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Thread: Audible hiss

  1. #1
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    Audible hiss

    Unfortunatle all of us in this forum are familar with the hiss noise that becomes audible as you raise the volume. What causes this audible hiss? What can be done to reduce it?

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    My new systems hiss is hardly audible
    I really have to stick my head against the speaker and max the gain to hear anything. I'm guessing it's all about the signal path, the electronics involved & grounding I believe. Can't go into more detail. Others will. I think the amp has a lot to do with though. In my case, the signal path in the amp is extremely short, with few obstacles in the way.
    AA

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    All powered electronic components produce some hiss normally. A well designed unit may produce less than a poorly designed one but all produce hiss to some degree.

    This is caused by the electricitity passing through the components and generating some degree of heat. For more details, check out something called "Thermionic emission".

    Like AA said, it's always gonna be there but unless you have to go out of your way to hear it, I wouldn't be too concerned.

    Oh, you'll be more likely to notice it on speakers with a rising high end.

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    I use a rotel 1080 so I do not suspect it is the amp. I have a question.......................How does running directional interconnects in the wrong direction affect sound. EX. on my acoustic research interconnects there is an arrow and it says signal path. If I ran the the signal path opposit of the way way it should go or one of the interconnects correctly and the other opposite how would that affect sound? As to my noise issue do you suppose a power conditioner will remove the noise.

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    Suspended markw's Avatar
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    Quote Originally Posted by Bigmoney
    I use a rotel 1080 so I do not suspect it is the amp. I have a question.......................How does running directional interconnects in the wrong direction affect sound. EX. on my acoustic research interconnects there is an arrow and it says signal path. If I ran the the signal path opposit of the way way it should go or one of the interconnects correctly and the other opposite how would that affect sound? As to my noise issue do you suppose a power conditioner will remove the noise.
    The arrow points to the grounded RCA plug. It should be in the target component for grounding purposes. that's all. If hum is an issue it may make a difference but no mention has been made of this. As for affecting the sound itself, well, there's a lot of debate over this but, IMNSHO, it's a load of hooey.

    As for the power conditioner,remember, the noise is intetrnally generated within he component itself, not extrenally and passed into the component from the power source.,

  6. #6
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    Quote Originally Posted by markw
    IMNSHO,
    Yeah, we can always count on that can't we? ...................j/k Mark.
    On topic: The only time I hear a hiss from my A/V setup is when I'm either playing a cassette, or a CD was transfered and tape hiss is still present. My Neil Young Greatest hits DVD-A has audible tape hiss on some of the songs. Someone here (guess who) said that if you select a source on your receiver with nothing connected to it, then turn the volume all the way up, if you hear ANYTHING, move on to another one.

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    I doubt the hiss is coming from your Rotel, the specs show a signal to noise ratio of 116db. Especially if your not running it to its upper limits. That's pretty darn quiet considering many CD/DVD players have an S/N of around 100db. It's possible it's coming from either your media or source component then passed and amplified by the Rotel.

    As Rich mentioned, if your media is tape or CD recorded from tape, you'll no doubt get hiss. Even tape processed with Dolby B or C will reduce the hiss by 10db/20db respectively, but it's still audible. I suppose you could use a processor like the old dbx units, but you don't see them on the market much anymore due to better/quieter engineered components. Run through all your inputs to see if the hiss is consistent on all sources. You don't mention what preamp you're using. Check it's S/N, could be the weak link in your system.

    Hum I can see being a problem with grounding or dirty source voltage and possibly cleaned up using a power conditioner. Some power conditioners also filter EMI/RFI, but as MARKW mentions it may be generated within your components themselves. You might try a power conditioner, but get one with a good return policy.

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    Hiss is white or Gaussian noise. That means it is just random background noise that has an equal frequency distribution across the audible spectrum. All electronics have this noise at some level, though in the better electronics it is at such a low level that it is often not audible.

    When you see a "signal to noise ratio" (S/N) figure, the "N" or "noise" part is the hiss. Just as an example, if you see a S/N figure of 70 dB, that means if the loudest part of the music hits 90 dB in your listening room, the random residual noise or hiss would be at a 20 dB sound level.

    The hiss that many are most familiar with is the noise from magnetic recording tape (open reels, cassettes, etc.) It is difficult for an analog recorder to have an S/N ratio of much better than 60 to 70 dB. CDs should exceed 90 dB, and many pre-amp and amps easily exceed 100 dB. The exception to the latter would be the phono preamp section. Due to the extra gain required to boost the small signal from a phono cartridge, a phono stage will often have a S/N ratio in the 70 dB range.

    Back to the original question, I'd suggest you try selecting different inputs on your preamp and see if the hiss remains the same. You may have a source component that isn't as quiet as it could be. Also note that higher efficiency speakers will tend to make hiss audible at lower volume control settings.

    Ultimately, the question for the listener is: do I hear the hiss during quiet music passages when the volume control is positioned at its normal listening position? Under typical circumstances, especially with CD material, the answer should be no.

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    Oh where have ye gone RL?
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    Thanks for that explanation. I just learned something.


    Quote Originally Posted by mlsstl
    ...Just as an example, if you see a S/N figure of 70 dB, that means if the loudest part of the music hits 90 dB in your listening room, the random residual noise or hiss would be at a 20 dB sound level..
    Is this what people are refering to when they use the term "noise floor"?

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    Yes, to my knowledge that is what we are referring to when we say " noise floor". I don't have the most high end equipment but I do have a marantz 3002 dvd player a rotel 1080 amp and a denon 2802 which is my receiver (preamp) monster z2 speaker wire. I am wondering if the noise is from using my denon, which I am sure has bad pre outs, as a preamp. I am sure the pre outs didn't have much time put into them as the average customer would never use them. Do you think it is the preamp. Or is it time to go power conditioning.

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    Have you tried the experiment suggested above?

    Step one is to switch your amp on with the receiver & sources off. See if you hear any noise. Then turn the preamp on but leave the sources off. See if the noise level increases. You can also try switching to different inputs to see if there is any difference between them in the residual noise.

    Finally try turning on the sources one at a time. (Be sure you turn your volume down when you turn something on. This will avoid large "pop" sounds that might damage a speaker driver.)

    Assuming your amp is not the source of the hiss, you'll probably find the residual noise increases when you turn on a specific device. If that is the case, you've found your noise. See if a friend has a similar component of a different brand that you can borrow. If the noise level improves, you'll either need your unit serviced, or if it is just inherently noisy, you can put its replacement on your wish list.

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    I was using the Rotel...

    ...RC-995 pre and the RB-991 power (still am, actually... now in the bedroom) and always had a slight bit of e-noise. Certainly not bad, only when the ear was near the tweeter, and during quieter passages. Nevertheless (can't believe that's a word!), it was always present.

    I was worried moving to my PrimaLuna (tubed) integrated, there were be much more noise. Luckily for me, it's almost dead-silent, much more so than the Rotel separates.

    All equipment makes a certain amount of noise, I'm not sure how intrusive yours is, but my Rotel stuff did (does).

    That might be one reason I prefer relatively inexpensive glass vs. sand (in my case)... quiet noise floor. I'm not trying to start a tube/ss debate, but I can hear more nuance now. The background is simply silkier/blacker compared to the Rotel. Also, I'm not saying either of my amps are the best in their respective pricing teir, but there is a palpable diff between the two.

    No-brainer for me, as long as you don't need the 200 watts... I don't!

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    When I purchased my 1080 rotel amp my dealer told me it would be an improvement over just the denon receiver especially becasue I am using b and w speakers. However, he urged me to consider getting a dedicated preamp because he says that using the denon as a preamp will be a limiting factor of my system. He said there will be a HUGE! difference between getting a good dedicated preamp versus using the denon preouts. Wasn't sure if he needed commissions or if his advice holds true the magnitude he expressed. Any comments. Dedicate pre vs. Denon pre outs big difference????

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    I also went from a Denon...

    Quote Originally Posted by Bigmoney
    When I purchased my 1080 rotel amp my dealer told me it would be an improvement over just the denon receiver especially becasue I am using b and w speakers. However, he urged me to consider getting a dedicated preamp because he says that using the denon as a preamp will be a limiting factor of my system. He said there will be a HUGE! difference between getting a good dedicated preamp versus using the denon preouts. Wasn't sure if he needed commissions or if his advice holds true the magnitude he expressed. Any comments. Dedicate pre vs. Denon pre outs big difference????
    ...receiver (forgot the model #) to the Rotel separates. Never tried the Denon as a pre, though.

    That's something you're gonna have to figure out on your own. I would borrow it for a home demo - many dealers will let you.

    I have a feeling it would be better, but not HUGE :^)

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    The receiver number is 2801 and around 4 years old. On a tight budget, would you say the difference in getting a 500 dollar preamp over the reci ver preouts would yield the biggest improvement.........over upgrading my source (marantz 3002 dvd), or getting a power conditioner...?

  16. #16
    Ajani
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    Quote Originally Posted by Bigmoney
    The receiver number is 2801 and around 4 years old. On a tight budget, would you say the difference in getting a 500 dollar preamp over the reci ver preouts would yield the biggest improvement.........over upgrading my source (marantz 3002 dvd), or getting a power conditioner...?
    1) I think the preamp would be a better upgrade than either the Source or Power conditioner.

    2) Though I think the preamp would be a fairly significant improvement..... I don't think it will be a 'huge' improvement.... apart from speakers, I've found most changes to be subtle...

    3) I owned the RC-1070/RB-1080 combo and had no hiss at all (well no hiss I could hear anyway).... even at full volume with no source playing (that was one of the first tests I tried when I got the combo)...

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    A little off subject............I am about to buy the tripplitte isoblock ultra for my1080 amp. I want to make sure it will proviide enough current for the amp. What specs do I need to look for to decide if something s high current. The isoblock has 15 amp 1800 watt output at 600 joules and up to 40 db emi/rfi filtering if that means anything.

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