[rollei_list] Re: Completely OT- Loudspeaker info
- From: Jerry Lehrer <jerryleh@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Tue, 15 Feb 2005 18:48:30 -0800
Richard
The people in the audio world refer to the planar speakers, such
as the ones made by SME , Magnaplanar, and Martin-Logan, as
dipoles. Some "dipole" speakers have the backwave absorbed
almost completely. Then, are ribbon speakers "dipoles"? All
that I have used, absorbed the backwave.
Jerry
Richard Knoppow wrote:
> ----- Original Message -----
> From: "Jerry Lehrer" <jerryleh@xxxxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Tuesday, February 15, 2005 10:06 AM
> Subject: [rollei_list] Re: Completely OT- Loudspeaker info
>
> > Akhil,
> >
> > We have had Likwitz as a guest speaker at our audio club.
> >
> > I am intimately familiar with his and his associate,
> > Riley's,
> > theories on crossovers
> >
> > I have an active crossover in which I can plug in a card
> > which can be configured to any order. The Likwitz-
> > Riley 2nd order is not to my liking.
> >
> > Jerry
> >
> > "A. Lal" wrote:
> >
> Boy is this a name from the past. I still worked for HP
> when Linkwitz published his paper on crossovers. He was not
> the first to suggest the use of low level crossovers nor of
> phase matching crossovers. I remember my friend Richard
> Heyser, who had some fame in audio himself, being very
> skeptical of this system.
> Low level crossovers and individual amplifiers are a very
> good idea for several reasons but this is a different issue
> from the nature of the crossover itself. Crossovers are
> still something of a compromise but the ability to introduce
> delay at will using digital circuitry allows a much closer
> approach to the ideal where the acoustic fields of the
> individual speakers add in a way that approximates a single
> source.
> I have no idea what he is doing with the very strange
> looking cabinets shown on the web site. Dipole suggests to
> me that the backwave is being radiated directly. I remember
> some talk of dipole speakers in the distant past and, by
> memory, that the idea was based on a misunderstanding of the
> way loudspeakers radiate. The text on the web site is chock
> full of the sort of hype which is so familiar in consumer
> audio. My once golden-ear hearing is no longer good enough
> to make judgments about some aspects of audio system
> performance but I can still tell the difference between
> loudspeakers, at least other than the very top frequencies.
> It would be interesting to compare is speakers with good
> conventional systems.
> Many years ago I worked with Dick Heyser on his method of
> making acoustical measurements called Time Delay
> Spectrometry. I tried at the time to get HP to buy the Cal
> Tech patents, they wouldn't and assured me that the system
> wound't work. In fact, I was making such measurements using
> a standard HP spectrum analyser at the time! HP then tried
> to break the Cal Tech patent. Cal Tech has very good patent
> attorneys so they had no luck. Cal Tech would have sold the
> patent rights for very little so I think there was a large
> dose of "not invented here" about the whole thing. Another
> company finally picked them up and made the equipment
> commercially. HP had to modify the tracking generator in its
> spectrum analysers to avoid an infringement.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
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