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Old 4th January 2010, 06:38 PM   #151
Pano is online now Pano  United States
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Glad to see you got it sorted. =)

Yes, I think you should build a resistor divider. You say you are using the headphone out because it's the only analog out. Do you normally use something else? A digital out, maybe?
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Old 4th January 2010, 06:46 PM   #152
Elbert is offline Elbert  Norway
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You bet I was glad it wasn't something more serious!!
For all I know, it could have been some inherent feature in the hardware which couldn't be fixed, after all, this little ASUS Eee laptop is a dirt cheap simple little thing not intended for any "serious" use!

And now I can do stuff with it that would otherwise require a rig of measurement equipment. amazing!

No, I don't use any digital out or anything, sort of gathered one can buy nice external ADC-DAC units that run through the USB, but for my use I don't really see the point as I really don't need perfect THD or noise performance as long as I can do decent frequency and phase on some DIY speaker projects!

See if I can dig out some resistors and hook up a voltage divider so I can run the output at higher level just to see if that will improve distortion.

Once again thank you very much!!
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Old 4th January 2010, 06:52 PM   #153
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Cool! Aloso check your mic input for DC. Some of them have 5V DC on them (I think) to power a microphone. If that's the case, you'll want a DC blocking cap.
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Old 4th January 2010, 07:05 PM   #154
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That's good that it worked out for you. If you want to explore the capabilities of the card a little further I recommend using Right Mark Audio Analyzer. It should give you an idea of what your card can and can't do as well as measuring which settings will work best with that specific card.
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Old 4th January 2010, 07:58 PM   #155
Elbert is offline Elbert  Norway
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Wow.. the advice keeps flowing in here!

Much appreciated though, because I'm getting some strange results..

Messed about a bit with a few resistors and pulling input/ output gain up and down to balance.

the THD curve changed several times (not only in overall magnitude), and suddenly a weird narrow "spike" appeared in the phase plot. Almost like something isn't behaving entirely consistent or stable..

Perhaps there is some DC messing things up? Better get a proper pot and a cap and do some more systematical measurements in order to see if there is some pattern to this.

That Mark audio analyser sounds interresting.. must check that out!

Thanks again!
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Old 7th January 2010, 07:00 PM   #156
Elbert is offline Elbert  Norway
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Oh.. this is so stupid!

Yesterday, I switched the laptop on again and played around, excellent results.

Switched it on again today, and after one loop-back test, there it was again, phase drift and THD!

Guess what?

Bad contact in one test-wire I had used to rig the loop-back!

Duh..
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Old 7th January 2010, 07:01 PM   #157
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Cold solder joints strike again. That would do it.
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Old 7th January 2010, 07:22 PM   #158
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Key View Post
Cold solder joints strike again. That would do it.
Thats why there are no solder joints in my speakers.
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Old 7th January 2010, 07:29 PM   #159
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Never trust a cold joint.

Glad you found the trouble.
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Old 7th January 2010, 07:58 PM   #160
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Quote:
Originally Posted by gedlee View Post
Thats why there are no solder joints in my speakers.
Crimping?
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