Questions on REW..

**brucek** · **02-14-08, 02:01 PM**

Quote:

And I cannot find where to disable this, so I can run direct Line In.

I'm confused how you were able to get a soundcard cal with the line-in and not able to use it when setting up the levels?

You have to find what has placed the card in "monitor loopback" mode and disable it, becuase there is really no other way to use REW..........

brucek

**jakelm** · **02-14-08, 02:20 PM**

I will work on it more tonight. I will retrace all of my steps and try to find out where I am wrong.

This might be a dumb question, but, in the graphs I have posted, does there look like something is wrong with how I am measuring?

Again, I appreciate all your help

**brucek** · **02-14-08, 02:43 PM**

Quote:

in the graphs I have posted, does there look like something is wrong with how I am measuring?

It's quite hard to comment, because there are too many variables here. It's easy to get a line on a graph, but if it's not reasonably and predictably accurate, it doesn't mean too much.

You first need to have a proper soundcard cal file using line-out to line-in, that results in a perfectly flat cable loopback measurement.

Then you require a microphone or meter that has a reasonably accurate calibration file to be used to take a measurement within its response limits. You're using an HK mic that you have no knowledge of its calibration.

Then all the levels have to be set up within defined parameters and a measurement is taken...

Then you can assess the results....

brucek

**jakelm** · **02-14-08, 03:02 PM**

I understand.

Could the soundcard Line In calibration be used on the mic in side as well? Instead of looping the soundcard through to the Line In, if I disable all effects for the mic In, could I loop it through the mic side? Or is the mic side input too sensitive and too off, to calibrate correctly?

The problem is, my soundcard has this auto/detection , that I have to keep turning off. The soundcard is built to change its outputs. the Line In becomes surround out, the Speaker out, becomes main speak out and the mic out becomes center out. if I am not careful and pay attention to whats going on, things can and do change in the settings. The soundcard is almost too complex.

Tonight, I will go over the Line In and make sure it stays at Line In and not switches to Stereo In or some other thing.

**brucek** · **02-14-08, 03:15 PM**

Quote:

is the mic side input too sensitive and too off, to calibrate correctly?

Yeah, the the mic input will offer too much gain since actual mic signals are quite low in relation to line level signal (such as the SPL meter outputs).

This extra gain at the mic inputs front end usually results in increased noise.

In addition, mic inputs usually enjoy a very limited bandwidth that is designed to comply with a narrow voice frequency range that a cheap microphone would supply.

It's just a bad idea to try and use a mic input. If you have a line input, then there is a way to make it work.

Quote:

The soundcard is almost too complex.

We run into this all the time. People go out and buy some soundcard that could be used professionally by a recording studio, just to use with REW. We keep telling eveyone, that the best cards seem to be simple stereo el-cheapo cards that REW can create a soundcard cal for. That's what I use. It's some piece of junk I got at Futureshop in the bargain bin with a broken taped up box. Works great.

brucek

**jakelm** · **02-14-08, 05:44 PM**

Its not a card, its actually and intergrated Soundmax soundcard, that came with my ASUS mobo. I might have to install my el cheapo sound blaster live card.

**jakelm** · **02-16-08, 09:53 AM**

Calibrated Soundcard. I think I know what was the problem. I was using the wrong channel. Right instead of left when using the mic.
The help file said right, so thats what I kept using, as soon as I switched it to left, I was able to use the Line In to adjust the input volume.

I feel so dumb...

This is the soundcard. I can adjust my eq to raise the lower end, but I think I will leave it be.

**jakelm** · **02-16-08, 09:56 AM**

When starting a new project, I can just load my soundcard, right? I dont have to keep recalibrating, do I?

**jakelm** · **02-16-08, 10:15 AM**

Ok here is a new measurement w/ RS mic using the Line In. What do you think?

**jakelm** · **02-16-08, 10:20 AM**

Stereo with C weighting checked on. And RS calibration loaded. But something doesnt sound right to my ears. Why is it rolling off so quickly around 15khz?

**jakelm** · **02-16-08, 10:31 AM**

Another after a small tweek in the treble.

**jakelm** · **02-16-08, 10:34 AM**

Sub to 500hz

**jakelm** · **02-16-08, 10:46 AM**

Sub recalibrated. Rumble filter on Rythik amp set to Low and 14hz

**JohnM** · **02-16-08, 11:53 AM**

The measurements look reasonable. The big bump around 5kHz and the rapid high frequency roll off are both characteristics of the RS meter, don't make adjustments based on an RS meter above about 1 - 2kHz.

**jakelm** · **02-16-08, 12:14 PM**

Quote:

JohnM wrote:

The measurements look reasonable. The big bump around 5kHz and the rapid high frequency roll off are both characteristics of the RS meter, don't make adjustments based on an RS meter above about 1 - 2kHz.

I thought the RS calibration tool was supposed to take care of that?

Anyways.....

I made my adjust ment mostly between 50hz-3kz.

Thanks for all the help..

**brucek** · **02-16-08, 01:02 PM**

Quote:

This is the soundcard. I can adjust my eq to raise the lower end, but I think I will leave it be.

You may be a bit confused. The soundcard cal file which is created once and then loaded into the slot completely compensates for the response problems of the soundcard. That graph of the soundcard is inversly added to any measurement and so compensates. In fact, to prove the soundcard cal file is working, the help files tell you to loop a cable from line-out to line-in and do a measure. If the soundcard cal file is working properly, you should get a perfectly flat line response.

Quote:

I thought the RS calibration tool was supposed to take care of that?

The calibration tool is only to match the actual level in the room as measured by an SPL meter with the REW SPL meter level. This way, when we measure 75dB with an actual SPL meter, the REW SPL meter will show 75dB (how else would it know if we didn't have a routine to match it).

The SPL meter calibration file for the Radio Shack meter compensates for the meters response problems at the lower end. It does not take care of the fact that it is inaccurate above 1000Hz. So, you should avoid measuring above 1000Hz with the RS meter. If you want to measure full range, we recommend the Galaxy CM-140 SPL meter.

brucek

**jakelm** · **02-17-08, 11:06 PM**

Bruce, you have been a ton of help.

Is there a .cal file anywhere that has measurements for the RS meter , higher than 200hz?

Also, take a look at my graph. Seems the Line In is working perfectly now. I tested soundcard cali, to line in cali. A perfect match.

Green is Line In and gold is soundcard via line in.

**jakelm** · **02-17-08, 11:14 PM**

After many tweeks, I think I got my bass responce as good as I can get it without eq's. Other than the hump between 50-60hz.

This is at 1/1, Should I stick with 1/3?

**jakelm** · **02-17-08, 11:19 PM**

Waterfall 10-500hz.

My waterfall looks like razorblades, why?

**brucek** · **02-18-08, 09:26 AM**

Limit your waterfall graph to 200Hz and change to LOG mode.

brucek

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