# You cannot EQ a subwoofer?



## Gabriel (Nov 7, 2017)

I been researching subwoofers too much lately. There is one guy Brain Elliot (Eliot?) everyone on the various home audio forums seems to reference. They say he has the best subwoofer set-up or one of they have ever heard. He uses multiple subwoofers, but what gets me is he uses no EQ or CROSSOVER SETTINGS at all. He also says that even with the evolution of the MINIDSP that one cannot EQ a subwoofer. I know a car environment is completely different, but how accurate is or are his opinions?


----------



## Bayboy (Dec 29, 2010)

I've heard of him and recall reading some of his writings or whatever, but maybe you're taking it out of context somewhat? What does he exactly mean by "can't"?


----------



## Holmz (Jul 12, 2017)

Gabriel said:


> I been researching subwoofers too much lately. There is one guy Brain Elliot (Eliot?) everyone on the various home audio forums seems to reference. They say he has the best subwoofer set-up or one of they have ever heard. He uses multiple subwoofers, but what gets me is he uses no EQ or CROSSOVER SETTINGS at all. He also says that even with the evolution of the MINIDSP that one cannot EQ a subwoofer. I know a car environment is completely different, but how accurate is or are his opinions?


With MiniDSP maybe not... (I don't know)

Technically one needs enough taps, or a sample rate that allows filters to be built. If it is a band pass then one would need taps for more more than 10 Hz which probably means >0.2 seconds. So at 48k sample rate then 16k of FIR taps or longer makes sense. (Or processing the Subwoofer with it resampled down to ~250 samples/second.

None of that works well for a DSP with a small bank of taps, or for a 5.1, or other system, that needs the sound to be in sync with the lip movements.

So technically it is possible in the general sense... but I cannot speak to the MiniDSP particulars.


----------



## dcfis (Sep 9, 2016)

Plays full range?


----------



## Elgrosso (Jun 15, 2013)

I can see not needing EQ with multiple subs well placed, but I’m curious about letting them play full range. Well maybe they’re all in bandpass or it’s just specific to these subs natural responses.


----------



## thornygravy (May 28, 2016)

I think there's more to the story here. No crossovers. Yeah ok.


----------



## SPLEclipse (Aug 17, 2012)

Lower frequencies fall in the modal range and you can't EQ nodes at the listening position. You can smooth the modal response by using several subs in differing locations throughout the room.

As for the rest of his claims - room treatment and multiple subs (to smooth modal response) are almost essential if you want the best possible reproduction. That doesn't negate the use of electronic filtering in my opinion. Is he one of those guys that uses a single fullrange driver in a back-loaded horn for his mains? Only listens to vinyl? Uses super esoteric signal cabling? His philosophy would be inline with that type of listener.


----------



## Gabriel (Nov 7, 2017)

Elgrosso said:


> I can see not needing EQ with multiple subs well placed, but I’m curious about letting them play full range. Well maybe they’re all in bandpass or it’s just specific to these subs natural responses.


Nope they're all sealed! I also believe they're 10"


----------



## Gabriel (Nov 7, 2017)

SPLEclipse said:


> Lower frequencies fall in the modal range and you can't EQ nodes at the listening position. You can smooth the modal response by using several subs in differing locations throughout the room.
> 
> As for the rest of his claims - room treatment and multiple subs (to smooth modal response) are almost essential if you want the best possible reproduction. That doesn't negate the use of electronic filtering in my opinion. Is he one of those guys that uses a single fullrange driver in a back-loaded horn for his mains? Only listens to vinyl? Uses super esoteric signal cabling? His philosophy would be inline with that type of listener.


Nope as I believe he is using $200 B&C 10" woofers.


----------



## dgage (Oct 1, 2013)

You can EQ subs as I do it all the time but you can’t EQ around a room mode. The room dominates the sound of speakers and subs way more than most people realize. The key to good sounding bass is multiple subwoofers in the room (spread out) to reduce the impact of the room on the sound. However, you need to make sure the subs are integrated well (timing and phase) or you’ll have a mess on your hands.

This “paper” is the most informative without reading a ton of technical details.
https://www.harman.com/sites/default/files/multsubs_0.pdf

And here is a good utility for optimizing multiple subs in a room. He also has some links to applicable reading.
Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software


----------



## Gabriel (Nov 7, 2017)

I just read the Harmon article, but it seems to me unrealistic. The article talks about a standard room size for theoretical testing purposes being a 20'x24' room. The article also talks about each subwoofer size being at least 12" yet they at one point simulated a response for 5,000 12" subwoofers. Mathematically this is impossible given the room size as they would never fit in the room!


----------



## dcfis (Sep 9, 2016)

My maths says that you could fit just under 7700 12"subs if the room had a standard height ceiling


----------



## Hanatsu (Nov 9, 2010)

Gabriel said:


> I been researching subwoofers too much lately. There is one guy Brain Elliot (Eliot?) everyone on the various home audio forums seems to reference. They say he has the best subwoofer set-up or one of they have ever heard. He uses multiple subwoofers, but what gets me is he uses no EQ or CROSSOVER SETTINGS at all. He also says that even with the evolution of the MINIDSP that one cannot EQ a subwoofer. I know a car environment is completely different, but how accurate is or are his opinions?


You can use multiple subwoofers in a room to eliminate room modes. I.e one sub in the back might have a dip at 50Hz but one in the front might cover up for that. Wavelengths are so long so the subs (probably) never go 180deg out of phase with each other, this will have the effect of evening the frequency response in the room.

In a car it's different, you "can't" fill the entire car with subs to control modes. You could technically build a front sub and combine it with a rear sub to fill up each others modal dips. You'd still require EQ though. Subwoofers respond particularly well to EQ and since the FR won't change much around the listening area (due to long wavelengths) you can use high Q filters to shape the response.


----------



## Gabriel (Nov 7, 2017)

dcfis said:


> My maths says that you could fit just under 7700 12"subs if the room had a standard height ceiling


With seating as they described and room to walk? God I'd hate to sit then realize I had to pee!


----------



## Gabriel (Nov 7, 2017)

I did find this software:
Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software


----------



## Gabriel (Nov 7, 2017)

Here's another:
Serious Audio: Two Great Articles on Multiple Subwoofers by Dr. Earl Geddes


----------



## dgage (Oct 1, 2013)

Gabriel said:


> I did find this software:
> Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software


I had linked to it above. There is a many page discussion on AVSForum,com, which is the premier home audio/theater forum on the net though DIYAudio is up there for people building speakers.

And you’re being a little cynical if you take them seriously about that many subwoofers being simulated. It was just the natural conclusion to how many subs can we simulate and what .000001% improvement will we get. They pretty much state that anything more than 4 provides a diminishing return on improvement.


----------



## dgage (Oct 1, 2013)

And Toole and Geddes are some of the absolute smartest but sometimes they do have some off the wall ideas, especially when talking about large subwoofers. Pretty much it seems like they’ve become a little cynical as they’ve gotten older and don’t try as many new things anymore.


----------



## Holmz (Jul 12, 2017)

dgage said:


> And Toole and Geddes are some of the absolute smartest but sometimes they do have some off the wall ideas, especially when talking about large subwoofers. Pretty much it seems like they’ve become a little cynical as they’ve gotten older and don’t try as many new things anymore.


Or they ran out of things to try.
If they were slow, then they would have the pleasure of a new idea every decade.


----------



## SPLEclipse (Aug 17, 2012)

Hey Hanatsu is back! (sorry for the OT post)


----------

