Solid state power amp choice. Is thd a valid criteria?

[Darren]

Hi everyone, I'm a none technical hifi enthusiast trying to choose between two, used, low cost power amplifiers. One is the pro use Yamaha P1500 and the other is the Rotel RB981.
If I'm reading the specs correctly the Rotel has a thd of 0.03% (at full rated output) and the Yamaha is 0.1%. Three times the amount. But at such low percentages will these differences be audible?
I'm thinking not. If true I'm wondering how else I might decide which is best based on measurements/specs?
Thanks for your advice.
Darren.

 

[MZKM]

I don’t personally believe distortion -60dBFS is audible with music.
That said, there are other aspects as well, just as THD at 1-10W, as well as the signal to noise ratio, output impedance, etc.

 

[Darren]

I don’t personally believe distortion -60dBFS is audible with music.
That said, there are other aspects as well, just as THD at 1-10W, as well as the signal to noise ratio, output impedance, etc.

Thanks MZKM. Excuse my ignorance. Could you please clarify? What percentage THD would "-60DBFS" be?
Thanks for taking an interest.

 

[RayDunzl]

0.1% = -60dB
0.03% = -70dB

http://www.sengpielaudio.com/calculator-thd.htm

Your speakers will (most likely) generate much more distortion.

If you play music (not distortion) at -60dB from your normal level, you'll be lucky to barely hear anything.

-70dB takes you to barely barely hear anything.

Which means you won't hear it when the music is playing...

 

[gene_stl]

Either of those amps will sound wonderful. I have a Rotel 870 power amp open on my great room floor. I have to replace two of the four speaker connectors which got knocked off during a move. The interior is a thing of beauty.

Yamaha amps are great too. The published distortion won't tell you much because you will be operating at a low level. Get them both and bi amp.

 

[amirm]

If I'm reading the specs correctly the Rotel has a thd of 0.03% (at full rated output) and the Yamaha is 0.1%. Three times the amount. But at such low percentages will these differences be audible?

Those specs are meaningless and cannot be compared to each other. You can pick the output level at different distortion levels. There are no standards.

 

[Blumlein 88]

Specs listed in manual for Rotel.

And the Yamaha.

 

[Blumlein 88]

So either amp would likely be equally good assuming they actually meet spec and that you don't have a speaker with a difficult reactive load that can catch one out vs the other.

 

[Darren]

Thank you gentlemen. It looks as though its down to me. The svelt Rotel Vs the macho (looking) Yamaha. Tough choice. Thanks, again for your time.

 

[restorer-john]

Thank you gentlemen. It looks as though its down to me. The svelt Rotel Vs the macho (looking) Yamaha. Tough choice.

Buy them both, use both and decide which one suits you. Sell the other one (hopefully at a profit). Use the money you made to put towards your next purchase.

 

[Darren]

Buy them both, use both and decide which one suits you. Sell the other one (hopefully at a profit). Use the money you made to put towards your next purchase.

Hahaha.... John..... You overestimate my budget and my patience

 

[A800]

I would choose the A800.

 

[Wes]

buy whichever one costs less and/or can be found used

you can also spend time pondering whether speaker distortion is entirely fungible with amp distortion