[rollei_list] Re: Completely OT- Loudspeaker info
- From: "A. Lal" <alal@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 16 Feb 2005 01:18:22 -0500
Jerry, a bare ribbon would in fact behave like a dipole. However, in
many designs material is put on othe back side to try to damp out
resonances.
> -----Original Message-----
> From: rollei_list-bounce@xxxxxxxxxxxxx
> [mailto:rollei_list-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Lehrer
> Sent: 15 February, 2005 21:49
> To: rollei_list@xxxxxxxxxxxxx
> Subject: [rollei_list] Re: Completely OT- Loudspeaker info
>
>
> 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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