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xls 1000 Voltage Gain?


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#1 UncleTony

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Posted 07 January 2013 - 09:28 AM

Can't find it in the specs or here. What is the voltage gain of this amp?

Thanks

#2 dakos

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Posted 08 January 2013 - 10:14 AM

Hello UncleTony,
Crown doesn't publish it's voltage gain specs because they use different philosophy for building bigger rigs. what comes out of that is the voltage gain is different on every amp. well, except for the itechs which you set it to whatever value you want. The good thing is we can calculate it ourselvs.

Usually people asking for data on the voltage gain for this or that amp are trying to mix amps from different manufacturers in one rig and if that's what you're trying to do, let me know because it doesn't really matter.

So, let's get our calculators...
An amp with a voltage gain of X40 will output 40 times it's input sensitivity spec to reach full power on the output, on the XLS series the input sensitivity is 1.4V.
That means that if we put 1.4V on the amps input we get at 8 ohm for the XLS 1000 215W per channel. So we'll calculate the maximum output voltage:
V out max = SQR(P max X R) = SQR(215 X 8) = SQR(1720) = 41.473V
The amps voltage gain is the ratio vetween the input sensitivity and the amps maximum output voltage. So we take the two figures (Voltage sensitivity=1.4V and Maximum output voltage=41.473V) and find the ratio between them, that's:
R = V1 / V2 = 41.473 / 1.4 = 29.625

Let's redo it for 4 ohm load:
V out max = SQR(P max X R)=SQR(350 X 4) = SQR(1400) = 37.417V
R = V1 / V2 = 37.417 / 1.4 = 26.726

That's it
Avi

#3 Deromax

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Posted 10 January 2013 - 12:55 AM

Except that the actual gain don't change with the load!  How could it change, the amp doesn't know the load.

The input sensitivity spec is stated for 4 ohms, so the gain you calculated for 4 ohms is correct but will be the same for 8 ohms.  A perfect amp would double it's power at 4 ohms.  Since we're in the real world it won't happen.  What will happen is that the amp will clip sooner at 4 ohms than 8 ohms.  So the amp will need a tad more signal on the input to give it's full 8 ohms power.  I'm too lazy to calculate right now!  :)

#4 dakos

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Posted 11 January 2013 - 12:11 AM

Dear Deromax,
Thank you for further clarifying the subject :)

I calculated the input sensitivity for 8 ohm load:
R = V1 / V2 => V2 = V1 / R = 41.473 / 26.726 = 1.55V

Avi

#5 Deromax

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Posted 11 January 2013 - 11:33 AM

1.55V looks just about right!  :)

This is actually a not well known concept and I had to devise it myself since it's rarely discussed or stated in amps specs.  Commercial amps (like the CTs) seems to give both input voltage spec more often.

#6 dakos

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Posted 11 January 2013 - 11:29 PM

Learning new things every day :)

#7 nexlar

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Posted 23 January 2013 - 03:51 AM

There is something which we can learn.