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Horns and toe in

Discussion in 'audio' started by hifinutt, May 23, 2020.

  1. hifinutt

    hifinutt hifinutt

    Nearly all the speakers i have ever had have needed toe in to achieve a good soundstage . Martin logans need very careful positioning to get the sweet spot right

    Recently I moved my horns [ impulse taus ] so they are firing straight ahead , down the room . the increase in soundstage was exceptional , almost as huge as martin logans . I was amazed . Whacking great holographic image across the whole front between the speakers

    What are other Horn owners feelings on toe in , I am sure there are many owners on here
  2. tuga

    tuga European

    Those Ta'us are not horns, they're a pair of forward radiating 2-way box speakers which happen to sue a BLH to augment bass extension instead of a bass reflex or a TL.

    How much toe-in they require is a matter of taste.

    Phantom image sharpness is inversely proportional to soundstage width / spaciousness.
    By firing them straight ahead / down the room you are increasing side-wall interaction and the reflections are widening the soundstage and making the listening experience more immersive. The downsides are fuzzy/blurry and overly stretched images and because your speakers don't use waveguides in the tweeter tonal balance is also negatively affected. The resulting relaxation in the presence region will give an impression of increseased soundstage depth also known as the BBC dip.

    If the speaker is flat on-axis toe-in at the listener will produce the most even tonal balance.
    YNWOAN likes this.
  3. hifinutt

    hifinutt hifinutt

  4. hifinutt

    hifinutt hifinutt

    understood , the taus have 3 ways , they have 2 binding posts for each driver [ a total of 6 per speaker ]

    these are the original type

    [​IMG] Impulse Ta'us: Effectively the H2 mk.2, this model had a curved front baffle which oversails the rest of the cabinet, making it slightly wider and taller than its predecessor although retaining the same driver complement. The rear of the mid-horn is enclosed in a sealed chanber stuffed with absorbant, a change from the H2. 94dB/W, 8ohm
    • Drivers: 8.5" Seas bass; 4.5" Seas mid; Focal TD90K tweeter.
    • Crossover ponts: 800Hz; 4.5Khz; 2nd order summed response.
    • Size: 1210mm H x 300mm W x 480mm D
    • Finishes: Painted cabinet with maple / Beech front baffle
    • Weight: approx 65KG / 140lb each.
    [​IMG]impulse taus and boenicke by , on Flickr
    in a previous life
    tuga likes this.
  5. tuga

    tuga European

    Those are not horn speakers. They use a horn in the tweeter range (from 2kHz up - upper-mids and treble).

    P.S.: not criticising the use of the horn, merely stating a fact. It's actually beneficial because it helps match the directivity of the tweeter to that of the mid-woofer. It didn't help make the Klipsch RP series particularly good performers though...
    YNWOAN likes this.
  6. tuga

    tuga European

    That didn't came up in the photos:

    Drivers: 10" Peerless bass; 4" Isophon mid; 1" Coles dome tweeter.
  7. hifinutt

    hifinutt hifinutt

    from the review

    Designing great horn speakers is as much about passion and courage as it is science (and also seems to require a touch of madness). The horn holy grail is a great speaker with minimal coloration. Horns will have your music echoing like some soaped-up bathroom baritone if they are improperly executed. In this case, the Ta'us horn speaker design is especially well thought out. Starting at the top end: Its tweeter goes from 4.5kHz to 20kHz, and is made by Focal. This 30mm (1.2") inverted dome features a special fiberglass diaphragm. Impulse says the fiberglass design gives it a very low resonant frequency, below 1KHz. Located above the tweeter is the midrange driver, a 109mm (4.3") doped paper cone similar to that found in many conventional box speakers. This driver sits at the speaker's rear, firing directly into a wood carved, parabolic horn, and carries the musical load from 750Hz to 4.5kHz. The Ta'us horn is also enclosed at the back and top. This blocked-off, rectangular horn reflects the company's experience with the speaker's predecessor, the H2, whose midrange horn was open to the rear. The redesign is meant to reduce cancellations (which can interfere with imaging) arising from listening room variations. The Impulse horns are carefully crafted, so the sound is not bounced back and forth off the horn walls on its way out. Tonal trampolining off the horn can cause time-smearing, producing a very nice echo, echo, echo....

  8. hifinutt

    hifinutt hifinutt

  9. tuga

    tuga European

    Wow, that's one strange topology. Didn't realise that from the photos.

    If I got it right, the dipole mid is pushed back and sits inside a horn, and the woofer is placed on the baffle of a slot-ported chamber.

    In that case I think that firing them straight ahead / down the room will have a significantly negative impact on tonal balance (assuming that the speakers are reasonably flat on-axis) and the widening of the stage that I mention previously will be very mild.

    If the crossover doesn't compensate for the delay of the recessed (by almost 50cm) midrange there will likely be some smearing of images.
  10. tuga

    tuga European

    They are endeed horns from the mid-mirange to the upper-mids, but I am confused about one thing: is the midrange diver "open-baffle" at the back (dipole)?

    Very curious speakers indeed...
  11. martin clark

    martin clark pinko bodger

    I have run Impulse H2s - which really are the same thing - across the room (which is 17 x 14 x 10'h) - well clear of the boundaries, for 15+years.
    And yes - no 'toe'

    (See stuff under 'Impulse' here: http://www.acoustica.org.uk/; many other thoughts, finding & measurements to add - one day...)
    hifinutt likes this.
  12. martin clark

    martin clark pinko bodger

    Tuga - H2s midrange are open back; the midrange driver setback is about 300mm; the ta'us have a closed mid rear enclosure instead.
    The bass loading in both is effectively a MLTL, with huge back chamber and truncated exponential horn opening to the floor - NOT slot-loaded.

    It all works way better than you might believe (if yes, sensitive to crossover values inc the parasitics.)
    tuga likes this.
  13. cooky1257

    cooky1257 pfm Member

    All from his computer. "Phantom image sharpness is inversely proportional to soundstage width/ spaciousness" what utter bull shit. Please state the units of measurement.
    martin clark likes this.
  14. martin clark

    martin clark pinko bodger

    Completely wrong.
  15. tuga

    tuga European

    Blame Google :p
  16. martin clark

    martin clark pinko bodger

    I'll take your usual effusive pronunciations as having the same degree of general applicability, then.
  17. hifinutt

    hifinutt hifinutt

    Thanks martin , i still can`t quite get over it , the sound is like 2 massive quad 2905 is front of you , very very wide soundstage and enveloping . just by moving them a few cm`s . to face forward
  18. Tarzan

    Tarzan pfm Member

    Interesting.... always had my H6's firing at the listening position will give it a go, ta.:)
    hifinutt likes this.
  19. tuga

    tuga European

    Care to elaborate?
  20. cooky1257

    cooky1257 pfm Member

    I think he means you talk out of your arse.
    stevied likes this.

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