OK, here's the new and improved bandpass sub. Basically it's the same sub as before, but the tuning frequency has been moved up. This increases efficiency at 50hz by 3db(!) and maximum SPL also. I intentionally 'tipped' up the response a bit because room gain will reinforce the low end.
The only change required is to use a port that's 14" long instead of 22". This also means you don't have to use two 90 degree elbows, which are quite expensive.
Here's the measured impedance with a 14" port, and it correlates well to the horn response model.
Also, this sub should be placed *face* down, at least 1.5" from the floor. The floor itself lowers the tuning frequency. (this is measurable.)
The only change required is to use a port that's 14" long instead of 22". This also means you don't have to use two 90 degree elbows, which are quite expensive.
Here's the measured impedance with a 14" port, and it correlates well to the horn response model.
Also, this sub should be placed *face* down, at least 1.5" from the floor. The floor itself lowers the tuning frequency. (this is measurable.)
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gedlee said:
No, the other way around. The inner tube, the smaller of the two tubes, is in two pieces. One piece is the front chamber, the other piece is the rear chamber. These two chambers are glued together, and the woofer baffle is the divider for the two chambers. Like this:
An externally hosted image should be here but it was not working when we last tested it.
After the two pieces are assembled, the outer tube is fitted over the entire thing. The only reason the outer tube is used is for constrained layer damping. I should go and weigh it, it's ridiculously light.
gedlee said:
I understand you like to vary the crossover points on your subs. Admittedly it would be nice if I could do this, but I can't justify the added complexity (and cost.)
If it's any consolation, the bandpass and the tapped horn have different passbands. The tapped horn has a much wider bandwidth than the bandpass.
Also, I am adding five subs to the mix, which are all sealed. I may wind up using passive crossovers with the sealed subs, as my plate amp only has 2nd order filters.
If anyone is interested in the tapped horn patent, here it is:
http://www.wipo.int/pctdb/images4/PCT-PAGES/2007/392007/07109075/07109075.pdf
http://www.wipo.int/pctdb/images4/PCT-PAGES/2007/392007/07109075/07109075.pdf
ew:USC1 - I didn't like mine in-home - a bass reflex or bandpass would have been cleaner at 30 - a smaller & lighter Kalrson was far cleaner - maybe mine was a dud (?) 21dB more K2 and ~10dB more K3 were not to my liking
An externally hosted image should be here but it was not working when we last tested it.
Re: Qts question from a dummy
In the tapped horn I raised QTS with a 5 ohm resistor, and in the bandpass sub from this thread I used both a 5 ohm resistor *and* added mass.
Another option for the tapped horn is to simply use two woofers instead of one. It raises the F3 of the design a bit, but it still plays plenty low, and of course your power handling rises by more than double.
The TH-SPUD uses dual eights.
flacoman said:
In the tapped horn I raised QTS with a 5 ohm resistor, and in the bandpass sub from this thread I used both a 5 ohm resistor *and* added mass.
Another option for the tapped horn is to simply use two woofers instead of one. It raises the F3 of the design a bit, but it still plays plenty low, and of course your power handling rises by more than double.
The TH-SPUD uses dual eights.
A year ago I started this thread, and I wound up building two bandpass subs and a two tapped horns. One of the tapped horns fell off my deck (no joke) and that left me with three subs.
A few months later I ended up adding five more subwoofers to the mix, for a total of eight.
I did this based on the smooth response that I achieved using multiple subwoofers.
Did anyone see the new Danley tapped horn? It used eight drivers, and has the flattest response I've ever seen in a horn subwoofer (conventional OR tapped.)
If this response graph isn't living proof that multiple subs = smoother response, I don't know what is.
If anyone reading this thread is still using one sub, summertime is around the corner, time to make some sawdust...
A few months later I ended up adding five more subwoofers to the mix, for a total of eight.
I did this based on the smooth response that I achieved using multiple subwoofers.
Did anyone see the new Danley tapped horn? It used eight drivers, and has the flattest response I've ever seen in a horn subwoofer (conventional OR tapped.)
If this response graph isn't living proof that multiple subs = smoother response, I don't know what is.
If anyone reading this thread is still using one sub, summertime is around the corner, time to make some sawdust...
An externally hosted image should be here but it was not working when we last tested it.
I assume you are talking about the actual lever. From what I'm visualizing, you can produce the outer diaphragm with the connecting rod/lever plus inner diaphragm quite easily with friction welding. Perhaps there might be one or two facilities in your area that would be willing to do a one-off.gedlee said:
Actually the easiest way to make a Lever is to just use a single cone where the "butt" end (where the voice coil would usually go) becomes the smaller interior surface and the entire cone as the larger exterior surface. You need a smallish cone with a big VC landing for this to work however. You can even use existing baskets if you are careful with the design. We made several of these when I was at Ford and they were quite simple, robust and inexpensive. Another option is a truncated cone piece molded in styrofoam supported with suspensions at the two parrallel surfaces. These are cheap, and sturdy and easily mounted.
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