Eminence 3015LF
I have ordered for one 3015LF driver. I would like to experiment with this in a Tuba 36 and hopefully a TH if someone is kind enough to show me the box layout. Then I will surely order for 5 or 7 more to complete the subs.
So anyone wants to help with sketching out the box layout for the 3015LF driver?
Thanks,
I have ordered for one 3015LF driver. I would like to experiment with this in a Tuba 36 and hopefully a TH if someone is kind enough to show me the box layout. Then I will surely order for 5 or 7 more to complete the subs.
So anyone wants to help with sketching out the box layout for the 3015LF driver?
Thanks,
"while DJK's design gain BW is impressive"
Unfortunately it all seems to be related.
On a direct radiator box for a given cut-off frequency, you double the box size, you double the efficiency (3dB). When you consider mouth area for a horn, it is a similar thing.
GMs pipe looks real good for 383L vs 991L. The ratio of volumes indicates there should be on the order of 4.13dB difference in efficiency, quite close as to what Hornresponse predicts.
The mouth is about 24" square. I think a regular horn in 0.5Pi would require a 48" square mouth to show this low of ripple.
"So anyone wants to help with sketching out the box layout for the 3015LF driver?"
What kind of form factor would be better; square-ish, or long and narrow? The mouth opening will be about 22.5" x 22.5" (inside).
Unfortunately it all seems to be related.
On a direct radiator box for a given cut-off frequency, you double the box size, you double the efficiency (3dB). When you consider mouth area for a horn, it is a similar thing.
GMs pipe looks real good for 383L vs 991L. The ratio of volumes indicates there should be on the order of 4.13dB difference in efficiency, quite close as to what Hornresponse predicts.
The mouth is about 24" square. I think a regular horn in 0.5Pi would require a 48" square mouth to show this low of ripple.
"So anyone wants to help with sketching out the box layout for the 3015LF driver?"
What kind of form factor would be better; square-ish, or long and narrow? The mouth opening will be about 22.5" x 22.5" (inside).
Flying visit - just here briefly before I go over to my sister's.
Interesting, GM. Looks like it's not ideal, but than again I'm only really looking for 50Hz and down. Is the graph at 1W? Room is quite small at 4x4m, and I can make two up and stick them right in the corners, so it might be worth a play. I'll have a look to see what else I have stashed away.
Interesting, GM. Looks like it's not ideal, but than again I'm only really looking for 50Hz and down. Is the graph at 1W? Room is quite small at 4x4m, and I can make two up and stick them right in the corners, so it might be worth a play. I'll have a look to see what else I have stashed away.
GM said:
I was pondering this over a glass of red wine. 105dB at 20Hz on the equivalent of a small chip amp is still very impressive, and would probably be fine in my small terraced house. Especially as I think that Xmax figure may even be rated as one way.
I must admit though, I've lost track of this thread a bit, did anyone ever come up with rough guidelines of parameters for suitable drivers? The only one I can remember off-hand is the mention that Fs doesn't need to be that low.
pinkmouse said:
Especially as I think that Xmax figure may even be rated as one way.
.........did anyone ever come up with rough guidelines of parameters for suitable drivers?
Don't know, it says 7 mm p-p, so to me that's only 3.5 mm Xmax. Regardless, from 30 Hz - up you can EQ it to ~12 W rising to ~36 W/80 Hz with just the 3.5 mm, so with any room gain you're looking at ~110+ dB peaks, not quite up to DD/DTS cinema reference, but not exactly a muted bass line either.
Not that I'm aware of, I mean any driver has an optimum gain BW for tapped pipe or horn loading, but I've seen no routine to calc the right driver specs for a given gain BW other than Dr. Leach's math, which AFAIK is what TD uses.
Yeah, in theory room gain will begin around 43 Hz and even with only a 6 dB Vs the theoretical 12 dB/octave rise with decreasing frequency, it could pound pretty good since above ~30 Hz it can handle more power. Or you could start with more gain BW beginning deep in the teens, though size jumps to ~507 L (5 W simmed):
GM
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pinkmouse said:
While playing around with simulations and reading toms posts i found out following rough guidelines. (and i may be very well wrong here
)- large xmax (obvious)
- vas affects mouth/throat size -> low vas = smaller horn
- fs a little higher than intended lower cutoff. perhaps 10-15hz higher.
- motor should not be too strong (like PA woofers are). qes around 0,4 seems nice, the stronger it gets, the more bandwidth you seem to get because the first big dip in the upper spectrum gets smaller, but less low frequency capability.
- mms should be high
all together, when i think of a good tapped horn driver, car sub drivers come to my mind. for example the TH-50 and matterhorn from danleysoundlabs uses a 15 inch car sub driver. th-115 seems to use a pa woofer, perhaps a b&c.
i think i remember which woofer was in the th-50 and matterhorn...
http://www.mtx.com/caraudio/products/subwoofers/thunder9500.cfm
with 138 liters, the vas of your driver is quite big, pinkmouse. the box could be made smaller with other drivers. in comparison, the 15inch mtx woofer i posted above has vas = 70 liters.
concerning motor strength, it seems to be easier to compensate for a too weak motor within the box design than to compensate for a too strong motor. making the path between the front of the membrane and the mouth longer has a similar effect as using a stronger motor.
http://www.mtx.com/caraudio/products/subwoofers/thunder9500.cfm
with 138 liters, the vas of your driver is quite big, pinkmouse. the box could be made smaller with other drivers. in comparison, the 15inch mtx woofer i posted above has vas = 70 liters.
concerning motor strength, it seems to be easier to compensate for a too weak motor within the box design than to compensate for a too strong motor. making the path between the front of the membrane and the mouth longer has a similar effect as using a stronger motor.
MaVo said:
Indeed, but I have too many drivers already! I don't really want to buy more!
Apart from the OEM Rels I mentioned above, the other drivers I have that may be suitable are some 10" Corals. I haven't measured them properly yet, but I previously noted on the box Fs 28, Qt 0.33 and Vas 80l. I really must get Soundeasy up and running...
MaVo said:
Greets!
I'm curious, where did you learn this, or is this yours or someone else's speculation? I mean TD offers up lots of good design info, but mentioning specific driver models and/or how he may have them modified for his prosound products isn't included in any post I've read.
GM
Greets!
You're welcome! Looking forward to a review.
Anyway, since I haven't built any TPs with a driver off-set from the mouth and knowing that too big is better than too small if for no other reason than it gives more tuning flexibility, I recommend rounding dims up to the next easy to measure unit rather than going the other way. Also, since moving the mouth to the side shortens the path-length back to the driver enough to noticeably affect the sim (I assumed square), I recommend either putting the mouth on the end or making the pipe longer as required and blocking off the excess length at the closed end, which in theory also serves to increase the pipe's acoustic efficiency a bit since this is the high pressure point.
GM
You're welcome! Looking forward to a review.
Anyway, since I haven't built any TPs with a driver off-set from the mouth and knowing that too big is better than too small if for no other reason than it gives more tuning flexibility, I recommend rounding dims up to the next easy to measure unit rather than going the other way. Also, since moving the mouth to the side shortens the path-length back to the driver enough to noticeably affect the sim (I assumed square), I recommend either putting the mouth on the end or making the pipe longer as required and blocking off the excess length at the closed end, which in theory also serves to increase the pipe's acoustic efficiency a bit since this is the high pressure point.
GM
GM said:
its a guess. in his post here, tom said that it was a stock driver. you could see them quite well in the matterhorn video. i made a search some time ago and this was the only stock driver i could find, which looked like the one in the video. also, it models ok in hornresp, so i figured, it could be the one.
