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In my latest Model 19-like enclosure, I'm mounting a pair of reconed drivers with a Q of 0.45. VAS is 23 cubic ft. The FS is 21.5 Simulations show really nice response in 10 cubic feet sealed. My guess is that lining the enclosure walls is sufficient; no additional fill. Any input would be appreciated.
thanks
Les
Hi Les- if they aren't Altec speakers you'd be better off in a general audio forum. I wouldn't call those 416 clones based on just what you provided. Have you exercised them? The cones will break in and the specs change. You need to work with what the speakers are after break in, not what they are right after reconing.
I would just add that in my recent experience there is something to be said for firmly and uniformly attaching the damping material to the cabinet walls.Quote:
My guess is that lining the enclosure walls is sufficient
Hi Old Guy. These used to be 421's. I reconed them into 416. Did your brother not provide me with a 421 frame?
Hi Bowtie. Attaching the fiber glass firmly was where I was heading.
Quote:
Originally Posted by les winter
Hi Les,
- How are you measuring the TS parameters of these hybrids ?
- Who made those recone kits ?
cheers <> EarlK
Hi Earl.
I used the DATS system from Parts Express to make the measurements. I used the test box method for the Vas.
The recone kit came from the Speaker Exchange in Tampa.
My two cents. In my experience, if the woofer is being used up into the midrange, filling the box with absorbent material (I use Acousta-Stuf) helps eliminate any "boxy" sound. I also use acoustic foam (the 2" wedge sort) glued to the walls.
So they used the GPA kit listed on their website? Speaker Exchange | Altec 416-8A DIY Recone Kit
Full DATS specs please?
FWIW, I calculated the M-19?s net Vb as ~8.353487847 ft^3 using 416A/802.
Using the Margolis-Small T/S design routine, these specs equate to a ~0.8 Qtc using a minimal lining of 1? acoustic fiberglass insulation [AKA duct board], i.e. bottom, one side and back of the bass cab, though for the M19, mounting it at the top to isolate the horn cab as well as all sides inside it is what I?d try.
This is a slightly under-damped alignment though, which more often than not is acceptable to most, but I recommend experimenting with heavy stuffing to theoretically lower it down to as low as 0.7 Qtc and for folks like me that are willing to potentially trade some mid-bass ?slam? for a ?heart attack fast?/critically damped 0.5 Qtc [higher F3], experimenting with a ~aperiodic alignment [heavily stuffed/vented] may be worth the effort.
Note that the latter theoretically has much better power handling down below driver Fs, so the best option overall if pipe organ symphonies and/or movie LFE playback is desired.
GM
Quote:
Originally Posted by les winter
Sorry that wasn't clear from your post. They should be "similar" to 416's. The magnet difference will have an effect.
I think GM is on the right track. Go for best LF not best efficiency, as the back vented assembly should handle more power. Just crank them up.
HI GM.
I made the cabinet a little deeper to get close to 10 cubic feet. Here are the DATS t/s:
re 7.638
fs 21.5
qts .459
qes .496
qms 6.197
le .448
mms 151.9
vas 23.19
I measured the vas in a 3 cubic ft test box.
I do not know if the kit was sourced to Speaker Exchange from GPA or not.
Old Guy: I taped off the back vent; the recone kit came with a vented dust cover.