# cheap external sound card?



## CypherBlaze1 (Aug 11, 2014)

I have an UMIK-1 microphone, which is a USB microphone that comes with a calibration file. I know there is no way to calibrate your sound card in REW when using a USB mic, but I get the feeling that the output on my internal sound card on my Dell Inspiron 5520 is not the best. I think this because the input on the sound card is horrible. the frequency response only goes from like 50hz to 7khz and it drops out in two spots within that range. I cannot calibrate the sound card because I'm using a USB microphone.

What if I bought one of those little cheap $10 audio adapters that you just stick in your usb port, that just have a 3.5mm speaker jack and 3.5mm headphone jack? Will that provide a good, flat enough output signal? Or do I need to get a quality sound card for more like $65?

Or maybe my output is fine? Are audio card outputs generally ok, and the input is the only thing that needs calibration anyway?


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## Phillips (Aug 12, 2011)

How old is the laptop generally they were good about 5-7 years ago?

What OS are you running?

Can you borrow a newer laptop and try that, if you can take measurements with both with the mic in exactly the same position and compare and come back with the results.


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## Dougme57 (Sep 4, 2013)

This is what I use and I am very happy with it. I have it going from an old PC with USB and into my receiver with optical. Works great.

http://us.store.creative.com/Creative-Sound-Blaster-XFi-Surround-5.1/M/B0044DEDCA.htm


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## CypherBlaze1 (Aug 11, 2014)

The laptop is no more than two years old, running Windows 7. I measure again with the only other laptop I have, which is a Dell latitude x300, which is 11 years old running XP, and it gave me a very similar wave shape, but a bit flatter. I'm going to do a few more measurements to see what kind of variation i get from one measurements to the next. I'm thinking that my output is probably fine. But still, if I get one of those cheap little audio adapters, is there a chance of it being worse than the internal sound card?


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## JohnM (Apr 11, 2006)

Your laptop's output is fine, just use that with the UMIK-1.


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## Lumen (May 17, 2014)

JohnM said:


> Your laptop's output is fine, just use that with the UMIK-1.


I'm curious and would like to ask a friendly question. How can a sound card with, say, a 3dB down point of 50Hz accurately portray a 20Hz signal generated by REW? Maybe I don't understand how REW works. 

Is there such a thing as a mediocre front-end measurement combo where REW is concerned? Where is the line drawn between casual tinkerer, serious hobbyist, or professional acoustician?

Again, just asking: Can you please give me an example of when, if ever, a precision-calibrated mic hooked to a low-noise preamp are preferrable to a laptop sound card and USB mic. *Is the more accurate gear considered overkill in REW's eyes under all situations?*


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## Phillips (Aug 12, 2011)

CypherBlaze1 said:


> The laptop is no more than two years old, running Windows 7. I measure again with the only other laptop I have, which is a Dell latitude x300, which is 11 years old running XP, and it gave me a very similar wave shape, but a bit flatter. I'm going to do a few more measurements to see what kind of variation i get from one measurements to the next. I'm thinking that my output is probably fine. But still, if I get one of those cheap little audio adapters, is there a chance of it being worse than the internal sound card?


The newer laptop will be better than the 11 year old one, so use that with the UMIK.


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## JohnM (Apr 11, 2006)

Happily, output stages are not 3 dB down at 50 Hz unless they are driving loads well below their rating, the weak point is typically only the mic stages of old (pre 2000) laptops that are unsuitable for measurement work as they had deliberately constrained bandwidths. Since the early 2000's just about all PC audio codecs have met or exceeded Intel's AC '97 specification, which required +/1 dB 20 Hz to 20 kHz minimum bandwidth for the analog interfaces. Within the frequency range of interest for acoustic measurement, PC audio interfaces are not a limiting factor - the main issues are the measurement microphone's frequency response (which can vary many dB in the band of interest), the background noise level of the measuring environment and the limited bandwidth of the speaker reproducing the test signal. Ironically enough 'professional' audio interfaces can be more problematic, since they sometimes have deliberately non-flat responses to impart particular tonal characteristics (e.g. a 'tube' sound) or tone controls which do not provide a flat response in their notionally 'off' positions.

Note that the purpose of REW's loopback calibration is not primarily to deal with the bandwidth roll-off of the audio interface, since that happens outside the range of interest for most acoustic measurements, but to make sure that there is no mixer feedback path active (monitoring).


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

BlueRockinLou said:


> Is there such a thing as a mediocre front-end measurement combo where REW is concerned? Where is the line drawn between casual tinkerer, serious hobbyist, or professional acoustician?
> 
> Again, just asking: Can you please give me an example of when, if ever, a precision-calibrated mic hooked to a low-noise preamp are preferrable to a laptop sound card and USB mic. *Is the more accurate gear considered overkill in REW's eyes under all situations?*


REW is designed to work with relatively inexpensive outboard equipment. With a calibrated mic and the sound card’s response flattened via the sound card calibration, you don’t really gain much by going with high-priced equipment.

Regards, 
Wayne


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## Lumen (May 17, 2014)

Thank you, John and Wayne, for the insight. And apologies to CypherBlaze1 for straying a bit off-topic. I hope it helped you as well.


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## CypherBlaze1 (Aug 11, 2014)

I went ahead and bought an external sound card for $60. I think there's something wrong with my laptop, I get a lot of noise on the Mic input, but the noise varies, coming on and off randomly, creating its own random up and down wave. And my other laptop is just old and I don't trust the sound card. I might not need it, but it comes with peace of mind. (Kind of a perfectionist with a little OCD). I could do with a good sound card anyway. The one in my desktop it's a bit lacking.

Thanks for all the responses, you guys are great 

Btw, I've got another issue. Could I split an output from my equalizer into two imputs in my car's factory amp? Would that cause any damage and/or reduced volume? Should I boost the split signal with a line driver or something? Maybe there's some kind of signal doubler I could get instead?


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