Sub Setup and Room Correction

The Moog

Member
Hi there guys,
Now that I have my lovely little SB-12Plus, and it is sat in the corner where it shall reside, I obviously want to set it up properly. As far as I understand, this involves getting hold of an SPL Meter, burning a CD of test tones, and measuring the room response. Plotting this data, finding the biggest nasty peak in the room, and flattening this off with the EQ controls on the back. Finally, running the whole thing again to see that you have achieved what you set out to do and not made thing worse seems like a good idea as well! Does this seem sensible?

OK then, I hope to buy a better amp at some point next year, and more than likely this will have some kind of room correction built into it (such as Audessey) where it can set itself up and perform its own room correction. My final question is this, if your amp can do this, are you better off:

a) Leaving your corrected sub as it is for the room calibration. The amp has a much better chance of getting it right if you have got the sub fairly close to where it should be already.

or:

b) Defeating the EQ settings you calculated for your sub and letting the amp do it all. It can achieve this much more accurately than you will be able to by hand, so just let it do its thing.

Cheers for the help,


The Moog
 
J

jackal

Guest
I have found that the Audyssey EQ on my Denon AVC-A11 has been very successful with the equalisation of my B&W - from my listening point of view it could not sound better. Unfortunately only the top Denon allows for more than one sub to be equalised (However shouldn't be an issue for you).
 

Mr_Sukebe

Active Member
Have to say that I've tried room correction in my own system, with some interesting findings. My room (like a lot of people) suffers from a serious bass "hump" at around 40hz of close on +15db. I'd love to know how the filters on the back of a sub can correct for that.

As for your question, I'd suggest you get the sub as best optimised as possible by hand, before then relying on any other room correction. Heavy room correction does seem to have it's own not so pleasant side effects.
 

Nimby

Distinguished Member
REW = Room Equalisation Wizard available as a free download from Home Theater Shack is a lot of fun once you are up and running.

The test sweeps are so quick that one can take dozens of quick measurements per hour.

By moving the sub a couple of inches and retesting you can actually see the response curve change.

Hopefully a satisfactory response can be obtained in a fairly short time without resorting to more than small movements of the sub to find the best position in your room.

The SMS-1 and BFD are (consecutively) expensive and cheap options for those eager to play around with filters to flatten the response curve or add a housecurve for more power in the deep bass. The SMS-1 has its own microphone while the BFD uses an inexpensive RS SPL meter as a test microphone.
 

Member 96948

Distinguished Member
I had great success setting up sjalloq's SB12 using my SMS-1 as a subsitute for running REW. I used it in the passive sense of turning all equalisation off and merely using it's ability to show the subs response on a screen.

Being able to see a visual representation of the response curve, takes a lot of the guess work out of the whole process and is especially useful for sorting the critical phase setting, so often ignored. It's also useful to use it to fine tune your main speakers positioning, before you even turn the sub on.

Used as a passive tool, REW would seem to offer a more acurate (read higher resolution) readout of whats actually going on than the SMS-1 can.

And it's free.:) Well, £30 if you factor in the cost of a Radioshack SPL meter (BK Electronics - £25) and a cheap, but long phono cable+ adaptor to your sound card's input, but the end results will far outway the cost.

Russell
 

Member 96948

Distinguished Member
My room (like a lot of people) suffers from a serious bass "hump" at around 40hz of close on +15db. I'd love to know how the filters on the back of a sub can correct for that.
They can equalise the worst of it out, revealing the rest of the bass this one room mode masks. It sounds to me like you're suffering the floor to ceiling dimension based mode, that dominates most rooms.

Russell
 

Mr_Sukebe

Active Member
They can equalise the worst of it out,
How do they do that? The subs I've seen seem to have high level cutoff filters and volume controls. Are they subs with equalisation that can chop out a bass hump at a specific frequency?
 

The Moog

Member
The SB-12Plus has three EQ dials,
these can be used once you have found out where your major hump is. The first sets where the centre of this hump is, the second sets the width, and the third is how far you want to pull it down.


The Moog
 

Member 96948

Distinguished Member
How do they do that? The subs I've seen seem to have high level cutoff filters and volume controls. Are they subs with equalisation that can chop out a bass hump at a specific frequency?
Indeed that's half the point of all of the SVS 'plus' series subs (in realwood finishes). Have a look at this lot:


Cheers

Russell
 

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