How accurate is RMAA distortion measurement? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 2nd May 2004, 09:35 PM   #11
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
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
  Reply With Quote
Old 3rd May 2004, 04:32 AM   #12
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
may i know how the connection from the amp to the pc input was made?
  Reply With Quote
Old 3rd May 2004, 04:54 AM   #13
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
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
  Reply With Quote
Old 3rd May 2004, 06:30 AM   #14
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to 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
  Reply With Quote
Old 3rd May 2004, 07:05 AM   #15
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
ChocoHolic, and others, Rightmark has listed many soundcards and their performance so you can compare.

http://audio.rightmark.org/results.shtml
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread || Diamond buffer |Thread for the group buy | Wiki
  Reply With Quote
Old 3rd May 2004, 07:47 AM   #16
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
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.
  Reply With Quote
Old 3rd May 2004, 07:50 AM   #17
diyAudio Member
 
Join Date: May 2001
Location: London UK
Quote:
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
--------------------------------------------------------------------------------
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.
  Reply With Quote
Old 23rd May 2004, 06:30 PM   #18
diyAudio Member
 
Join Date: May 2001
Location: London UK
Default Re: How accurate is RMAA distortion measurement?

[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%.
-------------------------------------------------------------------------------
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.
  Reply With Quote
Old 23rd May 2004, 07:19 PM   #19
diyAudio Member
 
Join Date: Apr 2004
Default Re: Re: How accurate is RMAA distortion measurement?

[QUOTE]Originally posted by fmak
[B]
Quote:
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%.
-------------------------------------------------------------------------------
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.
  Reply With Quote
Old 23rd May 2004, 09:07 PM   #20
diyAudio Member
 
Join Date: May 2001
Location: London UK
Default Re: Re: Re: How accurate is RMAA distortion measurement?

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]
-----------------------------------------------------------------------
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.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Accurate 20Hz THD measurement? Jeb-D. Equipment & Tools 12 22nd March 2009 06:58 PM
OP-amp distortion measurement CJ900RR Chip Amps 0 21st February 2009 10:06 AM
distortion measurement djdamix Solid State 1 20th August 2004 07:11 AM
distortion measurement audiobot Tubes / Valves 9 23rd January 2004 12:14 PM
Accurate weights for speaker Vas measurement Circlotron Multi-Way 9 30th December 2002 11:41 PM


New To Site? Need Help?

All times are GMT. The time now is 03:15 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2