FF165WK TQWP Experiment

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I've had the FF165WK in a set of metronomes for about 9 months now. I have never been satisfied with the bottom end response but the mids/highs and imaging has been great. The metronomes did not meet the WAF so i promised to come up with something different that would match the house better. Using a spreadsheet i found years ago online i came up with a folded horn. Inside dimensions 11" wide X 37" Tall X 7" deep. The port is 2'1" X 11" at the bottom. The baffle is 30" tall starting at the top of the port and ending up behind the center of the driver. I've applied a small amount of stuffing in the small part of the horn. For a BSC i used what i had from the metronome i believe 2.7ohm and a .7 free air coil. So far the bass is incredible, the imaging is great but it seems like i'm missing some in the lower middle end of the range. any suggestions?
 
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A sketch with dimensions would be useful, as would photos. It's difficult to picture the geometry based on written description. A simulation based on your geometry may reveal why some holes in bass are there. Based on my experience modeling bottom firing ports on MLTL's, the distance that the speaker is placed away from the wall makes a huge difference with holes/dips in the bass output from 60 Hz to 200 Hz. Usually moving speaker at least 5 ft away from back wall will give most neutral flat bass response with fewer dips. Have you tried moving them far away from the wall?
 
Well i do have them against a wall right now but i'll pull them out for critical listening later and report the results. The better half doesn't seem to like them out away from the wall since that puts them out in the room a bit. Hopefully this jpeg sketch comes through. i also have some stuffing i should lay with and maybe the BSC i have isn't perfect but i do like the sound. My wife and kids think these are much better than the metronomes.
 
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Sherpa,
I don't see the jpeg drawing - it not come through. I just made a Met model in AkAbak today so can try that if you give me the dims of your previous Met that you did not seem to like with the FF165WK. The Met when tuned correctly has a very nice flat response, but from the sims, I find its bass extension a bit lacking especially when paired with low Qts Fostex drivers.
 
Ok lets try this in GIF Format.
 

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Sherpa,
I built up the model of your 'Pointed throat Weems' horn' using the dimensions you provided and the FF165WK driver. The simulation with the speaker placed far from a back wall (5 ft) and with the microphone 1 meter away looks quite nice but has a minor dip around 180 Hz (first figure, red is driver direct radiation, green is horn mouth, and black is combined). However, as you move the speaker cabinet closer to a wall (second figure, 2 ft from wall) a dip in the frequency response around 110 Hz starts showing up. And the situation is even worse when you listen to the speaker that is 2 ft from the wall at 3 meters away (3rd figure) - equivalent to a normal listening position. One of the worst cases is to place the speaker only 1 ft away from a wall (4th figure) and listen 3 meters away. At this position, there is a gaping hole at about 180 Hz. There is no damping in this simulation so the very sharp peaks will be smoothed out, but the wider dips like these holes will still be present. I hope this helps, but sorry that it confirms your suspicion that there is something missing.
 

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Well that explains it. My wife thought i was crazy when i told her they were missing something around 150Hz. Placing them within the WAF i have them backed up against the wall and the listening position about 10ft away. My wife and both girls like the sound of them as they sit so i'll have to wait till the wife is out of the house to pull them out and really crank them up.
Any suggestions i could build instead at close to the same dimensions and possible a different driver? I have access to the local Air Force Base wood hobby shop which has about every top of the line woodworking tool i could want so building a new box is no big deal.
Thanks for working that up for me.
Paul
 
I've done the metronome and i was not happy with the bass response. they also were too big for the WAF. this 8X11X37 dimension seems to work for the design of our house but they will have to be set against a wall. A MLTL might be an option is i canfit it within these dimensions.
 
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