Umik1 problems with laptop input (always a similar graph)

[carsknivesbeer]

I am running REW using a calibrated Umik1 on two different computers. The first is a Mac desktop and the recorded sweeps are correct. When the same Umik1 is attached to the laptop, the graph always look the same. That is two entirely different rooms/speakers/amps.

The mic is recording the incoming sounds wrong when using the laptop. I have checked the settings the best I can, I know the mic works properly else where, I have tried using an external audio source output to record the sine sweep to eliminate the sound card being the issue, I have reinstalled REW on the laptop with fresh settings, the power output for the USB on the laptop is 500mha. The laptop is running Windows XP. Any ideas?

The attached graph is two completely different systems. The second attached is the functioning measurement from a Mac.

 

[John Mulcahy]

You have completely different graph scales, "LS50 desktop" has a vertical span of more than 220 dB so things will look very flat because the range is so large. "Two rooms" has a span of 60 dB, usual for response graphs. The responses on it are not the same as each other, despite them having a similar dip around 600 Hz or so. You can adjust the span using the Limits button at the top right of the graph or the zoom buttons in the top left corner when the mouse is over the graph. For further comment attach the mdat files rather than images of the graphs.

 

[carsknivesbeer]

Thank you for your response! Sorry it is a little confusing with 2 different computers and two different rooms/speaker sets.

The second graph (LS50) was only included to show that the Umik1 functions as it should, not as a comparison, when I plug it into my desktop. That eliminated the Umik1 itself from being faulty.

The two rooms graph is how every measurement I take from my laptop looks. The two measurements are of completely different rooms and sets of speakers.

The laptop is "hearing" the exact same thing through the Umik1, regardless of the actual sounds coming into it. Could it be an underpowered USB problem or a USB driver issue? The laptop is running older and running Windows XP.

 

[dannyboy51577]

carsknivesbeer - i just came across your post and following. from sounds of it i am having exact same problem.
i am not well educated on this. i use rew as simply as possible. i have emm-6 with blue icicle for power. i simply use it on laptop to get rta graph from car. i dont use sound card for source, simply mic for source. Rew worked fine until today. regardless of incoming sound, mute, etc, it always shows same graph, as if it is hearing sound from somewhere but i dont know where. i updated from rew 5.19 to newest version, same problem. it shows a 30-35db sound on the rta consistently regardless if i have sound coming into mic or if i am muted. as if it is reading sound from a different source than my mic. worked fine yesterday then started this today. any help is greatly apprecaited for this inexperienced car audio guy

 

[John Mulcahy]

Could it be an underpowered USB problem or a USB driver issue?

No. You really need to post mdat files to have anything else to comment on.

 

[carsknivesbeer]

Here are the attached files. The microphone and its placement, calibration file, speakers, and amplifier are all the same for both files.

The September 30th file Red line is using the laptop with the test frequency coming from the laptop. The Purple line is with the test frequency coming from the desktop.

The Feb 23 file is using the desktop as the source for the frequency test.

So it looks like the test frequency from the laptop is the issue?

 

[John Mulcahy]

I'm losing track of what you are after here. I though your original complaint was that measurements in different rooms gave the same results (though the graphs you posted were not the same)?

The Sep 30 (2007!) file only has one measurement in it.It looks very similar to the Feb 23 measurement, after aligning the levels:

The noise levels are quite different, with a lot of noise spikes in the Sep 30 measurement.

The mic input volume level is also set low for the Sep 30 measurement (0.25).

 

[carsknivesbeer]

The initial reason I posted this was 10db dip from 400 to 800 in my first graph of Two Rooms. Those two measurements were of 2 entirely different setups, measured on my laptop. I found it odd that JBL530 in a large room and LS50s in a very small room had the same huge valley in the mids. The second graph I posted was the LS50s tested through the desktop that did not appear to show the valley between 400hz and 800hz which made me think that the laptop is not giving me accurate measurements. I appreciate your time with this as I am new to this process and want to make sure I have acceptable values in my measurements before I start rearranging all my speakers.

I incorrectly saved Sept 30th as it did not include measurements showing the difference between laptop and desktop.

If the following measurements look reasonably close to you than I will assume the measurements from my laptop are accurate enough and will continue.

I still see a 9db drop between red and green when the source of the test frequency comes from the desktop (red) and the laptop (free) with everything else remaining the same. Maybe I am reading too much into the differences and the measurements from the laptop are good.

 

[John Mulcahy]

If everything for a measurement remains the same - mic position, your position in the room, background noise etc etc the results should be very consistent from one measurement to another. If they aren't, and those two measurement aren't, then make sure neither of the devices used has any kind of audio processing/effect/tone controls being applied to its output.

 

[carsknivesbeer]

I only unplugged the aux cable from one output to another. It must be some kind of processing. Is there a wav file i can play through a different source to compare or can I make one via audio check.net?

Edit: Nevermind I figured out how to create a wav. Thank you so much for your time John!