Long-excursion full range--drawbacks producing higher frequencies?

[hifu]

If the cone of a full range speaker is moving close to xmax to produce low frequencies, does that modulate the rest of the audio spectrum? Is it perceptible?

I'm building a small transmission line, thinking of using a single Dayton RS100T per cabinet, but also considering two Peerless 830986 in a 1.5-way configuration. The single Dayton blows away even two Peerless in almost every metric according to WinISD, so it looks good on paper. But with a few dB of BSC, the Dayton will be moving a lot...

Anyone have experience with this?

Josh

[JasonP]

Re: Long-excursion full range--drawbacks producing higher frequencies?

Even with an advanced motor designed for low distortion, my experience has been that once the cone is really moving in a full-range sound quality takes a nose dive.

This is the exact reason we have two way and three way designs.

[andy19191]

Re: Long-excursion full range--drawbacks producing higher frequencies?

If the cone of a full range speaker is moving close to xmax to produce low frequencies, does that modulate the rest of the audio spectrum? Is it perceptible?

Yes but within the context of the other significant compromises like SPL, bass, dispersion, etc... I would suggest it is possibly not a major concern.

Anyone have experience with this?

I did once have a 3-4" single driver in a transmission line enthusiastically demonstrated to me by the owner but was uncomfortably baffled by what there was to be enthusiastic about. I made positive noises but didn't enquire about the details.

Many decades ago I built at modest cost an on wall transmission line using a 5" midwoofer (multiple drivers not single) which seemed to work better than a small speaker using the same drivers. It couldn't play loudly enough but the gain from making it wide and not deep for placement against a wall seemed to work reasonably well given the undersized driver. It might be something to consider if applicable in your situation.

[fpitas]

Re: Long-excursion full range--drawbacks producing higher frequencies?

An interesting study on so-called Doppler distortion by Rod Elliott:

http://sound.westhost.com/doppler.htm

[Sydney]

Re: Long-excursion full range--drawbacks producing higher frequencies?

http://www.readresearch.co.uk/loudsp..._article_1.pdf
http://www.readresearch.co.uk/loudsp..._article_2.pdf
http://www.readresearch.co.uk/loudsp..._article_3.pdf

[philthien]

Re: Long-excursion full range--drawbacks producing higher frequencies?

An interesting study on so-called Doppler distortion by Rod Elliott:

http://sound.westhost.com/doppler.htm

That is a amazing paper and while the effect isn't limited to full-range drivers, I do believe that the wider the bandwidth (especially as a single driver is called on to play full-range), the more phase modulation you should expect.

The question is, can we hear it? The paper doesn't seem to talk specifically about full-range drivers, I have only skimmed it and have to read it thoroughly. If you search the paper for "audible," it doesn't appear that the effect can be heard under normal circumstances (listening to music) in the tests they indicated.

But again, nothing on full-range and I suspect the effect is more audible on full-range. Am I all wet on that?

Have anything on Doppler and full-range drivers?

[philthien]

Re: Long-excursion full range--drawbacks producing higher frequencies?

http://www.readresearch.co.uk/loudsp..._article_1.pdf
http://www.readresearch.co.uk/loudsp..._article_2.pdf
http://www.readresearch.co.uk/loudsp..._article_3.pdf

So how is this different from the Doppler/Phase Modulation paper posted by Francis? Is Klipsch talking about the same distortion, and Elliot's paper describing the source of the distortion?

[fpitas]

Re: Long-excursion full range--drawbacks producing higher frequencies?

That is a amazing paper and while the effect isn't limited to full-range drivers, I do believe that the wider the bandwidth (especially as a single driver is called on to play full-range), the more phase modulation you should expect.

The question is, can we hear it? The paper doesn't seem to talk specifically about full-range drivers, I have only skimmed it and have to read it thoroughly. If you search the paper for "audible," it doesn't appear that the effect can be heard under normal circumstances (listening to music) in the tests they indicated.

But again, nothing on full-range and I suspect the effect is more audible on full-range. Am I all wet on that?

Have anything on Doppler and full-range drivers?

The second Klipsch paper that Sydney posted above has something on a full-range speaker (most likely a Bose 901). It's not pretty. Audible? Most likely, but I'm sure some listeners may not find it objectionable.

[Sydney]

Re: Long-excursion full range--drawbacks producing higher frequencies?

Prior Background references to Elliot's article.

[fpitas]

Re: Long-excursion full range--drawbacks producing higher frequencies?

So how is this different from the Doppler/Phase Modulation paper posted by Francis? Is Klipsch talking about the same distortion, and Elliot's paper describing the source of the distortion?

I think Rod's main point was that it's phase modulation primarily, versus frequency modulation.

[billfitzmaurice]

Re: Long-excursion full range--drawbacks producing higher frequencies?

Is Klipsch talking about the same distortion, and Elliot's paper describing the source of the distortion?

Pretty much. What PK addressed in particular is that the longer the driver excursion the higher the distortion, and that one reason why horns have much lower distortion than direct radiators is the much lower excursion required of a horn loaded driver to reach the same SPL. The same is true of a direct radiator with a larger cone versus a smaller cone, the larger cone requires less excursion for the same displacement/SPL. So while you can realize the same displacement with a long excursion/small cone as a short excursion/large cone the rule that there's no such thing as a free lunch still applies.

[Sydney]

Re: Long-excursion full range--drawbacks producing higher frequencies?

... Is Klipsch talking about the same distortion, ...

In the Introduction of part 1 Klipsch confines the context to Modulation Distortion that produces "new frequencies, in-harmonically related to the original sounds."
A familiar reference is given to the Capstan flutter in tape decks.

[philthien]

Re: Long-excursion full range--drawbacks producing higher frequencies?

Fascinating stuff, Klipsch refers to some of the distortion being very clearly audible. It would be neat if there was some way to simulate these effects with a PC program and headphones (for example) to educate my ears and brain.

[Sydney]

Re: Long-excursion full range--drawbacks producing higher frequencies?

I'm fairly sure that Adobe Audition would allow the modulation of a sine wave in such as fashion. Not unlike a warble tone.
Mechanically by placing a tone generator on a vibrating platform - like a shake table.

[Sydney]

Related

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