¿ªÔÆÌåÓýThink harmonic distortion. With an FFT analyser you might see it (or not??? I think I got a glimpse of it¡) It might happen at 250kHz, but will extend far into the MHz, and AUDIO spectrum! Those with the ears to detect it, WILL HEAR IT! From my very limited experience with these high end audio equipment, you should look at the circuitry from a radio perspective. Harmonic distortion spreading far¡ (It¡¯s my best guess, anyway) ? Nuno T. ? From: [email protected] [mailto:[email protected]] On Behalf Of Epignathus
Sent: 07 December 2024 21:00 To: [email protected] Subject: Re: [electronics101] Drafted to help a friend who designs audio amps Importance: Low ? Years ago, I purchased new an Adcom GFA-545 which also sounded terrible. One channel was oscillating at around a megahertz, which bleed into the other channel too. The manufacturer ¡°stopped at nothing¡± to fix it, so I added a zero to counter the pole in the right-half-plane after the input differential pair in both the left and right channels, which reduced the high end bandwidth to about 100 kHz, and stopped the instability. There is no logical reason to have the -3 dB response extend to 250 kHz, especially when it leads to an unstable amplifier. -Doug, W6DSR ? From: [email protected] [mailto:[email protected]] On Behalf Of wn4isx via groups.io ? Jimmy designs complete home theater systems, video switching, audio switching, audio tone/volume/balance, he provides a loop for special effects like 3D decoders, and power amplifiers, "regular" stereo and subwoofer. The last two orders of Freescale (Motorola) act funny. He orders premium units, each one comes with it's own spec sheet. The specs are within norms for his previous but the power amps sound odd, hollow, sort of like left/right mixing giving sort of L-R. Even when he only drives one channel, or both channels in mono. The mid range, ~1kHz to ~4kHz is "wonky." He's my age and has been considering retiring, this might decide for him. ? But he enjoys his work. He is one of the few people I'd even consider going to this level of trouble. ? I warned him we are up against physics that neither of us understand nor have the training to understand. ? He has enough older stock to complete his current orders and isn't taking additional orders until/unless we can solve the problem. ? Oddly they work fine for sub-woofer amps and low level preamps. ? Somewhere I have a file devoted to snake oil smoke and mirrors. My favorite is a set of adaptors that allow the output of a AF power amp to a NEMA 15-R with matching NEMA 15-P to wires for the speaker so you can use a standard AC extension cord. ? The insanity was so intense I didn't believe it was real, so I ordered a set. They occupy a place of shame on my radio room wall. ? I love the "hand made porcelain speaker cable lifters." They hold the speaker cables off the floor, God knows dust mites might cause distortion. ? Although I think RCA connectors and 3.5mm connectors are both abominations and crimes against nature and man. -- Nuno T. |
