Designing for on-wall/near-wall speaker placement

morbo · 23rd November 2004, 08:56 PM

I've been asked to build some speakers for some friends. They want a cheap ($200-300 CDN) set of speakers that can be used to with a low-cost reciever to watch TV and some DVDs. I am planning a vented floor standing design (Fb = ~ 22 - 26hz) using the TB 871 for the a mid-tweeter, and the Dayton 8" RS driver as a true woofer. Yes, I know there is a price/performance mismatch here, but the future owner is a bass nut and I'm hoping being able to cross lower will simplify the crossover design process. The source and amplification will not be high end, so I don't feel the need for a higher end driver. The goal here is an inexpensive, shielded fullrange system with high quality bass.

One of the stipulations on these speakers is that they stand flush one either side of a big 51" RPTV. This means that the back of the speaker will only be about 2-3" from the rear wall. Since the speaker is 15" deep, this means the drivers will be roughly 17-18" from the back wall.

My question is this: How does one design for on/near wall placement? I haven't seen many speakers designed this way, and I'm curious what effect it has on the bass response and what to shoot for when modelling such a speaker?

kipman725 · 26th November 2010, 02:02 AM

I am also curious, I am building some new full range speakers that are going to have thier drivers only about 5" from the wall due to my desk been against a a wall and would like to design apropriate active compensation for this.

kipman725 · 27th November 2010, 04:59 PM

369 veiws and no reply?

I think the effect will be the reflection of waves from the wall delayed by one path length causing superpositioning and therfore comb filtering. So in my 5" example I should get a peak in repsonse at 2.68Khz, 5.36Khz... etc and dips at 1.34Khz, 4.02Khz. However as there is more than one length path from the driver to the wall these should be pretty low Q and posibly at least partialy corectable.

richie00boy · 27th November 2010, 05:30 PM

Putting speakers closer to rear wall means bass is more present than when they are further away. In general this means the baffle step correction is not needed. You might also tune a touch lower to give a more gentle roll off, but it looks like you are tuning very low for that size driver anyway.

kipman725 · 27th November 2010, 05:52 PM

Is the comb filtering known to be a significant problem?

23rd November 2004, 08:56 PM	#1
morbo diyAudio Member Join Date: Sep 2004 Location: Guelph, Ontario	Designing for on-wall/near-wall speaker placement I've been asked to build some speakers for some friends. They want a cheap ($200-300 CDN) set of speakers that can be used to with a low-cost reciever to watch TV and some DVDs. I am planning a vented floor standing design (Fb = ~ 22 - 26hz) using the TB 871 for the a mid-tweeter, and the Dayton 8" RS driver as a true woofer. Yes, I know there is a price/performance mismatch here, but the future owner is a bass nut and I'm hoping being able to cross lower will simplify the crossover design process. The source and amplification will not be high end, so I don't feel the need for a higher end driver. The goal here is an inexpensive, shielded fullrange system with high quality bass. One of the stipulations on these speakers is that they stand flush one either side of a big 51" RPTV. This means that the back of the speaker will only be about 2-3" from the rear wall. Since the speaker is 15" deep, this means the drivers will be roughly 17-18" from the back wall. My question is this: How does one design for on/near wall placement? I haven't seen many speakers designed this way, and I'm curious what effect it has on the bass response and what to shoot for when modelling such a speaker?

27th November 2010, 05:30 PM	#4
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Putting speakers closer to rear wall means bass is more present than when they are further away. In general this means the baffle step correction is not needed. You might also tune a touch lower to give a more gentle roll off, but it looks like you are tuning very low for that size driver anyway. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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26th November 2010, 02:02 AM	#2
kipman725 diyAudio Member Join Date: Jun 2007 Location: London/N.lincs	I am also curious, I am building some new full range speakers that are going to have thier drivers only about 5" from the wall due to my desk been against a a wall and would like to design apropriate active compensation for this.

27th November 2010, 04:59 PM	#3
kipman725 diyAudio Member Join Date: Jun 2007 Location: London/N.lincs	369 veiws and no reply? I think the effect will be the reflection of waves from the wall delayed by one path length causing superpositioning and therfore comb filtering. So in my 5" example I should get a peak in repsonse at 2.68Khz, 5.36Khz... etc and dips at 1.34Khz, 4.02Khz. However as there is more than one length path from the driver to the wall these should be pretty low Q and posibly at least partialy corectable.

27th November 2010, 05:52 PM	#5
kipman725 diyAudio Member Join Date: Jun 2007 Location: London/N.lincs	Is the comb filtering known to be a significant problem?

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