Thd %?

Discussion in 'Archived Threads 2001-2004' started by Bill Griffith, Nov 26, 2002.

  1. Bill Griffith

    Bill Griffith Supporting Actor

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    Is there a noticable differance in what I can hear between a reciever that has a 0.8% compared to a 0.07% THD?

    where will I notice the difference?
     
  2. Chu Gai

    Chu Gai Lead Actor

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    That's such a tough question to answer Bill as in part it depends upon where in the audio spectrum the distortion lies, the program material, the levels that you're listening to, the ambient noise around you etc. A level that's sometimes stated is that provided the THD is below 0.2% it can be considered inaudible. I wouldn't take issue with people that said 0.5% either. Now these levels were determined using test tones and not program sources, so the actual levels of distortion that become audible are actually higher. Some people, perhaps because they like staying on the safe side of things, opt for distortion levels that are 5 or 10 times lower than the amounts I cited above. With regards to your two choices, I'd say you'd be hard pressed telling the difference apart especially if you're primarily looking at a multi speaker setup for HT. Aside from that Bill, I'd focus more on determining things like what's the real power delivered by your two hypothetical choices and seeing how that matches up with your speakers and room. I'm assuming that both these receivers meet your requirements with regards to # of outputs, feature sets and all that.
    If you're of a mind to, this link will provide some additional information regarding THD and if you browse around that site, you'll gain additional insight to your own abilities at discerning audible differences.
    Also if you head on down to your local library, you may be able to have them get for your the following back issue:
    "The Audibility of Distortion" by Ian G. Masters, Stereo Review, January 1989, pp.72-78
    enjoy and happy holidays!
     
  3. Gianni

    Gianni Agent

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    Bill,

    I agree with Chu's input. Another thing to be aware of is that there are no requirements or standards for specifications for home theater amps unlike the minimal ones in place for traditional stereo amps.

    We might as well be reading bubble gum wrappers--hence the plea from NAD for some type of standardization. I would only use specs as a starting point, next look for reviews with lab measurements then let listening be the determining factor. In his book, one well known audio expert says that you can learn much more about a piece of equipment by actually listening than you ever will in the lab.

    What that means to most of us is that you should not expect to find answers in product specs. Talk to people who have experience with a particular unit for some background but always demo for yourself. And yes, that takes a little time.
     
  4. Jack Briggs

    Jack Briggs Executive Producer

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    An interesting and overlooked fact of audio history is that people, nearly all of them serious audiophiles, praised the early-'70s Bose 1801 stereo power amplifier (the electronics the company produced back then received close attention from the so-called "underground" audio magazines). What is noteworthy is that the amplifier had unusually high total harmonic distortion at its rated power (I remember it being 1.18 percent!). Yet the distortion was considered "euphonic." In other words, a "coloration" (which must be considered genuine at 1.18 percent THD) that sounded pleasing.

    The amp's designer—somebody help me with his name, please (seasoned audiophiles), Dr. somebody—acknowledged the distortion and admitted to designing the model that way.

    A lot of people like their audio not entirely super-accurate (sort of like altering one's monitor/TV from its most accurate settings).

    So, distortion, even at the relatively low levels common to transistor amps, can be heard under certain circumstances. The lower the better in my book.
     
  5. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    I also agree with Chu, he stated very important points. On the search for the "holly grail" of accuracy the industry appears to send a message regarding how much we need a low distortion number. You will see manufacturers claiming 0.000000 something of distortion as if that meant their equipment is "better".

    But as Chu pointed out, going to a number close to no more than 1% is enough for practical purposes. Even more, if that distortion number is taken from a tube amplifier you might like the distortion, because it will be a pleasant one.

    Again, returning to the accuracy seekers, they say horrible things about this "euphonic distortions that color the music" forgetting that the most important thing about an equipment is that it help us to enjoy our music. Who cares if some engineers armed with their measuring devices tell us what we should like?
     
  6. Ludwig Crumb

    Ludwig Crumb Agent

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  7. Bill Griffith

    Bill Griffith Supporting Actor

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    Thanks guys thats was a big help.
     
  8. AaronBatiuk

    AaronBatiuk Second Unit

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  9. Chu Gai

    Chu Gai Lead Actor

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    the FCC's been working on this HT multi-channel power spec thing for a long time. i'm not sure what the hold up is or if its just the speed that these regulations move at. suffice it to say the lack of honest or non-standardized specifications has no benefit for us.
     
  10. Phil Mays

    Phil Mays Second Unit

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    I have an Onkyo TX DS 797 with .08% THD & 100WPC. I noticed when I added my amp of .03% THD & 150WPC that I was able to "clean" the music up substantially, however I did not notice a big difference in Home Theatre.

    Perhaps the difference was the wattage or perhaps the THD.
     
  11. Chu Gai

    Chu Gai Lead Actor

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    might've been getting more honest watts at the levels you play at? tough to say without "shudder" conducting tests!!! Good holidays to you Phil [​IMG]
     

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