Low response level from REW to RS meter.

[Chrisbee]

Hi

When I connect my RS meter to my soundcard I can't get the signal level high enough to satisfy REW. I even tried connecting a cheap mike to check if something was broken in the RS meter. I obtained a 129dB reading in REW! I was then told my signal level was too low again! Woops!

I have tried switching the RS meter up and down in scale without useful effect. I played around with the soundcard options: Wave, Soundblaster, default etc. I have Volume Control set at maximum and have played with the mute options on other channels. I must have tried all the other useful-looking buttons in REW. But now I seem to have run out of ideas.

After loads of stepped sinwave test runs and recording the results manually I'd really like to try the fast sweep option in REW now.

I can hear the sweep on my sub but I can't record the results in REW.

Help?

Thanks
Chris

[Malice]

Are you using a line-in or a mic input for connection of the SPL meter? When I first tried the REW with a laptop I soon found similar problems with not having a line-in on the laptop. Dragging my trusty desktop into the equation "solved" the "level" problem by connecting to a line-in and not mic input. FWIW I found having the RS meter on 80db range the best for the readings into the REW.

HTH
Bob

[JohnM]

What soundcard are you using and what input have you selected?

What level is shown on the REW SPL meter bar graph when playing a sub cal signal that shows 75dB on your RS meter with your RS meter on the 80dB range? What is the level when you stop the sub cal signal?

[Chrisbee]

I'm using a Creative Audio PCI card in a fairly modern XP SP2 PC. Line in using turquoise jack socket.

The Calibrate function works okay. I'm using 80dB and the big box dB SPL figure changes slowly around that figure.

But when I try to set input level I'm getting no bars on the db fs meter.

RMS and Peak change constantly with RMS about 85dB and peak 10dB lower @ ~75dB.

This still happens even when I have the RS meter switched off. So what is REW reading when there is no signal present?

Even when I pull the jack on the RS meter REW is still showing the changing dB figures as if nothing had happened.

EDIT:I just ran a sweep after careful calibration and had the low signal warning showing -76dB.

But the graph area shows a nice flat curve above 85dB!

BTW: I had to set the level to -6dB to get my RS meter up to 75dB at the listening position on the Pink Noise level test.

[brucek]

RMS and Peak change constantly with RMS about 85dB and peak 10dB lower @ ~75dB.

This still happens even when I have the RS meter switched off. So what is REW reading when there is no signal present?

Even when I pull the jack on the RS meter REW is still showing the changing dB figures as if nothing had happened.

These statements seem to indicate a bad cable from the RS meter to the LINE-IN jack of your PC.

Hopefully you are using a shielded mono cable that feeds into a stereo splitter plug, and are using the right channel only.

Does this 85dB signal that is present even when the RS meter is unplugged remain when you remove the cable from the LINE-IN jack of your PC?

If it does, do you have all the 'recording' properties of the volume control turned off except line-in and volume.

brucek

[JohnM]

Creative mixers operate a little differently than others (not even consistent within their own range). You will probably find that you have to unmute the Line In in the source panel of the creative surround mixer, and the symbol above that input should have a '+' sign which when you click it will bring up a box to choose whether or not you want to monitor the input - make sure this is set to NOT monitor, and read the wording carefully because on some creative cards you check the box when you don't want monitoring, on others you check the box when you do want monitoring!

The reason you are getting SPL readings with no input is you have been through the SPL cal process, which has told the wizard that the signal level with no input corresponds to whatever cal level you used. Once you have got actual input signals to play with (as shown in the bar display) redo the SPL cal and all should be well.

[Chrisbee]

Thanks for all the useful responses.

I seem to be getting no input to my soundcard from any microphone I own regardless of which socket I try, which cable or which "mixer" settings I use.

Output is fine.

I am being told the device is working properly.
I'll just have to try again tomorrow.

Thanks again
Chris

[Chrisbee]

Hi again

I have replaced my soundcard and can now show a nice curve. RS meter at the listening position
@ 9 feet from my SVS 16-46PCi in my 30 feet long attic room open plan to lower floor via open stairwell.

This uses the RS meter correction values borrowed from the Shack.

NO house curve applied.

NO BFD. Computer driving the SVS cylinder amp direct via low level in.

NO speakers.

Crossover disabled.

Calibration at 82dB.

[brucek]

NO BFD

and you don't need one.....

[Chrisbee]

brucek wrote:

and you don't need one.....

Not bad is it?

Any thoughts about the ideal vertical axis settings (in dB) for sharing these graphs?

I'm going to test my IB next. I think that will show the same trough around 12-14Hz too.

Life just isn't the same without one's full share of 12-14Hz!

[Malice]

Chrisbee wrote:

NO BFD. Computer driving the SVS cylinder amp direct via low level in.

x 10

[brucek]

Any thoughts about the ideal vertical axis settings (in dB) for sharing these graphs

We always recommend 45dB to 105db vertical and 15Hz to 200Hz (but lower if your sub is worthy) horizontal , and 800 pics wide graph.

That way we all compare the same thing..

brucek

[Chrisbee]

45-105dB? Do we really need that much room?




This is my 4 x 15" AE IB15 Infinite Baffle vertical array. In-wall just left of left speaker centred on speaker baffle. Graph includes speakers. 4 BFD filters on sub. I've been too lazy to mess about with the filters once I set them manually using REW as an on-screen guide. It sounds great anyway.

Note that same 12Hz room mode sucking away all my bass!!

[Chrisbee]

This is the authorised graph size.

With apologies to those vertically challenged by their curves.

[Chrisbee]

brucek wrote:

15Hz to 200Hz (but lower if your sub is worthy).

brucek

When is REW going to offer 5Hz sweeps and graphs?

[Chrisbee]

Malice wrote:

x 10

Hi Malice

I always knew I had a good room.

Now if I could just cure that 12Hz dip...!

[Sonnie]

I am jealous!

[brucek]

Chris, can you explain the other line on your graph?

brucek

[Malice]

Chrisbee wrote:

Hi Malice

Now if I could just cure that 12Hz dip...!

Opinions have been expressed that the dip is too narrow in Octave terms for you to notice any difference should you boost it.

You may not hear any difference, but any fillings in your teeth may!

[Chrisbee]

brucek wrote:

Chris, can you explain the other line on your graph?

brucek

I really can't remember now...

Most likely my soundcard calibration curve (?)

Now don't go shooting down my response curves.

I knew it was too good to be true!

[brucek]

Most likely my soundcard calibration curve (?)

I think the soundcard cal file is a dashed line?

Just wondered if it was your RSMeter calibration file? Hopefully not.

brucek

[Sonnie]

If it is then that means his response at 10hz is gonna be like a atom bomb exploding.

[brucek]

If it is then that means his response at 10hz is gonna be like a atom bomb exploding

Yep.

What do you think it is Sonnie?

Sonnie, are your response lines red? Mine are purple?

brucek

[Sonnie]

I don't know what else it could be besides a mic cal file. As you stated, the soundcard line is dotted or dashed.

My response line is purple too. But I think you get the different colors depending on what channel you measure on. For example, if he used "Left" speaker channel it may be red, "Right" may be green, "Sub" is purple, etc.

Chris, what channel did you measure on?