So, I just plugged in my recently purchased, used setup (72, Hi-cap, 250) and am getting a ton of static-sounding noise from my amp. I noticed it when I turned on the amp for the first time, after I connected the speakers, but before I had connected the hi cap. The noise is constant, though I can change the volume by changing the orientation of the interconnects and speaker cables. In fact, if I allow the interconnect between the amp and Hicap to touch the amp case, I can hear a radio station (Latin National Public Radio-- I kid you not)through the speakers.
At first I thought the noise was likely from my wall power source, but I noticed that when I unplug the amp (with the switch remaining in the "ON" position) the noise continues until the capacitors discharge. This implies to me that the source is not my home power, as the noise should stop immediately after unplugging.
Thus, I suspect the source of the noise is airborne radiofrequency interference. The fact that the noise continues without the amp actually connected to the wall, coupled by the effect of changes in character and volume elicited by movement of the cables (a la an antenna), makes me pretty convinced that this is my problem. I also noticed for the first time that my apartment is in direct line of sight to three radio towers approximately 2 miles away. (I am in Seattle, for those of you familiar with the area, and the towers are the ones located on the top of Queen Anne hill).
Does anybody have any ideas? Am I totally off base in my assumption that the problem is likely due to airborne interference? And, more importantly, is there anything I can do about it?
Sorry for the long post, but I am stumped.
Thanks.
Posted on: 26 March 2001 by ken c
will, this may not address your problem directly. the problem you describe (w.r.t RF) is familiar to me. i have NOT completely eliminated it. when my pre-amp is on phono (my lp12 is prefixed), and with a certain volume setting, but without any record playing -- i can oftem hear a radio station very clearly. there are several things i have done to minimise this interference:
(a) connect the lp12 earth lead to the pre-amp earthe connection at the back. i also found that a seperate lead from this earth to a copper pipe buried in the garden outside helps -- although i must admit my attempt at a proper outside earth is a bit half hearted - and i need to do it properly - the pipe is currently not that deep in the ground
(b) if you have a tuner, make sure its not too near the pre-amp. re-configure if this is the case. experiment a bit with position, (of the tuner relative to the pre-amp i mean!)
(c) tidy up the various cables - its a good idea to keep mains from signal cables as separate as possible. in any case the very act of tidying up might actually minimise rf.
i doubt you can eliminate it completely. there are always sources of radiation here and there in this modern world -- mobile phones, etc. however, what i do find is that when i actually playing a record, i cannot hear rf, neither is the sound degraded in any way. i have NOT experienced rf on other sources (except radio of course, but thats not interference!!!)
hope that helps.
enjoy...
ken
Posted on: 27 March 2001 by Derek Wright
I was picking up the local taxi radio service on the lead that went from the TV to the pre amp - I placed a set of RF Stoppers from audioquest onto the line, The interference died down. They are supposed to absorb the radio frequency interference. I bought some at my local hifi shop many years ago.
I expect the purists will now raise a hate storm for suggesting the use of a ferrite medium within 2 miles of the Naim equipment <g>
I suggest you give them a go - ymmv
Derek W
[This message was edited by Derek Wright on TUESDAY 27 March 2001 at 09:14.]
