Jump to content

can I measure speaker distortion at home? Does anyone measure speaker IM, Harmonic or FM anymore?


garyrc

Recommended Posts

We used to see distortion figures reported in speaker reviews, but I haven't see any in a while. Is measured distortion no longer considered informative? Heyser used to include the results of his distortion measurements in his Audio magazine speaker reviews. I remember that the IM levels he found in the Klipschorn (in the'80s) were considerably lower (per dB of SPL) than those of some other speakers. Keele also ran IM and Harmonic distortion levels on the speakers he reviewed, such as the Platinum Studio 2 in about 1999. And, of course, PWK used to measure frequency modulation distortion.

Is there a way to measure comparitive levels of distortion in the various different speakers you may have in your home?

Link to comment
Share on other sites

The Soundstage site does distortion measurements on speakers. They don't show percent distortion because that is too general. What they do is plot across frequency and show two curves. The dB difference between the two curves indicates the distortion (in dB) at any frequency you care to check. Knowing the dB difference, you can figure the distortion at that frequency as a percentage... their explanation:

Both curves are reported in dB which can be read off the vertical axis. In order to
convert to a percentage one must read the top line (frequency response) and then determine
the dB difference between that line and the bottom line (THD+N line). Translation from dB
to % is as follows:



Equal (or 0dB difference) = 100 %

-10dB = 31.6%

-20dB = 10.0%

-30dB = 3.16%

-40dB = 1.0%

-50dB = <0.5%

If you look around their site, they have examined some pretty high end speakers (and amps). To do a home distortion measurement might be pretty difficult. You would need to compare the signal going to the speaker with another signal derived from a microphone. The influence of your room acoustics would likely prevent any reliable conclusions.

Link to comment
Share on other sites

Is there a way to measure comparitive levels of distortion in the various different speakers you may have in your home?

You can measure distortion with Room EQ Wizard, which is free software...but on par in performance with professional tools like Smaart.

One of the downsides to in-room distortion measurements is that it is often the case where the room acoustics will mask many of the distortion products from the measurement method. However, that doesn't mean we don't hear the effects from those distortions. Doing the measurements in an anechoic environment will prevent any masking from occurring. Going outdoors is one way to accomplish this, but then you have to factor in the effects of boundary gain, which is crazy important for speakers like the Khorn that are relying on the acoustic loading provided by the corner...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...