rlafon1714 Posted March 31, 2012 Share Posted March 31, 2012 i was listening to my rf7-II the with my pioneer pl41 turntable played thru a harman kardon hk3490 and after i was finished i turned off the turntable and turned down the volume and the i noticed this low kind of static hiss coming out of the horns then checked to see if volume effected it and it did not i have never noticed this before and was wondering if its the reciever causing this or if the speakers are damaged or if it is the reciever and if it is the reciever will it damage the speakers Quote Link to comment Share on other sites More sharing options...
WMcD Posted March 31, 2012 Share Posted March 31, 2012 Welcome to the forum -- if you have not been welcomed before. The noise you're hearing is coming from the amplifier. If I understand correctly is is actually the sound caused by electrons bouncing around in the transistors.. Speakers themselves can't create noise or sound except what they are sent from the amplifier. An exception is when the speaker wires work as antenna for close by radio frequency energy from radio transmitters or household appliances. You didn't mention but you will probably find that the hiss goes away when the amplifier is turned off. I had an HK for a little while before returning it to Fry's. It was not particularly noisy on horns except when the digital signal processor for surrond, etc. was in operation. No, this noise will not hurt the speakers. It is too low in level. WMcD Quote Link to comment Share on other sites More sharing options...
TheEvan Posted April 1, 2012 Share Posted April 1, 2012 The phono section is inherently noisier than the line sections. It will make its own hiss. Does the noise go away when you switch to another input? Quote Link to comment Share on other sites More sharing options...
rlafon1714 Posted April 1, 2012 Author Share Posted April 1, 2012 Yes it does Quote Link to comment Share on other sites More sharing options...
LarryC Posted April 1, 2012 Share Posted April 1, 2012 The phono section is inherently noisier than the line sections. It will make its own hiss. Note that he said the noise is not affected by the volume control, which should control the noise level from the phono section. Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 1, 2012 Share Posted April 1, 2012 Well, it is becoming unclear exactly under what conditions the noise goes away. But maybe this all can be explained. In a classic analog system I'd expect that the noise could be coming from the output transistors (I'll call that the "final" or power amp.) In that case the noise would not be attenuated by the volume control which controls the input to the finals. In accord with this, if noise originates with the phono pre-amp circuit, the volume control should attenuate it. But, I look back on my experience of a few decades ago. It was the microprocessor used for multichannel which was the noise generator. In a straight through mode, with horns, the amp was not noisy. So I looked at the HK site about subject unit. It is relatively low end machine. Nonetheless, it has some processing for simulated Dolby. It makes me think there is likely a processor controlling many functions,, even simple ones. Generally speaking, even though we have a volume knob on a modern unit, it often is not connected (physically) to a potentiometer -- which is a variable voltage divider (say, reducer) via variable resistors. Rather, the knob is connected to a shaft encoder which through its digital information output tells the microprocessor that the user wants to increase or decrease gain. You may have noticed that on your newer car radio you can twerl (sp?) the volume knob though more than 360 degrees. You can't do that with a pot! It would also make sense that the RIAA equalization for the phonograph input is being implemented via a digital filter in the microprocessor. Here we have an Analog to Digital converter, processing, and then a Digital to Analog converter. That same hardware and software could be implementing volume control. The bottom line here is that the receiver's output noise could well be the product of various funtions of the microprocessor -- the rules of the old days based on analog circuits do not hold. Again, this is not something which will hurt the speakers. WMcD Quote Link to comment Share on other sites More sharing options...
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