# HAS anyone ever tested head units for voltage output?



## JAX (Jun 2, 2006)

I know I have seen a post here and there where someone said a head unit did not clip at full volume. 

Makes me wonder what voltage output is on my kenwood excellon 891 and all the others I have tried. 


anyone ever tested multiple units to see?

what is the process to test what the voltage output actually is at the end of your rca cable that your about to plug into the amp?


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## chad (Jun 30, 2005)

Erin has, I've tested a few Alpines.


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## nosaj122081 (Apr 7, 2012)

I tested my Clarion on a meter and a scope... Pleasantly surprised that it output a legit 4V and that it never clipped a 0dB tone, even at 40/40 volume. Not bad considering that I only paid $100 refurb'd for it.


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## JAX (Jun 2, 2006)

how do you test it with a voltage meter?

I know some of the people have tested some units. never seen a test like they do with drivers.


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## dales (Dec 16, 2010)

i tested my old cda 7930, 7949 and 7941. no clip at 0db. sub output will clip on them at +7 at full output (35) my old ivac800 clipped at 28/29 0 db. have not tested my d310 and never got to test my 9815.


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## benny (Apr 7, 2008)

My cda9855 was tested by chad and showed no clipping at 35/35 0dB. Peels volume off the top to account for eq boosts too.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

P99

Doesnt clip on Tweeter, Mid, and Woofer channels, voltage is right around 2 volts at 62/62, tested on a tektronix scope.

Sub channel clips at 62/62, not at 61/62, with everything flat. It showed about 5.4 volts. At 61, is shows somewhere around 4.7


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## JAX (Jun 2, 2006)

TOOSTUBBORN2FAIL said:


> P99
> 
> Doesnt clip on Tweeter, Mid, and Woofer channels, voltage is right around 2 volts at 62/62, tested on a tektronix scope.
> 
> Sub channel clips at 62/62, not at 61/62, with everything flat. It showed about 5.4 volts. At 61, is shows somewhere around 4.7


P99 only putting out 2 volts a volume but more than double to sub. interesting. 

that is what I would like to know.

anyone test out a older Kenwood excellon? 

or tell me what to do to test it myself.


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## IDGAF (Dec 27, 2009)

Where are you in La? We could put it on my little scope. But generally, just probe the amp end of the RCA's with a DMM to get output voltage.


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## JAX (Jun 2, 2006)

IDGAF said:


> Where are you in La? We could put it on my little scope. But generally, just probe the amp end of the RCA's with a DMM to get output voltage.



I am in shreveport. I will mess with it.


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## hirino (Aug 2, 2011)

i did test an older model KENWOOD EXCELON KDC -X969 . this h.u. never clipped at full volume and put out 3.5 volts . it was werid tho because the last few turns it seamed like it would drasticly increase the voltage .


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## D-Bass (Apr 27, 2012)

they are not a linear volume know. they do make bigger jumps as you get toward the top of the volume level. every kenwood excelon we've tested did not clip(disclaimer---->) resolution at 35/35 was hard to tell if there may have been a slight clip or not.


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## hirino (Aug 2, 2011)

D-Bass said:


> they are not a linear volume know. they do make bigger jumps as you get toward the top of the volume level. every kenwood excelon we've tested did not clip(disclaimer---->) resolution at 35/35 was hard to tell if there may have been a slight clip or not.



i used an smd dd1 to test the h.u. and mine did not clip


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## Spyke (Apr 20, 2012)

chad said:


> Erin has, I've tested a few Alpines.


Thanks chad, That's how I know that my 9887's don't clip at full output.


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## Spyke (Apr 20, 2012)

hirino said:


> i did test an older model KENWOOD EXCELON KDC -X969 . this h.u. never clipped at full volume and put out 3.5 volts . it was werid tho because the last few turns it seamed like it would drasticly increase the voltage .


I think alpines are the opposite of that. It seems like they increase normally until about 28/35 and then it's very gradual until 35/35. Maybe they did that because they know most people set gains at 3/4 volume. idk.


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## robert_wrath (Apr 24, 2011)

Anyone test the Eclipse HU's?


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## hirino (Aug 2, 2011)

Spyke said:


> I think alpines are the opposite of that. It seems like they increase normally until about 28/35 and then it's very gradual until 35/35. Maybe they did that because they know most people set gains at 3/4 volume. idk.



id prefer more of a gradual increase . my h.u. is worthless below 20 /35


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## JAX (Jun 2, 2006)

then buy my 9855 as its not needed now. will come out soon


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## hirino (Aug 2, 2011)

lmao . im working on it buddy . if you accept my offer you can send it ou now .


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## chad (Jun 30, 2005)

JAX said:


> then buy my 9855 as its not needed now. will come out soon


^^does not clip peels any EQ boost off the top end of "the numbers"^^


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## electro (Jun 7, 2012)

I dont work much with DMMs I only know how to get the voltage of an amp to speaker. Where would you put the ground for the RCAs? 

how can you tell with a DMM that the headunit is clipping?


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## hirino (Aug 2, 2011)

a dmm cant be used to detect clip . if you are refering to my post i use an smd dd1 its a distortion detector


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## adrenalinejunkie (Oct 17, 2010)

electro said:


> I dont work much with DMMs I only know how to get the voltage of an amp to speaker. Where would you put the ground for the RCAs?
> 
> how can you tell with a DMM that the headunit is clipping?



A local mechanic/Electrician may have a O-Scope you can borrow for a few minutes.


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## t3sn4f2 (Jan 3, 2007)

hirino said:


> i did test an older model KENWOOD EXCELON KDC -X969 . this h.u. never clipped at full volume and put out 3.5 volts . it was werid tho because the last few turns it seamed like it would drasticly increase the voltage .





D-Bass said:


> they are not a linear volume know. they do make bigger jumps as you get toward the top of the volume level. every kenwood excelon we've tested did not clip(disclaimer---->) resolution at 35/35 was hard to tell if there may have been a slight clip or not.





Spyke said:


> I think alpines are the opposite of that. It seems like they increase normally until about 28/35 and then it's very gradual until 35/35. Maybe they did that because they know most people set gains at 3/4 volume. idk.





hirino said:


> id prefer more of a gradual increase . my h.u. is worthless below 20 /35



Programming Volume Controls

About Volume Controls
Most audio software nowadays has sliders or even rotating knobs to control the volume. The intention is to simulate the sliders of ‘classic’ audio hardware. *Unfortunately, there is one thing about a lot of volume sliders which makes them a pain in the ass: they are LINEAR. You might ask, what could possibly be wrong with a linear slider: it is zero at the one end, 100% at the other end, and neatly linear in between, isn't that just ideal? The answer is a big no.
Just try this: open your favourite audio player, start playing a song, grab the volume slider, and wobble it to and fro at the ‘loud’ end of the volume range. Next, do the same at the ‘silent’ end of the volume range. Chances are that you will experience the following: almost no audible volume variations at the ‘loud’ end, and extreme volume variations at the ‘silent’ end even if you made smaller excursions with the latter. In that case you can be pretty sure the slider is linear.*
A few popular applications that suffer from this flaw at the time of this writing, are: 

•QuickTime Player
•iTunes (fixed in the newer versions!)
•Windows Media Player
•YouTube and pretty much every other Flash-based video player(1).

The evil has even spread to hardware. Velleman sells a solderable kit of a graphic equaliser, K4302. I don't know if this has been corrected now, but when I bought the kit around 1995 it had linear sliders while they should be logarithmic (C law if I'm correct). Even the G3 iMac's volume control was linear, and I'm afraid that this is just one of many examples. *The result is that the most silent volume setting is still way too loud even if the volume increments are small, and the perceived maximum volume level is already reached around the middle of the slider. Ultimately this leads to frustrated people cursing the damn volume control, or feeling uneasy while using your product without really knowing why*. Luckily there are lots of products with correct volume controls, but I have the feeling that they are only a minority. 

*What is going wrong?
Now what exactly is wrong with a linear volume slider? The answer lies within the way our ears perceive sound. The point is that our sensation of ‘loudness’ is LOGARITHMIC.
This means that with silent sounds, we are much more sensitive to small variations in amplitude than with loud sounds. This allows us to cope with a very large dynamic range of sound amplitudes. It also means that with a linear volume slider we have a logarithmic sensation of volume variations, and that just doesn't feel right. At the right you can see a logarithmic curve. Two identical sections are marked on the horizontal axis (read: the volume slider). The vertical axis shows the perceived volume changes. As you can see, the corresponding section marked by the curve at the ‘silent’ end is much larger than at the ‘loud’ end.* 










*The solution to implementing a REAL volume slider is fairly simple: instead of being linear, a volume slider should be EXPONENTIAL. Because log(exp(x)) = x, hence the sensation of volume variations will be linear, and that's what we want. *


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## Osyman (Oct 20, 2012)

Clarion cz401 0db, techtronix tds5054. Clipped at 22, 1.7 volts before clipping.


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## Bluliner (May 16, 2011)

robert_wrath said:


> Anyone test the Eclipse HU's?


They're clean all the way up to the last click, that's where the waveform starts to look a little different but by no means looks like broken glass or a square wave. The output voltage at the end of a 20' run of signal wire was as advertised.


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## hurrication (Dec 19, 2011)

JAX said:


> anyone test out a older Kenwood excellon?


x711 and x911(unbalanced), both no clipping with just shy of 4v


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## chad (Jun 30, 2005)

Love those scopes..... Solid.

Any adversity to sine waves?


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## hurrication (Dec 19, 2011)

Sine waves are great.. they really are.

But "watching" music play is pretty cool too. 

That's Madonna playing in the pic btw.


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## tnbubba (Mar 1, 2008)

I love my 2225 too!!!


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## 14642 (May 19, 2008)

Besides understanding the difference between linear and log, it's also helpful to remember that double the voltage is only 6dB AND that the input sensitivity ratings on amplifiers are often spec'ed for RMS voltage and if you're watching the sine wave and picking the voltage at the top of the unclipped sine wave, that's peak voltage. Multiply that by .707 and you'll get RMS.

So, if you're reading 4V at the top, the RMS voltage is 4 x .707 = 2.83V RMS. The highest RMS output voltage that's possible from a 12V supply s 4.24 V RMS. So, in order to make more than about 4V, your head unit MUST have a DC/DC swotching power supply.

It's best (according to me) to set your amplifier input sensitivity to allow about 10dB of clipping so that song that are recorded without a lot of dynamic range compression still sound loud. We don't hear clipping on transients very easily, so this setting makes the car sound loud and makes the best use of the amplifier's output power. If your head unit puts out 4V RMS, the amplifier's input sensitivity setting would be about 1.25V. 

It's also helpful to remember that boosting or cutting the EQ changes the voltage. A modest 6dB cut reduces the voltage by 6dB. If you are checking the output of a factory radio or factory amplifier, it's best to check the frequency response so you can read the voltage at the frequency with the highest voltage.

Finally, if you don't have access to a scope, but you can afford a 100 dollar soundcard and some resistors, get the Art USB Pre. It has differential inputs, mic inputs and you can connect it to just about anything, so long as you current limit the source to less than 1V. A few voltage dividers will make this easy and you can build them with 1/4 resistors from Radio Shack. If you'd find a storage scope helpful, download Audacity at Soundforge. You can use it as a scope and also use it to generate all the test signals you want.


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## tnbubba (Mar 1, 2008)

why just get the $29 behringer.. and lug your rca straight in and limit the voltage to less than 1.25 or make up your own attenuators
btw I have both and the behringer is A Lot cleaner than the art..
although i used the art becasue of the mic preamp!


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## hurrication (Dec 19, 2011)

The Dayton DATS woofer tester also doubles as a scope.


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## captainobvious (Mar 11, 2006)

It's also very important to recognize that the same model of a head unit will not clip at the same point/frequency in most cases. The board components used by most of these manufacturers are not as tightly toleranced as you might expect. So your buddies Pioneer may clip at 61 out of 62 on the volume knob at a specific frequency, or may not clip at all while your Pioneer of the exact same model number may clip at 55 of 62. In addition, not even all of the outputs on the _same deck_ are going to be the same either. You may have 7 out of the 8 outputs with clean unclipped signal all the way to max volume and have one output that clips at 85% volume. 
It's very important to test each individual output and test them with a range of sine waves if you want to find an accurate clipping point/voltage.


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