EQ and SPL question for diy subs

C

Clownaphobia

Enthusiast
Hey guys, not long ago I asked for advice setting up my diy subs. I finally settled on having both near field in my oversized living room. This way they produce tactile feel for the main listening area and I don’t have to have them turned so loud to try and fill the entire room. I am pretty happy with them there. I finally got a minidsp and U mik and Rew up and running. I took measurements at the main listening position. I also have measurements of their output before hitting compression. I have some output down to about 12 hz...but its pretty useless in this large room (93db). So my question is...if I put a steep filter at 20 hz, would this allow more headroom for 20hz and up? Right now at 20 hz, I’m only getting 102 dB, but by 50 hz I’m at 120 dB. That is also assuming I’ve done everything correctly...which is a big assumption lol. Thanks for your help! Basically I would be changing the curve to act more like a ported subwoofer. Similar to the Hsu Uls settings
 

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annunaki

annunaki

Moderator
Short answer is yes, however it is how you do it that matters. If your drivers and amplifier are not capable of adding 10db or more output near 20hz (not any I am aware of on the market) you could end up with some smoking coils. The key is to pull down your room peaks with Eq to flatten response and only add small amounts of boost where needed.

You have the right idea with a steep filter at 20hz to increase headroom.

Do you have a screen print of the raw driver response at the listener position with no Eq applied? That would help us identify what modes to tame with the Eq and what notes could be boosted some getting you closer to your goal.
 
TLS Guy

TLS Guy

Audioholic Slumlord
I can't really answer your question as you have not provided nearly enough information.

From the looks of your FR it seems this is a sealed sub with and F3 around 40 Hz.

To answer your question we need details of the sub driver and the modeling of the enclosure. We also need details of your amplification.

Sealed subs are highly inefficient. Saving of enclosure volume is really their only advantage, after that it is all downsides. The issue is that F3 is higher than for other alignments. If you have enough power available and the driver has a motor system that will tolerate the extra power and cone excursion for the required Eq, then yes, the driver can be boosted 12 db per octave below F3. However there comes a frequency boost combination in ALL sealed designs were a high pass filter is required to prevent driver damage and the nasty sounds of driver over excursion.

It is a myth that a sealed sub will have tighter bass than other alignments. It can have, but the issue comes down to Q. to have nice tight firm bass requires a low Q design.

Unfortunately for sealed designs this results in higher F3 before Eq. So this right away limits power output at the lower end. If higher Eq is accepted then some degree of ripple will occur just above F3 which can make for bass that is anything but tight.
 
William Lemmerhirt

William Lemmerhirt

Audioholic Ninja
Be a lot easier to corner load em. Personally That curve would drive me bonkers.
 
C

Clownaphobia

Enthusiast
I played around quite a bit with minidsp and taking measurements today. I ended up with putting a steep filter at 20 hz, and boosting 25hz by about 5db. I also got the peaks tamed quite a bit. For reference...clean spl for 25 hz is up to around 110 dbs, and got the peaks around 60 hz down to about 115. It does sound quite a bit smoother. Already in bed tonight, due to an early morning tomorrow so don’t have any graphs. Also they’re dual Alpine Type R 12’s in separate sealed 2.5 cu ft boxes pushed by an EP2500. And the design of the room doesn’t Allow me to corner load. Completely Open floor plan. Having them near field has been the best Option so far. I guess I can just use my ears to make sure I don’t hear anything objectionable
 

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