THD ratings

[jslomax]

Sometimes THD is given with the load impedance, such as 0.08% @ 8 ohms and sometimes it is given with a frequency, such as 1% @ 1Khz. Is there a means to correlate these specs to choose which is the better receiver?

Thanks

 

[no. 5]

This may sound rude, but you won't find the 'better' receiver by comparing manufacture specified THD figures.

 

[3db]

Sometimes THD is given with the load impedance, such as 0.08% @ 8 ohms and sometimes it is given with a frequency, such as 1% @ 1Khz. Is there a means to correlate these specs to choose which is the better receiver?

Thanks

Better how? Better is a really sujective term because what is important to one buyer may not be that important to another buyer. One may look at features being more important, the ability for the a/v receiver to video conversion with marginally higher values of THD then a receiver who has marignally lower THD but can't do the video conversion. Thats just an example. However strictly speaking about the amplifier section of a receiver as your question states, the receiver with the THD of 1% is very poor and you will be able to hear the distortion. Anything lower than 0.5% THD ( may be wrong here) is inaudable. So yes, the receiver with .08% will be better than a receiver with 1% becuase you are able to hear the difference. Comparing a receiver of .08% with one that of .1% .. now you have to look at a whole more than just THD because both have distortion levels below human's ability to hear it.

 

[jslomax]

more info

Thanks for the responses, however the point of the question was missed. I realize that THD is not the end-all-be-all measure of a receiver's worth. I have been reviewing some receiver specifications and have noticed that some manufacturers provide THD in a percent at a given frequency format while others provide it in a percent at a load impedance. Knowing there is no industry standard for this test, how can one compare two values when the units are not the same? for example 0.1% @ 1Khz vs 0.1% @ 8 ohms. All things being equal, which receiver would provide the more accurate audio reproduction (least distortion)?

 

[markw]

You're still comparing apples to oranges

Unless all the units you're comparing state their specs the same way. you really can't make a quantative judgment.

Among other things, you can't compare a rating stated for 1khz with one stated for the full bandwidth.

But, my spidey sense tells me that the one that states the most specific and stringest method they used to arrive at those figures would be the one I would choose, even if the final number is higher than the others, within reason of course. They have less to hide.

FWIW, what unit advertises ".8% at 8 ohms"? I've never seen that.

 

[no. 5]

Thanks for the responses, however the point of the question was missed. I realize that THD is not the end-all-be-all measure of a receiver's worth. I have been reviewing some receiver specifications and have noticed that some manufacturers provide THD in a percent at a given frequency format while others provide it in a percent at a load impedance. Knowing there is no industry standard for this test, how can one compare two values when the units are not the same? for example 0.1% @ 1Khz vs 0.1% @ 8 ohms. All things being equal, which receiver would provide the more accurate audio reproduction (least distortion)?

The two specs are not exactly comparable, the 0.1% @ 1kHz is a measure of THD with a single frequency input, 0.1% @ 8 ohms is (presumably) a measure of THD across the amplifier's bandwidth into an 8 ohm load.

Furthermore, THD is Total Harmonic Distortion, that is, the sum of all added nonlinear harmonic components, it does not tell you what the spectra of the distortion is; 1% THD with even order harmonics can sound fine, 1% THD with high order harmonics... not so much.

 

[AcuDefTechGuy]

1st, I don't think you can compare 2 amps/receivers unless both were measured in the same lab using the same standards, etc.

2nd, you can't hear any differences between a 0.1% THD & a 0.00001% THD.

3rd, I think Signal-to-Ratio is more important than THD% because SNR is where you will actually hear the hissing of your speakers if the SNR is not great.

4th, we can't assume anything. A 0.1% THD @ 1kHz may be exactly the same thing as a 0.1% THD @ 8 ohms because the 2 most common standards are for 8 ohms speakers @ 1 kHz.