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volvotreter

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    ACR Klipschorn clone, help on crossover needed!!

    in Technical/Restorations

    Posted

    Hi there,

    Yesterday I picked up the first one (because on one fits into my Volvo 850 estate) of a set of Klipschorn clones, which I bought for approx US$ 500.

    The DIY kit was originally sold by a Swiss company called ACR sometime in the late eightieth. I was called Eckhorn Standard which is like corner horn standard version. The kit consists of particle board bass enclosures, a aluminum die cast mid horn (identical to the one which is used by Klipsch in Khorns and La Scalas) with a driver called K55 by ACR (? OEM from Klipsch since it looks pretty much like an original K55 but no stickers, logos etc). The tweeter is an original square magnet T35 by EV (which, as far as I know Klipsch uses too).

    The original bass driver was replaced in 96 with a MULTICEL MB-38A (info on http://www.lsv-speaker.de/tief/tief15p/00050154.html). Regarding the specs, the driver should be ok (low fs, average Xmax, Z: 8 Ohm, 97 db 1W/1m, fs: 25 Hz, Re: 5.2 Ohm, Qms: 3.32, Qes: 0.35, Qts: 0.32, Vas: 400 Liter, Sd: 880 cm², Xmax: 3 mm, Vd: 265 cm³, Le: 0.9 mH)

    Now here is my problem: The crossover network consists from very cheap parts and was modified from the original somehow and I don t have the original plans of the networks which came with the kit.

    From that what I think it is very far away from the optimum. Especially the critical mid/high section inspires little confidence in me.

    So is the somebody out there whos got the original ACR or even better the Klipsch or ALK plans for the Klipschorn?

    For the bass unit with the drivers Z of 8 Ohm (instead of 4 Ohm of the K33E) I will need to do some experimenting

    Any help or comments appreciated!!!

    Erik (volvotreter)

    Progress on MiniPseudoLaScala

    in Technical/Restorations

    Posted

    quote:
    Originally posted by William F. Gil McDermott:

    John,

    The response from 200 to 500 Hz is about level and even goes to 1 kHz, at 102 to 104 dB at 1 watt/ 1 meter. Therefore, I believe the choice of the Eminence Beta 10-A was a good one.

    The problem is that there is a big dip in the 100 to 200 Hz region (I was not hoping for anything under 100 Hz).Gil

    Gil,

    I found someting similar with my mini La Scalas. The response I got is at level from 200Hz to approx. 1KHz. Below 200Hz it drops -20dB at 100Hz. As you know, mine driver is more like a HiFi driver: low fs and a little to high Qes, low BxL. The back chambers are perfecly air tight. So, that could not be the reason.

    Currently I am trying to get my measuring system to work (sticking around with a mic. pre amp). Then I will give more detailed results.

    But Gil, how deep is the dip in your La Scalas response?

    Erik

    Progress on MiniPseudoLaScala

    in Technical/Restorations

    Posted

    I'm also working on La Scalas for 10" drivers and some 300Hz Edgar midrange horns.

    My goal is to enhance my existing system. It consist from a (selfmade) Klipschorn subwoofer, mains (selfmade): Eminence 8" bass, old Aduax 6.5" midrange (the one Bruce Edgar mentioned in his "Edgar Midrange Horn Article"), and Fostex FT66H tweeter. The center is a Magnat Vintage Center 5.

    The mini La Scalas will replace the mains.

    Right now, I just hooked the horns in front of the audax to see (hear) what they do.

    I'm thinking of tuning the back chamber of the cabinet so that the system resonates at the cut-off of the horn flare frequency approx. 95Hz (to extend the response as far as possible downwards)? I don't know if it's worth the extra effort?

    The driver will be a WESTRA 10" with fs=40Hz, BL=6.8, Qes=0.62, 4ohm, 92dB/W.

    My mayor concern in this driver: it's weak efficency.

    I'll give a report when I got the whole thing together.

    Erik

    A good driver replacement for the Klipschorn

    in Technical/Restorations

    Posted

    Currently I'am looking for an improvement of my k-horn. I am using it as subwoofer only (fs-80Hz). So, what driver could improve the low end?

    In the following, I included two posts of other people to have a basis for a good discussion.

    So, you horn addicted folks: Please name speakers for the k-horn you have tried and share your experience with us (especially the low end)!

    ____________________________________________

    John Warren wrote:

    I have experimented with a few drivers in the K-horn. Since the throat baffle covers most of

    the cone area it is important that the woofer surrond does not touch. I have built a K-horn

    with a removable throat panel (like the old design) and routed an annular groove in it to

    accomodate different driver surrounds. Don't have to do this if the mounting gasket is a 1mm

    or so thicker than half of Xmax. Based on horn theory and my tinkering, what should works

    best are drivers with:

    very low Fs (<25Hz)

    high Qts (>0.5)

    large Xmax (>6mm)

    large BL

    products >10 T*m

    nominal impedence at 4ohms (horn loading brings it closer to 8 inoperation)

    Compliance numbers around 0.3mm/N. The "orginal" plans call out a driver with

    lowest possible Fs preferably below 25Hz.

    I have found that the high end roll-off will suffer if the driver has a low Qts.

    The Eminence unit, K33E, is a pretty decent driver for this application and it moves more air

    than the old (Xmax limited) EV 15WK. The only down side is that the Eminence unit it real low

    end. Also, I have purchased remanufactured units from authorized dealers that have warped

    baskets, rust, big air gaps in the motor curcuits where the iron is against the magnet, magnet

    cracks, and so on.

    $250 for any Eminence driver would be hard for me to swallow. I recently heard a pair of old

    LaScalas with (new?) EV DL15W subwoofer 15" drivers installed. I do not know what had to

    be done to make them fit but they really cranked! They cost $207 ea. (Parts Express).

    Lammers, check the Parts Express web site out (www.partsexpress.com) and compare the

    unit in the picture with the one you just bought, look the same?? Look under Electro Voice.

    ___________________________________________

    These are the T/S paramters for the K33E:

    Znom = 4 ohms

    Re(vc) = 3.5 ohms

    L = 1 mH @ 1kHz

    R = 1.03 ohm @ 1KHz

    Fs = 27Hz

    Sd = 0.0890 sq. m (13.5" diameter)

    Xmax = 6.67 mm

    Vas = 343 liters

    Qts = 0.633

    Qes = 0.684

    Qms = 8.5

    BL = 9.8 T*m

    Mms = 106 grams

    Cms = 305 microns/Newton

    Pmax = 150 Watts

    A lower Fs and larger BL product will improve the low end performance and transients

    respectively of both the LaScala and the K-horn. Last time I checked the Eminence website, I

    did not see a driver with suitable T/S parameters for the Khorn.

    John

    ____________________________________________

    What's right? (on La Scalas)

    in Technical/Restorations

    Posted

    Hi there,

    I took a close look on the plans for Klipsch La Scala floating on the net. Basically they

    are all the same but they all differ in a certain point.

    The distance indicated in the

    ?

    'drawing' with <->

    varies from 2 1/2" over 2 3/4" to 3"

    in my plans:

    +----------\ /----------+

    / ? V xxxxxx /

    / <-> +-----------+ y /

    / / chamber / y /

    / / with 15" / y /

    / / bass / y / horizontal

    / / driver / / cross section

    / / / /

    / / / /

    / / / /

    / / /

    I think 3" is right, because everything below 3" would mean the area of the horn decreases at the transition

    x to y in my 'drawing'.

    So, could you please take an inch rule and give me the right

    measurement?

    Or just mail me your plans if you

    got some wink.gif

    Thanks in advance!

    Erik

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