Acoustic damper pad

[Nickd]

Was there a 2" fiberglass bat between the boxes in the M19 box? Or perhaps some other type of pad / resonance trap?

It is mentioned in the service information of the manual. I was just going to line the upper box with insulation.

[GM]

Don't recall seeing one and if I interpreted the assembly notes correctly, none was called for: Vintage Altec Lansing Model 19 Cabinet Plans

GM

[Nickd]

Thanks GM,

I checked the plans, but they were not clear. That's kind of what brought up the question. I have never seen inside an original un-disturbed box. The plans call for lining the top sides and back of the upper horn box with 1 1/2" fiber glass stapled down.

The "service information" on page 2 of the manual says "the horn/driver assembly is accessible when the acoustic damper pad is removed" upon second read, I think it may be referring to a fiber glass bat stapled to the inside of the top box around the horn mounting bolts. That is not called out in the plans either?

as I understand the horn mounting, it is screwed in from the inside of the top box, I do not think they were talking about the "foam" fitted to the outside front of the horn box, but not sure on that either.

I still think originally there may have been a pad between the two boxes acting like a resonance trap? It is not mentioned in the plans though. I seem to remember reading that the some of the Altec cabinets were built by subcontractors. Maybe the drivers were installed at the factory and the pad installed at that time?

[juniper]

My M19s have no pad and all the pictures of 19s I have seen apart I have never seen one.

[GM]

All I can say is that I had a DIYer's relationship with the local distributor that among other things allowed me to audition any new/whatever speakers, components and neither the sales prototypes nor the few I was exposed to early on had them, though over time I noticed the scrim to hide the stuffing disappeared in later units bought/sold by CMC Stereo as did at least some of the horn foam inserts.

Regardless, the cab acoustically is a crude dual chamber reflex, so not sure I'd want to damp down what little mid bass boost it offers, though I always damp the horn for any HIFI app to a greater or lesser extent depending on how/where it's mounted.

GM

[Nickd]

Good info GM,

I will just do a nice job dampening the upper box and horn. Nice to know some of you guys were listening back in '76. Now I don't feel so old.

[GM]

Some of us a lot longer..........

GM