Distortion Magnifier
I have built the Cordell Distortion Magnifier (DM) from the parts kit sold by Pilgham Audio. (Pilgham Audio - Cordell Dist. magnifier). I found that the range of amplifier gains that were allowed was insufficient for the F5 and other Pass designs, so I added a rotory switch for R3/R4 to support additional, lower amplifier gains. Additional modifications are probably desirable for balanced amplifiers.
I am using the DM with a M-Audio Audiophile 192 sound card and the free Sillanumsoft Visual Analyser (Visual Analyser 2011 XE) . I found that the M-Audio AP-192 has such low noise and distortion levels that accurate THD distortion measurements can be made well below .001% WITHOUT using the DM. (Actually I use the DM in bypass mode).
I have built the Cordell Distortion Magnifier (DM) from the parts kit sold by Pilgham Audio. (Pilgham Audio - Cordell Dist. magnifier). I found that the range of amplifier gains that were allowed was insufficient for the F5 and other Pass designs, so I added a rotory switch for R3/R4 to support additional, lower amplifier gains. Additional modifications are probably desirable for balanced amplifiers.
I am using the DM with a M-Audio Audiophile 192 sound card and the free Sillanumsoft Visual Analyser (Visual Analyser 2011 XE) . I found that the M-Audio AP-192 has such low noise and distortion levels that accurate THD distortion measurements can be made well below .001% WITHOUT using the DM. (Actually I use the DM in bypass mode).
Hi Ihquam
I have the same sound card and tried the Visual Analyser
I got a problem with my set up as even loop back (out conected to input) is realy noisy.
Spikes all over the place 200hZ is prety bad and levels not lover than 60dB.
I am thinking:
1 Noisy computer messing things up
2 I am doing sometink badly wrong
Can you post details of your set up.
PM maybe as I do not want to hi jack this tread.
Tanks
Al
I have the same sound card and tried the Visual Analyser
I got a problem with my set up as even loop back (out conected to input) is realy noisy.
Spikes all over the place 200hZ is prety bad and levels not lover than 60dB.
I am thinking:
1 Noisy computer messing things up
2 I am doing sometink badly wrong
Can you post details of your set up.
PM maybe as I do not want to hi jack this tread.
Tanks
Al
please give more than a few details.
A write up on the hardware and software and wiring and how to set up would be much appreciated.
That's a good idea. I just fliped the values on the input pad on the source input as most of my amps are 10X or lower gain.
Sound Card Distortion Measurement Techniques
OK, I am working on documentation of two things:
1. Simple interfaces to sound cards (of preferably high quality) for distortion measurements of unbalanced or balanced amplifiers. I have implemented this for the unbalanced case of the F5 amplifier and the M-Audio AP-192, and the free Sillanumsoft Visual Analyser software.
2. Modifications to the Cordell Distortion Magnifier and use with the free Sillanumsoft Visual Analyser software.
I need advice on whether these should be new threads (which forum?), or articles. I do not know that I can spend the time needed to "polish" these contributions to the quality level of the current DIYAUDIO articles.
OK, I am working on documentation of two things:
1. Simple interfaces to sound cards (of preferably high quality) for distortion measurements of unbalanced or balanced amplifiers. I have implemented this for the unbalanced case of the F5 amplifier and the M-Audio AP-192, and the free Sillanumsoft Visual Analyser software.
2. Modifications to the Cordell Distortion Magnifier and use with the free Sillanumsoft Visual Analyser software.
I need advice on whether these should be new threads (which forum?), or articles. I do not know that I can spend the time needed to "polish" these contributions to the quality level of the current DIYAUDIO articles.
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