How accurate is RMAA distortion measurement?

[ChocoHolic]

Alright the Lap Top looks much better.

Frequency response is +/-0.5 db up to 16 kHz
and drops below -3db above 20kHz.
Noise and dynamic: about 84 dB
THD: below 0.01 %
IMD: around 0.02 %
Cross talk: around 80 dB

Altogether: May be helpfull for one or the other measurement.
Great! Thanks for the link to Right Mark!!!!!!

Bye
Markus

[arnoldc]

may i know how the connection from the amp to the pc input was made?

[AJT]

amp out connects to the line in of your pc's sound card, you have to use an attenuator, like an l-pad, as the pc's soundcard inputs can only take line-level signals...

you will have to use the 1/8in baby plug....



analog_sa,
may we know what attenuator did you use to test your amp? a simple schematic of your test set-up would be nice...what frequencies did you use?

thanks,
tony

[arnoldc]

joan2, thanks for the confirmation of the attenuator. i know i have to have something between the speaker out and the PC but i don't know what it should be

analog_sa, may we know?

will the attenuator be a variable in the test?

at least i can now test my foreplay pre and see how bad, or good it really is

[peranders]

ChocoHolic, and others, Rightmark has listed many soundcards and their performance so you can compare.

http://audio.rightmark.org/results.shtml

[analog_sa]

i know i have to have something between the speaker out and the PC but i don't know what it should be

I just used a fixed attenuator so as to set the amp gain to unity. This will obviously lead to inferior S/N but should not affect the distortion tests.

[fmak]

Originally posted by peranders
ChocoHolic, and others, Rightmark has listed many soundcards and their performance so you can compare.

http://audio.rightmark.org/results.shtml

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Proves what I have found out measuring Creative cards - crap.

I am not sure of the absolute accuracy of the results as RMAA works perfectly on some cards/computers only. I have has 'infinitely flat' freq responses and no figures for some tests.

[fmak]

[QUOTE]Originally posted by analog_sa
[B]I wonder if anyone has experience using RMAA to test amps. Last night i tested my latest IT PP creation and RMAA reported unbelievably low THD (around 0.02%) and absolutely disastrous IMD of around 5%.
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The Rightmark seems to give much better numbers than my WinAudioMLS 64 bit FFT using ASIO input. I suspect that the software reports band limited numbers to 22kHz even on 24/96 setting. This is the 5.3 version.

[Gordon McGregor]

[QUOTE]Originally posted by fmak
[B]

Originally posted by analog_sa
I wonder if anyone has experience using RMAA to test amps. Last night i tested my latest IT PP creation and RMAA reported unbelievably low THD (around 0.02%) and absolutely disastrous IMD of around 5%.
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The Rightmark seems to give much better numbers than my WinAudioMLS 64 bit FFT using ASIO input. I suspect that the software reports band limited numbers to 22kHz even on 24/96 setting. This is the 5.3 version.

It depends of your sound card and measuring settings. You need to control the level of input signals as well, if your soundcard clips at some levels http://members.cox.net/alexhardware/images/imd.png , you may get unpredictable results.

I use RMAA for a long time since ver.4.3 (measuring amps and AV processors as well as sound cards) and have no problems with it at all.

[fmak]

I use RMAA for a long time since ver.4.3 (measuring amps and AV processors as well as sound cards) and have no problems with it at all. [/B][/QUOTE]
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But have you compared it with an accurate measurement system. If you examine measuirements made on sound cards using iyt, you will find surprisingly good distortion and noise nos.

The software up to 5.0 was quite quirky.