Loss of bass & full spectrum sound

I have experienced the same with my Pass Labs 250. It is not speakers as I have several. I just wonder if it's the density or the air in the room at the time. Mine has no pattern to it. I get blow you out the room bass most of the time, but then all overtime the amp is just thin sounding in the bass. Come to think of it, this has happened with several of my amps. I have no answer.

i had that same problem, i had wrote in to the forums as well.  what it turn out to be was the output cap or trans in my amp were going bad and jeff at cj called me to tell me the amp was getting a little long in the tooth.  i sent it in and they rebuilt it and that was it....bass is back and dynamics have retuned.  i dont know what you amp is or how old it is but if you have psb speakers they need lots of power....

@kennesawjet Inteseting. Yeah I have been trouble shooting this amp/speakers for a few days now. I took all the speakers out the other day and ran a multimeter through them to check the resistance. All speakers were getting a healthy reading. Then I took my amp into an authorised Yamaha specialist, and they ran some tests on the amp.  I have the Yamaha RN803D.  Here's the video & test results...

Anyway, to sumarise. It was getting 28V output at 1khz. When they switched the frequency to 10hz (bass), it was only outputting 16V.  I was told that's much lower bass output than it should be. Almost half the bass output is gone!!

 

i went thru the same thing,  i changed tubes, got a power condt, changed wiring and speakers still the same thing.  i have a cj mf 2500a and it sounds like new mated with a et 3se.....