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Discussion Starter · #1 ·
I'll start by saying thankyou to everyone for the wealth of knowledge I've gained from just reading the forum, over some time. Now it's my turn to ask stupid questions :)

First some details about the room and the kit. I'm converting one of my rooms into a dedicated HT here in the UK. The room is approx 16'5" long, 12'2" wide, and 7'2" high. It's not actually entirely regular, since the house dates from around 1850, the walls aren't entirely square to each other and vary by several inches at opposite ends etc. I have a bit of bass-trapping - floor to ceiling corner tri-traps from GIK. Can't do much more due to doors and shelves in awkward places.

I'm starting by trying to set up my Seaton Sounds Submersive. I'm using a Classe SSP-800 processor, which has PEQ for each channel, although only 5 filters per channel. The Submersive has masses of headroom in this relatively tiny room, it's pretty much at its lowest gain, so if I grasp this right I should be able to EQ without worrying out of headroom.

The Submersive is placed against the left wall, about a third of the way from the front of the room. I placed it there by ear by sticking it in the 'main' listening position and doing a 'sub crawl'. There are a couple of other possible placement options, of which more below.

There are two rows of couches, the back one on a plinth about a foot high, and with three seats per couch.

So far, I've tried taking measurements across the front 3 seats, which are the 'primary' ones mostly because the rear 3 seats are a bit close to the surrounds than ideal. Annoyingly, the front center seat which I'd mostly use for 2 channel listening, is about smack bang in the center of the room which with 20-20 hindsight I should have tried harder to avoid, but I'm stuck with it now.

I've got things configured with an 80Hz crossover, and a 24dB/Octave rolloff.

Here's the graphs for front left seat, front center, and front right. I've violated the rules slightly and my graphs run down to 10Hz since I have useful output there still, hope that's ok!

Front Left :
sub-lf-before.jpg
Front Center :
sub-cf-before.jpg
Front Right :
sub-rf-before.jpg

My reading of these are that I have peaks and dips that fit in pretty well with the predicted room modes from calculators, around 34hz, 46hz, 58hz, 69hz, and round 78-85hz.

After some eyeballing of the graphs, and playing with averaging them, I did my filter building from the left front trace. I've used a hard knee house curve from +6dB at 30hz down 0dB gain at 80hz.
I took the peaks and suggested filters from REW, then tuned things by hand, trying to reduce the number of filters and do broader changes. I ended up with these 4 filters :

Filter 1: ON PK Fc 81.9Hz Gain -13.4dB Q 5.3
Filter 2: ON PK Fc 65.8Hz Gain -11.1dB Q 7.1
Filter 3: ON PK Fc 46.2Hz Gain -7.9dB Q 7.5
Filter 9: ON PK Fc 147.1Hz Gain -11.1dB Q 3.2

These yield the following measurements at the same positions :

Front Left:
sub-lf-after.jpg
Front Center:
sub-cf-after.jpg
Front Right:
sub-rf-after.jpg

So, my questions are :

Am I on the right track here, or have I got the wrong end of the stick anywhere in my approach so far?

Is there anything I can do about the dips and peaks that are around 45hz and centered round 34hz or so, since I don't know how to deal with things that are dips in one seat and peaks in another. Apart from just sitting in the front right seat as it all seems a bit better there :)

Will I gain anything by trying a different position for the sub? From my crawling, there seems to be another possible placement option on the front wall, about halfway between the left speaker and the center speaker. Moving it is a 2 man job though, so it's not an each change!

Thanks for reading this far!
 

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Discussion Starter · #3 ·
Most people just EQ for the sweet spot. Alternately, REW can perform an "average" of the three, and you could equalize that curve.
Thanks, that's what I figured. I've seen how to average, so I may well try that.

The only reason I didn't try and equalise for the sweet spot is that I wasn't really sure how to try and handle the response I get in that center seat, and if I should be trying to do anything about that fairly monster dip around 45hz plus, or whether that's a highroad to nothing - or alternatively whether that's a big hint to play with the sub position first. I've read your discussions about whether pushing things up with EQ is ok or not, but I'm not sure whether these dips fall into those categories

Also, since I have a gently rising response from about 30hz downwards, I dunno whether to try and 'fix' that to be flatter, or be happy that it does that and leave it to it since my ability to actually here it will fall at the 10hz rise anyhow.

Thanks again,

Sam.
 

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Hi Sam,

I was reading your post. I have SSP-800 and added two subs to my system. I am running some measurements and have similar dip around 31HZ. What did you end up doing with it?
Thanks a lot for your help,
Albert
 
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