to average out its eigenmodes, though I don't know for sure who 'invented' this variation.

Regardless, glad to see someone besides me around here taking a 'hands on' interest in selective damping of a horn's internal reflections (AKA Dr. Geddes's higher order modes (HOMs)).

Absolutely, so many come to the DIY forums with their 'hands out' to primarily save $$$, but for me it's always been about getting the performance I want instead of just accepting the status quo of a particular price range.

I haven't done, nor am I aware of, any cloth covered foam/whatever termination experimentation, but it seems reasonable to me that it would mimic felt to some extent with the right cloth weave, so probably worth trying.

WRT damping the vanes, these act as HF dispersion reflectors, so any damping of their flanks will reduce off axis HF response. Since you're using a super tweeter though, wrapping them with absorption along with damping the vertical internal sides of the horn to at least the same depth as them same as me and a few others have experimented with might improve its clarity through the XO BW if you can find the right absorption factor to cover it.

The global approach of tightly stretching double knit cloth over the horn mouth has subjectively sounded good to me, so hope to pursue it further along with the two stage foam plugs currently in the 511s once I get them back on line.

Right on! A lot of horn 'honk' is due to all these various reflections, though IME, throat restriction is the worst villain and why one either has to XO a typical horn well above its design cut-off like was done on the M19, 9842 and later A7s along with the selective damping or swap it for a pure WG and foam plug, both of which still need CD horn EQ if used wide range with no super tweeter.

GM

[bfish]

Here's how Peavey does it;



(90x40 800Hz 1.6")

[Steve Mac]

You just missed them. Not to diminish your inventiveness, but pipe foam or similar horn 'lips' experimentation has been posted about on various forums for over a decade with quite a bit done after Charlie Hughes (Peavey, ex-Altec?) 'invented' the foam terminated 'quadratic throat waveguide' around 2000, then more recently when 'Patrick Bateman' and/or one of his several aliases re-invented it for some very interesting DIY horn designs for his Honda using soft rubber terminations IIRC. I assume a Google search will find them all.
....
GM

Wait...what I was referring to is a technique for getting a foam lip easily onto an altec horn. I've seen the work on the net by these gentlemen which is inspiring but unless you can hack easily and reverse when you screw up, experimentation is difficult.

[Art J.]

Wait...what I was referring to is a technique for getting a foam lip easily onto an altec horn. I've seen the work on the net by these gentlemen which is inspiring but unless you can hack easily and reverse when you screw up, experimentation is difficult.

Since I stirred the pot here, I would like to add that I like working with felt fabrics for a
project like this and many other types of projects. Its good looking and easy to work with.
That along with 2 sided carpet tape make the job neat looking and easily reversible if needed.
I've done my share of experimenting with horn damping with only subjective results that are
questionable but I want to be supportive of anyone looking for improvements.

Felt

[Altec Best]

How much of a difference does it really make though ? Are we talking big or slight differences ?

You do a nice job Steve, Thanks for all the Tips !

[Steve Mac]

How much of a difference does it really make though ? Are we talking big or slight differences ?

You do a nice job Steve, Thanks for all the Tips !

You're welcome. We're all here to help each other...maybe confuse sometimes...but eventually we get there.

My ears say big difference. But I have a question for GM...

[Altec Best]

You're welcome. We're all here to help each other...maybe confuse sometimes...but eventually we get there.

My ears say big difference. ..

I have a few pair of the 511E so I would very much like to experiment with a set as I will be using a set to finish off my project... :2thumbsup:

Thanks Again & Happy Holidays !

[Steve Mac]

Since I stirred the pot here, I would like to add that I like working with felt fabrics for a
project like this and many other types of projects. Its good looking and easy to work with.
That along with 2 sided carpet tape make the job neat looking and easily reversible if needed.
I've done my share of experimenting with horn damping with only subjective results that are
questionable but I want to be supportive of anyone looking for improvements.

Felt

Thanks...my gut tells extending the bell plus fabric overlay should have a positive result.
My first thought about fabric is that there are two orientations...
1) fibers parallel to surface...like in felt
2) fibers orthogonal to surface...like in a velour?
...don't know which one...but it seems reasonable to consider