Thd <0.05%

[Art_H]

I realize this may be a fairly vague question. I'm trying to figure out when THD can be audible and affect performance. I assume that is one reason for lots of power from the amp to keep the THD down at a given level of output.

What then is the biggest factor that affects THD within the circuit of the amp?

I'm trying to also determine what I should be looking for in a dedicated amp, and possibly to design/build my own.

Any info appreciated
Thanks

 

[Pyrrho]

I realize this may be a fairly vague question. I'm trying to figure out when THD can be audible and affect performance. I assume that is one reason for lots of power from the amp to keep the THD down at a given level of output.

What then is the biggest factor that affects THD within the circuit of the amp?

I'm trying to also determine what I should be looking for in a dedicated amp, and possibly to design/build my own.

Any info appreciated
Thanks

This is no one precise number that can be given for how much THD it takes to be audible, as it will depend upon the exact frequencies involved. Human hearing is most acute in the midrange, so one will typically be able to notice lower levels of distortion there than at extreme bass and treble. But it is even more complicated than that, as human hearing is such that when there are two frequencies that are very close together, with one being much louder than the other, one tends to not hear the lower volume tone. Thus, if one is listening to music, which tends to have a broad range of sound, the music may mask distortion that would be audible if one were playing simple test tones.

 

[annunaki]

THD tends to become audible at about .1% with midrange test tones. This tends to be dependent upon the individual. Some people are more sensitive to it that others.

With music, I would say that it needs to reach 1%-2% in the midrange for most to deem it audible.

Bass frequencies tend to be harder to hear distortion with, since our hearing is not as accute there. THD is said to be able to reach near 10% before it is audible below 80hz or so.

 

[mtrycrafts]

I realize this may be a fairly vague question. I'm trying to figure out when THD can be audible and affect performance. I assume that is one reason for lots of power from the amp to keep the THD down at a given level of output.

What then is the biggest factor that affects THD within the circuit of the amp?

I'm trying to also determine what I should be looking for in a dedicated amp, and possibly to design/build my own.

Any info appreciated
Thanks

Here you go, some good ready

http://www.axiomaudio.com/distortion.html#

http://www.mastersonaudio.com/features/20040401.htm

I would worry more about a speakers distortion than modern amps and receivers

Also, you may want to look at same speaker measurements, their THD included. However, that THD has to be derived from the curve differences

http://www.soundstagemagazine.com/measurements/energy_rc_10/

Here is an explanation for the measurements and the table how to figure the THD:

http://www.soundstagemagazine.com/measurements/test_loudspeakers.htm

Design and build your own amp? I don't see a real need to do that, unless you are in business to sell, then you need a lot of knowledge.

 

[Art_H]

Design and build your own amp? I don't see a real need to do that, unless you are in business to sell, then you need a lot of knowledge.

I know what you mean. It's something I have been meaning to do for a great number of years. I'm going to start with speakers first, then go from there.

I appreciate the links, I realize there is an amazing amount of info to digest. The problem is that I have so many "hobbies' that I research extensively. This won't be any diffferent, just getting back into it.

I now realize why amps are rated @ 1k for their THD where it gives the best representation of the quality output. The standard is 1k 1 watt isn't it?

 

[fmw]

I've never done any tests on it personally so I can't comment very specifically. Most experts agree that THD below 1% is not audible.

 

[AcuDefTechGuy]

The Audio Critic wrote:

"It may be possible for humans to distinguish distortion of 1% (-40dB). I am not aware of any controlled experiments which show that distortion of 0.1% (-60dB) is audible."

 

[mtrycrafts]

I now realize why amps are rated @ 1k for their THD where it gives the best representation of the quality output. The standard is 1k 1 watt isn't it?

Yes, knowledge is power
The FTC power standard is 20Hz to 20kHz. But companies can also quote them otherwise when they so specify the condition. With a 1kHz test, you do get a bit more power than from the 20-20k test and consumers like numbers, the higher the better whether they understand its meaning or not