Modified A Driver

"What's a tapped horn?"

Tom Danley gave the name "tapped horn" to a tapered pipe that is loaded some distance down the line.  Driver offset is used to manipulate standing wave modes above the first 1/4λ, to reduce the peaks and notches from higher pipe modes.  This helps smooth the response of an undersized basshorn.

If you really want to understand a loudspeaker system like this, see the work of Martin King at Quarter-Wave.com.  He has explored this kind of system in detail, and has models that accurately predict response based on driver parameters, driver/mouth position, length and taper.

• Basshorn or Transmission Line
• Actual verses expected performance
• Quarter-Wave.com

 

NeverWinter wrote: @Opus Jody - if i'm not mistaken, yes you are sending more amps resulting in higher SPL, but think of it this way...   say your 8ohm driver is already supplied it's RMS or lets say it's in it's safe 25% over RMS rated power *a little rule i follow my self*... no you're replacing thatt 8ohm VC with a 4ohm. now you are ofcourse ABLE to send much more current to the driver. but did you ever think about the fact that maybe some of that extra SPL is actualy harmonic distortions from too much power? or that maybe it could be distorted bass that is being dificult to detect?   not saying that what you are doing is wrong, but the "increase of SPL" could be something along those lines.   i've read that harmonic distortion can actualy make specific playable ranges seem louder to the human ear when it's really no diffrence from before. also on my own ears dealing with dual VC drivers, the diffrent ohm loads do help with SPL but alot of the time it's distortion escaping the human ear.   i'm also being extremely technical though too, if it even "seems" louder then what it really is, kudos! means the people there enjoying them selfs get a louder feel

The particuar examples i was thinking of were 1/ a double 24" reflex with2 x 1000w 8 ohm cones we tried, running off 2 x 2000w channels (2000 into2 ohms) where with one channel/cone would only give 500/600w into the 8 ohm loads, where as with 2 x 4 ohm loads, the amps could give 1000w into the 1000w, 4 ohm drivers, AND you're bang on the money with your 25% rule, so we 'relaxed' the limiters (built into the amps) a bit for a bit more output voltage.
the other was 2 x single 15" 750w PD drivers, running off a single 2000w/ 2 ohms channel, so each 4 ohm cone gets 1000 odd watts. bit naughty, but PD are (as it has been mentioned before) fairly conservative with their ratings.

I know well the 'perceived volume increase' of distortion, but more from not having enough of it. ie. drum & bassers (for example) saying 'its not loud enough' when db's are 130+ db , but not 'sounding' loud (ie not distorted).  a  5 k mackie fusion rig 'sounds' louder than mine, but i don't think it is

each 4 ohm single 15 was as loud (almost) as a double 15 with 8 ohm cones, and sounded cleaner and tighter, probably because of having no other source to comb filter with, as in the 2 coned 215. comb filtering of multiple drivers is in itself a sort of distortion avoided in mid top frequencies by arraying, but actually quite nice in bass frequencies. dance floors seem to like the added 'chunk' of non arrayed bass, i'm sure you'll agree!

4 ohm cones must surely be advantageous in horn loaded systems (not that i've had that much experience of horns), where a single cone can do a whole freq range on its own, eg 2000 w (into4) amp  channel driving a 4 ohm ciare12 into a bass horn
, or a 500w (into 4) ampchannel driving a 4 ohm 400w mid cone etc.

4 ohm cones may be a better option than bridging amps, with the same sort of  results? thoughts?