I've seen talk on the net about the function of the upper chamber in the Model 19. Specifically that it was a reverberant chamber. In one of my shop built enclosures, I did not join the upper and lower chambers. Other than further extending the bass, am I missing something? If I am, is the size of the opening between the upper and lower sections critical?
Technically, it's an acoustic band-stop filter, which normally is used to notch out a peak in a signal's response and while I haven't modeled it, it seems more a byproduct of the desired 'look' than intentional performance tweak since the net volume [Vb] combined with large vent area [Av] of it implies a very high tuning, not to mention I've never seen/heard anything from Altec about it, so apparently of no marketing benefit. In short, a doubled tuned reflex.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Thanks GM. I figure 3-4" holes would do it. You agree?
???
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
I meant 3 4" holes in the underside of the upper cabinet and the same in the lower; the cabinets separated by the specified riser/throat.
You're welcome!
Well, this will tune the resonator [horn box] lower than stock due to the vent will being smaller. Since this is a simple Helmholtz resonator its tuning [Fb] can be 'ballparked' with an online calculator, but can't find my notes where I calculated its net volume.
Ideally need to measure your two to see how it affects the frequency response.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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