Thoughts on SMS-1 Graph - AVS Forum
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Old 02-17-2013, 07:40 PM - Thread Starter
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Hi All,
I would really appreciate some feedback on the below SMS-1 graph. I've recently upgraded to twin SVS SB13-plus subs (large room, 6m x 6.5m x 2.8m) and the below shows the current tweaked room response. I prefer a "house curve" instead of a flat response for movies. So far I've managed to leave the volume of the SMS-1 at 15 (unit gain). I'm however wondering that if I make some more adjustments for a straighter slope (between 48-80Hz), I would have to boost the volume of the SMS-1 a bit as the sub volumes are getting close to max.

One other clarifying question around the operation of the SMS-1; once I've adjusted the below graph of preset 5 using 'setup' I can go into say, present 4 and create a new EQ curve (assuming preset 4 is showing in the top left hand corner of the screen (during curve editing). Then swap between preset 4 and 5 to compare the two?





Regards,
Stephen
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Old 02-17-2013, 08:44 PM
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I don't use the set-up screen for anything. When you go to the set-up screen by pressing 1-2-3-4-5, I then press pre-set #1 and just make my adjustments there. I then set the default to pre-set #1 so when I turn the SMS-1 on it will automatically go to that pre-set. You can create any curve you want for all of the pre-sets. Just press the pre-set you want to change and make the adjustments. Then you can switch back and forth to compare which one sounds better to you. Your graph looks OK. The only real issue I can see is that you seem to have a large peak at around 26 hz. You have reduced that area by about 13 dbs. That is a big reduction. I would try moving your subs around some to get a flatter response first and then using the SMS-1 to make final adjustments.

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Old 02-17-2013, 08:57 PM
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Originally Posted by whmacs View Post

Hi All,
I would really appreciate some feedback on the below SMS-1 graph. I've recently upgraded to twin SVS SB13-plus subs (large room, 6m x 6.5m x 2.8m) and the below shows the current tweaked room response. I prefer a "house curve" instead of a flat response for movies. So far I've managed to leave the volume of the SMS-1 at 15 (unit gain). I'm however wondering that if I make some more adjustments for a straighter slope (between 48-80Hz), I would have to boost the volume of the SMS-1 a bit as the sub volumes are getting close to max.

One other clarifying question around the operation of the SMS-1; once I've adjusted the below graph of preset 5 using 'setup' I can go into say, present 4 and create a new EQ curve (assuming preset 4 is showing in the top left hand corner of the screen (during curve editing). Then swap between preset 4 and 5 to compare the two?





Regards,
Stephen

Well here's how I see it. Now everyone will have different opinions on eq'ing, so take this as my opinion.

1) That is a huge cut at 28hz. I feel that is unnecessary. I'm all for a house curve, but cuts can be just as detrimental as boost, as you are having to increase your sub gain to compensate (which it sounds like has happened as you have stated in your post).

2) A ruler flat slope is great, but not if it's overdone. You want to use as little boost/cuts as possible to achieve the best results. The SMS has too much smoothing going on to really drill down too much into problem areas.

3) It looks like the cut and boost at 45 and 50ish are being counterproductive. You might look at the q on those and see if they aren't playing nicely together.

4) You can certainly change the gain structure by either upping the sub out on your receiver or the SMS1. Ideally your sub gain shouldn't be more than about half. Be careful about raising the volume on the SMS1 too much though. I've O scoped clipping on mine at a volume of 28. I know that's a lot higher than you are at, and probably won't get near there, but just food for thought.

5) Frequency response is most easily corrected by sub placement (and room treatments).

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Old 02-17-2013, 09:31 PM - Thread Starter
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Hi Capricorn kid and Bass addict,
Thanks for taking the time to help me out, i really appreciate it.
I'm a bit stuffed as far as moving the two subs around. Where they currently are is the only option I have (if I dont want a divorce).
To avoid the large -13DB cut is there any other options (a number -6 DB cuts over higer Q's maybe? It is quite a large hump around that area. I could also try fiddling with the phase of one of the subs to reduce that hump?
I'll have a play with that 48 to 80hz range to see if I can improve on it.

Regards,
Stephen
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Old 02-17-2013, 09:42 PM
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Why cut it at all? Based on your particular sub, that's an area I'd want to optimize. You really don't need your house curve that aggressive either. A 3 db rolloff is essentially halving your output. I'd personally see how the 28hz curve looks with 0 cuts, and start the house curve roll off from there.

Our hearing is more acute to higher frequencies than lower ones. An 80hz tone will sound louder than a 20 hz one. The whole point of a house curve is to equalize these differences, so they sound similar in output. A house curve is purely subjective, and will vary from one listener to the next.

I prefer a house curve for HT use, but a ruler flat curve for music. That's another thing that makes the SMS handy; the fact I can switch between eq options on the fly, not to mention volume.

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Old 02-18-2013, 01:35 PM
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Originally Posted by whmacs View Post


To me, this looks more like a recession through the mid bass than a big hump at 28 Hz. You have a substantial cut at about 52/53 Hz. Is that a wide Q cut? If so, work to bring that up rather than bringing 28 Hz down.

It would be interesting to see each sub in isolation with no EQ applied, and the speakers shut off. Then both subs combined with no EQ applied. IOW, it would be nice to see the "native responses before EQ to see what you're dealing with.

Also, what crossover(s) are you using in the AVR? Finally, have you tried changing the subwoofer Distance setting in the AVR? If you're getting a cancellation due to an incorrect subwoofer Distance setting, that can increase the output around the crossover frequency substantially.

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Old 02-18-2013, 07:35 PM - Thread Starter
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Hi Craig John and Bass Addict,
Thanks for all the great ideas, I'll have another go this weekend to see if I can improve on things.I put the cut in around the 52hz to try and bring down the peak at that point to tame the two valleys either side of it. But as you say If I could raise up the overall mid bass, that would help improve things as well. Cross overs in the AVR are set to 80Hz..

While I can change the phase on the SMS-1, would there be any benefit to try adjusting the phase of each sub?

I'll double check the distance in the AVR. I'll also check how things sound if I remove all EQ and just adjust the volume levels, as you say I have a big hump at 28hz and then it trails off from there (not dissimilar to a house curve).

regards,
Stephen
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Old 02-18-2013, 07:58 PM
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Originally Posted by whmacs View Post

Hi Craig John and Bass Addict,
Thanks for all the great ideas, I'll have another go this weekend to see if I can improve on things.I put the cut in around the 52hz to try and bring down the peak at that point to tame the two valleys either side of it. But as you say If I could raise up the overall mid bass, that would help improve things as well. Cross overs in the AVR are set to 80Hz..
It's hard to look at the EQ'd result and then make recommendations. It's a lot easier if we can see the baseline response of the subs with no EQ applied and no speakers.
Quote:
While I can change the phase on the SMS-1, would there be any benefit to try adjusting the phase of each sub?
This is why I asked to see independent graphs and then a combined graph. It's hard to predict, but it's worth trying. Do this with just the subs playing, with the speakers turned off.
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I'll double check the distance in the AVR.
Don't just check it, try adjusting it. Do this first, with no SMS EQ applied. You may be able to improve the response around the crossover without any EQ. You'll need to turn the speakers on to see the interaction of the subs with the speakers.
Quote:
I'll also check how things sound if I remove all EQ and just adjust the volume levels, as you say I have a big hump at 28hz and then it trails off from there (not dissimilar to a house curve).
Post the graphs with no EQ, and we'll go from there.

Craig

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