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Discussion Starter · #1 ·
Rewatched "Fury" yesterday and had the SPL logger going during the tank scene where it was the 4 tanks vs. the one. I had the volume set to 0db on the x4000 and here was my results below.

I'm pretty flat response down to 12-13hz in the current single sub scenario. This is with the sub centered between the center channel and right speaker. I moved it to the corner and re-ran Audyssey and only picked up 1db at the peak but this was also without cranking up the sub either. comparing the same audyssey center vs. corner. The corner did offer the flattest response but I did not like the result there compared to center.

Possibly by adding the second sub and moving both into each front corners then I would have better integration.

My question is if I just added a second VTF-15H MK2 how many db do you think this would add on the low end?

(note: audyssey had all front speakers set to large, rear as small and crossover at rear was 40hz and LFE was 90hz)

peaks are right at the 107.2-107.8db range
 

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I believe it will be 3db.
 

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I believe it would be 0db. if your current sub is not maxed out adding a sub and then matching the level will still get you to the same level.
 

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Discussion Starter · #4 ·
I believe it would be 0db. if your current sub is not maxed out adding a sub and then matching the level will still get you to the same level.
ya I can see that.

Then how do I calibrate my system for reference. it's the peaks yes? 105db for speaker and 115db for bass...

I need to read up on how to calibrate the system for reference then maybe. Find out where the limit is.

what do you think
 

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Not sure about subs but adding the ".5 woofer" in a 2.5 way speaker is used to compensate for the ~6 dB stop loss in those designs. If you were adding an identical sub it seems fair to expect +3-6 dB.


...but don't quote me.
 

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I believe between 3-6 also. When you calibrate them, each subs gain will just be reduced. So each sub might read 72db separately, but 75-77db together. This equals out to be more headroom basically.
 

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Discussion Starter · #9 ·
I believe between 3-6 also. When you calibrate them, each subs gain will just be reduced. So each sub might read 72db separately, but 75-77db together. This equals out to be more headroom basically.
Well thats my main desire. Just headroom. Ya I'd love to be able to play reference but it's not needed. But the more headroom I add the better imho.

-5db produced max peak of 102db while 0db on the volume produced the results above (107db)

I think the -5db was too loud and really -8db is just about perfect for me personally.

...but when I wanna scare kids I need all the headroom I can get MWUAHAHAHA
 

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...but when I wanna scare kids I need all the headroom I can get MWUAHAHAHA
You think its fun scarring kids? Try cats.
 

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Discussion Starter · #11 ·
You think its fun scarring kids? Try cats.
my one cat has a cord chewing problem............


doors remain close into my HT room and cat not allowed. Here's praying that this remains true.
 

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I believe between 3-6 also. When you calibrate them, each subs gain will just be reduced. So each sub might read 72db separately, but 75-77db together. This equals out to be more headroom basically.
I concur and will hopefully have time to test this theory tonight.
I added a 2nd sub recently and immediately noticed more impact but never thought to check the output at the main LP. :coocoo:
 

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Adding a second sub should produce more db but usually that is not what we should look for.A 2 sub home theatre system should produce more flat bass response if tuned properly.Which in turn improves the total surround envelope of your system.A single sub system will have peaks and dip in the bass response which muddles the surround experience.
 

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Put simply 3 dB.

Wouldn't view the benefits of an additional sub in terms of dB for the purpose/logic of doing it. You already have a world class sub operating in rare range of 12-13 Hz. You can't even feel the bass until it gets to 15 Hz becoming audible at 20 Hz. The 12-13 Hz measurement is impressive, but if the range below 15 was removed at random you wouldn't know which one still had 0-15 Hz in it. None of our 5 senses can detect frequencies or changes in them below 15 Hz. Audibly at 20 Hz.

When you add another subwoofer you're providing the proper stage needed for the 'best'.
While the quality of a subwoofer and it's importance in a system are essential for my the representation of the audio I desire the sub is overemphasized and overhyped.
It's job is to produce the first 3 octaves. 20-50 Hz is where she thrives, also helping every midwoofer out there as they don't being to produce until 40-50 Hz (Low-mid 30's on that speaker costs more than a Benz range) on up to 80 Hz.
Mids take over around 200 Hz and handle 80% of all audio your system can play.

With the MKII it's safe to say you're good on the bass at 108 dB.
Note on volume level. Try to run sub near 50% volume, and never operate it above 75%.

Put that money on better quality speakers and the results will be better than any other improvement you can do every time
 

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Discussion Starter · #17 ·
Put simply 3 dB.

Wouldn't view the benefits of an additional sub in terms of dB for the purpose/logic of doing it. You already have a world class sub operating in rare range of 12-13 Hz. You can't even feel the bass until it gets to 15 Hz becoming audible at 20 Hz. The 12-13 Hz measurement is impressive, but if the range below 15 was removed at random you wouldn't know which one still had 0-15 Hz in it. None of our 5 senses can detect frequencies or changes in them below 15 Hz. Audibly at 20 Hz.

When you add another subwoofer you're providing the proper stage needed for the 'best'.
While the quality of a subwoofer and it's importance in a system are essential for my the representation of the audio I desire the sub is overemphasized and overhyped.
It's job is to produce the first 3 octaves. 20-50 Hz is where she thrives, also helping every midwoofer out there as they don't being to produce until 40-50 Hz (Low-mid 30's on that speaker costs more than a Benz range) on up to 80 Hz.
Mids take over around 200 Hz and handle 80% of all audio your system can play.

With the MKII it's safe to say you're good on the bass at 108 dB.
Note on volume level. Try to run sub near 50% volume, and never operate it above 75%.

Put that money on better quality speakers and the results will be better than any other improvement you can do every time
I just put money on better quality speakers. The SVS Ultra system and the towers are no slouch. My towers produce down to mid 20hz range by themselves.

So far the single sub plays loud enough for my needs and leaves nothing to be desired. I do agree a second sub would help create a better surround. When I place the single sub in one front corner I love the smoothness I get but can still localize it due to the rumble. My room is on the second story so you can source the "vibration" very easy and that is what is causing me to localize the sub... not the audio. Yes I cannot hear hardly at all below around 22hz for me but I can still feel the bass down to 15hz. I don't care to get lower then that however I want maximum headroom. With my current single sub the best spot for me is the center so it integrates better.

With me wanting dual HSU subs crossed at 60hz (two octaves 15-60hz) and then letting the Ultra towers handle the 60hz+ range leaves me with a great headroom. So far to my ears crossing them over at 60hz sounds really good. Especially once Audyssey does it's testing. My testing with audyssey at 85hz of pink noise produces a very flat response from 12hz to 85hz.

My problem beyond this is my room has some major dips/peaks from 100hz to 200hz range (see the photo).
 

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I think your plan is fine. Get the 2nd one, put em where they're best(corner?). Look forward to around 6db, do some treatments, and scare your family members....maybe the cat too. Lol
 

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In general the idea of two subs is to equally pressurize the room, get rid of any localization. The added bonus is a slight increase in dbs. :hsd:
 

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Discussion Starter · #20 ·
Ya I think I should just pull the trigger and order the second HSU and call it quits. No need for more.
 
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