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Question about Lab 12 tapped horn placement


snailtrax

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The picture below shows where I have my Lab 12 tapped horn in my living room. The room is 20 x 20 and open on the left to the kitchen which is 20 x 13. The living room also has a 14 foot cathedral ceiling.

I am wanting to build another one for more SPL. You can never have too much. :D I already have everything except the wood for the build. I was going to make one with a single fold and put it on the right side standing up, but have changed my mind. I want to make another one just like this one, and stack them below the tv.

The question I have is, should I stack them with the mouths on opposite sides facing me, or should I put one mouth facing the wall or both facing the wall?

I have read about one sub canceling the other out and want to avoid this if possible. I can't put it behind me because there isn't enough room. I have to live with what I have. The only place that will work is stacked under the tv.

The subs will be powered by a pair of Bash 300 plate amps and a Pioneer VSX-1121-K.

Questions and advice welcomed. Thanks, Bill

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I have a Lab tapped horn sub no longer in use (very good BTW). If got me hooked to the point where I got TWO Danley DTS 10's to replace it.

Best place is one in the center of the front wall and one in the center of the back wall.......JBL research data.

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At the wavelengths we're talking here, the "high frequency" coupling really isn't going to be an issue.

I personally would place them so that both mouths face forward, but have the exits on opposite sides because it will increase the density of standing waves in the room....which statistically usually reduces the depth of the nulls created from room modes.

In other words, you should see a smoother in room response by have non-collated mouth exits. I would not ever recommend firing the sub into the wall because it will change the behavior of the tapped horn.

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  • 2 weeks later...
  • 3 weeks later...

At the wavelengths we're talking here, the "high frequency" coupling really isn't going to be an issue.

I personally would place them so that both mouths face forward, but have the exits on opposite sides because it will increase the density of standing waves in the room....which statistically usually reduces the depth of the nulls created from room modes.

In other words, you should see a smoother in room response by have non-collated mouth exits. I would not ever recommend firing the sub into the wall because it will change the behavior of the tapped horn.

I agree with Doc, here. Helped a friend with his 3 spuds and we played around with the two. Mouths apart gave a better room response than mouths together. I build a LAB 12 Tapped Horn also but it crossed at 60 Hz, which is really low and mouths closer will not be better overall.

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  • 2 weeks later...

I am wanting to build another one for more SPL...

Are you saying the sub cannot keep up with the speakers? You will get +6db gain from a second sub. Will your AVR just turn the gain down 3db on each sub?

Here are my thoughts depending on that answer:

1. If the sub isn't keeping up, then mouths together on one side. That worked best for my two THT's as compared to flanking my center LaScala.

2. If the sub does keep up, but there are just very quiet places (standing waves). If that is the case, I'm with DrWho. You need to use positioning to reduce the severity of room modes by putting the subs in different locations.

Either way, you will be flattening the bass response if the mouths are within 5' of one another (I remember Bill Fitzmaurice saying this).

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1. If the sub isn't keeping up, then mouths together on one side. That worked best for my two THT's as compared to flanking my center LaScala.

Does that apply to tapped horns as well? THT's are FLH's as are all BFM's designs.

I don't really know the answer to that. I always understood it to mean that at sub-bass frequencies, the radius of sound would be from a single source if within 5'. That way there is not cancellation between the two somewhere in the center. If I am correct in that assumption, then it would apply to any subwoofer.

What do you think?

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If you're speaking of the subs "acoustically coupling" then yes. I was wondering if tapped horns benefit from "V" plating or something similar.

Beats me. I do know you don't get anything v-coupling THT's. BFM has said that more than once. The pro tubas like the T30 and T-60 do benefit from it. In fact, it adds another 3db on top of the 6db gain you get from having two subs. +9db total.

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I am wanting to build another one for more SPL...

Are you saying the sub cannot keep up with the speakers? You will get +6db gain from a second sub. Will your AVR just turn the gain down 3db on each sub?

Here are my thoughts depending on that answer:

1. If the sub isn't keeping up, then mouths together on one side. That worked best for my two THT's as compared to flanking my center LaScala.

2. If the sub does keep up, but there are just very quiet places (standing waves). If that is the case, I'm with DrWho. You need to use positioning to reduce the severity of room modes by putting the subs in different locations.

Either way, you will be flattening the bass response if the mouths are within 5' of one another (I remember Bill Fitzmaurice saying this).

I think the sub keeps up just fine. I just figured two would add to the fun. Flattening the bass response is a good thing right? How would one know if the sub was not Keeping Up?

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I am wanting to build another one for more SPL...

Are you saying the sub cannot keep up with the speakers? You will get +6db gain from a second sub. Will your AVR just turn the gain down 3db on each sub?

Here are my thoughts depending on that answer:

1. If the sub isn't keeping up, then mouths together on one side. That worked best for my two THT's as compared to flanking my center LaScala.

2. If the sub does keep up, but there are just very quiet places (standing waves). If that is the case, I'm with DrWho. You need to use positioning to reduce the severity of room modes by putting the subs in different locations.

Either way, you will be flattening the bass response if the mouths are within 5' of one another (I remember Bill Fitzmaurice saying this).

I think the sub keeps up just fine. I just figured two would add to the fun. Flattening the bass response is a good thing right? How would one know if the sub was not Keeping Up?

For me it was playing music at high volume levels. The low frequencies diminished more and more as the volume was increased. Adding a second THT allowed all the frequencies to increase no matter the volume level.

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If you're speaking of the subs "acoustically coupling" then yes. I was wondering if tapped horns benefit from "V" plating or something similar.

Not really unless the tapped horn isn't fully "tapped" - in which case, the frequency response of the single cabinet will be horrible.

In other words, a tapped horn with a flat frequency response does not see any benefit from V plating like you will often see with standard horns.

Another difference with tapped horns is that the "tapping" also cancels out any potential room gain. I'm specifically referring to the slow rise in LF response from the pressure vessel gain of the room. You do see the extra output when going from 1/2 space ground plane to 1/8 space corner loading.

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