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Please help me decifer my REW graph

Tyler Durden

Distinguished Member
Okay, so I have just bought an SVS SB12+ and I am trying to get the best out of it, so I have got myself REW and have managed to get a graph.

Now what?

Any advice on how to improve it would be appreciated.

I do have one question, why don't my readings start at the bottom left of the graph like most of the others I have seen?
 

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thomasmacleod1

Active Member
Hi there hows the new sub going?

Is there a massive difference over the AE sub ? for the money I'm well impressed with the sound and swmbo is happy with the look:D

yet to try with music but filling that bass gap with the genies i was getting and my last sub! while watching movies.

think i might have a little play with REW tomorrow !
 

Tyler Durden

Distinguished Member
It is a step up from the AE but not huge. A bit more range on the bottom end, that's all.
 

Badger0-0

Distinguished Member
Okay, so I have just bought an SVS SB12+ and I am trying to get the best out of it, so I have got myself REW and have managed to get a graph.

Now what?

Any advice on how to improve it would be appreciated.

I do have one question, why don't my readings start at the bottom left of the graph like most of the others I have seen?

That graph is not right, imo.

The readings at the very bottom end are often inaccurate, so don't worry about that.

I suspect you have altered the smoothing setting.

Don't ask me what it should be, I can't remember and I'm not playing with REW this time of night :D
 

Tyler Durden

Distinguished Member

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Badger0-0

Distinguished Member
That's incredibly humpy and still seems wrong, imo.

I'll have to mull that over.

Can you describe your room mate?

Size, furnishing etc.
 

Member 639844

Former Advertiser
I agree with Badger on this one. Ideally the subs response should follow the blue line. This assumes your using a crossover around the 80hz mark. The fact your graph doesnt follow the blue line and carries on straight on shows your running sweeps with the speaks on too. Badger will stop me here and say this is better as we all listen to out kit with the speakers on and he's right, but I prefer to measure the sub first, then add the speakers later to see whats going on. This way you can see what your sub is doing and make sure its rolling off as it should, and see exactly how your speakers are changing the subs response overall, if at all.

The graph does look a little wavy, and a bit high on spl at the bottom end. Did you calibrate your mic to 75 db before running sweeps. Although not critical you should do this as the target blue line is at this reference point. Also if your line looks a little off it is worth calibrating your sound card to see if this makes any difference. If not fine but if it does at least you know. For what its worth most modern soundcards seem to be very good and dont really need calibrating buts its always worth a check.

If your reading on the left starts at the bottom its because its quiet at low frequencies. Its hard for inferior subs to produce these frequencies, but something SVSs are very good at :smashin:. That said your does look a little high for an SB12 which is why I questioned if you calibrated your amps volume with the spl meter at 75db before running sweeps.

On the SB12 you have room comp. By adjusting this you can bring down that low end boost down, and it needs to be closer to the blue line, or at least flatter and in line with the rest of the graph. Other than that there isnt a lot you can do to improve the response as the rest of your line, although its wavey, has no one big obvious peak. You could play with phase but I dont think this will do much, still dont discount anything and play anyway if you have the inclination.

Check your calibration level, and try again. Make sure you apply the 1/3 octave smoothing to your graph, and run the sweep without the speakers to start with so we can take the speakers out of the equation for now. Also I would calibrate the soundcard just for peace of mind. When you've done that, post the new graph and take it from there. It may just come out the same though so dont be shocked if it does. I have a feeling it'll come down a little closer to the blue line when you set your systems volume to 75db (although I could stand to be corrected), and the sound card cal may alter that bottom end response so see what happens.

One last thing, its a stupid question, but your mic is at your listening position isnt it? If it is, is this position near to your walls, i.e a seat that is back to a wall. I'll explain why Ive asked later as it might not be a relevant question.
 

Tyler Durden

Distinguished Member
Thanks for the responses so far, I'll try and answer all the questions.

First of all, here are a couple of photos of my room.






It is about 20 feet by 13 feet.

These photos were taken before I had the SB12+, and since it is smaller than the one in this photo I have positioned the it just between the right speaker and the shelves.

I calibrated the SPL at 70db, so later I will do it at 75db to see what difference that makes.

Room comp was set to Bypass, and crossover duties being done by the amp.

The mic was placed on the back of the best listening (the right hand corner of the sofa facing the TV.)

I'll try again later tonight and report back.
 

IRobot

Well-known Member
The mic was placed on the back of the best listening (the right hand corner of the sofa facing the TV.)

That's only a couple of inches from the wall judging by the pics, which probably explains the lumpy base response. Move the mic a couple of feet away from the wall.
 

Member 639844

Former Advertiser
Your amp uses Audyssey Auto setup right? If so which version of it does it use, or rather how many measurements does it take? Also, its probably better to place the mice in the center of your sofa, at ear height and and centrally forward to. Putting it next to the wall is bad really.

FWIW, your response doesnt look to bad, just a bit wavey, which as Irobot says is probably due to putting the mic so close to the wall. That bottom end boost, if it remains, can be cured using the room comp dial. Unless your head is that close its not really what you will hear, and if you your anything like me, a slough potato, the mic will be better in the position Ive suggested.
 

stevefish69

Well-known Member
That's second graph looks exactly the same as the graph that i got when i was recently trying to set up REW again to post some after shots of what the EQ1 does.

Something is not right so i'd suggest starting again and going through every step. I got so frustrated with the thing that i gave up as i had no need to re-measure. It had something to do with the settings on my soundcard as it used to work perfectly on my old PC until i built a new one and updated the soundcard drivers / software :mad:

Have a good look here to help.

Sorry to be the bearer of bad news.
 

-Ad-

Well-known Member
Edit: Fixed ir, my emu had some aux malarky settings on and cranked up as default, which was giving those massive SPL readings at low frequencies.
 
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Member 639844

Former Advertiser
Again, dont place the mic so close to your wall unless this is central of your sitting position as the boost your getting is boundary gain. Theres no room comp on the Monolith so you cant do anything about that low end boost with the settings on the sub, you need to move the sub to change that.

The graph your showing though hasnt given a target line at 75db so something is out IMO. Also the graph you have posted isnt just the sub unless it producing frequencies right upto 200hz which I doubt. Also, as a check you could calibrate your sound card to see if the end result differs any.

The response doesnt look that bad TBH, you only have one peak and a bit of a dip, and given the Monolith is tuned to 20 hz, if you getting that kind of response at 10 hz then you should be pleased. It could be down to boundary gain though.
 
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-Ad-

Well-known Member
Again, dont place the mic so close to your wall unless this is central of your sitting position as the boost your getting is boundary gain. Theres no room comp on the Monolith so you cant do anything about that low end boost with the settings on the sub, you need to move the sub to change that.

The graph your showing though hasnt given a target line at 75db so something is out IMO. Also the graph you have posted isnt just the sub unless it producing frequencies right upto 200hz which I doubt. Also, as a check you could calibrate your sound card to see if the end result differs any.

The response doesnt look that bad TBH, you only have one peak and a bit of a dip, and given the Monolith is tuned to 20 hz, if you getting that kind of response at 10 hz then you should be pleased. It could be down to boundary gain though.

Mic is central to the seating position which is against the back wall and the only place for the seating to go.

It is all calibrated to 75db, it just seemed to be that setting in the emu software causing the hickup. Sub response sorted now and working now, roughly following an inputted house curve. Also cured a massive dip around 60hz by putting the mono inside the speaker next to the av cabinet.

BFD configuration later then a movie night :D

Good luck Tyler.
 

Tyler Durden

Distinguished Member
Okay, moved my SPL away from the wall, calibrated the sound card, and SPL and now I get this!!?

What's going on there then?
 

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Tyler Durden

Distinguished Member
I just switched from the red to the black for the SPL and got this.

I guess I need to recalibrate it now.

*edit* recalibrated and the line hasn't changed, so I guess this is where I am now.

What gives, why do I not have the line start at the bottom like I feel it should?
 

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Badger0-0

Distinguished Member
I still have a sneaky feeling something isn't right.

Ignore anything at less than 10 hz, the meter just isn't accurate enough.

Just to prove things are relative, introduce a maximum cut at say 40hz and re-measure. You should then see a fair dip around 40hz on the curve. Do the same for a couple of other freqs.

I'm still suspicious, because the response is ruler flat at 70ish up.
That's incredibly lucky or just wrong in some way.
 

Tyler Durden

Distinguished Member

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Tyler Durden

Distinguished Member
Okay, I set the EQ to "Low" "Max" and mid point which should be 50hz, and got this.
 

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Tyler Durden

Distinguished Member
"Hi" "Max and 50hz gives this.

It doesn't seem to be making any difference! :confused:
 

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Badger0-0

Distinguished Member
And it's done absolutely nothing.
Sorry mate, I suspect somthing is still wrong :(
 

Tyler Durden

Distinguished Member
Something........?

Can anybody shed any light on this?
 

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