DIY Home subwoofer design

[crexrun]

DrWho has been giving me some very good information on subwoofer design tips on my "KP-301" thread, and it was starting to get a little long, so I thought I'd start a subwoofer one as well.

DrWho, In the other post, you mentioned cancellations from having my 301s off of the floor approx. 14", do you recommend having them lower, or do you think that with the add. of a sub, I will do away with the reduction in low end, from refraction from the ceiling? I would very much like to have the mid horn at ear level of somewhere close, it seems to sound so much better, like I'm in front of the stage, versus above it. Angling the speakers while on the floor raised the soundstage, but not as much as I prefer. I would like to build an attractive sub cabinet underneath the 301's to reduce floor space as much as possible. I would also like to (when possible) have these speakers placed more in a corner, as I believe they were designed for, (the original "Cornwall" was named do because of corner, wall placement I read on Klipsch.com) and have the subs underneath, to reinforce the very low end a little more, and also to simply make a more attractive arrangement for day to day living.

I could easily make an L shaped cabinet if needbe, that would go under and behind the kp-301s, so I could have the volume, and long ports, and plenty of room to mount the 15's, and also be able to keep the base at whatever height I want.

I have the amp end taken care of, I picked up another Technics SE-9060, this was the TOTL in the late 70s, it operates at 70 wpc RMS at .002% dist. 20hz-20khz, and a 120 db S/N ratio. They are very clean, good sounding amps with plenty of power. It is also a stereo/mono amp, it is basically 2 seperate amps in 1 chassis, that are bridgeable. It goes to 180 watts mono, rms, and will operatedown to a 4ohm load in mono, and will push around 210 to 4 ohms. I was thinkning of just running this into a stereo, 4 ohm load, using a DVC 8 ohm sub, and having the coils in parallel. I could also run them in 8 ohm mode, if I got a dual 4 ohm sub, and just turn the level up on the amp to the desired volume. I may not get 125db out of the subs that way, but I don't need that, I listen to it at a talking level, or slightly higher, 95% of the time, I don't need to really crank on it that often. When I DO crank on it, the 15"s in the 301s become a little more active, and they fill in the low end a little more anyway.

One more thing, I think some of my low end woes are possibly due to the fact that these speakers were in a church for the last 12 years, and probably never operated at a very high level, and probably never really had the woofers broken in, as they seem to be very stiff, basically "new" stiff, IMO. I have been running some bass heavy music through them, and they already seem to be a tiny bit better on the bottom end, after a few hours. I put in a test CD, and the low end bass notes seem to almost make the woofers "pop" at low levels, like the coils want to move the cone, but the surround and spider are still too stiff to let it move like it should. I'm not damaging them, I am very careful of things, and this only happens at very low levels, less than 1 watt.

Anyway, I'd like to hear your opinions on the height of the KP-301s, and if you think my power will be sufficient to fill the room with what I'm looking for from what you've seen. Thanks a lot, It's much appreciated, Justin