Jubilee bass bin frequency response compared to Khorn

[Coytee]

I emailed Roy some questions I had about the Jubilee and he sent this to me.

I thought some (who better understand this stuff than I do) might like to see it so I asked him if it was ok to post it.

He said he'd try to get me the curve for the 69 driver on the 402 horn as well.

khjub.PDF

[colterphoto1]

There are many items of comparison between the two that aren't going to show up on most test results. Distortion and transient response for example. Just the -3 db downpoint will not show how much superior the Jubilee is. Look at the slope below the -3db point, the smoothness in the upper ranges, etc.

Then listen.

Did anyone get to a/b the Khorn/Jube in Hope this past year?

[Coytee]

Did anyone get to a/b the Khorn/Jube in Hope this past year?

Not a strict a/b. They had the (mono) Jubilee in the lab's listening room while the Khorns were in the plants listening room.

[mark1101]

In that particular test the Jubilee did much better on the bottom end than its advertised spec of -10db @34Hz.

The Khorn looks to be about at its advertised spec on the bottom end in that particular test.

[Guest " "]

It certainly has more SPL above 500hz.

When considering a 2-way scenario the SPL chart provided takes a more attractive meaning then if one were considering a 3-way scenario.

If one were to actually do a data compare, there is a point where sound is no longer omni-directional, for illustration purposes I'll say 120hz. Above that point, SPL charts are more meaningful if they are present in axis form (polar response charts).

[ZAKO]

Pretty darn good out to 1 K too.

[DrWho]

There are many items of comparison between

the two that aren't going to show up on most test results. Distortion

and transient response for example. Just the -3 db downpoint will not

show how much superior the Jubilee is. Look at the slope below the -3db

point, the smoothness in the upper ranges, etc.

Then listen.

Did anyone get to a/b the Khorn/Jube in Hope this past year?

Totally agreed, but there are other measurments floating around (like

the JAES article) that show the distortion being incredibly lower.

[PrestonTom]

The comparison is a tough one and I am not sure how much we can glean from the graph.

The K-Horn must be put into a corner so its response measured in an anechoic chamber would not make sense. So these cabinets would need to be measured in a room (I assume they measured them in some sort of architectured environment).

Think through this. The wavelength at 100Hz is about 11 ft and at 50 Hz it is about 21 feet and at 30 Hz it is about 36 ft. These are huge wavelengths. I don't care how big your listening room is, what you hear down at these spectral regions is very much dominated by your own listening room. Both speakers will produce energy down there but the resulting SPL would be difficult to guess at and it certainly would not be very even across frequency or across the space of the room. It would be very difficult to effectively "treat" the room, and is not clear "how much" treatment would be required. I guess my point is that these curves are insufficient to decide whether the Jubilee would sound "better" in your living room.

This must have had an effect when folks were listening to the individual models.

Good Luck,

-Tom

[DrWho]

You can actually predict the gain of your room fairly accurately. All you need is the HxWxD and a little bit of math. I think this is the reason the khorn sounds very much better in smaller rooms (where it'll actually have a strong bass response).

As far as the measurements, since its LMS I'm pretty sure the khorn was mounted in the corner of the revolving door, along with the Jubilee. This will effectively represent what happens with corner loading and is in fact the whole reason the rotating door was invented in the first place.

[PrestonTom]

You can actually predict the gain of your room fairly accurately. All you need is the HxWxD and a little bit of math. I think this is the reason the khorn sounds very much better in smaller rooms (where it'll actually have a strong bass response).

As far as the measurements, since its LMS I'm pretty sure the khorn was mounted in the corner of the revolving door, along with the Jubilee. This will effectively represent what happens with corner loading and is in fact the whole reason the rotating door was invented in the first place.

Dr Who,

You are trivializing the issue. A room repsonse is much more than its height, width, and length. The room has furniture, it has dry wall (or brick or plaster or wood), it has furniture (perhaps with much padding), it has carpets (perhaps with pads) it has doorways, it has windows, it has drapes. Those formulae are poor approximations and (depending on the frequency/wavelegth) may miss quite a bit. It really does need to be measured. A little math will not suffice. But I think you have caught my point, a strong bass response can be produced (or not produced) in a particular room.

-Tom

[DrWho]

I guess it comes down to what you define as "fairly accurate". The easy

math method will give you a frequency where room gain starts to

begin...below that point it's a pretty linear 12dB/octave rise until

the room starts to get leaky and then the gain dies off (usually

somewhere between 10Hz and 20Hz). Any furnishings in the room will only

work to raise the frequency where the gain begins (smaller volume) and

perhaps might make the slope a bit shallower (due to absorbtion

characteristics). And then of course you have issues with sound

transmission through the walls and all that crap. But the point being

that it still ends up within a few dB.

But ya, I totally agree that it's easier to measure when you've got the

measuring equipment available. And once you find the transfer function

of the room it can be applied to any future changes.

You could also go with "averages" that are floating around the internet - typically somewhere around 10dB of gain at 20Hz.

[PrestonTom]

Mike,

Regarding the measurement issue: It is not all that difficult to do a decent measurement job.

Ideally, you would like a B&K microphone etc, but these are very expensive. However, with a Behringer mic ($50) and a preamp for the phantom power ($50) you can hook this to a sound card and get some adequate measures of relative (not absolute) levels. Once you figure out that the speed of sound is about a 13in per msec., then you can start to identify the problems in your room. Combine this with some rudimentary knowledge of room acoustics (T60 etc, absorbtion, & bass traps) you can now tackle quite a bit. It is fun to learn about also. BTW, this is certainly cheaper than messing with esoteric amplifier technolgies and will have a much greater impact on the sound (I will stop preaching now...)

Again, the speaker measures, esp at low fequencies, really need to be considered in conjunction with the room response.

-Tom

[bodcaw boy]

In that particular test the Jubilee did much better on the bottom end than its advertised spec of -10db @34Hz.

The Khorn looks to be about at its advertised spec on the bottom end in that particular test.

for cinema, the specs are gathered at 1/2 anechoic (most cinema speakers are mounted into baffles behind the screen). this graph is 1/8 space (corner loaded) anechoic in order to compare apples to apples.

roy

[bodcaw boy]

i must say that i am little confused with some of the responses. that one graph contains quite a bit of information. for one, this should show on a blueberry to blueberry (i grow blueberries ) comparison the khorn to the jub in a corner and shooting into an anechoic chamber. this totally removes any room aberrations or nulls or whatever and tells you what the speaker can do. after all, we cannot guess what room the speaker will eventually be in and we cannot adjust the frequency response of a speaker for a room; we can just adjust and design around that which we can control. and if you think that you can't measure or feel 20 Hz in a room, that what is that that is rattling my gut in my son's truck (s10 reg cab); one clue; it's not the exhaust.

in my opinion, and it's only my opinion, certain speaker parameters that are related to sound quality can only be measured independent of the room; back to my blueberries.

roy

[WMcD]

Roy,

May I ask about the testing conditons for the units reported in the AES paper? I'd like to test my constructions with some appreciation of what I'm trying to judge them against.

When we met at PWK's house in '01 I was a bit sheepish in asking deep technical questions. Big brother (cousin) might have questioned motives for questions or answers.

I assume that these were run at an outdoor, concrete corner at Hope.

I recall the microphone was placed at 2 meters in your tests.

The issue is whether the mike was at the ground, or above. I look at the graphs and there seems to be a comb filtering effect every 100 Hz. Yet the math in my head thinks the path delay (floor bounce) if the mike was at, say three or four feet above ground would not do this.

My present thought is that in my apartment (site for testing with DOS LMS), the carpet over concrete is a good ground plane for deep bass and we have an image of the speaker mouth radiator. Yet at higher freq the ground plane is absorptive. Or maybe my implementation has problems.

I can noodle with these issues. Naturally you can not comment on my testing conditions. My noodling, though, could be less prone to go off the deep end if you can let me know about the microphone height in the AES.

Naturally I'll share data with everyone here.

Best,

Gil

[mikebse2a3]

Besides the obvious extended frequency response from (500Hz to over 1KHz) there is I believe another very important difference between the Jubilee and the KHorn frequency response and that is the nearly +4db increase in response from (50Hz to100Hz range) and if you doubt the audibilty of this increase then try an experiment for yourself if you have an equalizer because a +4db increase in this range will be very noticeable.

Also take note of the overall reduction in the 2nd and 3rd Harmonic Distortion reported in the article published in the (AES Vol. 48 No. 10 2000 October).

So if we add all we know about the low frequency horn of the Jubilee versus the Khorn we get:

(1) The Frequency Response of the Jubilee extends as low as the Khorn with an improvement in the 50Hz to 100Hz range as well as frequency extension to above 1KHz. Actually if you look at the graph and lets say used a +/-5db range the Jubilee reaches down to 45Hz where as the Khorn under the same conditions goes to 85hz before dropping out of this range.

(2) The Jubilee has overall much less 2nd and 3rd harmonic distortion versus the Khorn.

My guess is also that the Jubilee will also have a better behaved overall phase response and maybe Roy can comment on this aspect of the Jubilee's performance when he has some time.

Since the folds of the horn are simpler and closer to an ideal horn, frequency response is more extended/smoother and distortion is lower all this added together IMHO indicates a real improvement of the Khorns bass design.

mike[] TN

[sunnysal]

I think tom may have forgotten that Klipsch had a turntable/corner built for his anechoic chamber that allows comparisons between corner speakers and "normal" speakers. this comparison is quite useful and obviously shows exactly what PWK and Roy explained in thier JAES paper, better upper end extension and smoother response throughout...quite an accomplishment IMHO. Makes me want to try crossing at 1200hz....tony

btw thanks coytee for posting that response curve!

[DrWho]

The issue is whether the mike

was at the ground, or above. I look at the graphs and there seems to

be a comb filtering effect every 100 Hz. Yet the math in my head

thinks the path delay (floor bounce) if the mike was at, say three or

four feet above ground would not do this.

The wavelength of 94Hz is 12 feet so you will have some cancellation

with a boundary 3 feet away (1/4 wavelength to the boundary = 3 feet,

and then another 1/4 wavelength for a total of 180 degrees of phase = 6

feet). This is actually a trick I use all the time for PA work, so I'm pretty confident you're not off the deep end []

[djk]

"Besides the obvious extended frequency response from (500Hz to over 1KHz)"

Where did those graphs come from? Neither resemble the ones published in the JAES.

[mikebse2a3]

The graph is from Roy and it compares the the khorn lf cabinet to the jub lf cabinet; no crossovers. the graphs are in the corner in the chamber and smoothed 1/6 octave.

mike TN[]