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Designing my headphone amp
Designing my headphone amp
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Old 14th April 2021, 07:52 AM   #111
NickKUK is online now NickKUK
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Join Date: Dec 2019
Quote:
DC component:-162.89

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+3 1.994e+0 1.000e+0 -6.82 0.00
2 2.000e+3 2.443e-2 1.225e-2 -100.42 -93.60
3 3.000e+3 2.715e-4 1.361e-4 -34.66 -27.84
4 4.000e+3 7.735e-6 3.878e-6 67.89 74.70
5 5.000e+3 1.168e-7 5.858e-8 141.32 148.14
6 6.000e+3 1.705e-7 8.549e-8 -120.25 -113.43
7 7.000e+3 1.483e-7 7.437e-8 70.60 77.41
8 8.000e+3 4.105e-7 2.058e-7 165.46 172.28
9 9.000e+3 2.254e-7 1.130e-7 -64.21 -57.40
Total Harmonic Distortion: 1.225063%(1.225063%)
I know some of the geeks will notice something.

Inverse Flutterman without feedback, first run, using a a LTP differential amp with the 12BH7As and paralleled flutter man PP section - 2x.

Tonally very different given the 3rd order harmonic "increase". In reality it compared to before it appears the cancellation of the other harmonics just reveals the 3rd more.

Screenshot 2021-04-14 at 08.51.12.png
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Old 14th April 2021, 02:58 PM   #112
NickKUK is online now NickKUK
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Join Date: Dec 2019
So continuing to look at an inverse flutterman with a concetina BH7A phase splitter, the output of each phase looks like this:

Screenshot 2021-04-14 at 15.56.07.png

However the PP section really isn't optimal at the moment - output THD is 2.1% with 2nd and 3rd almost identical at 1.705e-2!
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Old 14th April 2021, 06:05 PM   #113
NickKUK is online now NickKUK
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Join Date: Dec 2019
Made the same mistake that others have made on the futterman.. accidentally grounded the feedback into the phase splitter.

Just going to see what the outcome in THD if this run will be, an early FFT of the output, however you'll note the little output drop of the fundamental:

Screenshot 2021-04-14 at 19.03.27.png

Promising, and needing a little more tuning..

Last edited by NickKUK; 14th April 2021 at 06:07 PM.
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Old 14th April 2021, 06:22 PM   #114
NickKUK is online now NickKUK
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Join Date: Dec 2019
Code:
Fourier components of V(output-left)
DC component:3.93979e-07

Harmonic	Frequency	 Fourier 	Normalized	 Phase  	Normalized
 Number 	  [Hz]   	Component	 Component	[degree]	Phase [deg]
    1   	 1.000e+3	 4.857e-1	 1.000e+0	   -6.87	    0.00
    2   	 2.000e+3	 9.936e-3	 2.046e-2	 -104.19	  -97.32
    3   	 3.000e+3	 4.019e-5	 8.276e-5	  -47.32	  -40.45
    4   	 4.000e+3	 4.290e-6	 8.834e-6	   65.12	   71.99
    5   	 5.000e+3	 1.098e-7	 2.260e-7	  159.65	  166.52
    6   	 6.000e+3	 1.568e-8	 3.229e-8	 -131.72	 -124.85
    7   	 7.000e+3	 1.733e-9	 3.569e-9	  -27.88	  -21.01
    8   	 8.000e+3	 1.956e-9	 4.027e-9	  123.11	  129.98
    9   	 9.000e+3	 1.513e-10	 3.115e-10	 -136.68	 -129.81
Total Harmonic Distortion: 2.045861%(2.045861%)
Screenshot 2021-04-14 at 19.21.22.png

Now I worked out what is the issue - I suspect that the LTP version of this may reduce the harmonics too. Also need to add the global feedback output-to-input in too.

Last edited by NickKUK; 14th April 2021 at 06:24 PM.
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Old 15th April 2021, 10:24 AM   #115
NickKUK is online now NickKUK
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Join Date: Dec 2019
Needs a little more - this is an LTP based phase splitter..

Quote:
DC component:0.000391201

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+3 4.110e-1 1.000e+0 -3.52 0.00
2 2.000e+3 3.791e-3 9.222e-3 55.44 58.96
3 3.000e+3 3.510e-4 8.539e-4 -18.03 -14.50
4 4.000e+3 4.299e-6 1.046e-5 -91.65 -88.13
5 5.000e+3 1.256e-7 3.057e-7 169.67 173.19
6 6.000e+3 1.580e-9 3.844e-9 125.77 129.30
7 7.000e+3 3.514e-10 8.548e-10 -146.94 -143.42
8 8.000e+3 4.692e-10 1.141e-9 1.34 4.86
9 9.000e+3 1.767e-10 4.299e-10 -8.33 -4.81
Total Harmonic Distortion: 0.926183%(0.926183%)
Attached Images
File Type: png Screenshot 2021-04-15 at 11.23.26.png (114.2 KB, 28 views)

Last edited by NickKUK; 15th April 2021 at 10:41 AM.
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Old 16th April 2021, 05:42 PM   #116
NickKUK is online now NickKUK
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Join Date: Dec 2019
This weekend's task.. figure out where the pesky harmonics are creeping in from this run:

Screenshot 2021-04-16 at 18.40.00.png

LTP-based futterman.

I suspect a little TLC is needed in front end tuning.

Quote:
Fourier components of V(output-left)
DC component:0.000303191

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+3 2.048e+0 1.000e+0 5.69 0.00
2 2.000e+3 5.365e-2 2.620e-2 -81.33 -87.03
3 3.000e+3 9.620e-3 4.697e-3 4.84 -0.85
4 4.000e+3 8.000e-4 3.906e-4 -102.25 -107.94
5 5.000e+3 9.588e-4 4.682e-4 -4.33 -10.03
6 6.000e+3 3.298e-4 1.610e-4 -99.95 -105.64
7 7.000e+3 2.665e-4 1.301e-4 -7.05 -12.74
8 8.000e+3 1.730e-4 8.446e-5 -101.65 -107.34
9 9.000e+3 9.299e-5 4.541e-5 -9.17 -14.86
Total Harmonic Distortion: 2.662130%(2.662138%)
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