Thd

[Shadow_Ferret]

I was looking at the specs to my 28 year old Pioneer SX-780 stereo receiver and it says it has less than 0.05% harmonic distortion and intermodulation distortion.

Just for grins I went and checked the specs for NAD recievers. I couldn't find that spec.

But I checked Marantz's top of the line reciever, the SR8500 THX Select Surround Receiver, and it only can claim 0.08% THD.

I've noticed the 0.08% seems to be the norm for most receivers.

Are they checking this value differently nowadays? I find it hard to believe that my receiver, which I don't think was Pioneer's best at the time, could possible outdue the products of today. I would have thought advances in technology would be putting THD at near infinitesimal range.

 

[sjdgpt]

% THD is a pretty worthless number, in that, the THD would have to be above 1% for golden ears to hear, and above 10% for the real world.

If you read a THD curve, you will find a power output point that THD rapidly rises. Most manufacturers back off the point to a point that the receiver has ample power ratings, and relatively low THD.... usually a point that is less than 1/10th of the amount of THD "Golden Ears" would claim to be able to hear.

Modern receivers have made dramatic improvements. Check S/N ratings. SN is a real number that reflects the quality of the receiver.


PS: Yes, THD would be an infinitely small number, IF we accepted lower power ratings, smaller levels of signal gain etc.

 

[Shadow_Ferret]

My other thought was that perhaps in this day and age of "home theater" that those things just aren't that important any more. Stereophonics, once upon a time, were owned by people who cared about music, who wanted their equipment a step above. By that I mean not everyone owned components, they owned all-in-one systems. Some owned giant consoles that housed the turntable and radio and speakers all in one cabinet. Or they owned small turntable/radio combos with small separate bookshelf speakers.

But the ones who owned the components, receivers, integrated amps, etc., we cared about S/N ratios, THD, wow and flutter numbers. We were numbers geeks and I still recall arguments with a friend who had a Technics receiver that had 0.04% distortion. That 0.01% mattered. And manufacterers were publishing those numbers and bragging about those numbers because they knew we cared.

Now, I'm wondering, what with home theater, if the emphasis hasn't shifted and now what matters most is number of channels, number of watts, and most importantly, the number of inputs and outputs.

It could be, like you said, that those numbers under a certain point are meaningless, but I also wonder if it might just be different generations caring about different things. We were geeks about it and today's people aren't.

 

[sjdgpt]

We are still number freaks.

There are some of us that calculate our gas mileage to three decimal points (you know 31.324 mpg). Which really doesn't make much sense as we are never certain as to the point the gas tank is exactly filled as previous fillings(oops, that was more than 1/2 half way up the fill spout and could add 0.25 ounces), or whether we have traveled 403.2 miles or 403.17 miles.

We could chase THD decimal points, but why? Those decimal points are pretty much meaningless, especially since we can't hear even moderate levels of THD.

Even "Sterophile" and "The Absolute Sound" don't chase the THD decimal points. If THD was actually important, I would suspect some of those tin eared tweek freaks to boast about the 5 decimal point values of some $100k amp.


PS: Just a note. Testing standards change with time, as do the equipment that is used. There have been significant advances in the accuracy of electronic analyizers during the past 25 years. As technology advances, it is quite possible that the current testing method is actually stricter, using far more accurate & sensitive equipment than what was used in the past. Which could mean that yesterday's 0.04% THD would actually measure a significantly higher value, even exceeding 1% if tested today!