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DIY sub for Klipschorn based HT (and music) - Tuba HT - build done (except for finish)!


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You will get the most standing wave trouble in the middle of the room. That is your problem here. The sub should be touching the wall on the side, and 18" from the wall the mouth is facing. Under the DVD racks would be perfect. The side of the sub against the wall under the DVD's, and the mouth 18" from the right wall pictured.

Interesting! You are the first to suggest placement right up against the wall. I'll give it a try to see how it measures later this week (I have several 12-foot freshly painted suspended ceiling metal tracks sitting there now). Moving the sub there permanently would when removing the DVD/CD racks since they would be hard to get to with a 30-inch wide sub in the way.

For the record, I had tried it facing the back wall, 18 inches away.

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You will get the most standing wave trouble in the middle of the room. That is your problem here. The sub should be touching the wall on the side, and 18" from the wall the mouth is facing. Under the DVD racks would be perfect. The side of the sub against the wall under the DVD's, and the mouth 18" from the right wall pictured.

Interesting! You are the first to suggest placement right up against the wall. I'll give it a try to see how it measures later this week (I have several 12-foot freshly painted suspended ceiling metal tracks sitting there now). Moving the sub there permanently would when removing the DVD/CD racks since they would be hard to get to with a 30-inch wide sub in the way.

For the record, I had tried it facing the back wall, 18 inches away.

I did not actually recommend that, Bill Fitzmaurice did. Once again, here are the placement instructions for the THT:

Placement

Boundary loading should be used whenever its practical to do so. Having subs next to a wall gets you 6dB of additional sensitivity below about 80Hz, and putting them in a corner an extra 12dB. In most cases youll have best results with the cabinet mouth on the floor against one wall, about 18 inches from the adjacent wall. If the cabinet mouth is a quarter-wavelength from a boundary there will be up to a 24dB deep cancellation at that frequency. Within the nominal bandwidth of the THT a quarter-wavelength ranges from 19 feet at 15 Hz to 2.8 feet at 100 Hz, so middle of room placement usually wont work well.

"On the floor against one wall" - this means against the wall, as in touching the wall.

"about 18 inches from the adjacent wall" - this means the mouth is 18" from a wall.

Try swapping the bike and THT, and have the THT under the DVD rack facing the right wall.

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  • 2 weeks later...

Should have read that more carefully 3 years ago then! Surprise

Cool, something to try anyway. Yes

Not your fault, the placement instructions were poorly written IMHO.

This is a link to the BF site with photo's of my 1st experiment. It starts from the final installation and works backwards. You can see how the mouth is positioned 18" (out from the corner of the room), Note that there are 3 ways to achieve this. In this is case the speaker is wall mounted and pointing down towards the floor. The walls are brick and the floor concrete with carpet.

http://billfitzmaurice.info/forum/viewtopic.php?f=5&t=17511

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  • 2 weeks later...
  • 1 month later...

Just thought I'd top up this thread... it took me a long time, but I finally stained the sub and found a better location for it along my back wall.

dsc_13596r.jpg

The frequency response varies a lot between my four seats and the music sweet spot. Here it is at some locations after some manual EQ on a miniDSP, with gains of up to +5 dB and reductions of up to -5dB. Note that the sub mean level is about 6 dB below the mains, so even at +5dB I am still reducing the gain structure. Running through the RCA-plug version of the miniDSP drops the output by about 7 dB, so if you want to use one make sure you can accommodate the gain structure.

rew-sub-fr-witheq-20131108.png

The magenta one is pretty nice, I think.

If I want to run a movie with the sub hot, then I have a volume control since it is fed by a single channel of my previous HK receiver (the 40-lbs avr325).

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It was not long ago because I just finished mine with stain! :lol:

As for rattles in the CD rack, surprisingly it's the doors at the other end of the room and a light ficture on the opposite wall that do most of it! :huh:

Anyway, I am happy with it all and finally realizing that I lost 7 dB in the miniDSP reassured me that I don't need another sub. I have lots of headroom left. This things is more efficient than Klipschorns.

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Just thought I'd top up this thread... it took me a long time, but I finally stained the sub and found a better location for it along my back wall.

dsc_13596r.jpg

The frequency response varies a lot between my four seats and the music sweet spot. Here it is at some locations after some manual EQ on a miniDSP, with gains of up to +5 dB and reductions of up to -5dB. Note that the sub mean level is about 6 dB below the mains, so even at +5dB I am still reducing the gain structure. Running through the RCA-plug version of the miniDSP drops the output by about 7 dB, so if you want to use one make sure you can accommodate the gain structure.

rew-sub-fr-witheq-20131108.png

The magenta one is pretty nice, I think.

If I want to run a movie with the sub hot, then I have a volume control since it is fed by a single channel of my previous HK receiver (the 40-lbs avr325).

It looks like the red line isn't suffering from standing waves like the pink and gold ones. Are these reading taken with different sub positions or different microphone locations?

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Shouldn't very much. The XO is set to 200Hz for those plots to get the sub output measurements rather than the KHorn output. But I guess it depends on how steep the filters are.

I didn't know you set it that high for the graph. You're right, it shouldn't affect the results.

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  • 8 months later...

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