Model 19 Acoustic Inserts on ebay-what's is it?

[sura]

I haven't seen these before. Anyone know about them? What are they supposed to do?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140018705093&fromMakeTrack=true

[Mr. Widget]

They replace the original factory foam inserts that came on the Model 19 and rot out after many years.

http://audioheritage.org/vbulletin/showpost.php?p=120802&postcount=13


Widget

[Gary L]

This is another one Widget that I never found to make much difference at all.
The original foam, similar to what Tempurpedic beds have turned to mush after alot of years. I removed it and never replaced it.
I have seen these inserts on the auction site many times and they appear to look like the originals but are simply just foam so not sure they would meet any Altec Specs if any such specs exist.
Same as the horn ring question in another thread, Do these do anything at all?????
Was the foam originally put in by Altec an attempt to address the RING question?
My 19s sound fine with or without this foam so it would take a great pair of ears or some sophisticated measuring devices to scientifically prove their value.
I do wish I had asked Altec back in the mid 1970s what the purpose/benefit of this foam was.
Maybe someone here could locate the technical info about this?????

Gary

[Mr. Widget]

Hi Gary,

I guess you either didn't click on the link or aren't convinced by Don's statement... here, I'll post it so that no clicking is required.

"No, that foam has negligible impact on damping the horn. It is intended to address diffraction problems caused by HF reflections from the sidewalls of the enclosure that extend beyond the horn mouth." -Don McRitchie


It is the same as the foam ring that surrounded later L100 tweeters. Is the speaker's performance dramatically different when installed? No. Does it make a difference? To some extent in some listening circumstances. If you listen in a room that has no acoustic treatment, casually listening, you'll never notice these things... you'll never notice the possible improvements, or miss them if they're lacking... the effects of diffraction will be most noticed in an improved stereo image. If you don't have your speakers set up in an equilateral triangle with your head at the third vertex, you will miss much of this. Many casual listeners have the speakers almost randomly placed in the room and then go about their business walking to and fro and wonder what all the hype is about stereo...

Damping the resonance of these horns or controlling the horn/cabinet diffraction are acoustic refinements... they are not bold blazingly obvious changes that will jump out at you. Well, to some who listen critically with high end electronics in a well controlled room, they may jump out at you, but if you are cranking rock and roll and taking apart a carburetor on your couch, you aren't very likely going to notice the difference.;)

The last line was meant as a joke... I won't name names but I can imagine that at least one or two of our members have been there.

Beyond all that, the black foam is also an aesthetic improvement over having the horn simply stuck in a box.


Widget

[John]

but if you are cranking rock and roll and taking apart a carburetor on your couch,


Widget

Been there ,done that:bouncy:

[John]

When I installed a pair in my 19's the stereo image became more focused.
For the money I think it was worth it as well it gives a nice finished look to the horn area. If you just want the acoustic benifits I would bet stuffing that space with any foam would do the job and once you replace the grill no one would know?:p

[Gary L]

Just to add a bit to this discussion I found this pic while searching the auctions.
Sorry about the poor photo but this is the real Original Foam inserts that came in them.
If you were to pinch this stuff it would remain pinched and it is likely worthless at this point in time.

Hope this helps and I am very surprised to see it has made it this long and still in tact to this degree.

Gary
http://img.photobucket.com/albums/v722/Gamalot/19Foam.jpg

[majick47]

Does Sonofagun make these for Model 19 owners?

[JBLRaiser]

Damn, what gave it away?