Pano's graph shows about 360 degrees rotation from 20 Hz through 100 Hz. I think mine had several more. Need to check what's happening. I haven't played around with the port tuning. I'll do it over the holidays.
I blame the drivers. I'll try some other 15" woofs to see if it changes anything. Have some 2226s lying around.
I blame the drivers. I'll try some other 15" woofs to see if it changes anything. Have some 2226s lying around.
My mod, to a friends A7.
They did get stood up, but not in this room...
Now in service in another friend's house.
The original client/friend wants it back from the second, now that he has become more experienced and heard it at the second's place!
The A7 *definitely* needs much work, the walls stiffened (I doubled them up) and the horn flares backed with something solid.
Again, I used a different non-Altec driver to better match the T/S requirements in order to get down to ~35Hz flat, not counting any room lift/effects. The game is to maintain enough sensitivity and still do this... of course if you are not married to low power tube gear for the bottom section (the second owner is not) then the sensitivity issue goes quite away. The horns seen are good to 300Hz, so the A7 box *actually* is not used per the original design - i.e. the horn flare is actually a hindrance, not an asset! But it does have the major advantage of a physical setback of the acoustic center of the woofer to match the acoustic center of the horn!
My measurements say the horn flare's effect is gone completely at 100Hz. Lift I found to start >200.
They did get stood up, but not in this room...
Now in service in another friend's house.
The original client/friend wants it back from the second, now that he has become more experienced and heard it at the second's place!
The A7 *definitely* needs much work, the walls stiffened (I doubled them up) and the horn flares backed with something solid.
Again, I used a different non-Altec driver to better match the T/S requirements in order to get down to ~35Hz flat, not counting any room lift/effects. The game is to maintain enough sensitivity and still do this... of course if you are not married to low power tube gear for the bottom section (the second owner is not) then the sensitivity issue goes quite away. The horns seen are good to 300Hz, so the A7 box *actually* is not used per the original design - i.e. the horn flare is actually a hindrance, not an asset! But it does have the major advantage of a physical setback of the acoustic center of the woofer to match the acoustic center of the horn!
My measurements say the horn flare's effect is gone completely at 100Hz. Lift I found to start >200.
Attachments
Do you mean original VOT only 100Hz ???
cheers
The original VOT was the 'A' series dual 15" ~70 Hz flare frequency reflex vented horn, while the later 800 series is a single 15" ~100 Hz variant. As such, each has an F6 around a half octave higher and 'on the pipe' at ~ one octave.
GM
thanks GM,
VOT of mine friend has 1 wf only 416/8????, do not remeber, remagnetized.
so only 100 Hzcut off 24 dB/oct??
You're welcome!
No, just the mid horn's output, the vent extends the reflex cab's tuning [Fb] down to whatever frequency you want as Pano stated, though at a significantly lower efficiency that rolls off with decreasing Fb.
GM
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