Too much bass for the space? - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 113 Old 02-14-2017, 09:10 PM - Thread Starter
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Originally Posted by A9X-308 View Post
When using dissimilar subs I work out the total volume displacement and calc the SPL from that.
i modelled it in REW and it adds approx 4.6 decibels.

wow, that changes things.

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post #32 of 113 Old 02-14-2017, 10:26 PM
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Am I the only one who feels the OP should be banned from this forum for even thinking this much less starting a thread about it?
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post #33 of 113 Old 02-14-2017, 11:12 PM
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Banning a DIY'er from the DIY section seems like "extreeme vetting" for an "obvious" temporary lapse of reason. most likely from being snow bound or getting the credit card bills from christmas and not seeing any HT improvements on the bills . . .

How about 30 days of community service proselytizing the good word about the 1 Real and Only Truth about Subwoofers in the B.O.S.E threads,

that oughta' learn him . . .

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post #34 of 113 Old 02-14-2017, 11:42 PM
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Your absolutely right. I was being way to harsh. Let's sentence him to 30 days with his subwoofers off and the last 7 days he has to turn off his center channel as well
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post #35 of 113 Old 02-15-2017, 05:39 AM
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Your absolutely right. I was being way to harsh. Let's sentence him to 30 days with his subwoofers off and the last 7 days he has to turn off his center channel as well



30 whole days without bass???


...you are a sick monster......
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post #36 of 113 Old 02-15-2017, 05:43 AM - Thread Starter
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you guys are too funny.

ok, to avoid the ban hammer how about I buy two more um 18s? would that be redemption

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post #37 of 113 Old 02-15-2017, 05:49 AM
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Originally Posted by 1201 View Post

dilemma is it only adds 1.5 decibels but now I will have multiple subs that I would want to time align and that is a lot of effort.
Yes they must be in phase or else why bother. It's really not that hard and once you get the hang of it. The small amount of time invested is worth the reward several times over.

Compilation of Multiple Sub setup info


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post #38 of 113 Old 02-15-2017, 07:51 AM
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Originally Posted by 1201 View Post
you guys are too funny.

ok, to avoid the ban hammer how about I buy two more um 18s? would that be redemption
2 UM 18's that's it, you call that an offer?!?! What, are you a baby or something? Only a baby would suggest 18's as an offer of redemption, I say we flog you with a wet noodle for even suggesting 18's. No sir its 21's and up ONLY to begin to get back in the people good graces
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post #39 of 113 Old 02-15-2017, 07:57 AM
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Originally Posted by liffie420 View Post
2 UM 18's that's it, you call that an offer?!?! What, are you a baby or something? Only a baby would suggest 18's as an offer of redemption, I say we flog you with a wet noodle for even suggesting 18's. No sir its 21's and up ONLY to begin to get back in the people good graces

No no no.... multiple 24's FTW!
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post #40 of 113 Old 02-15-2017, 08:03 AM
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No no no.... multiple 24's FTW!
Well that's why I said 21's and up lol. 21's just barely gets him on the path to the good graces
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post #41 of 113 Old 02-15-2017, 08:04 AM
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Well that's why I said 21's and up lol. 21's just barely gets him on the path to the good graces
Oh ok... my mistake...


Carry on...
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post #42 of 113 Old 02-15-2017, 08:17 AM
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Well that's why I said 21's and up lol. 21's just barely gets him on the path to the good graces
I'm sure if you guys pay for the drivers, he'd be MORE THAN HAPPY to install!
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post #43 of 113 Old 02-15-2017, 11:02 AM - Thread Starter
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Originally Posted by cdy2179 View Post
Yes they must be in phase or else why bother. It's really not that hard and once you get the hang of it. The small amount of time invested is worth the reward several times over.

Compilation of Multiple Sub setup info


they are all in phase. I checked this with the four 12s last night (18s will be finished tomorrow)


adding a second sub added 6 decibels
and doubling that again to 4 subs added another 6 decibels.





Now Im messing around in rePhase to try to actually align the impulse response. I don't know if it will help but It cant hurt to try.

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post #44 of 113 Old 02-16-2017, 07:43 AM
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You must have them stacked as the responses as you add subs (unless stacked) will changes the response drastically. Yours are all linear. Also when showing sub responses we don't use smoothing. Looks like they need some possible placement work. Seriously weak bass being 10db down under 50hz, probably worse with no smoothing.

To see if they're in phase you need to take individual measurements then adjust phase for most positive summation between them. The 6db gain is never linear like that unless stacked.. but the higher you stack the more it'll change. But you seem to have a good bit of smoothing applied. It'll have dips and peaks with at best an average of 5 to 6db but it's the positive summation we look for so if you're just looking for gain.. that's incorrect.

I posted the link to the multiple setup above. Pretty sure if you follow the steps laid out you'll end up with an awesome response.


Also crank those puppies up when you measure. Taking measurements at 60 db isn't even opening them up. Try something more realistic 90db or so. The higher you are above ground floor the more accurate.
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post #45 of 113 Old 02-16-2017, 08:44 AM
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What is a "nearfield" sub? I've got two 12" at the front corners of my 9' h x 12 x 14 deep room and an 18" at the center rear 40" behind the MLP. Is that one nearfield? I'm using a y connector for the two fronts from sub 1 and the rear as sub 2 for an audyssey calibration.

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Originally Posted by Ted99 View Post
What is a "nearfield" sub? I've got two 12" at the front corners of my 9' h x 12 x 14 deep room and an 18" at the center rear 40" behind the MLP. Is that one nearfield? I'm using a y connector for the two fronts from sub 1 and the rear as sub 2 for an audyssey calibration.
Usually when people say nearfield sub they are talking about one place near the MLP most often behind the couch or what have you
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post #47 of 113 Old 02-16-2017, 09:07 AM - Thread Starter
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Originally Posted by cdy2179 View Post
You must have them stacked as the responses as you add subs (unless stacked) will changes the response drastically. Yours are all linear. Also when showing sub responses we don't use smoothing. Looks like they need some possible placement work. Seriously weak bass being 10db down under 50hz, probably worse with no smoothing.

To see if they're in phase you need to take individual measurements then adjust phase for most positive summation between them. The 6db gain is never linear like that unless stacked.. but the higher you stack the more it'll change. But you seem to have a good bit of smoothing applied. It'll have dips and peaks with at best an average of 5 to 6db but it's the positive summation we look for so if you're just looking for gain.. that's incorrect.

I posted the link to the multiple setup above. Pretty sure if you follow the steps laid out you'll end up with an awesome response.


Also crank those puppies up when you measure. Taking measurements at 60 db isn't even opening them up. Try something more realistic 90db or so. The higher you are above ground floor the more accurate.

thanks for the response.

unfortunately you are wrong on a couple of things. maybe science of has not fully caught up to how bass behaves in very small rooms.

this is a 10x12 room and the subs are front left corner, front middle, and front right corner. fourth sub was on left wall about mid way.

the response simply didnt change by adding subs.


2. 10 dbs down vs 50hz?
look at the graph again, look at the top line. at 50hz, its about 68dbs. it does not fall below 68 dbs till about 18hz.

I dont apply smoothing. I did use a frequency dependent window which i guess does smooth it out a bit as it removes later impulses.

here it is with zero smoothing or fdw applied




also, these were cranked up. i just didnt calibrate the db meter
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post #48 of 113 Old 02-16-2017, 09:40 AM
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thanks for the response.

unfortunately you are wrong on a couple of things. maybe science of has not fully caught up to how bass behaves in very small rooms.

this is a 10x12 room and the subs are front left corner, front middle, and front right corner. fourth sub was on left wall about mid way.

the response simply didnt change by adding subs.


2. 10 dbs down vs 50hz?
look at the graph again, look at the top line. at 50hz, its about 68dbs. it does not fall below 68 dbs till about 18hz.

I dont apply smoothing. I did use a frequency dependent window which i guess does smooth it out a bit as it removes later impulses.

here it is with zero smoothing or fdw applied




also, these were cranked up. i just didnt calibrate the db meter
You're 10db down above 50hz not below it.. actually more. You're lower bass will sound bloated and overpowering compared to upper bass. Waterfall graph will probably help explain it. Anyways with multiples you should easily get a much smoother response pre eq, once setup properly.

And we all have small rooms and have setup small rooms so not sure where that came from.

When you show subs in different places in the room you show them individually and then post them all so you can analyze them and you can find locations that would help you out above 50hz. It will also show you if you're out of phase if you're response summations are destructive.

Here's 3 seats in my room. Yes there is a little eq but only a few cuts to knock down small peaks.



The methods I'm explaining and in the link are not some made up nonsesne. They're what's taught and used by the best in the business based on how low frequencies behave in rooms. It seems you feel you know it all so maybe you'll check it out .. if not have a good day!
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post #49 of 113 Old 02-16-2017, 09:41 AM
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I am a little puzzled. Why is your frequency response almost identical up to 55 Hz no matter how many subs you have on?
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post #50 of 113 Old 02-16-2017, 09:46 AM
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I am a little puzzled. Why is your frequency response almost identical up to 55 Hz no matter how many subs you have on?

This is confusing me too.... If I turn one of my drivers on/off my response changes....
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post #51 of 113 Old 02-16-2017, 09:47 AM
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I am a little puzzled. Why is your frequency response almost identical up to 55 Hz no matter how many subs you have on?
he also said his mic isn't calibrated which is why it's showing such low SPL. Looks wrong in many ways and the response in no way reflects 4 subs or even 2 subs in phase and properly placed.

But yea 3 subs spread corner spaced, 1/2 spaced along a wall (all in different locations ) will not look like that. His response is basically unchanged as he's "adding" subs. Possibly some hardware or setup issues. The sub at the midwall point will have a vastly different response down low as it's not exciting room modes like the corner loaded subs.

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post #52 of 113 Old 02-16-2017, 10:20 AM - Thread Starter
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You're 10db down above 50hz not below it.. actually more. You're lower bass will sound bloated and overpowering compared to upper bass. Waterfall graph will probably help explain it. Anyways with multiples you should easily get a much smoother response pre eq, once setup properly.

And we all have small rooms and have setup small rooms so not sure where that came from.

When you show subs in different places in the room you show them individually and then post them all so you can analyze them and you can find locations that would help you out above 50hz. It will also show you if you're out of phase if you're response summations are destructive.

Here's 3 seats in my room. Yes there is a little eq but only a few cuts to knock down small peaks.



The methods I'm explaining and in the link are not some made up nonsesne. They're what's taught and used by the best in the business based on how low frequencies behave in rooms. It seems you feel you know it all so maybe you'll check it out .. if not have a good day!
i dont feel i know it all, but I get the feeling you think you know way more than me about my room

I dont hear bloated sound at all. equal loundess curves need to be louder as you get lower in frequency. a flat curve from 10hz to 100 hz will sound anemic

I can get the response flat within 0.1 db but for right now (that may change ) I prefer to let the room do its thing. the drivers are flat anechoichally, so any null is based on the room and boosting it would be unwise. same thing to a similar extent with knocking down the peaks - i feel, with no science behind this, that if you knock down the peaks to match the nulls and then raise everything, well you just boosted the nulls in a backwards way.

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I am a little puzzled. Why is your frequency response almost identical up to 55 Hz no matter how many subs you have on?
hehe, its either natural phenomena, or magic. and I dont know magic so...

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Originally Posted by uniquepattern View Post
This is confusing me too.... If I turn one of my drivers on/off my response changes....
care to post a graph?

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Originally Posted by cdy2179 View Post
he also said his mic isn't calibrated which is why it's showing such low SPL. Looks wrong in many ways and the response in no way reflects 4 subs or even 2 subs in phase and properly placed.

But yea 3 subs spread corner spaced, 1/2 spaced along a wall (all in different locations ) will not look like that. His response is basically unchanged as he's "adding" subs. Possibly some hardware or setup issues. The sub at the midwall point will have a vastly different response down low as it's not exciting room modes like the corner loaded subs.
my mic is calibrated, i just havent calibrated the db meter in REW.

if you think its setup, pray, tell, what you think the setup issue may be?

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post #53 of 113 Old 02-16-2017, 10:30 AM
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I dont hear bloated sound at all. equal loundess curves need to be louder as you get lower in frequency. a flat curve from 10hz to 100 hz will sound anemic

I prefer to let the room do its thing. the drivers are flat anechoichally, so any null is based on the room and boosting it would be unwise. same thing to a similar extent with knocking down the peaks - i feel, with no science behind this, that if you knock down the peaks to match the nulls and then raise everything, well you just boosted the nulls in a backwards way.

if you think its setup, pray, tell, what you think the setup issue may be?


Knock down peaks to match nulls? You're showing a huge lack of understanding here. You don't eq peaks to match nulls. You fix nulls by moving the subs and getting them in phase. There's a video in the link I posted that assist in placing subs to do just that. BTW.. You can not boost a null.

I think you have something setup wrong as your responses can not be accurate. No offense but that response is also not smooth at all. It drops like a rock above 50hz. That's not a house curve but a poorly setup sub. I run my subs hot so I agree with flat is boring. But what you have would be the response of a sub just thrown in a room .. definitely not a response after proper setup.

Honestly I think you just got some subs, starting messing with REW and now think you know how it all works. To those who understand sub responses in a room.. little you say makes any sense.

Do yourself a favor and click the link. Follow the steps to set everything up right and take measurements, see what you have and then begin working on the issues.

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post #54 of 113 Old 02-16-2017, 10:40 AM
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my mic is calibrated, i just havent calibrated the db meter in REW.
This made no sense either.

If you're using a usb mic with a cal file like a Umik-1 you don't calibrate the SPL.

https://www.roomeqwizard.com/help/he.../inputcal.html

If you're using some old mic you have to load a cal file to make the measurements accurate. some mics aren't capable of measuring low in freq so they are useless here.
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post #55 of 113 Old 02-16-2017, 10:46 AM
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I have a 950 ft3 room with four 12" subs.

950 Cubic Feet, that doesn't tell us much, it would be better to have the actual dimensions of the room. However, if we find the Cube Root of 950, that is only 9.83 feet. That is a very small room. But if we assume 8ft ceilings, then the room is about 10.9 x 10.9 x 8ft, still a pretty small room for all those Subs.

Next, where are the Subs place in the room, which direction are they facing, and what is driving them? By what is driving them, I mean the signal source and the amps.

With FOUR 12" Subs now combined with TWO 18" Sub, I would speculate that you have a confused mess in the room. So, much bass bouncing around that it is cancelling itself out. Especially in a small room like that.

First, with out a buffer, you can only hang just so many inputs on a Line Level Ouput. A Line Level Output (Sub Out) does not have an infinite driving capacity. You are trying to drive Three Outputs if we assume you AV Receiver has TWO Sub-Outs. Otherwise you are trying to drive SIX inputs with the Sub outputs. Three is marginal but probably workable, but SIX might be a step too far.

Next as other have pointed out, this is not they way to determine increase in volume.

iirc, the um 18s modelled 121 db at 30hz. the 4 12 modelled 118 db at 30, so 121+118 =122.8
so I guess a 1.8 db increase?


I have speakers wtih 2x8" bass drivers each, when I turn on my second full range speakers with 1x12" each, I get close to a 6db increase in output as measured using Pink Noise. One 12" driver is about 30% larger than TWO 8" drivers. So when the second set of speakers come on-line, you get a bit more than double the air moving ability.

An 18" driver is approximately 49% larger than a 12" bass driver. So, using TWO 18" is like using THREE 12" bass drivers. I would guess you would have no trouble getting about a 9db increase in output.

Further, if you have Subs in Front that are Electrically in-phase with Subs at the Back, while electrically in-phase, they are mechanically OUT of Phase. That is likely to cause significant cancellation in the room.

While not a prefect graphic for this circumstance, it still illustrates the underlying principle -



I really don't think you need that many Subwoofers in that seeming tiny space. Likely you are pushing the air so hard and from so many directions that the air is in essence stagnant.

If you have about $100 to invest, then a good Calibration/Measurement Microphone combined with Room EQ Wizard Software which is free, should allow you to do a pretty decent analysis of what is going on in your room. Science can tell you so much more than your ears.

You will find a discussion of REW (Room EQ Wizard) here with links, videos, and Microphone recommendations -

SPL meter recommendation


Frankly, I think 6 large Subwoofers in a room that is short of 11ft x11ft, is excess, and likely the source of your problem.

I would speculate, that if you insist on that many Subwoofers, you work very hard on proper placement and phase of those Subwoofers to assure that they are working together rather than fighting with each other. And in that relatively tiny room, you will most certainly have to make some efforts to control the Room Acoustics.

Make of it what you will.

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post #56 of 113 Old 02-16-2017, 11:24 AM
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Could the Audessey Mic work as a SPL meter for REW?
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post #57 of 113 Old 02-16-2017, 11:40 AM
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Hey @1201
Adding those UM18s will definitely make your room overkill, which isn't a bad thing.

Is there any chance you could run a graph with each individual sub by itself? (A line for only Sub A, then only Sub B, etc.)

Also, were the front 3 sealed and the side one ported? I can't remember.

Thanks buddy
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post #58 of 113 Old 02-16-2017, 12:14 PM
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Quote:
Originally Posted by liffie420 View Post
Could the Audessey Mic work as a SPL meter for REW?
No it wont. Most of us get a Umik-1 or a few others as Blue Wizard linked to above. It's $100 shipped but for what we spend on the hobby overall it's a small price to pay to allow us to get all the performance we can out of our gear.
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post #59 of 113 Old 02-16-2017, 12:32 PM
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I think it's silly to use this many large subs in such a tiny room. Half the thread responses seem to stress SPL. Adding more subs is rarely about more bass unless the subs in question are sub-par (no pun intended). A good sub usually has more headroom than the rest of the system. The actual reason for more subs--almost always a good idea, is uniform coverage. In fact, one poster thought the result would be too much cancellation but a single sub will always sound different, with differing SPL's, as you walk around the room. Cancellation with a single sub is unavoidable. Three or four subs would be great although with such a small room, hard to predict. If one uses more subs, each driver's excursion will be reduced and you'll enjoy less distortion although the benefit is likely to be subtle. So, in summary, it's about the quality of the bass, not the quantity. There's a correct amount of bass. More is not better.

I manufacture subs under the Bob Carver name and rebuild Sunfire subs every day of my life (ugh), so this is empirical--not speculative. You may call for advice but we do not sell product directly to consumers so this is, in no way, a solicitation. If you don't know the sub crawl, or you're using subs in a home theater and do not have a firm grasp on crossover settings, give me a call. I'll help anyone. I'm a hobbyist just like you. I do not check forum messages--too busy.

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post #60 of 113 Old 02-16-2017, 12:36 PM - Thread Starter
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Quote:
Originally Posted by cdy2179 View Post
Knock down peaks to match nulls? You're showing a huge lack of understanding here. You don't eq peaks to match nulls. You fix nulls by moving the subs and getting them in phase. There's a video in the link I posted that assist in placing subs to do just that. BTW.. You can not boost a null.

I think you have something setup wrong as your responses can not be accurate. No offense but that response is also not smooth at all. It drops like a rock above 50hz. That's not a house curve but a poorly setup sub. I run my subs hot so I agree with flat is boring. But what you have would be the response of a sub just thrown in a room .. definitely not a response after proper setup.

Honestly I think you just got some subs, starting messing with REW and now think you know how it all works. To those who understand sub responses in a room.. little you say makes any sense.

Do yourself a favor and click the link. Follow the steps to set everything up right and take measurements, see what you have and then begin working on the issues.
one of us is definitely showing a huge lack of understanding here

please explain how you can have phase issues when adding a second sub produces a perfect 6 db doubling of output. and then adding 2 more subs produce another perfect doubling of output.
how can there be phase cancellation when you are getting the theoretical maximum output possible from the additional drivers?

Quote:
Originally Posted by cdy2179 View Post
This made no sense either.

If you're using a usb mic with a cal file like a Umik-1 you don't calibrate the SPL.

https://www.roomeqwizard.com/help/he.../inputcal.html

If you're using some old mic you have to load a cal file to make the measurements accurate. some mics aren't capable of measuring low in freq so they are useless here.
this must be a joke. haha Im laughing
you honestly dont know the difference between a mic calibration file and an spl calibration?

fwiw I use a dayton emm-6 measurement microphone into a tascam us144 audio interface for my measurements

64 base level speakers $10k
28 height speakers $10k,
14 subwoofers $10k
90% of the movie sound coming from the center channel - priceless.
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