background hiss...

Discussion in 'Archived Threads 2001-2004' started by Ferran Mazzanti, Jun 3, 2002.

  1. Ferran Mazzanti

    Ferran Mazzanti Stunt Coordinator

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    Dear friends,
    after many days of reading posts in this forums and trying to understand things, I've come to the conclussion that the best thing is to ask directly to all you gurus of HT [​IMG] Once again, this is related to the background hiss my receiver produces on the analog channels when connected to a source (VCR, TV,...) that is turned off. My receiver let's you turn the volume between -75db's and +15db's, while usual listening level goes around -30db's to -15 db's depending on the source, going to -15db's at most. That doesn't mean I never listen at hogher values... but I susally don't. I think the highest value I've ever used is -5db. Furthermore, I don't own an SPL to properly calibrate the speaker levels.
    Well, the hiss I hear is more or less the following:
    +0db's: I hear a faint hiss that can only be heard at 2 inches from the speaker or less.
    +5db's: the hiss can be easily heard at 2 inches, but not at my usual listening position which is 10 feet away from the speakers.
    +10db's: I already hear a faint hiss at my listening position.
    +15db's: I can clearly hear the hiss no matter where I am in the room, although it's not very high.
    So the question is plain and easy: do you think this is normal, so I don't have to worry about it, or on the other hand it is too bad?
    Thanks a lot for your kind help...
     
  2. Ferran Mazzanti

    Ferran Mazzanti Stunt Coordinator

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    Uhmm... no answer anybody? [​IMG]
     
  3. Greg Schwabacher

    Greg Schwabacher Stunt Coordinator

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    Ferran, did you ever get a response to this thread? My new Sony receiver behaves almost exactly like your Marantz with regard to background hiss. What's particularly strange, though, is that the hiss on my receiver is louder on those inputs that have nothing connected to them. Of the three inputs that I use, my CD input is definitely the quietest, with my MD and DVD inputs being in the middle. When I've connected wires to the inputs that are normally disconnected, they all generate the same amount of hiss as the MD and DVD inputs, and at almost precisely the same levels as you describe. I know that open RCA inputs can be susceptible to RF and EM interference, so I was thinking of getting some RCA shorting plugs from here to use on those inputs. On the other hand, I might just live with the hiss since it's only audible at insanely high volumes. And, like your, my receiver is completely quiet on all digital inputs!
    Let me know if you ever found a solution or if you just concluded that the hiss was "normal." The shop where I purchased my receiver from tells me that the hiss is simply the nature of the beast.
    FWIW, my speakers are Klipsch References, which are extremely efficient and which tend to pick up the slightest bit of noise.
     
  4. Greg Schwabacher

    Greg Schwabacher Stunt Coordinator

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    I just did a little more checking, and I think I might have an idea why the CD input is quieter than the others. When you switch into and out of the CD input, you can hear a distinct "click" coming from the receiver...almost like the CD input is on a completely separate circuit or something. I don't hear a click when switching among the other inputs...not even my two multichannel inputs, unfortunately. Lucky for me the hiss is only really audible from my listening position at -5 dB and up (my receiver's volume range goes from -115 dB to 0 dB)...I don't think I'll ever get above -20 dB.
     
  5. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I'd say that hiss is normal

    Total hiss depends on the noise and condition of all the equiptment. It also includes any line noise that can be caused by lamps and appliances on the same circuit. And also be interference that wires/cables pick up from transformers and such.

    At max gain I get 55db measured 1 inch from my tweeter. This is on a sound card analog out and separate rotel amplification.

    If the layer of hiss bothers you during movies, then I'd consider it a time to isolate the problem. If the tweeter hisses at max volume then I don't think you should worry.
     
  6. Greg Schwabacher

    Greg Schwabacher Stunt Coordinator

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    Chris, good call! I took your cue and used my Radio Shack SPL meter to measure the level of the hiss I was hearing. With the DVD input selected and the receiver set to "Analog Direct" mode, the level of hiss, though clearly audible at max gain, wasn't measurable (both A- and C-weighted, fast and slow), which means it was at most 50 dB at one inch from my tweeter at max gain. The CD input's level of hiss with the same receiver settings is even less. However, if I turn on any type of digital signal processing (DPL-II, dts-neo:6, etc.) when the receiver is in analog input mode, the noise floor raises significantly...I measured 71 dB at one inch from the tweeter. However, I suspect that's just what you get when you try to apply DSP to an analog signal, and it's easy to get around...only use DSP on digital signals! When I do that, the noise floor doesn't raise at all. In order to test the DSP noise floor with digital signals, though, I had to find a low-level digital source to compare to, because the receiver mutes its output when it can't detect a digital signal. So, I found a very low-level digital signal (I have a CD where several minutes of near-silence were recorded), and when I applied a DSP mode to this digital signal, the noise floor didn't raise at all -- completely different from the DSP's effect on analog signals.

    Anyway, thanks for providing your 55 dB number...I think I'll put this "problem" to bed, because it's pretty clear my receiver is functioning properly.
     
  7. Steve Adams

    Steve Adams Second Unit

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    I had a sony and the thing was absoulte crap! the hiss that came through the surrounds was unbeliveable. even with the volume as low as it could go. I will never again buy any sony product. my 2 car units are crap as well. sony is going the same way pioneer did in the early 90's. building substandard products and surviving on the name. Pioneer has since come around with their products, i guess it's sony's turn to be bottom on the electronics totem pole....[​IMG]
     
  8. Greg Schwabacher

    Greg Schwabacher Stunt Coordinator

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    Thanks for your comments Steve; they were very enlightening. [​IMG] Why is it that when you mention the brand name Sony that the Sony-bashers come out of the woodwork? Sheesh.
    Anyway, based on Chris' measurements of the noise floor in his system compared to the noise floor in mine, you'll see the Sony is in quite good company. FWIW, I don't notice any hiss out of my rear speakers unless the system is cranked and analog DSP processing is active. At volumes up to -20dB (my receiver's volume ranges from -115dB to 0dB), the system is practically silent in all analog DSP modes, and in Analog Direct and digital modes, the system is virtually silent all the way to max volume. I think this receiver is a keeper.
     
  9. Richard.J

    Richard.J Extra

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    Hmm. I have a Sony DVD/SACD player that just recently came out, and personally I think it's a great unit. Home Theater Magazine also gave Sony a top rating in the sub $300 USD range for receivers... Perhaps you just had some bad experiences with them.
     
  10. Steve Adams

    Steve Adams Second Unit

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    sorry i should have cleared myself a little better, the de series sounds like crap, the car audio sounds like crap, the db series is a little better, and the es is not bad. the sa-wm40 flat out rocks for the price. but i have had alot of bad experiences with sony so im voicing my opinions. im allowed that im sure, im saying anything bad about anybody else on this board just a product that i have had bad experiences with. I am getting two sa-wm40's for my ht system because of the performance to price ratio. there will eventually be two svs but that's a few years off.
     
  11. Greg Schwabacher

    Greg Schwabacher Stunt Coordinator

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    Hey Steve, I'm with you now...I don't think I'd buy a DE-series receiver either. However, I think the Sony DE-series stuff is comparable in quality with other brands in its price range. My old STR-DE915 that I got back in 1995 or 1996 is still kicking like it's brand new!!!
    I wasn't trying to bash you specifically, I'm just sensitive to the Sony-bashers. If you stick around this board long enough you'll see what I mean. [​IMG]
     
  12. David S

    David S Stunt Coordinator

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    Ferren - this would be normal (unless of course its from the now famous Outlaw 950 - which is considered not normal/to be of a major conspiracy/quality control issue, yada yada). All joking aside, if it cant be heard during normal listening(ie you are going out of your way to hear it ala "ear to tweeter"/crank to max volumn with no source playing), it should be fine.
     

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