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Subwoofer - Using SMS-1 - Flat or House Curve ?

post #1 of 11
8/6/09 at 10:06am
Thread Starter 
It's been a while since i poked my head into the subwoofer forum.

I know there is a poll for this but no thread so i thought before tinkering with my SMS-1 and subwoofer i would ask here. I have an SVS-PB-12-Plus/2 Subwoofer hooked up via the SMS-1. I have just upgraded the firmware for the SMS-1 after almost a year of meaning to do it. It's been a few years since i last had a stab at calibrating it using the SMS-1 and Avia and a sound level meter but it's in need of calibration again.

I have two ports blocked on the subwoofer and it's set to 16hz on the subsonic filter knob.

First off i wonder if any opinion can be given on having two ports blocked. Should i go for the 20hz option and just one port blocked or leave it the way i have it ?

Concerning the SMS-1....I bought it because the room had a few peaks in it. Am i right in thinking it's better to lower the peaks rather than to increase the other frequencies to compensate for these peaks. I read somewhere that it's best to lower by 3db maximum but the SMS allows for a lot more than 3db. Does lowering peaks have any negative effect ?

Should i get the line as flat as possible with no humps whatsoever or should i add a house curve at some frequencies. Now i know i could try it out but i would love to hear opinions on this.

I will be using a pretty cheap digital sound level meter from Radioshack which is now about ten years old and my concern is when using Avia test tones i'm not sure how accurate it is once you get down low. Do i compensate for the lower frequencies in some way when using a sound level meter ?

I'll be crossing over at 80hz and setting all speakers to small but i always seem to have a problem at the crossover point as i'm unsure how you get it precise and spot on so all speakers match. How do other people make sure it's a smooth transition ?

I think i'm right in saying the subwoofer should be 10db higher than the other speakers as thats how they are at the cinema. It's just getting that 10db higher all the way down to 20hz that is troublesome due to the sound meter probably not being accurate that low.

I watch movies on Blu Ray only these days.
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post #2 of 11
8/6/09 at 10:18am
Quote:
Originally Posted by FoxyMulder View Post

It's been a while since i poked my head into the subwoofer forum.

I know there is a poll for this but no thread so i thought before tinkering with my SMS-1 and subwoofer i would ask here. I have an SVS-PB-12-Plus/2 Subwoofer hooked up via the SMS-1. I have just upgraded the firmware for the SMS-1 after almost a year of meaning to do it. It's been a few years since i last had a stab at calibrating it using the SMS-1 and Avia and a sound level meter but it's in need of calibration again.

I have two ports blocked on the subwoofer and it's set to 16hz on the subsonic filter knob.

First off i wonder if any opinion can be given on having two ports blocked. Should i go for the 20hz option and just one port blocked or leave it the way i have it ?

Concerning the SMS-1....I bought it because the room had a few peaks in it. Am i right in thinking it's better to lower the peaks rather than to increase the other frequencies to compensate for these peaks. I read somewhere that it's best to lower by 3db maximum but the SMS allows for a lot more than 3db. Does lowering peaks have any negative effect ?

Should i get the line as flat as possible with no humps whatsoever or should i add a house curve at some frequencies. Now i know i could try it out but i would love to hear opinions on this.

I will be using a pretty cheap digital sound level meter from Radioshack which is now about ten years old and my concern is when using Avia test tones i'm not sure how accurate it is once you get down low. Do i compensate for the lower frequencies in some way when using a sound level meter ?

I'll be crossing over at 80hz and setting all speakers to small but i always seem to have a problem at the crossover point as i'm unsure how you get it precise and spot on so all speakers match. How do other people make sure it's a smooth transition ?

I think i'm right in saying the subwoofer should be 10db higher than the other speakers as thats how they are at the cinema. It's just getting that 10db higher all the way down to 20hz that is troublesome due to the sound meter probably not being accurate that low.

I watch movies on Blu Ray only these days.

You've got a lot of questions there, but let's start with "I think i'm right in saying the subwoofer should be 10db higher than the other speakers as thats how they are at the cinema."

That's wrong. The speakers and subs should be calibrated the same. Some folks do like to run their subs a little hot, maybe by a couple of db's, but +10 is a bit much. The 10db higher that you are referring to has to do with the way many movies are mixed allowing for bass peaks that are 10db higher than the other channels. You don't calibrate 10db higher.
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post #3 of 11
8/6/09 at 10:37am
Thread Starter 
Quote:
Originally Posted by mojomike View Post

You've got a lot of questions there, but let's start with "I think i'm right in saying the subwoofer should be 10db higher than the other speakers as thats how they are at the cinema."

That's wrong. The speakers and subs should be calibrated the same. Some folks do like to run their subs a little hot, maybe by a couple of db's, but +10 is a bit much. The 10db higher that you are referring to has to do with the way many movies are mixed allowing for bass peaks that are 10db higher than the other channels. You don't calibrate 10db higher.

Thats good to know then. Currently i run it 3db higher but would have probably set it 10db higher. Now i'll not do that.

What about the other things i asked ?
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post #4 of 11
8/6/09 at 10:45am
Let's discuss "I have two ports blocked on the subwoofer and it's set to 16hz on the subsonic filter knob.

First off i wonder if any opinion can be given on having two ports blocked. Should i go for the 20hz option and just one port blocked or leave it the way i have it ?"

With the two ports blocked, do you have sufficient output for your needs without noticeable chuffing from the remaining port or distortion you can hear? If your clean output is enough, then it's fine. If not, pull out a plug and tune to 20hz.
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post #5 of 11
8/6/09 at 10:56am
Thread Starter 
Quote:
Originally Posted by mojomike View Post

Let's discuss "I have two ports blocked on the subwoofer and it's set to 16hz on the subsonic filter knob.

First off i wonder if any opinion can be given on having two ports blocked. Should i go for the 20hz option and just one port blocked or leave it the way i have it ?"

With the two ports blocked, do you have sufficient output for your needs without noticeable chuffing from the remaining port or distortion you can hear? If your clean output is enough, then it's fine. If not, pull out a plug and tune to 20hz.

Goes down deep and low and i can't hear any distortion at all but i'm not entirely happy with the crossover between the subwoofer and the main speakers. I feel i might have that slightly wrong.

I have been running the subwoofer now for well over three years but just like projectors need re-calibration i figure it's now time to re-calibrate this subwoofer and perhaps change the room position. I basically want to experiment with a few things but i'd like to get everything working even more precise than when i last calibrated it as i feel i can improve it.

I have been trying to locate Radioshack digital sound level meter correction values but can only locate the analog ones.
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post #6 of 11
8/6/09 at 11:23am
Quote:
Originally Posted by FoxyMulder View Post

Goes down deep and low and i can't hear any distortion at all but i'm not entirely happy with the crossover between the subwoofer and the main speakers. I feel i might have that slightly wrong.

I have been running the subwoofer now for well over three years but just like projectors need re-calibration i figure it's now time to re-calibrate this subwoofer and perhaps change the room position. I basically want to experiment with a few things but i'd like to get everything working even more precise than when i last calibrated it as i feel i can improve it.

I have been trying to locate Radioshack digital sound level meter correction values but can only locate the analog ones.

The transition between the mains and the sub is one of the most important aspects of realistic bass. Fortunately, you have one of the best tools available for optimizing the crossover area, the SMS-1.

You should use the SMS-1 to view the frequency response and take notice of the 80hz region. Is it smooth or is there a deep valley? If there is a valley, use the SMS-1's phase adjustment to get the 80hz area a smooth as possible. Then fine-tune with the PEQ controls.
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post #7 of 11
8/6/09 at 11:35am
The issue of whether you should use a house curve or not is somewhat controversial. The new SVS EQ-1 DOES NOT allow for a house curve.
On the other hand, the AntiMode 8033 has a two position switch to allow for a boost down deep which qualifies as a house curve to me.

I think of a house curve the same way I think about tone controls. Some people wouldn't be caught dead using tone controls, others find them quite beneficial.

Compared to the 8033, you have at least as much flexibility to create a house curve with the SMS-1. That is one of the nice things about the SMS-1, you can adjust it to your liking.
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post #8 of 11
8/6/09 at 11:37am
Quote:


The issue of whether you should use a house curve or not is somewhat controversial. The new SVS EQ-1 DOES NOT allow for a house curve.

that's what I've read also
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post #9 of 11
8/6/09 at 11:56am
Re: The house curve, the SMS-1 is great for this sort of thing. It allows you to custom-make up to six different curves for the presets. I'd suggest making a flat curve and several other curves with different boosted areas. Then you can switch among the different curves by remote to find your preference.

I usually prefer flat, but I find I prefer some different curves for different material.
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post #10 of 11
8/6/09 at 12:17pm
Thread Starter 
I think trying different curves is a good idea. Especially one for music and one for movies. I can leave one flat as you say. I also plan on trying a few things in the room to see if furniture and other things in the room has an impact on the peaks.

I plan on hooking up some six channel analog cables to my receivers input when i buy the new Oppo Blu Ray player which is another reason for calibration as i want to get it very good before that arrives. I figure i'll save a fortune by renting more movies rather than buying so the player pays for itself.
( sick of buying movies i regret paying for that i only watch once anyways )

I have been reading i can simply use component video cables since they are 75ohm.

The cables i have are these and they are good quality.

http://www.futureshop.co.uk/ixos-xhv...-3m-p-872.html

Since i already have two pairs of these cables do you think this is fine to use as a 6 channel analog cable even though it's originally intended as a video cable ?
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post #11 of 11
8/6/09 at 12:22pm
Those cables would be fine.

As far as the room furniture goes, the things that will make the biggest difference would be anything that is big and stuffed like a sofa or an over-stuffed chair. These are like bass traps.
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