From: firstname.lastname@example.org (N. Thornton)
Subject: Re: Bullshit wins v. science
Date: 7 Nov 2002 05:35:40 -0800
References: <email@example.com> <3DC634B7.C303BC8E@scazon.com>
NNTP-Posting-Date: 7 Nov 2002 13:35:40 GMT
John Woodgate wrote in message news:...
> I read in sci.electronics.design that N. Thornton
> wrote about 'Bullshit wins v. science', on Wed, 6 Nov 2002:
> >Some speakers are designed to distort, eg bass reflex units. They
> >produce resonant bass, consequently real life distortion is
> >considerable, though that wont show up on a steady sine wave.
> I don't think I've ever seen so much misleading information in three
Lol. Hi John :)
> ALL moving-coil loudspeakers have a low-frequency resonance.
> very important part of system design is to control this resonance so
> that a high-pass filter response, as close to maximally-flat as desired,
> is obtained.
If you were aiming to build a LS with flat response from 20Hz to
20kHz, which incidentlally implies a largeish budget and large
cabinet, then what you say would be true. But IRL the vast majority of
speakers dont have response flat down to 20Hz, so there is some bass
Most domestic speakers have a lot of lf missing, and resonance is
often deliberately not minimised, to add more bass. As someone said,
flatulent bass is very popular. Flatulent bass is very resonant, and
its motivation is lots of bass for small money and a small box. Its a
differnce between ivory tower design and real life.
I think what you say is a classic acedemic mistake. Resonance has been
deliberately used for a very long time to improve bass output.
> This applies whatever the nature of the system - closed-
> box, vented box ('reflex'), ABR ('drone cone'), double-chamber ....
I would say there are equally a lot of speakers it doesn't apply to.
> The resonances (one or more) of these systems do not involve any non-
> linearity at all, so no non-linearity distortion is produced.
It is still distortion, since the audio output does not accurately
follow the electrical input. The level of distortion can be quite
large too. Bass notes lack attack, go on long after they should end,
and in the more extreme cases most of the bass comes out near one
frequency. No doubt you've heard such systems. They're popular with
teen car owners, the more expensive portable stereos, and, with higher
f_res, bottom feeding domestic stereos have been using deliberately
resonant cab backs for a long time to give a bit of bass. Mobile
phones also use resonant bass.
> The overall system response is that of a high-pass filter, and, just
> like a wholly electronic high-pass filter (including any recording chain
> that does not have a flat response down to d.c.), there is an associated
> phase/frequency characteristic and a group delay/frequency
> characteristic. It could be argued that these are 'distortions', but
> this does not mean that they sound unpleasant or are even audible.
This is true of your ivory tower system, but not of a lot of real life
> Of course, it's possible to design the system badly, so that the sound
> pressure/frequency response is far from flat; this has been called
> 'linear distortion', a confusing term, and IS audible, of course. But
> anything badly-designed is likely to be unsatisfactory.
I think it is generally not a bad thing, just a case of maximising
what you can do with limited size and limited money. I wouldn't say
that's bad myself. Warm resonant bass is better than a gaping lack of