# Can't get REW to work....any suggestions??



## Prize78 (Aug 15, 2009)

Hi all.
Having ordered an external soundcard with a line in so that i can use it with my laptop, i have tried to get REW up and running to see how my new sub is responding in my room.
I just can't seem to get REW to work.
I'm using a RS spl meter (with calibration file loaded)
Denon 1610 avr
DIY Acoustic Elegance dual 12" sub
Monitor Audio RS5 speakers

I have two rca-3.5mm stereo jack cables. One is connected from the spl meter (using red connector, white's dangling free) and the 3.5mm jack is plugged into the line in on the external soundcard.
The other cable is going to the denon avr and L&R are connected to the v.aux port on the front of the receiver. (btw, i've tried the right on it's own, and the left on its own as i haven't got a splitter to split just the right cable)

The external soundcard is connected via USB to the laptop, and all is activated on the control panel, and is seemingly working. 

Two nights ago i tried a quick run through, set up as above. The graph (having set the axis limits as advised) looked completely wrong, with response at 10Hz up beyond 120dB, coming down quite steeply to settle down 30Hz and beyond. (i haven't saved the first graph - sorry!)

Then, having given that up as a bad job, i tried again this morning, setting it up exactly the same as above.....only this time, i can't get any sound out of it....no sweep sounds, nothing. Despite all of this, REW is telling me that the levels are fine. When "checking levels", the level bars on rew are fluctuating as you would expect, but there's no sound. So therefore the spl meter isn't registering. It's as though i've got "mute" activated on the amp (except i haven't!)

Has anybody got any suggestions, or spotted where i may be making the wrong connections, as this is really frustrating?

Thanks in advance


----------



## PassingInterest (Mar 29, 2009)

Try plugging the sound card into the _exact same original _USB port you used the first time.
Use only that USB port for your sound card every time.


----------



## Prize78 (Aug 15, 2009)

PassingInterest said:


> Try plugging the sound card into the _exact same original _USB port you used the first time.
> Use only that USB port for your sound card every time.


Yeah i'll try that then.....so there's nothing obviously wrong in the way i've connected it then?


----------



## Prize78 (Aug 15, 2009)

This is what it's come up with today....


----------



## Prize78 (Aug 15, 2009)

this is with audyssey off....


----------



## Moonfly (Aug 1, 2008)

Download REW V5, and start again with that version, it is better.

From first glance it doesnt really look as though there is anything wrong with hows it measuring, although it does suggest its an un-eq'd response as it should be much flatter if Audyssey has done its work properly. You werent kidding about that peak though were you, and thats certainly going to be dominating more of your experience than anything else, and more than it should.


----------



## Prize78 (Aug 15, 2009)

I'm sure something's amiss???

I'll try V5 then....


----------



## laser188139 (Sep 19, 2009)

Are you calibrating your SPL level once, hopefully with the mains instead of the sub, and then using that one calibration to measure both with Audyssey Off and On? 

Your two curves show Audyssey reducing the level around 80Hz, making it more even, yet the peak is higher at 30Hz. I can suggest two hypotheses:

First, if you have Audyssey DynEQ enabled, which it is by default immediately after running Audyssey setup, this will boost the bass frequencies, with greater boost at the lower frequencies. Unless you are trying to study the effect of DynEQ, you want to disable DynEQ when generating measurements for comparison, and then re-enable it for normal/movie listening. 

Second, I've seen something like this where my Radio Shack meter differed significantly from the generic calibration file. It showed elevated levels from mid-20Hz down, where Audyssey should have created a level response. When I purchased a calibrated meter, this elevated response went away as the calibration file matched the individual meter I was using. Everything you are seeing, below about 15Hz, certainly reflects differences between your meter and the generic calibration file. 

Bill


----------



## Prize78 (Aug 15, 2009)

Thanks for the reply...i've just done a graph with dynamic eq off......

This is with 1/3 smoothing.....


----------



## Prize78 (Aug 15, 2009)

Right, having tweaked a few things here and there, this is the most recent graph. It shows before and after audyssey....with audyssey is the green line. Looks as though i'm stuck with the dip around 35Hz, but it seems audyssey has worked pretty well, wouldn't you say?

Any thoughts??


----------



## Prize78 (Aug 15, 2009)

I also did a waterfall, although frankly, i've no idea what i'm looking at!!....Would anybody care to enlighten me??


----------



## Prize78 (Aug 15, 2009)

....looking at it, i think i may need to lower my amp's volume to get my response nearer to the 75dB line, although i definitely calibrated the spl meter with REW's tone generator? :huh:


----------



## laser188139 (Sep 19, 2009)

Yes, it does appear your sub level is higher than your mains, if you calibrated the SPL meter levels using the main speaker signal. 

The two long duration peaks appear to be at ~32Hz and ~59Hz. Is this what you see when you place the cursor on the peaks? As simple longitudinal modes, these would correspond to distances of 5.4m and 2.9m, or multiples thereof. Do these match your room dimensions? 

Bill


----------



## Prize78 (Aug 15, 2009)

Yeah, 32 and 59Hz is indeed where the peaks are...which is, without measuring, i think, half and full length of the room. Does this mean that i'm stuck with the peaks?


----------



## laser188139 (Sep 19, 2009)

If they were half and full length of the room, you would see 32Hz and 64Hz. 59Hz should be something else; full length in another dimension, diagonal, vertical, ...

You can try moving the sub around to see if you can position it to where it doesn't energize a particular modal resonance, after you figure out what the mode is exactly. After that, you can look at absorption, which is difficult at the lower frequencies, or you can attack a single long delay with equalization. Some have been successful tuning a parametric equalizer just right to combat the ringing. You should be able to do some searching to find threads on this. Audyssey does do some changes to reduce the ringing, but it is frequently hard to separate this in the waterfall charts from the changes it makes to level the frequency response. 

Bill


----------



## Prize78 (Aug 15, 2009)

Oh, ok. Thanks for that Bill...as you can tell, I am very new to all this!! Other than the two room mode peaks, how would you say the graph looks?? And what does the waterfall chart show? Sorry for all the questions, but I'm determined to get my head round it all!
_Posted via Mobile Device_


----------



## laser188139 (Sep 19, 2009)

It looks pretty typical, except for the initial level being so high. You have the two large peaks that persist to 300ms. The stable ridge at ~100Hz is likely a power line component from the computer generating the signal and may not be a characteristic of the sound system itself. 

Besides reading a lot of threads and looking at other people's charts, I found I learned a bit by moving the sub around and seeing what changed. Tangential and oblique modes stand out more when the sub is in the corner. 

Have fun,
Bill


----------



## Prize78 (Aug 15, 2009)

Thanks again Bill, to be honest, the sub is in pretty much the only position i can get it in, in the room. Plus, it's pretty heavy at over 50kg!! So to be honest it's going to have to stay where it is. I find the whole REW thing fascinating, and am trying to learn all the time. Is the 'spectral decay' graph of any use to me? I notice that generating this, the graph only goes up to 70Hz?, or have i done something else wrong?!!


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

Prize78 said:


> Yeah, 32 and 59Hz is indeed where the peaks are...which is, without measuring, i think, half and full length of the room. Does this mean that i'm stuck with the peaks?


A parametric equalizer could take care of the room mode at ~32 Hz. The thing at 60 Hz might just be 60-cycle noise. It’d be easier to tell with a longer window, say 600 ms.

Regards,
Wayne


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

laser188139 said:


> It looks pretty typical, except for the initial level being so high.


 According to acoustics experts, to get the best information from a waterfall the signal should be at least 50 dB above the room’s ambient noise floor. Our standard 45-105 dB graph is better suited for basic frequency response plots than waterfalls, as most rooms have a lower noise floor than 45 dB.

Regards,
Wayne


----------



## Prize78 (Aug 15, 2009)

Wayne A. Pflughaupt said:


> A parametric equalizer could take care of the room mode at ~32 Hz. The thing at 60 Hz might just be 60-cycle noise. It’d be easier to tell with a longer window, say 600 ms.
> 
> Regards,
> Wayne


But no obvious major issues from the graph??


----------



## Prize78 (Aug 15, 2009)

I've just been looking through this thread at the various graphs....does anybody have any idea why my latest graphs in post #10 are different to the graph in post #9?? I'm sure everything was the same....i.e. soundcard and position in room etc etc?? How come the graphs aren't identical??


----------



## JohnM (Apr 11, 2006)

Prize78 said:


> I've just been looking through this thread at the various graphs....does anybody have any idea why my latest graphs in post #10 are different to the graph in post #9?? I'm sure everything was the same....i.e. soundcard and position in room etc etc?? How come the graphs aren't identical??


Post #9 says it was with 1/3 octave smoothing, post #10 looks like no smoothing.


----------



## Prize78 (Aug 15, 2009)

True enough. I just thought that the 'height' of the line was a little different in the early Hz's of the graph. Presumably, if it's set up right, it will read right, and if it's not, the line will be way out? I did also wonder why the line starts so 'high' at 6Hz? I wouldn't have thought i'd have any output at that frequency??


----------



## laser188139 (Sep 19, 2009)

Prize78 said:


> ... I did also wonder why the line starts so 'high' at 6Hz? I wouldn't have thought i'd have any output at that frequency??


What you are seeing is likely background noise, elevated by the adjustment in the mic calibration file and perhaps the soundcard calibration file. The generic Radio Shack calibration file adds 37dB at 10Hz, so with much background noise at all this gets elevated to very high levels. Below 10Hz, I believe you are seeing the C-weighted curve or flat, depending on whether you checked the C-weighted meter box. You would be better off following the posted advice for the common graph format and not even measuring below 15Hz. Even there, you may see manufacturing variation at the lower frequencies between your RS meter and the generic file, so if you see anything surprising below ~20Hz you might chalk it up to this rather than a real speaker/room effect. 

Bill


----------



## Prize78 (Aug 15, 2009)

Oh! Ha ha, 37dB? So in a very inaccurate world, i could 'take off' 37dB below 10Hz? That makes sense. I was only measuring that low because i wanted to see what the Acoustic Elegance drivers were capable of dropping down to. I know it's inaccurate down there and the human ear can't really hear much at all below ~20Hz, but i was just curious. To my VERY inexperienced REW mind, the graph doesn't look too bad, bar the two peaks. But i'm not too fussed about them as to be honest, the sub can't really go anywhere else at this point in time. I think i may hook up REW again for a more concerted effort. Maybe an EQ device is called for? What do you guys think?


----------



## glaufman (Nov 25, 2007)

"Taking Off 37dB" wouldn't really be proper... that would give you an idea of the signal put out by the microphone at that frequency, but without the 37dB added it wouldn't give you an idea of the actual SPL, because of the mic's response... that's what the 37dB is added for... the issue is that at a certain point the mic needs so much correction that noise floor (think of this as the ambient random noise in the room from HVAC, traffic, your breathing... there's also electrical noise, but I digress) gets in the way of seeing the true signal. The trick is figuring out where on the graph this occurs. Usually it's more evident than on yours as the graph (going lower in f) dips showing the true rolloff, then suddenly turns around and starts rising again inexplicably. 
If it's important to you, you might run a measure of just the noise floor (leave the mic connected and working, as well as everything else, just don't connect the output of the soundcard) and see if that gives you any idea as to where it starts taking over.

Oterwise, looking at your previous graphs, I'd say this occurs a little above 10Hz, maybe 12Hz or so as a guess.


----------



## Prize78 (Aug 15, 2009)

Right, i understand. What i was initially after is whether or not i'd got REW working right in the first place? I've took a good few measurements from the 'listening bubble', as per audyssey, and all readings are nigh on identical, so i'm assuming all's well on the setup front? (I ask this as i have had to purchase an external soundcard so that i can use the laptop) I did wonder about two of my graphs being different from seemingly the same listening position, but i think this was because i'd applied the 1/3 smoothing? So essentially, i think i'm heading in the right direction....now it's a case of analysing my graphs...assuming of course that it is indeed correctly set up.


----------



## glaufman (Nov 25, 2007)

I haven't seen anything that would indicate an incorrect setup.


----------



## Prize78 (Aug 15, 2009)

That's good then. I think i may run a couple more sweeps today, to see if i can emulate the graph from the other day, and then to follow the advice given above, in terms of the range of the graph etc. It may also be worth keeping my eye out for a BFD perhaps?


----------



## Prize78 (Aug 15, 2009)

Right, i've followed the Shack's guide to sizing the graph, with the correct range, in the 'log' format, etc, and this is my latest measurement.....


----------



## Prize78 (Aug 15, 2009)

PS: This is with the sub channel +2dB hot (forgot about that!!)


----------



## Prize78 (Aug 15, 2009)

Latest, sub channel, as per audyssey, at -4.5dB, spl meter calibrated with REW program, (74dB).....

Ok, not a lot of difference between this and the previous graph, but i like to have it 'right' in line with others. :T


----------



## glaufman (Nov 25, 2007)

Are you saying this is sub only? It looks like this is with the mains. It also looks like Audyssey had a beneficial affect on the phase between the sub and mains.


----------



## Moonfly (Aug 1, 2008)

that looks pretty spot on to me now fella. I would be happy with that, so I would just listen for a while and see if your content or not. The eq game can drive you nuts if it turns into an endless search for another 2% performance all the time. A bfd may get it flatter, but there has been the occasional talk that Audyssey doesnt always eq perfectly flat so that what you hear is flat. If you buy into that, then leaving it as you are is the best way forward.


----------



## Prize78 (Aug 15, 2009)

glaufman said:


> Are you saying this is sub only? It looks like this is with the mains. It also looks like Audyssey had a beneficial affect on the phase between the sub and mains.


No, not sub only, this is still with the mains hooked up....i've yet to do a sub only graph. I think you're right about audyssey though.
_Posted via Mobile Device_


----------



## Prize78 (Aug 15, 2009)

Moonfly said:


> that looks pretty spot on to me now fella. I would be happy with that, so I would just listen for a while and see if your content or not. The eq game can drive you nuts if it turns into an endless search for another 2% performance all the time. A bfd may get it flatter, but there has been the occasional talk that Audyssey doesnt always eq perfectly flat so that what you hear is flat. If you buy into that, then leaving it as you are is the best way forward.


Yeah, I think i'm gradually getting my head round REW, and I know what you're saying about the endless search!! I find it staggering just how bad the graph is 'outside' the audyssey listening bubble. Just shows you how good a tool like audyssey really is eh??
_Posted via Mobile Device_


----------



## glaufman (Nov 25, 2007)

I'm with Dan. Listen to this and see what you think before you drive yourself nuts with anything else.


----------



## Moonfly (Aug 1, 2008)

Prize78 said:


> Yeah, I think i'm gradually getting my head round REW, and I know what you're saying about the endless search!! I find it staggering just how bad the graph is 'outside' the audyssey listening bubble. Just shows you how good a tool like audyssey really is eh??
> _Posted via Mobile Device_


Thats exactly the point. Bass is weird when you try contain it in a room, and I wander home many people buy super expensive retail subs, and waist the potential by plonking it in a corner and leaving it. I have to say that I noticed how bass differed around a room way before I knew anything about eq, but it wasnt until I got into it that I realised it was an issue, and there was a great amount of depth to the subject.

The only thing you need to come to terms with now, is being conservative when chatting with other about their systems when you hear them in their homes


----------



## Prize78 (Aug 15, 2009)

Moonfly said:


> Thats exactly the point. Bass is weird when you try contain it in a room, and I wander home many people buy super expensive retail subs, and waist the potential by plonking it in a corner and leaving it. I have to say that I noticed how bass differed around a room way before I knew anything about eq, but it wasnt until I got into it that I realised it was an issue, and there was a great amount of depth to the subject.
> 
> The only thing you need to come to terms with now, is being conservative when chatting with other about their systems when you hear them in their homes


Ha ha, yeah, i read you! 
I'm quite pleased with how the response is to be fair, as the sub can only realistically go where it is now, without a major rearrangement of the room. 
My previous graphs all offered the characteristics of my latest graph, but it was just a case of fine tuning REW's settings to get the graph where i wanted it on the page. I think what i'll do today, is plot a sub only graph (which i assume involves unplugging the main speakers), which should reveal exactly what the sub is doing. Then, assuming all is well there, i think it may be a case of sitting back and enjoying it. It's done nothing but impress me since i got it, it just seems to eat up soundtracks and spit them out!


----------



## Prize78 (Aug 15, 2009)

As promised, a sub only graph. 
Green line is sub only (i.e. mains disconnected), and the beige line is sub+mains. Seems to nosedive after 60Hz? maybe i should check my settings on the amp?

Edit: Just checked the amp settings, and it's telling me that the sub is set up as it should be, i.e. 80Hz. Does anybody have any ideas how come there's this massive nosedive after 60Hz, even though the crossover is set at 80Hz??


----------



## Moonfly (Aug 1, 2008)

Looking at your graph, it looks like the response is correct once the speakers are added to the subs response in the crossover area. Audyssey not only takes your room into account, but it also integrates your sub and speakers properly. If the subs response didnt dip a little like that, then the sub+speakers response would have a hump from 60-90ish hz. The dip is likely induced by Audyssey to ensure the overall response is as flat as possible when the speakers are taken into account as well.


----------



## Prize78 (Aug 15, 2009)

Well, here's an interesting graph.

(green=closed mic (3inches from cone) sub only, no audyssey
purple= sub only with audyssey
red=sub only no audyssey)

Where's my 60Hz nose dive gone????!!! :blink:


----------



## laser188139 (Sep 19, 2009)

Prize78 said:


> Well, here's an interesting graph.
> 
> (green=closed mic (3inches from cone) sub only, no audyssey
> purple= sub only with audyssey
> ...


Of course, room issues are likely to disappear when you take a near field measurement of the speaker. So your green curve confirms that your 60Hz dip is a function of placement of speaker or mic or both. 

I'm guessing that the red curve is supposed to match the green curve in your earlier post. Is this correct? 

The differences between these and your earlier green curve suggest that your 60Hz dip is a function of your listening position. You might confirm this by moving the mic in a pattern around your primary listening position and see how the curve changes. Or you can use the RTA feature in REW to look at a pink noise signal from the speaker, see if you can reproduce the dip, and then move the mic in real time to see when the dip disappears. But it is so narrow, it may not appear in the RTA graph, and it may not be noticeable to the ear, either. 

Bill


----------



## glaufman (Nov 25, 2007)

laser188139 said:


> Of course, room issues are likely to disappear when you take a near field measurement of the speaker. So your green curve confirms that your 60Hz dip is a function of placement of speaker or mic or both.
> 
> I'm guessing that the red curve is supposed to match the green curve in your earlier post. Is this correct?
> 
> ...


Words of Wisdom right there! :T


----------



## Prize78 (Aug 15, 2009)

Yes indeed, the line is supposed to match the line in my earlier post. So it could just be a positional thing with the listening area/mic then? Or possibly the nosedive 'lift' could have been a different noise source in/around listening area?
_Posted via Mobile Device_


----------



## laser188139 (Sep 19, 2009)

The best way to see how much is the effect of mic positioning is to take the measurements. I would suggest 2' each side of the primary listening position, then a row of three points 2' in front of the LP and another row of three points 2' in back of the LP. That way you can see which effects appear from changes fore-and-aft, which from side-to-side, and which might be unique to a single point. 

Bill


----------



## Prize78 (Aug 15, 2009)

Ok mate, i'll give it a go. I'm going to have to get the rest of my family out of the listening room, which could prove difficult!!!


----------

