Giganova
gimmi your mic!
Hey guys --
I bought these 1980s vintage ADM pre + eq modules (ADM 2783 pre, 1540 eq modules) a while ago and finally racked them up, using a bipolar +/-24V power supply (see picture). It seems that the wiring is correct since all knobs and buttons are working (gain, phase reverse, equalisers, etc), and the sound is very full and NEVE-esque (well).
However, there's distortion on the signal which makes the modules useless! The higher the gain, the more distortion. Below is a screenshot of the wave profile for -35, -45, and -55dB gain, and a link to the MP3 file of these recordings. All files are normalized for ease of comparison. I just put up a mic (Gefell M930) in front of a speaker cabinet and played a Norah Jones songs clip with 25sec each at -35, -45, -55dB gain. The phantom power supply is external and cannot be the reason for the distortion. I get the same results with a dynamic mic without phantom power.
What do you guys think could be wrong? I'm caling on all DIU guys here too! Is the eq module clipping (there's a clip indicator on the pre which works, but the samples are not clipped)?? Could it pick up interference from the unshielded power supply which is rather close to the wiring? Hope you all guys can help me coz I'm lost here and have NO idea. I also noticed that the higher the gain, the more assymetric" the wave form gets: there's more gain on the lower half of the wave form than on the upper half. What could that be???
Thanxxx!
AUDIO FILES
I bought these 1980s vintage ADM pre + eq modules (ADM 2783 pre, 1540 eq modules) a while ago and finally racked them up, using a bipolar +/-24V power supply (see picture). It seems that the wiring is correct since all knobs and buttons are working (gain, phase reverse, equalisers, etc), and the sound is very full and NEVE-esque (well).
However, there's distortion on the signal which makes the modules useless! The higher the gain, the more distortion. Below is a screenshot of the wave profile for -35, -45, and -55dB gain, and a link to the MP3 file of these recordings. All files are normalized for ease of comparison. I just put up a mic (Gefell M930) in front of a speaker cabinet and played a Norah Jones songs clip with 25sec each at -35, -45, -55dB gain. The phantom power supply is external and cannot be the reason for the distortion. I get the same results with a dynamic mic without phantom power.
What do you guys think could be wrong? I'm caling on all DIU guys here too! Is the eq module clipping (there's a clip indicator on the pre which works, but the samples are not clipped)?? Could it pick up interference from the unshielded power supply which is rather close to the wiring? Hope you all guys can help me coz I'm lost here and have NO idea. I also noticed that the higher the gain, the more assymetric" the wave form gets: there's more gain on the lower half of the wave form than on the upper half. What could that be???
Thanxxx!
AUDIO FILES
