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the real Duke Spinner

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Posts posted by the real Duke Spinner

    RF 7 III vs. Forte IV

    in 2-Channel Home Audio

    Posted

    3 hours ago, jjptkd said:

     

     It would be nice if @Paducah Home Theater could re-do this versus video as there is clearly something wrong with the bass output on the RF-7 III's- possibly wired out of phase? Everything I have read or heard about the 7's indicate they should smash the forte's in the bass department if nothing else, which is clearly not properly represented in their video. 

    I had 7s

    Quickly sold them for KLF 30

    They just did not sound right to me. Low output also

    Your first experience

    in General Klipsch Info

    Posted

    On 4/5/2024 at 11:14 AM, Marvel said:

    Dug these up, just for the history. Wendy Carlos studio with the Cornwalls hanging from the ceiling. She lived in a Brownstone, and had her studio there.

     

     

    corns.jpg

    bsst3.jpg

    That's BAD Room dimension wise. ,🙄

    Your first experience

    in General Klipsch Info

    Posted

    1990 something..I purchased some Forte 2. In State, picked up at a NYS Thruway Exit

    This was on a recommendation from a friend waaay Downstate NY

     

    w0w. !!

    Like my JBL 4430 for mixing

    But For fun listening

    It's KHorns Or KLF 30. 🙂

    What is the DJK bass mod for La Scala's?

    in Technical/Restorations

    Posted

    On 11/20/2005 at 10:51 AM, Marvel said:

     

    Michael,
    You just need to try it on a pair. It is reversable too.

    These might wander a bit:

    http://forums.klipsch.com/idealbb/view.asp?topicID=36054&forumID=68&catID=19&search=1&searchstring=&sessionID={BFBBCFBD-74CC-4815-870C-D89BB808B72B}

    I just removed two of the old links as they eventually time out. Sorry.


    You'll have to read through these, but the info from djk is in there. As I recall, the box to place under the LS is ten inches high. The two ports are 4 inches in diameter, 10 inches long. You can get pvc at Home Depot or Lowes, with the 4 inch inside diameter, very cheaply.

    As djk says, the K43 works the best, the K33 is okay. No one makes a comparable speaker, especially for the money.

    I will point out that I don't have any LS.

    Marvel

    PS Old text from DJK, so read at your own risk:

    I dearly love K-horns. And for most people they are too much work to build for a 50hz horn.57 trapezoid shaped boards some with compound mitre angles.About two gross of screws and nails on edge sometimes at an angle into 1/2" plywood.A LaScala is 3/4" butt-jointed.The front 'V' can be done with a $20 brad nailer.I have a mod for LaScalas that with the stock K33E woofer will give -3dB at 31hz.With an EV DL15W a -3dB of 28hz is possible and it will be an 8 ohm load for SET fans.With the K33E it will be a C6 with less than 1dB of ripple or with the EV DL15W a maximally flat B6.The mod can be done to a stock Klipsch LaScala with no externally visible changes.I have a tweeter that fits the K77/EV T35 footprint that is +/- 2dB to 20khz instead of -5dB at 17khz.I also have a 2" throat mid driver that has 1/10 the distortion that the 5/8" throat drivers have.Any or all of these changes may be done to a stock unit.

     

     

    The taper rate of a LaScala is 100hz,The mouth area is good for 125hz.Below this it is a big woofer in a small sealed box.If we plug the T/S parameters for the K33E into a box program we will see that the Qtc=.85, the Fc=82.5hz, and the F3=70.9hz . If we close in the back of the high frequency cabinet and open the woofer rear chamber up into this volume and fill with fiberglass we now have Qtc=.577, Fc=58.2hz, F3=73.6hz .Bessel=Qtc.577=D2 gives the best transient response and the least group delay of all the sealed boxes.At 30hz the Qtc=.577 has 4.5dB more output than the Qtc=.85 .Compared with sealed enclosures,the transient performance of the best vented enclosure is worse than the best sealed box enclosure.Since we have made great gains in performance some may elect to stop here.But please read on.The next step is to port it.The K33E is not the optimum woofer for this but it works pretty good.With the box size optimized for a D2 we can port the stock woofer to an SC4.The transient response of an SC4 while not as good as an SBB4(more on this later)is better than the more common QB3.Unequalized the F3=49hz and has 3dB more output at 30hz than the D2.The response curves are parallel with the D2 the only difference being the Fc being a half octave lower with the SC4 and the output being 3dB higher from 30~70hz.The output of the SC4 does not drop lower than the D2 until you go below 17hz.Again this may be a stopping point for some.But by adding a simple two pole high pass filter ahead of the power amp we can now have a C6 with a -3dB point of 31hz.Since this is the Fb of the system there is no increase in cone excursion or distortion.The filter consists of a cap an inductor and a pot.The pot allows adjustment at Fb of +/- 3dB.This is similar to being able to change the Qtc of a sealed box from .5~1.0 .If you think about it we have the choice between a D2,SC4,and a C6 in the same box by plugging the port and/or bypassing the eq.If you have a SET amp or simply want to get the most out of the LaScala you will want to upgrade the woofer to something with a lower Qts.The Klipsch K43E does the trick,as do the EV DL15W and the JBL 2205.The EV and JBL drivers require some minor network changes.The lower Qts drivers allow for an SBB4 alignment which has the best transient response of the vented alignments.With no eq they have 3dB more output at 30hz than the stock woofer.With eq we have a maximally flat B6 and the F3 of the system is 27~28hz.If using a solid state amp with the low Qts woofers a small resistor must be added in series with the driver to have the same Rg as the SET does.This mod can be backed out of a stock LaScala with no externally visible changes if you don't like it.No one has ever gone back to stock after hearing this mod.Paul Klipsch was violently opposed to the venting of horn speakers bassed on his experience with venting the K-horn.In retrospect it is easy to see why.The 12" Jensen field coil woofer he was using had an Fs of 60hz and a quick calculation of the vent area vs the Vb based on the photographs of this experiment looks like an Fb of ~80hz.I am sure this sounded horrible.Paul Wilbur Klipsch is a giant in audio.If I appear to see farther than PWK it is only because I am standing on his shoulders.

     

     

    None of the stock Eminence Delta,Kappa,etc series drivers will work.The K43Es that I have measured has Fs=31hz and Qts=.25,the TS parameters that Klipsch hands out are bogus.The EV DL15W has an Fs=30 and Qts=.23 and the JBL 2205 has an Fs=30 and Qts=.21 .After taking into consideration the dc resistance of the woofer inductor and the output impedance of the amplifier the optimum Qts for the vented LaScala would be .312 with a Vas of 10.5 cu ft and an Fs of 30hz.

     

    I'm looking for a total net volume of about 4.8 cu ft. I figure the stock back volume is about 2.25 cu ft. Call it an internal height of about 9" (22.5 X 22.5 X 8.70 = 4404 cu in = 2.55 cu ft). Two 4" ID by 10" long ports displace about .15 cu ft so 10" outside is close enough.
     

    Thanks. !!

    Class D amps

    in 2-Channel Home Audio

    Posted

    On 3/22/2024 at 12:37 PM, CWelsh said:

    A key part of my question that I may not have articulated well is, regardless of the amps rated power, how much of that power is used to drive the speakers to an equal SPL?

     

    There was a thread sometime back where a simple method of measurement was described that identifies just how many watts are actually being used to drive the speakers to the desired level. If an equal two amps with significantly different power ratings can drive the amp to the same level, it makes sense to me that the same wattage is being used to do so. And, if that is the case and you are noticing obvious benefits from the higher power amp, I have to wonder if the benefits are from something other than the actual power at the speaker terminals.

     

    Please understand, I am not questioning or disputing your experience...others in these forums have said similar things. I'm just wondering if there are factors other than just the power capabilities of the amp that make the difference, or if that extra wattage contributes to more than just the power used by the speakers.

    P.R A T.    Perhaps ??

    CF Media

    in 2-Channel Home Audio

    Posted

    I have taken a swing at Compact Flash Media .....  Have a Recorder on the way, Maranyz... I reluctantly went to CD because of the superior dynamic range and Frequency' response .now this venture

    I will post a review when appropriate

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