# Question for those who have tested your headunit's clipping volume



## eXistence (Aug 5, 2015)

I just purchased a NANO Oscilloscope DSO201 and I want to test my Kenwood DDX 719 ( http://www.kenwoodusa.com/Car_Entertainment_2013/2012_Car_Entertainment/DDX719 ) to see how loud I can turn it up before it starts clipping. Volume is 0-35. Now when I hook up the probe connector that comes with my Oscope do I just take one of the RCA's and attach the ground to the outer shield of the RCA and take the positive and attach it to the male end of the RCA which is in the middle?



















Also I need to be playing a tone as well correct? If so do I need to play a 50hz tone or a 1khz tone?


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## Jepalan (Jun 27, 2013)

What you have sketched out should work, you have the polarities correct.
But I prefer to probe the RCA while it is actually connected to and loaded by the amp I will be using - then I am 100% sure I am seeing the clip point under actual use loading of the HU. To do this, I made a little male to female RCA test jig that exposes the center and ground conductors. I put this inline with the amp input and clip onto the exposed conductors.

I usually check a few different tones just for good measure - easy to do once you've hooked it all up.


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## eXistence (Aug 5, 2015)

Jepalan said:


> What you have sketched out should work, you have the polarities correct.
> But I prefer to probe the RCA while it is actually connected to and loaded by the amp I will be using - then I am 100% sure I am seeing the clip point under actual use loading of the HU. To do this, I made a little male to female RCA test jig that exposes the center and ground conductors. I put this inline with the amp input and clip onto the exposed conductors.
> 
> I usually check a few different tones just for good measure - easy to do once you've hooked it all up.


I just want to know if my head unit can be at max volume without clipping. I thought you would need to remove each set of RCA's to do this. Since I am running two amps (Pioneer GM=D9601 Mono and a GM-D8604 Four Channel) I was going to unplug all RCA's and test them. But I don't think I need to, do I? I would just need to test the 4 Channel amp since I am running Components up front and Coaxial in the rear. (BTW this is in a C6 Corvette) so the components are 90% of the sound. So I would prob want to test the RCA's that go to the components, yes? 

Then after I get my results (hopefully I can max volume without clipping) then I go to start setting my gain on my amps for all speakers by hooking the Oscope to the speaker out on the amp, yes?


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## gijoe (Mar 25, 2008)

An o-scope is nice, and provides useful information in some cases, but for car audio it isn't a tool that anyone should really need. Measuring the source for clipping is nice, but using it to set gains is pretty pointless. Having gains set "perfectly" with an o-scope will not improve the sound quality over setting them by ear (unless you really can't hear the obvious signs of clipping). Now, you already own the o-scope, so at this point you may as well play with it, but for anyone who doesn't already own one there is no good reason to buy one (unless you just want to use it for educational/fun purposes). A good DMM will take care of everything you need in an install, and a RTA mic will take care of what you need for tuning.


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## eXistence (Aug 5, 2015)

gijoe said:


> An o-scope is nice, and provides useful information in some cases, but for car audio it isn't a tool that anyone should really need. Measuring the source for clipping is nice, but using it to set gains is pretty pointless. Having gains set "perfectly" with an o-scope will not improve the sound quality over setting them by ear (unless you really can't hear the obvious signs of clipping). Now, you already own the o-scope, so at this point you may as well play with it, but for anyone who doesn't already own one there is no good reason to buy one (unless you just want to use it for educational/fun purposes). A good DMM will take care of everything you need in an install, and a RTA mic will take care of what you need for tuning.


I used a DMM previously for my current setup. I have another thread where I was running a Alpine Type R 10" in 1ohm at 34 volts and it seized up. I was pushing 1200w RMS in which i was told it could handle it. Well it did not. So I got it replaced with a 4ohm that I will wire down into a 2ohm. 

I like my music loud so I really would like to know if I have been clipping this whole time or not. I know an Oscope is more precise than a DMM. I don't know what clipping sounds like through my ears. I am still kinda a noob when it comes to car audio, but i am very mechanically inclined.


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## InstantCrush (Sep 2, 2015)

eXistence said:


> Now when I hook up the probe connector that comes with my Oscope do I just take one of the RCA's and attach the ground to the outer shield of the RCA and take the positive and attach it to the male end of the RCA which is in the middle?



Yes.




eXistence said:


> Also I need to be playing a tone as well correct? If so do I need to play a 50hz tone or a 1khz tone?


1kHz is a standard test frequency for speaker related things, but you might as well run a few test tones.


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## Weigel21 (Sep 8, 2014)

What Is Distortion?

Using test tones to set amplifier gain

https://www.youtube.com/watch?v=WhrDqke8BKo

And since you went setting your gains via the DMM method, I'll even leave a link to a video showing how accurate the method is, or should I say how much it can vary. 

https://www.youtube.com/watch?v=gg2gl-fz2Qc

As you can see, they were trying to set for 300RMS and got 334RMS and 345RMS and then got 593RMS when trying to set for 600RMS. 

Now those numbers may well look close, and they are, but there's no telling just how much over 1200RMS the amp could produce before clipping. And if you watch to the end, he even says it's not a good method for setting an amplifier for maximum output. 

On top of this, there isn't any guarantee the amp can produce [email protected] ohm, though it probably can. 

And you may say, but it's CEA compliant. Well, last I knew, CEA testing standards were only for 4 ohm loads, so an amp that is CEA complaint to produce it's 4 ohm output, could just as easily be over rated at 2 ohms and 1 ohm, but still be within the CEA compliance. 

Many HU's and amplifiers even produce a higher pitch tone (the unit itself) when they begin to produce a clipped output.


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## subterFUSE (Sep 21, 2009)

I have a bunch of these for my O-Scope. A lot easier than trying to clip onto the end of an RCA.

Do an Amazon search for BNC to RCA female.


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## eXistence (Aug 5, 2015)

Good info. I have a frys by here that's sells all kinds of stuff. I'll check it out.


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