Getting humming-couple of questions

[FredEmmerich]

I just hooked my turntable back up to my system. I had not used it with my current speakers. I have a set of 4425's. I was playing a record with some good bass and it sounded like I was getting a HUGE amount of hum. I thought maybe it was an electrical signal, but I am not sure. I have a set of 250ti's that I can switch to quickly and I did not get the hum off those. When I turned down the volume, the hum went away but it lagged me turning the knob by just a little bit. In between tracks it sounded like an electric razor running through the speakers.

As the record ended I walked to the turntable and it felt like that whole unit was vibrating.

Questions:

1) Would it be safe to assume I am not getting electrical interference but something vibration induced?

2) My room is a vaulted living room. Speakers are on a short wall, stereo is on a long wall. Should I have the stereo gear between the speakers? That short wall has a fireplace and after the JBL's are stuck on the ends there is no wall space.

thanks
Fred

[Alan Fletcher]

Hi, Fred.

It sounds to me like you have yourself a little feedback problem. The low-frequencies from your speakers are resonating whatever you have your turntable sitting on, the floor that is sitting on, and also probably the turntable itself.

Some solutions:

1) Turn on the subsonic filter if your preamp/receiver has one. You'll lose the really deep bass, but it will solve the problem.

2) Place the TT on a large, heavy slab of marble, granite, or other similarly heavy, flat object (this is what I did).

3) Try putting Sorbothane feet under the TT. This will help, but will most likely not be as effective as the first two.

As with all three of these suggestions, please be sure your turntable is absolutely level. Measure from the platter, not the plinth.

For further info, visit http://www.audioasylum.com/audio/vinyl/bbs.html

Hope this helps.

Regards,

Alan

[FredEmmerich]

I will try those isolation techniques, thanks.

I also have a DVD player hooked up, I was fast forwarding and during that time I was getting a huge buzzing thru the speakers, would this be in the source material? I *thought* maybe I could hear it during regular playback, but I am not sure.

thanks
Fred

[louped garouv]

http://pbellsound.com/shows/TopOnCodaStage.html

http://pbellsound.com/shows/FrontOnCodaStage.html

this is an old night-club trick, if it can work in those high SPL environments...
uses restaurant type ashtrays and rubberbands...


cheap fix that really works, you do need to replace the rubberbands as they wear out though......

there are also more modern feet you can buy, but these are much cheaper....

[FredEmmerich]

ingenius!

[louped garouv]

but I can not claim any of the glory -- that should properly go to someone back in the 70,s -- methinks AL Firestein (spelling???) of acoustilog and Richard Long RIP.... but this technique could pre-date them as well......

[louped garouv]

prefab isolation feet....

http://www.custommade.cc/eliminator.html

as I understand it they run about $150 for a set of 4 feet (one for each foot of the TT)

[Mr. Widget]

Back when I had my turntable in a location where feedback was a problem, I floated a base (MDF) in a wood veneered box. The base sat on a very under inflated BMX bike inner tube. Virtually complete isolation.

Widget

[louped garouv]

I have also heard of medical grade tubing (like for IV,s etc) wound into a coil and used the same way...

and alternative to using the ashtrays is to use empty tuna cans....