Are my speakers clipping? Sustained booming bass

[spider_duggan]

Rega Brio amp, B&W CM4 speakers, Rega P3 TT.

When the volume on the amp reaches about 40%, the speakers begin to produce a very loud sustained bass note, with no other sounds from the woofers.

Is that clipping?

 

[ironlung]

Sounds like a 60hz hummmmm. Do a search for ground loops

 

[skrivis]

Sounds like a 60hz hummmmm. Do a search for ground loops

I agree that this is likely.

Does it make this noise with all inputs?




Some other possibilities:


You mentioned a TT, so is it specific to that?



If it's the 'table, does it change when the motor is on or off? How about with how close the cartridge is to the motor?

Hmmm... have you made sure that the cables from the 'table to your preamp are plugged in properly and in good condition? A loose or defective plug or cable could cause hum.

 

[newtoitall]

As my log in name implies I don't know a lot about this stuff, but is it possable you are getting feed back from the turntable?

Frank

 

[markw]

Yep. sure sounds like acoustic feedback through the turntable to me.

If it doesn't happen with other sources you can bet on it.

 

[mtrycrafts]

Yep. sure sounds like acoustic feedback through the turntable to me.

If it doesn't happen with other sources you can bet on it.

That would be my bet as well, feedback. TTs are sensitive to such feedback, especially at higher volume levels, a dead give-away

 

[spider_duggan]

THanks to everyone for the help,

How would I eliminate the feedback?

Dan

 

[mtrycrafts]

THanks to everyone for the help,

How would I eliminate the feedback?

Dan

Not sure more TT isolation would help, but you could experiment with some inexpensive solutions, foam under to feet, lower level playback, etc, to start with.

 

[mustang_steve]

I would just come up with an easy way to disconnect the turntable when not in use. Such as using a shorter RCA on the turntable, and a longe rone on the preamp/reciever, and using butt connectors in a place you can easily reach to disconnect them when not using it.

It's kind of ghetto, but simply removing the signal is easier than trying to design something around it.

....unless you actually plan on playing your records that loud

 

[markw]

first, move the tt away from the speakers.

THanks to everyone for the help,

How would I eliminate the feedback?

Dan

Then, make sure it's on a rock solid mount, such that any vibrations from the floor or wall are not (re)transmitted to it. These two generally knock it out for most realistic listening levels.

If all these are done and it's still a problem, looking into a good subsinic filter might be an option.

 

[markw]

Uhhhh....

I would just come up with an easy way to disconnect the turntable when not in use.

If it is acoustic feedback, it only occurs when playing the turntable.

 

[spider_duggan]

I'll try some isolation methods like brass feet and a better rack. A better rack may not be an option so if I were to place something under the TT in the current rack, what would I use? Granite? Cement?

It's my only source on this system, so unplugging it is not an option because I would have no music to create feedback.

Thanks for all the help!

Dan