Just checking in to see if anyone has recommendations or experience in powering an 8256 cab (aka A6, with 2 x 3156 LF).
I'm thinking of using one side of a 9444A to do so(and hence the other side to run the 299, as this will be electronically XO'd) but am concerned it may be a little under powered, with its 300W at 4 ohms, vs the power handling of the 8256 being rated at 500W.
Any thoughts?
Nat
I suspect if you drive the amp to clip in your living room, you won't hear the distortion, as you will now be deaf.
Your neighbors called. They like your music.
.................... and have a bunch of broken nick knacks to clean up and pictures to straighten.Originally Posted by Old Guy
Not all vegetables make good leaders.
Hmm, based on published specs, dual 3156 have a calculated ~104.37 Sens [dBv] base voltage sensitivity and the 9444A has a published 32.6 dB dual mode voltage gain [Vs a calculated ~34.64 dB] = ~136.97 dB/m, so ~37 m [121.4 ft] back from an outdoor movie screen one can enjoy it at THX reference.
If we assume a 500 W amp is derated by the same amount, then it has a 42.09 dB dual mode voltage gain [Vs a calculated ~44.72 dB] = ~146.46 dB/m or ~118 m [387.2 ft].
Really significant for prosound apps, but otherwise not so much, plus factor in thermal power compression at 500 Vs 300 W and the gap could narrow significantly.
I?ve no measured thermal info on any Altec woofer, so no clue what reality might be, but info on some older ferrite JBL woofers indicates that most, if not all [and them some], of the difference would be ?burned? off.
When you go back to the AlNiCo and into the beginning of the ferrite era, drivers routinely began compressing at as little as 20% rated power and 3-4 dB down at half power and why so many drivers were required just to do basic PA without having to worry too much about the cost/inconvenience of replacing drivers high overhead.
Anyway, short of doing your own measurements, no way to know for sure.
So, what?s the app?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
The intended use is portable cinema (3 stage channels), generally in mid sized cinema rooms, with the occasional outdoor gig, where my single 15" and horn won't quite cut it. Its not rock n roll high level stuff.
Even the outdoor gig is half the throw than what you mention GM, so I'm sure I will be fine.
Given I can choose a LF cut off frequency of anywhere from 40-100 Hz, I can always trade off some LF in any case. Dolby would like you to run down to 45-50 Hz on the stage channels in an ideal world, but 60 Hz is no real sweat, given the real oomph is from subs.
Whisper has it that the power rating of the 9444A is rather conservative anyway
I like the ability to use the 15881 plug in module in the back of the 9444A for XO, its ideal for temporary cinema setup like this. 8256 Lf, 299 HF.
Previous to this Altec setup I had dual JBL 2226, which love lots and lots of power, with less efficiency though than the 3156.
With a published 38 Hz Fs, just re-tune the cabs to 45 Hz then and since you have power to ?burn? @ 300 W, EQ flat by shelving down [lowering mains effective efficiency].
5? i.d. dia. PVC x 3.75? [assumes ?? baffle thickness] will get you close enough based on published data. Make ?? plywood mounting flanges and screw/through bolt the assembly on with a thin gasket to ensure a good seal.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Great idea, thank you!
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