How to measure AVR pre-outs for clipping? - AVS Forum
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post #1 of 7 Old 11-25-2013, 07:27 AM - Thread Starter
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I'm trying to optimize the gain structure of my AVR and amp and I want to measure the pre-outs of my AVR to see where the point of clipping occurs. I have REW and Omnimic software on laptops and a Tascam USB interface for my condensor mic.

Can I use REW or Omnimic and the Tascam to measure the pre-outs for clipping. If so, how do I do that?

If not, what equipment/software do I need/

Thanks very much!
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post #2 of 7 Old 11-26-2013, 06:25 AM - Thread Starter
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I think this may be the wrong place for this, but if anyone happens to catch this on the bump that could give me some guidance, I'd appreciate it.

Turns out I can't find my Tascam USB interface so I will have to buy something new. But I think I"ll wait for guidance so I can buy the right tool for the job.
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post #3 of 7 Old 11-26-2013, 06:36 AM
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Quote:
Originally Posted by Gooddoc View Post

I think this may be the wrong place for this, but if anyone happens to catch this on the bump that could give me some guidance, I'd appreciate it.

Turns out I can't find my Tascam USB interface so I will have to buy something new. But I think I"ll wait for guidance so I can buy the right tool for the job.

Your AVR might put out up to 10 volts RMS or more on its line outputs before it clips. Most audio interfaces that lack passive input level controls will clip well before that.

I use attenuators of various kinds ranging from 5 K ohm 2 watt potentiometers to custom built fixed resistor attenuators for this purpose.

http://www.jameco.com/1/1/816-rv4naysd502a-rv4-potentiometer-53c35k-5k-ohm-2-watt-10.html



I've also used these:

http://www.amazon.com/Hosa-Female-Male-Input-Attenuator/dp/B000K67U52



I use the audio interface to observe for clipping. I then use an actual DVM to measure the voltage.

http://www.amazon.com/UNI-T-Digital-Ranging-Multimeters-Multitester/dp/B007THZMWi

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post #4 of 7 Old 11-26-2013, 09:48 AM - Thread Starter
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Thanks Arnyk!

I use a pro amp so I have the flexibility to optimize my gain structure directly without the need for attenuators. I would like to not just measure max voltage but see when clipping starts and perhaps even where significant distortion starts prior to actual clipping.
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post #5 of 7 Old 11-26-2013, 10:50 AM
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Quote:
Originally Posted by Gooddoc View Post

Thanks Arnyk!

I use a pro amp so I have the flexibility to optimize my gain structure directly without the need for attenuators. I would like to not just measure max voltage but see when clipping starts and perhaps even where significant distortion starts prior to actual clipping.

The best approach would be to get hold of an oscilloscope. That will measure the voltage and allow you see any clipping visually at the same time.
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post #6 of 7 Old 11-26-2013, 11:02 AM - Thread Starter
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Originally Posted by FMW View Post

The best approach would be to get hold of an oscilloscope. That will measure the voltage and allow you see any clipping visually at the same time.

Never an oscilliscope around when you need one! biggrin.gif

Mmmm, I'll need to look into that
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post #7 of 7 Old 11-26-2013, 03:15 PM
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not sure if your pro amp has clipping meters, but my crown does. what I have done is disconnect your speakers and set your avr/preamp to reference or what ever max level you would go to and slowly increase your channels gain until it just starts to clip and then back off a hair. use 50-60hz test tone or some heavy music. although, not exact science I've come pretty close into dialing it in.

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