A K-402-Based Full-Range Multiple-Entry Horn

[Chris A]

Yes.  But it also has a lot of potential without a sub.  I find that it fills the center position quite well with LF coverage down even lower...like the Jub bass bins.  I cross the Jubs and the Center at 40 Hz to the TH subs. 

 

Chris

[mikebse2a3]

Harmonic distortion at low frequencies. First the Jubilee bass bin, 100 dBC at 1 metre:

Next, the New Center, 100 dBC at 1 metre:

Chris very interesting thanks for posting your test.

What was the test signal and measurement parameters used to set the 100dBC 1 meter reference level you show for both systems?

I apologize if this has already been answered but was both systems raw or equalized as flat as possible for the test?

I'm thinking it would also be very beneficial to test the systems with EQ applied especially if one is going to try to compare/operate the systems over the same bandwidth.

The Jub bass bin data shows a fundamental level of 112.1db @ 89.8Hz

The New Center Bass shows a fundamental level of 99.6db @ 89.8Hz

This is a difference of 12.5db and for me indicates the complexity/difficulty in choosing how to match levels for valid comparisons of two different systems

especially when their SPL vs Frequency Response and Frequency Bandwidth differences are taken into consideration.

I'm not familiar with the program your using but from what I see the fundamental's level are being normalized to 100%.

It would be interesting to see what happens to the distortion of the two systems at reference levels of 90dBC 1m and 110dBC 1m to get a

better understanding of the dynamic distortion properties and capabilities of the two systems.

miketn

Edited March 14, 2016 by mikebse2a3

[Khornukopia]

On the spectrogram displays of post #436, how do we read the colors and shapes to determine that a speaker is performing as desired?

[Chris A]

The Jub bass bin data shows a fundamental level of 112.1db @ 89.8Hz The New Center Bass shows a fundamental level of 99.6db @ 89.8Hz This is a difference of 12.5db and for me indicates the complexity/difficulty in choosing how to match levels for valid comparisons of two different systems especially when their SPL vs Frequency Response and Frequency Bandwidth differences are taken into consideration.

 

Mike,

 

The two measurements were made with the same SPL readings of 100 dBC on the hand-held Radio Shack SPL meter at one metre, trust me, and both bass bins were EQed as flat as possible, with a small rise in response toward the LF end at the listening position.  The actual SPL for both at one metre was the same within ~1 dB.  There was only a difference in setting the "microphone calibration level" within REW.

 

Remember that we're looking at harmonic distortion levels, not modulation distortion.  Remember the HPS4000 report.  There are two 15" woofers in the New Center, and two 12" woofers in the Jub bass bins.  Both bass bins have compromises: one in length and the other in folding, mouth size, and expansion profile.

Edited March 14, 2016 by Chris A

[Chris A]

On the spectrogram displays of post #436, how do we read the colors and shapes to determine that a speaker is performing as desired?

 

Look at the decays above 10kHz for both charts.  The second plot is much, much cleaner for the TAD.  The first plot shows a great deal of ringing at or around ~14 kHz, indicating non-pistonic motion by the titanium diaphragm in the K-69-A driver relative to the TAD's beryllium diaphragm performance, which is much, much stiffer and lighter.

[Chris A]

This is a difference of 12.5db and for me indicates the complexity/difficulty in choosing how to match levels for valid comparisons of two different systems especially when their SPL vs Frequency Response and Frequency Bandwidth differences are taken into consideration.

 

You've been tripped up by believing the one measurement that wasn't calibrated.  In order for me to actually produce 112 dB, I'd have to change the gain structure of my AVP (pre-amp) and the downstream amplifiers, since it currently runs out of gain at about 106 db at one metre using a sine wave input at the level of that input channel from the laptop.

 

Since I took the higher SPL measurements with the Jubs, I've recalibrated the REW microphone input to match the hand-held SPL meter readings as part of my measurement procedure.  In the past, I found the REW microphone calibration dialogue to be very misleading, resulting in the higher apparent readings at that time.  I've always used the hand-held SPL to make sure that my measurements were calibrated to the right SPL.

 

Chris

Edited March 14, 2016 by Chris A

[NBPK402]

Would 4 woofers bring the bass SPL up to the Jubs?

[Chris A]

I don't understand your question...

 

The New Center already has bass that equals or exceeds the Jub bass bins in all measurements and, more importantly, listening evaluations thus far. 

 

The only difference that remains are "intermodulation distortion" (modulation distortion) measurements, which I expect will not differ by enough to prefer the Jub bass bin over the New Center design.  The reason why I can say this is because of the design compromises of both bass bins is basically a toss up.  If the Jub bass bin had a larger, single tractrix mouth and smoother horn folds with greater horn curvature radii, then it might be a different story, but note that there would still be a compromise at midbass frequencies that the New Center design would easily beat.

 

The New Center has no folds and a smooth expansion, with a larger mouth that is tractrix vs. the Jubilee's exponential flare.  The only improvement might be horn depth, but that would also reduce its coverage angles (nominally 90 x 60 degrees).  I think it's much more useful to mate the New Center with a good front-loaded horn subwoofer or tapped horn at or about 40-60 Hz.  

 

I know that's a bit a shock to those that have focused on the Jubilee bass bin design, but the real gem is the K-402 horn, IMO.  It has significant untapped potential in its present two Klipsch configurations (K-402-HF and KPT-305) as a a full-range horn.  The multiple-entry design draws out this potential in a way that is difficult to believe until you hear it.

 

Chris

Edited March 14, 2016 by Chris A

[Quiet_Hollow]

In the past, I found the REW microphone calibration dialogue to be very misleading, resulting in the higher apparent readings at that time.

+1

 

When using the SPL meter function of REW, the mic has to be calibrated every time the meter function is activated. 

 

I've seen very little mention of SPL calibrators in all the REW forums over the years, yet possessing/using one is as much of a requirement to the proper use of the software as having a multimeter when setting up gains.

 

Edited March 14, 2016 by Quiet_Hollow

[Chris A]

I do believe in checking the calibrated level every time I set up.

 

But what I was referring to was the REW dialogue box text that I had been misinterpreting.  I finally figured out how to re-interpret the text to be the opposite of what I had thought beforehand.  Voila! the measurement SPL matched the hand-held SPL.

 

Once I got past that, no issues, in fact I find everything to be quite stable as long as none of the hardware is plugged/unplugged, hardware dials left alone, and the microphone position not moved.

 

Chris

Edited March 14, 2016 by Chris A

[NBPK402]

I don't understand your question...

 

The New Center already has bass that equals or exceeds the Jub bass bins in all measurements and, more importantly, listening evaluations thus far. 

 

The only difference that remains are "intermodulation distortion" (modulation distortion) measurements, which I expect will not differ by enough to prefer the Jub bass bin over the New Center design.  The reason why I can say this is because of the design compromises of both bass bins is basically a toss up.  If the Jub bass bin had a larger, single tractrix mouth and smoother horn folds with greater horn curvature radii, then it might be a different story, but note that there would still be a compromise at midbass frequencies that the New Center design would easily beat.

 

The New Center has no folds and a smooth expansion, with a larger mouth that is tractrix vs. the Jubilee's exponential flare.  The only improvement might be horn depth, but that would also reduce its coverage angles (nominally 90 x 60 degrees).  I think it's much more useful to mate the New Center with a good front-loaded horn subwoofer or tapped horn at or about 40-60 Hz.  

 

I know that's a bit a shock to those that have focused on the Jubilee bass bin design, but the real gem is the K-402 horn, IMO.  It has significant untapped potential in its present two Klipsch configurations (K-402-HF and KPT-305) as a a full-range horn.  The multiple-entry design draws out this potential in a way that is difficult to believe until you hear it.

 

Chris

I think it was a misunderstanding on my half of what was posted. I thought the 106db was for the bass and the 112db was for the horns...totally my mistake in reading.

[mikebse2a3]

The two measurements were made with the same SPL readings of 100 dBC on the hand-held Radio Shack SPL meter at one metre, trust me, and both bass bins were EQed as flat as possible, with a small rise in response toward the LF end at the listening position. The actual SPL for both at one metre was the same within ~1 dB. There was only a difference in setting the "microphone calibration level" within REW.

 

Chris I would trust you to always want to do as accurate comparison as possible....

 

Chris this is just like when I was doing waterfall plots looking at decay distortions and it became very evident that it was critical at what Frequency/SPL I was going to hold constant to achieve as valid a comparison of two different drivers responses over the bandwidth I wanted to compare.

 

That is why I asked   "What was the test signal and measurement parameters used to set the 100dBC 1 meter reference level you show for both systems?"

 

Since the RadioShack SPL Meter nor a test Mic are capable of telling us what Frequency was used to set the level constant for both systems on it's own we have to have a method to pick the frequency within the bandwidth we want to compare to set as a reference level to hold constant. I'm assuming since you are comparing the bass of these systems between 30hz-400hz you did your constant level match at some frequency in this region and that is why I was asking for clarity what the details of your method to achieve this were so I can get a better understanding of your results.

 

 

Thanks in advance for any additional insight you can offer me about this Chris.

 

miketn
 

[mikebse2a3]

Remember that we're looking at harmonic distortion levels, not modulation distortion.

 

 

Never thought otherwise Chris.....

[mikebse2a3]

I know that's a bit a shock to those that have focused on the Jubilee bass bin design, but the real gem is the K-402 horn, IMO.

 

I think they are both gems Chris....

 

And from all your reports so far it looks like the  "K-402-Based Full-Range Multiple-Entry Horn" is also.....

 

 

miketn

[Chris A]

That is why I asked "What was the test signal and measurement parameters used to set the 100dBC 1 meter reference level you show for both systems?" Since the RadioShack SPL Meter nor a test Mic are capable of telling us what Frequency was used to set the level constant for both systems on it's own we have to have a method to pick the frequency within the bandwidth we want to compare to set as a reference level to hold constant. I'm assuming since you are comparing the bass of these systems between 30hz-400hz you did your constant level match at some frequency in this region and that is why I was asking for clarity what the details of your method to achieve this were so I can get a better understanding of your results.

 

REW always uses pink noise to set the microphone calibration level.  That's what I use.  I spot checked the SPL during the sine sweeps using the hand-hand meter (not that it means much). 

 

The harmonic distortion calculation used is detailed here:

 

If Use harmonic frequency as ref is selected the reference will be the frequency of the harmonic, for example, at 1 kHz the 2nd harmonic figure will depend on the level of the fundamental at 2 kHz, the 3rd harmonic will depend on the level of the fundamental at 3 kHz and so on. This follows a recommendation made by Steve F. Temme in "How to graph distortion measurements" presented at the 94th AES convention in March 1993.

 

If the response of the system being measured is flat this makes no difference to the results, but when the response is not flat (as for most acoustic measurements) it can remove the influence of the loudspeaker's fundamental response from the distortion figures.

 

As an example, suppose the loudspeaker response was flat apart from a 6 dB peak at 2 kHz. 2 kHz is the 2nd harmonic of 1 kHz, so the 2nd harmonic level shown at 1 kHz will be increased by 6 dB due to the boost in the fundamental when using the excitation frequency as the reference. Similarly the 3rd harmonic level at 667 Hz (2/3 kHz) will be boosted by 6 dB. If the harmonic frequency were used as the reference the distortion figures would not show this boost.

 

Using the harmonic frequency as the reference also provides a more meaningful view of distortion at frequencies below the LF roll-off of the system as otherwise the distortion levels are boosted as the level of the fundamental drops.

 

Chris

[Chris A]

--

[mikebse2a3]

Thanks for the reply Chris..!      I'll check out the link

 

 

miketn

[ClaudeJ1]

The multiple-entry design draws out this potential in a way that is difficult to believe until you hear it.

 

I had the same experience when I got my first pair of Danley designed horns almost 2 years ago. It's a very real paradigm shift, for sure. No matter what, you need subs below 80 Hz., 40-60 Hz. being my personal preference, currently set to 50 Hz. in my setup.

Edited March 18, 2016 by ClaudeJ1

[ClaudeJ1]

So Chris. I'm wondering if the EVM 15 L would be a better driver for this purpose since it has a low Le and higher mass rolloff than the Crites woofer you are using. It would produce better midrange without sacrificing the bass, since it's crossing below 60 hz. to a subwoofer anyhow. Thoughts?

[Chris A]

You can decide--first the dual Crites 15" cast frame woofers:

And the dual EVM-15L

 

 

 

Chris

Edited March 21, 2016 by Chris A