100W Ultimate Fidelity Amplifier

APEX AX14 and AX14P input sensitivty

Hi there
i'm using Apex AX14 with my PC sound card as input signal which is (0.7v)
it's gives me less power output so i used a preamp and it's now full power

- My Question is how to ensure that the amplifier get it's signal level exactly as it should be not more to avoid signal clipping?

there is a lot of preamp circuits out there ( Elliot P06,Apex p30,Apex TB3 ...)

how to avoid clipping??:confused:
 
Hi there
i'm using Apex AX14 with my PC sound card as input signal which is (0.7v)
it's gives me less power output so i used a preamp and it's now full power

- My Question is how to ensure that the amplifier get it's signal level exactly as it should be not more to avoid signal clipping?

there is a lot of preamp circuits out there ( Elliot P06,Apex p30,Apex TB3 ...)

how to avoid clipping??:confused:
If your source/s are digital, then you can use Pano's test signal to find what maximum power is needed to just avoid clipping at the levels you normally listen at. You could mark your vol pot at that setting and then all your digital sources that put out the same 0dBfs signal will never clip your amplifier.
 
thanks AndrewT...what about measuring the signal with multimeter and add a gain selector switch at the preamp to be adjusted depending on the signal measure... does the reading with the multimeter will be reliable ?
Measuring the average level of audio files is not good enough.
The max to average level/ratio of music and audio can vary from 6dB to 30dB
Digital sources can overcome this indeterminate level by using the Pano test.

Analogue sources are often specified at maximum or some level below maximum and this can be used with the amp gain to arrive at maximum attenuation needed to avoid clipping.
You need to do some measurements or reading of specifications.
 
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my friend have little edited FH12 bimo mod,+laterals in output

I ran the attached file and the FFT looks like it has too much hash above H3 - it will not sound clear. Even though the THD is 0.0028%, there is too much higher harmonic content.

Code:
Harmonic	Frequency	 Fourier 	Normalized	 Phase  	Normalized
 Number 	  [Hz]   	Component	 Component	[degree]	Phase [deg]
    1   	1.000e+03	3.231e+01	1.000e+00	   -0.09°	    0.00°
    2   	2.000e+03	7.425e-04	2.298e-05	  101.98°	  102.08°
    3   	3.000e+03	3.909e-04	1.210e-05	   71.10°	   71.20°
    4   	4.000e+03	1.426e-04	4.412e-06	  166.81°	  166.90°
    5   	5.000e+03	1.810e-04	5.600e-06	   78.64°	   78.73°
    6   	6.000e+03	8.510e-05	2.633e-06	  171.01°	  171.10°
    7   	7.000e+03	1.823e-04	5.642e-06	   82.78°	   82.87°
    8   	8.000e+03	5.425e-05	1.679e-06	  173.90°	  174.00°
    9   	9.000e+03	1.393e-04	4.312e-06	   85.07°	   85.16°
Total Harmonic Distortion: 0.002802%(0.002837%)

606015d1489777170-100w-ultimate-fidelity-amplifier-fh12-bimo-mod-miro.png


Although this is a headphone amp, this is what an amp that may be a bit higher in THD, but will sound a lot cleaner and more pure - notice no high harmonics. This is my Pocket Class A amp.

605051d1489391909-xrk971-pocket-class-headamp-gb-pocket-class-nhb-fft.png
 

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Last edited:
Pano test

Measuring the average level of audio files is not good enough.
The max to average level/ratio of music and audio can vary from 6dB to 30dB
Digital sources can overcome this indeterminate level by using the Pano test.

Analogue sources are often specified at maximum or some level below maximum and this can be used with the amp gain to arrive at maximum attenuation needed to avoid clipping.
You need to do some measurements or reading of specifications.

so i googled pano test but got nothing useful ..what is it?
Regards