How many is too many? - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 31 Old 02-24-16, 09:59 PM Thread Starter
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How many is too many?

Ok, first of all, I realize I'm asking this question in a dedicated DIY sub thread, where most folks are pretty serious about bass. I'm trying to decide between 4 or 8 HST-18's in a from scratch theater I'm putting together. Regardless if I choose 4 or 8, they would all be individually EQ'd. All would be in 4cuft flat packs, most likely positioned in the four corners with appropriate acoustical treatments in the room. Each set of 4 would be powered by a bossobass A4-12K-TT on separate 220V breakers. The room is going to be around 20 x 31 x 9, or whatever comes out to be the best size acoustically in that range.

With 4 subs, I'm getting the benefits of a much smoother response throughout the space, with the addition of another 4, stacked on top of the first set, am I more increasing the spl vs smoothing the response?

Right now, I have 2 HST-18's in a small little theater in my basement and they rattle the oven out of place in the floor above, so I know what these beasts are capable of.
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post #2 of 31 Old 02-24-16, 11:27 PM
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Re: How many is too many?

Think spl is mainly what you would get from 8. 4 is I think the magic number for most rooms. I have 3 and am real happy with the results, 1 front and 2 rears. Wish I had room for that last corner.

My life is one big speaker project.
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post #3 of 31 Old 02-25-16, 06:26 AM
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Re: How many is too many?

Everyone has a different feeling on this but I feel you should EQ the subs as one. As long as they are all the same design then eq the same. 8 would be the best answer. Buy now and then stop searching. This DIY bug is horrible and can cause you to constantly want to change speakers and give you very empty pockets fast.
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post #4 of 31 Old 02-25-16, 09:24 AM Thread Starter
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I'm wondering, if you have the ability to easily eq all subs individually, why treat them all as one? Especially if they're located in different positions in the room.
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post #5 of 31 Old 02-25-16, 11:56 AM
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How many is too many?

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Rhuarc wrote: View Post
I'm wondering, if you have the ability to easily eq all subs individually, why treat them all as one? Especially if they're located in different positions in the room.

I think wayne pflughaupt talked about this before. I think it has to do with summed response and a mono signal. (Sorry, read it a long time ago). I use 3 subs in my system and it's worked well to do it that way. Maybe I'll post my new graphs if I get time.


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post #6 of 31 Old 02-25-16, 12:00 PM Thread Starter
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Quote:
Rhuarc wrote: View Post
I'm wondering, if you have the ability to easily eq all subs individually, why treat them all as one? Especially if they're located in different positions in the room.

I think @wayne P. talked about this before. I think it has to do with summed response and a mono signal. (Sorry, read it a long time ago). I use 3 subs in my system and it's worked well to do it that way. Maybe I'll post my new graphs if I get time.


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Interesting, I'd like to see those charts if you have time. I'll be usingood a Trinnov Altitude 32 as my pre amp, so it can handle all of the subs easily.
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post #7 of 31 Old 02-25-16, 12:03 PM
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Re: How many is too many?

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Interesting, I'd like to see those charts if you have time. I'll be usingood a Trinnov Altitude 32 as my pre amp, so it can handle all of the subs easily.

Sure thing. I've never had the ability to EQ separately, and it may very well be better, but I just remember Wayne talking about it. I'm using a BFD 1124.


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post #8 of 31 Old 02-25-16, 12:06 PM
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Re: How many is too many?

8 is fine, but, I wouldn't do 8 different locations. Either one in each corner or one in the middle of each wall is ideal. If you want double that, put them side by side or start stacking them.
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post #9 of 31 Old 02-25-16, 07:28 PM Thread Starter
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8 is fine, but, I wouldn't do 8 different locations. Either one in each corner or one in the middle of each wall is ideal. If you want double that, put them side by side or start stacking them.
I was planning on two stacked in each corner.
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post #10 of 31 Old 02-25-16, 11:16 PM
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Re: How many is too many?

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I'm wondering, if you have the ability to easily eq all subs individually, why treat them all as one? Especially if they're located in different positions in the room.
With 3+ subs likely there will be some interactions between them… Treating them all as one offers less chances of messing up and might be a good recommendation for most. This is certainly a good place to start!

Individual EQ can give improvements in some instances (see below), but requires a lot of measurements to understand/map the listening area and the possible sub locations.

Some subs will work against others at some frequencies (e.g. out-of-phase wrt to a room mode etc...). The output of some may be undesirable at some frequencies because they cancel each other. Individual EQ prevents spending power/excursion to get no output...

One sub is strongly exciting a mode causing a peak and the others not. You would like to tame that one and maybe not the others.

Adjust the phase/distance individually for better summation

Minimize/control seat-to-seat variations (Welti algorithms, I’m not there yet!)

-----
To prevent getting lost doing that, you need to be systematic and never assume that an EQ change made to one sub will be seen directly in the summed response. At each correction made, re-measure the corrected speaker response and the summed response. That way you validate your understanding of the room as you go.

After each has been EQ'd, use another (global) set of filters to fine-tune the total response and add your “house curve”.

As for corner vs mid-wall, it really depends on the room shape…
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