Hi audioguru,
Sorry audioguru, i'm new with this stuff and i'm dying to learn more
This is the closest that i could get because the scpro oscilates before returning the final THD. (or is my fault setting it up)
Output level is stable at 1.0V AC(before clipping)
(Tone 1 = f1) = 1001 (Hz) = 0,3 dB rms
Freq.(Hz) Harmonic Value (dB rms)
2003 (2*f1) -62,5
3101 (3*f1) -80,3
4005 (4*f1) -74,4
5039 (5*f1) -94,1
6105 (6*f1) -76,5
7149 (7*f1) -93,7
8096 (8*f1) -92,1
9119 (9*f1) -90,4
10153 (10*f1) -91,7
THD = 0,0767%
Here is some more information that i could measure from circuit at 1.0V output, 40 ohms load.
Signal from source:
R 1.505V AC/ L 1.515V AC (Xbox audio output)
L/R difference:
1% (From Sample Champion)
Input level after R4:
0.125V AC
Input Level after R9:
0.123V AC
Output level before R7/R8:
1.001V AC- 1.002V AC
Output level after R7/R8:
1.000V AC- 1.001V AC
Output level before R12/R13:
1.021V AC - 1.022V AC
Output level after R12/R13:
1.020V AC - 1.021V AC
Circuit Power Consumption:
25mA
Voltage Output (with negative at D1 cathode, positive at 7805 VOUT):
5.68V DC (stable)
Voltage Output before D1 (with negative at D1 anode, positive at 7805 VOUT):
5.03V DC (stable)
Voltage Output before R1(positive at 7805 VIN):
11.90V DC - 12.58V DC (variable charge/discharge)
Voltage Output after R1(positive at 7805 VIN):
10.19V DC - 10.23V DC (variable charge/discharge)
Voltage Output before R1(positive at 7805 VOUT):
7.35V DC- 8.00V DC (variable charge/discharge)
Voltage Output after R1(positive at 7805 VOUT):
5.68V DC (stable)
Now that i've decided to do all this measurements, it would be nice if some one could simulate or test with a osciloscope to see the influence of R1 with the ripple voltage, because without R1 i can hear the hum at the output. Also D1 at the regulator, i know that it will boost the output voltage by 0.7V but removing this diode i also can hear a small hum noise at the output.
Changing for example the 7805 (5.03V DC) to 7806 (6.02V DC) (so i could remove that voltage boost diode) it will not get any better, 7809 (9.03V DC) is worse, the hum noise increases. So the R1/D1 was added (by trial and error) in the attempt of remove the anoying hum at the headphones (by the way, this noise is much worse with the original headbanger), that worked fine, if there are some noise at the output i can't hear it in a very quiet ambient with this configuration and the volume shut.
Give it to me strait audioguru, there is something wrong with the circuit? :shock: