Crate BX Series Amps

[dadroadie]

Hi To All,
I wanted to check and see if anyone in the forum owns one of the older Crate solid state BX Series bass amps. (BX-25/ BX-50/ BX80/ or BX100 . I had a post about a low hum coming out of the speaker on a BX50 amp and went through all the suggestions given by the folks here without clearing it up. All the tests that where done seem to show the amp is working ok. I just wondered if anyone else has a soft low frequency hum out of the amp that doesn't change by adjusting any of the amp controls and with nothing plugged in. If any one that has one could let me know it would be appreciated.
Regards
dad roadie

[olddawg]

Are you trying to find out if it’s “normal”? Probably not. Sounds like power supply ripple caused by old filter caps. Check your rail voltage for ripple. I don’t have a schematic but I would guess a 2200 or 4700uf cap is used. It’s a pretty common issue in modern SS amps.