SpeakerLab Khorn Plans??

[Tom Mobley]

Gil, if you see this, I was able to dig out that package you sent me back in Nov '04. Thanks again for taking time back then.

I notice the plans on paper are SpeakerLab, are these still thought to be good? Or has maybe something better become available since them?

[WMcD]

I don't have any reason to believe there is anything better. I havent seen anything about modifications to dimensions.

The theater units by Klipsch are interesting in that they enclose the backs and extent the mouth out to the front. This should give a bit more length and a bigger mouth -- both of which should be some, if small, benefit.

As far as extending bass. Some time ago I looked at throat impedance of the Jubilee using transmission lines on SPICE, or at least a single path horn of about the same size in a corner.. It shows that most of the effect of horn loading disappears below, say 50 Hertz. It was about 200 percent of a driver in a baffle.

PWK wrote his paper showing a mathematical analysis of throat impedance of a finite 100 Hz horn below cutoff. This was to contrast it with that of an infinite horn where throat impedance goes to zero.

This might be a real revelation. Finite bass horns below cutoff present a sight improvement over a driver in a box -- but maybe not a bass reflex.

OTOH, driver in a box or otherwise have a peak at resonance (the size of the peak depending on Qts damping). And resonance in a box is driven up by a small box. Therefore PWK made mods to the bass bin to open up the greatest air volume. I also suspect that the early K33 had a high Qts of about 0.7 and low Fs of 28 Hz so that it would resonate with some vigor.

The bottom line is that actual performance below 50 Hz relies heavily on the K-Horn being the eqivalient of a sealed box speaker feeding a lightly improved load, room modes from corner placement, and having two of them in adjacent room corners. This means that no tweeking of the horn is going to improve things below 50 Hz.

My computer work does not include the effect (if any) of the 3 x 6 slot..

WMcD

[boom3]

(snip)

The bottom line is that actual performance below 50 Hz relies heavily on the K-Horn being the eqivalient of a sealed box speaker feeding a lightly improved load, room modes from corner placement, and having two of them in adjacent room corners. This means that no tweeking of the horn is going to improve things below 50 Hz.

My computer work does not include the effect (if any) of the 3 x 6 slot..

WMcD

This is what some of us have suspected/intuited for years, thanks Gil for crystalizing the concept. It's worth remembering that Paul's notion of what was an acceptable bass cut-off evolved over the years. When the Klipschorn entered production, 78s were the standard. Then came LPs and more compliant styli, then magnetic tape, then CDs. I recall ad copy for the LaScala that stated "...45 Hz, as low as phonograph records go..." Paul often said "The midrange is where we live". He knew, as all audiophiles should remember, that "midrange" is not defined by a human-assigned crossover point of 400-500 Hz; it really begins about 250 Hz where the Klipschorn bass bin is still operating. The clean lower midrange is to my ears a greater advantage of the Klipschorn (or any other well-executed bass horn) than sub-50 Hz bass anyway. See Heyser's review of the Klipschorn in Audio for some supporting discusion.

[Guest " "]

I don't have any reason to believe there is anything better. I havent seen anything about modifications to dimensions.

from personal experience, I would say the Patrician IV is better. It uses an 18 woofer, is 4way with a 200hz direct firing horn...that deals with the upper mid bass dip that exist in the normal khorn very well. The one I build had a bass bin that was 20% bigger than the traditional bass bin used for a 15" driver. The bass was deep and the sound very robust. Better than the klipsch khorns I owned (1985 and 60th anniversary model) and better than the speakerlab models.

here's a link for the ev diy manuals.

http://archives.telex.com/archives/EV/Speakers/DIY%20Manuals/

[Edgar]

This is what some of us have suspected/intuited for years, thanks Gil for crystalizing the concept. It's worth remembering that Paul's notion of what was an acceptable bass cut-off evolved over the years. When the Klipschorn entered production, 78s were the standard. Then came LPs and more compliant styli, then magnetic tape, then CDs. I recall ad copy for the LaScala that stated "...45 Hz, as low as phonograph records go..." Paul often said "The midrange is where we live". He knew, as all audiophiles should remember, that "midrange" is not defined by a human-assigned crossover point of 400-500 Hz; it really begins about 250 Hz where the Klipschorn bass bin is still operating. The clean lower midrange is to my ears a greater advantage of the Klipschorn (or any other well-executed bass horn) than sub-50 Hz bass anyway. See Heyser's review of the Klipschorn in Audio for some supporting discusion.

For what it's worth, the Hornresp model of the Klipschorn seems to agree with you. The attached graphic shows the standard KHorn in gray, and exactly the same design with the back chamber volume reduced by half in black. It appears to me that PWK increased the back chamber volume in order to extend the bass response below the natural cutoff of the horn, at the expense of some output in the 50-70 Hz region.

Greg

[boom3]

This is what some of us have suspected/intuited for years, thanks Gil for crystalizing the concept. It's worth remembering that Paul's notion of what was an acceptable bass cut-off evolved over the years. When the Klipschorn entered production, 78s were the standard. Then came LPs and more compliant styli, then magnetic tape, then CDs. I recall ad copy for the LaScala that stated "...45 Hz, as low as phonograph records go..." Paul often said "The midrange is where we live". He knew, as all audiophiles should remember, that "midrange" is not defined by a human-assigned crossover point of 400-500 Hz; it really begins about 250 Hz where the Klipschorn bass bin is still operating. The clean lower midrange is to my ears a greater advantage of the Klipschorn (or any other well-executed bass horn) than sub-50 Hz bass anyway. See Heyser's review of the Klipschorn in Audio for some supporting discusion.

For what it's worth, the Hornresp model of the Klipschorn seems to agree with you. The attached graphic shows the standard KHorn in gray, and exactly the same design with the back chamber volume reduced by half in black. It appears to me that PWK increased the back chamber volume in order to extend the bass response below the natural cutoff of the horn, at the expense of some output in the 50-70 Hz region.

Greg

Yeah, Paul cut 'windows' between the back chamber and the voids on either side of the first horn expansion.

[WMcD]

I can't disagree with SpeakerFritz in principle. If you build a bigger bass horn, it probably will work better in the deep bass. OTOH, it may not work better at the high end. The bigger bass driver has more mass in the diaphragm and will not have enought output at 400 Hz. The bends in the folding have a larger radius and could be lossy. Then you have to find a mid horn which goes lower to fill the gap. This may be why the 18 inch bass driver needs more treble drivers for bandwidth

In any case, I think the original question was whether alternate plans of the K-Horn in the normal scale (same overall size) were better or worse. I traded some e-mails with Tom.

My view is that physics says that once you have the overall dimensions for the horn, nothing is going to change. Of course you want to have cuts which fit together and a sealed back chamber including the "sinuses" or bays.

I do worry that someone out there is worried about 1/16th inch here or there and might think that such things are critical. Physics says "no." If we're looking at 400 Hz, the wavelenght is more than two feet. A fraction of an inch is not going to have an effect.

= = = = = =

It is nice to see that the HornRespnse verifies my thoughts on what I think PWK was thinking. This is just reverse engineering on my part because PWK did not share all his thoughts on tweeking the bass horn below cut off with a systematic description. I can't blame him. The harpies (critics) would attack.

But we have seen that he was looking for the lowest system resonance with the limitations of 1) drivers and 2) back box volume. A driver with a floppy surround would lower resonance and so he doped the surround of the driver in the early days (but this may have caused mechanical problems with keeping the voice coil positioned). He also sought the max back box effective size.

= = = =

Again, this is just my thoughts (but no one else is talking, so I'll put in my two cents): In the HornResponse plot with the small back chamber, we see a bump up at about 60 Hz where otherwise it would be falling a bit. That is probably the mechanical system resonance which is increased because of the increased spring of the smaller back chamber. It gives more acoustic output as shown. It is good for that little range. (I think you see a similar bump in the Valerie LB patent graphs down lower.)

But turning to HornResponse again, look at the data points farther down. This little improvement at 60 Hz has caused a 5 dB loss at every data point farther below (rather than up higher). That is quite a bit when we and PWK is looking for more bass down to 32 Hz by any means possible.

I may be overstating the obvious.

Best,

WMcD.

.

[Guest " "]

Yes, something got Paul's attention....between cutting out compartments to extend the bass and changes to the throat slot size and the quasi phase plug he tired at the horn mouth....looks like he was trying to extend the performance of the bass horn in both directions in order to stay with a 3 way design.

The EV 4 way patrician was larger, did a better job in the lower bass area, and to mitigate the inherent weakness of the khorn in the lower mid bass area Ev went 4 way using the upper horn section cabinet area as a mid bass horn. Very cleaver. The crossover point used by EV in the patrician IV were carefully selected and out of coincidence the same crossover points used in the MCM grand IV decades later.

If I was going to buiild a khorn system I would build the patrician iv using the EV plans.

[tigerwoodKhorns]

Gil, if you see this, I was able to dig out that package you sent me back in Nov '04. Thanks again for taking time back then. I notice the plans on paper are SpeakerLab, are these still thought to be good? Or has maybe something better become available since them?

Tom,

If you are looking at building a set of these, I have a pair of Speakerlab bass bins (Factory built), JBL2420's and JBL 2404 tweeters for sale in Las Vegas Nevada, which is close by. I have new mahogony sheets cut out to refinish them.

Drop me an email if interested, I can make you a really good deal.

Chris

[WMcD]

This adds to the old thread. One thing I did not have then was data on the T-S parameters of the two 15 inch drivers sold by Speakerlab for use in the SK. Four and eight ohms. See attached.

WMcD

Speakerlab T-S data.pdf

Edited June 11, 2015 by William F. Gil McDermott