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Re: Harbeth Monitor 40.1 In-Home Audition

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  • Robert Greene
    I agree. The removal of the screen on the M40 tweeter got rid of a resonant peak and made the treble smoother, not brighter. I am at a loss as to why the top
    Message 1 of 86 , Oct 2, 2008
      I agree. The removal of the screen on the M40 tweeter got rid
      of a resonant peak and made the treble smoother, not brighter.
      I am at a loss as to why the top end of the M40.1 once one is away
      from crossover should be any different from the M40 (sans mesh) since
      the tweeter is the same.
      Of course, much of what people speak of as "highs" is really 2,3 4 k


      --- In regsaudioforum@yahoogroups.com, "Tom Mallin" <tmallin@...>
      > I removed the tweeter guards from my M40s long ago, so that is the
      sound to which I'm comparing the M40.1s. I don't think that the M40s
      got brighter sounding in any way when I removed the guards. More
      open and a larger presentation and better resolution of spatial
      details yes, but the highs actually got smoother sounding.
      > The M40.1s have a guard, but it is a very "open weave" affair with
      large openings, similar to the one now used on the C7-3.
      > >>> laurie483000@... 10/2/2008 1:51 PM >>>
      > I wonder if any of the treble differences can be partially
      explained by
      > the domed protective tweeter grill differences. This is much more
      > on the 40.1 compared with the M40. On the other hand, I can't
      > for sure Tom, whether or not you removed this cover from your
      > M40s. You probably did and if so, from your descriptions, it may
      be of
      > minor significance, except maybe explaining the slight difference
      > in 'shimmer'.
      > Laurie
      > --- In regsaudioforum@yahoogroups.com, "Tom Mallin" <tmallin@>
      > > . . . . The M40.1 seems different in subjective high frequency
      > balance and easier on the ears. Unequalized, they seem to have
      > high frequency energy than the M40, the Gradient 1.3, or the
      > 1.5. I will have to listen more before I can judge whether this is
      > better/more accurate. Sometimes, less distortion can sound like
      > energy, but when you accommodate to that less distortion the result
      > increased naturalness of balance. I will try some known-to-be-
      > on-other-speakers material and see how the M40.1s react, or at
      > how I react to their presentation of such material.
      > >
      > >
      > ------------------------------------
      > Yahoo! Groups Links
    • laurie483000
      i rember the old Ar adds about how low the distortion was in the AR3s. John Crabbe of Hifi News was impressed by the bass from the AR LSTs when he compared
      Message 86 of 86 , Oct 9, 2008
        i rember the old Ar adds about how low the distortion was in the
        AR3s. John Crabbe of Hifi News was impressed by the bass from the AR
        LSTs when he compared them with his Mk2 concrete horns many years
        ago. I suppose it's swings and roundabouts. The BBC seemed to have
        been worried about the effect on the roll surround at the edge of the
        speaker cone, rather than the cone itself.

        I'm mildy surprised that the air loading of the box is sufficient to
        substantially damp resonances within the cone though. Sealed boxes
        tend to use heavy speakers as part of the design, in order to keep
        the fundamental resonance as low as possible and I imagine air
        loading would only have a small effect on the material within the
        cone, but maybe I'm wrong. I'd previously assumed that air loading
        was only significant in the case of lightweight diaphragms like
        electrostatics or in the damping of lightweight cones / diaphragms in
        pressurised horns (i.e. throat smaller than cone).

        Bass reflexes were also meant to reduce distortion too by reducing
        the cone movement, but the way AR used the air in the box as the main
        cone suspension is obviously effective as regards distortion. The
        more gentle bass roll off in sealed boxes compared with reflexes is
        also desirable of course. Noting this fairly common knowledge stuff
        is a way of getting round to mention that the Isobarik principle
        presumably removes the BBC objection about the effect on the roll
        surround, as the air pressure behind the outside cone is much reduced
        and at the same time bass extension and power handling are
        significantly improved.

        Isobariks seem to have somewhat gone out of fashion, but M&K used to
        make a reasonably priced Iso sub until recently, which I've heard
        good reports about and wouldn't mind trying. There is a more
        upmarket large UK made Iso sub (name escapes me) too, that's supposed
        to be very good. As it happens, at the recent London hifi show
        Martin Logan were demonstrating their new CLX electrostatic model,
        the bass panels of which, they said used this principle, which sounds
        intriguing. They were in a large room and weren't playing loud and
        no really bassy music, but they sounded nice there.


        --- In regsaudioforum@yahoogroups.com, "Tom Mallin" <tmallin@...>
        > Yes, the air pressure certainly presses against the cone. That's
        part of the idea. It keeps the cone moving linearly with less
        breakup. The original AR-1 woofer from the 1950s has distortion
        figures in the low bass that are probably lower than most modern
        speakers which don't use acoustic suspension. About 6% at 20 Hz with
        10 watts of input, and 10% with 20 watts input, as I recall. A 1970
        brochure shows a medical school auditorium where four AR speakers are
        used to reproduce heart sounds, which have most of their information
        below 40 Hz, for the listening students.
        > I have restored AR-3as and AR-5s and the bass sounds very good even
        today. No, they will not play as loud in the bass as large reflex
        designs, but the bass quality is special, very solid, very natural.
        The old KLH 5 and especially the 12 (a musician friend had a pair in
        college and I heard these a lot for a few years) also have this kind
        of bass and the 6 is no slouch either.
        > >>> laurie483000@... 10/7/2008 9:33 AM >>>
        > I think I mentioned a while ago that I read somewhere that the BBC
        > deliberately decided not to go for Acoustic suspension in their
        > powered monitors as the air pressures stresses the speaker unit
        > surround in a way that affects the sound. They felt that the Bass
        > Reflex was a better overall compromise. I wish I could find this
        > article which I did read a very long time ago (I'm sure it was by a
        > man).
        > Laurie
        > --- In regsaudioforum@yahoogroups.com, "Robert Greene"
        > wrote:
        > > .............................
        > > 3 GF likes sealed box alignment, and actually so do I,[hey an
        > > agreement!] other things being equal. I think it was a bad idea
        > > historically to go away from the sealed box a la AR to the all
        > > ubiquitous ported box. But not one asked me at the time!
        > >
        > > And one cannot just willy nilly convert one to the other by port
        > > stuffing and expect it always to work. Sometimes it works,
        > > sometimes it does not. Experimentation is the rule. It is worth a
        > > try but it can affect other things further up to disadvantage.
        > ------------------------------------
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