buzzing from speakers

well, since my initial post, I've disconnected the cable box, which made no difference. Following that, i disconnected speaker cables (and actually introduced others that I had lying around), attempted to isolate the speaker cable as best i could, yet the buzzing remains.

It's non-intrustive when music is playing and not noticeable, even without music playing, from the seating area.

I was told by a service technician whom i trust that static is not likely to cause any damage to an amp, however I'm still somewhat concerned only because I hadn't noticed it beforehand (although i never actually LISTENED for it when I first set up all the used gear).

Beyond that, another audio store owner suggested that many somewhat 'esoteric' amps have some background noise to them and that the amp may be working within its parameters (it's a Sugden A48b running Rega Ara speakers. Source is a Rotel rcd971).

Another point I failed to mention is that the amp has been modded by one Dan Santoni (I don't know if this means anything to anyone) who is apparently quite reputable.

For the moment, I'm simply going to live with it, as everything will be upgraded eventually anyway, starting with the CD player, i think...

Which brings me to a new thread ...see the Digital section .... 'Weak Link'

"Stay amused!" ... oh, I am ...

You don't need to open case to create static damage. Even with properly grounded equipment it might happen if voltage is high and it is repeated many times. You'll find testimony of that here on Audiogon forum. I am able to destroy prototypes of industrial electronics zapping them few hundred times with 10-20kV zapper to heavy metal case that is grounded directly to copper ground rod (not the flimsy inductive 3th prong). It is not issue of "IF" but rather "WHEN". Situation of repeated static discharge is unacceptable.

It gets much worse if you touch something else than case - like metal knob sitting on the metal shaft of the volume pot and not touching case (small gap). Or even better zap speaker wire (and I assume that grounding is non-inductive and perfect).

If you read more about static damage - one of the first thing advised is humidity control. You'll find many posts of people who damaged their computers by strong discharge to a case.

Stay amused!

This is one of the most amusing threads I've ever been a part of... If the amp is properly grounded a static discharge from you to the case is going to pose no threat to the amp. You're erroneously imparting a level of concern here to the original poster that's totally unfounded. He's not opening the case and zapping internal components for crying out loud.

Ryder - "Believe" is the right word. Static might zap the input (or output) if you touch it even if you turn equipment off. Damage to speakers was just an example.

Analog Devices application engineer told me once that they had problems with customer's A/D converters loosing linearity after being zapped by static. To me it is even worst than damage (that can be repaired).

Kijanki, I agree it depends on what we're touching. I was referring to the metal casing and switch at the front panel of the amp when I mentioned it is unlikely the component will be damaged with ESD when touching them with bare hands. I wouldn't risk touching the inputs and outputs of the amp at the back panel with my fingers when the amp is running and risk frying myself. In this case, you are correct that the amp or speakers may be damaged. However, this is more towards plugging and unplugging interconnects when the amp is not on standby mode whereby this static electricity will send a loud pop to the speakers that may damage the tweeter or drivers, or the amp. I hope you are referring to this as I believe components won't get damaged if we touch them(the metal casing or knobs at the front panel) that subsequently cause this ESD to take place.

To minimize or eliminate shock when touching the amps, I am now more prudent by touching some wood before I touch the switch on the amp.

Ryder - It depends what you're touching. If it's grounded case then chances of damage are very low. What if you connect and disconnect something and touch input (or output). Even if you discharge yourself by touching ground or grounded case you might have to go to another room (phone call) and charge yourself back walking on the carpet. I found post on Audiogon where somebody damaged speakers by strong static discharge to TT arm. Again - most likely it will not happen but why to risk your investment. Portable humidifier is a very inexpensive (and healthy) way to prevent the problem.

When somebody tells me that you cannot damage SS gear by static I want to ask this person if he is willing to pay others for damage if he is wrong.

As for the hum - how loud is it? When did you notice? (was it sudden?). Have you changed anything (plug to different outlet, add component etc.)

Pickup from the speaker cable is not very likely. In order to get electromagnetic pickup you'll have to have source (transmitting cable) in order of tens of MHz for 2m speaker cable (2m cable is 1/4 wave antenna at 37.5MHz). Capacitive pickup is possible but you would notice change just moving the cable.

Occasionally I also encounter this electrostatic discharge phenomenon when I touch my amps, mainly because of the room that has carpet floor and thick fabric seats. I don't think the amp will be destroyed for this, but one thing is for sure -it ain't doing any good to my body if I get too much of this shock.

Audible hum from speakers may be due to bad tubes, bad power supply, faulty capacitors or any other failing parts within the electronic circuit of the CDP, preamp or amp. You may want to try isolating each item to determine which component is at fault.

Inputs (and outputs) are protected to human body model 2kV/2ns standard at best. You can easily get tens of kV on your body in dry room with carpets.

Assembly houses that build boards for many manufacturers have very stringent static control. Everybody is grounded all the time (wrists and shoes) and grounding test is mandatory for every employee in the morning and after the lunch. It is of course possible that they do all of this just to impress me.

Static not only can damage but also change value of components (precision resistors).

Give me a break. Static isn't going to kill an amp.

If you don't have anything damaged now you will. Why not to use portable humidifier?

I highly doubt you've damaged anything - hopefully it will stop once you disconnect the cable.

you know, I just might have something from the cable box still connected...I'm going to disconnect it when i get home after work and report back. (I've had this problem in the past at my old place...for some reason, i didn't think of it this time).

But my real concern is that I've somehow damaged the amp w/ static electricity.

Is this even possible? I know that one can blow out computer boards w/ static electricity, but i'm not 100% certain on whether or not it can damage amps.

...and all this JUST when i was getting my system to finally start sounding halfway decent. arrgh

Do you have anything connected to the amp that is also connected to your Cable-TV box? If so, disconnect it and see if it goes away and report back.