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Jubilee (KPT-KHJ-LF) Fact Sheet


mikebse2a3

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Mike, Thanks for getting together with Roy and making this fact sheet on the Jubilee bass bin.

It is an important source of information and also has an archival value. I hope the thread does not become corrupted the way the fact sheet for the HF horn (K-402) did.

Keep up the good work.

-Tom

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Mike, thank you for getting this together.

one thing i'm wondering about is the PEQ filter. obviously has a substantial impact on the low end extension.

could you (or others) say more about the PEQ filter? not sure how this works.

any thoughts appreciated.

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Daddy Dee thanks for asking.

The LF PEQ values for extending the Fc of the system are: PEQ Freq= 32Hz, Q= 12, Gain= +7db

Basically Roy has implemented a modest electrical drive increase in this narrow frequency range because the Jubilee's Horn/Drivers design are very low in distortion in this region when corner loaded while also having a high spl output capability for the Jubilee LF system and again note especially this has been accomplished while still maintaining a very low distortion for the system.

The PEQ filter can be implemented in either active crossover or passive crossover implementation of the Jubilee as long as one has an equalizer capable of the parameter settings given above.

mike tn

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Did Roy develop some other PEQ tweaks for the LF? There have been threads that mention several more than just the 32Hz PEQ.

Brad, I haven't seen anything more from Roy on this subject other than the PEQs used in conjunction with the 400-450 Hz Dx38 crossover settings in order to achieve a steeper effective crossover slope than 24 dB/octave (Linkwitz-Riley). Those extra PEQs listed around the crossover frequency are for that purpose, IIRC.

The 32 Hz PEQ boost is something that I initially proposed from my experiences at home using a very similar PEQ boost filter...believe it or not. Roy patiently listened to my arguments then tested his preferred settings in the Hope chamber. It was there that he found that the increase in distortion was minimal.

The other bass bin PEQs that I've listed in-room are also derived from my in-room test and measurement experiences. The latest settings that I posted last fall are ones that you already have access to, and are what I gravitated toward after getting my tapped horn subs built and setup in-room.

I'm now about to embark on another Behringer DEQ2496 exercise using both the expander function and miketn's "Cello" EQ filter setup for the DEQ2496 to try to compensate for any poor recordings that I own, which includes mostly pop and rock recordings, but also a small number of jazz and classical recordings, too.

I also intend to try out the Yamaha SP2060 (2-in, 6-Out) that has extra PEQ filters than the Dx38's capabilities. But that exercise will have to wait until this summer to try out.

Chris

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AES Paper

In section 5.2 of the AES paper the horn length is cited at 3.378 m. Table 1 Flare Rate Analysis has a table of lengths that add up to 2.352 m.

I am not an audio engineer, but would still like to understand what the horn length in section 5.2 refers to. And for the purposes of caclulating the delay what LF horn length do you use?

The reference to rubber throat in the fact sheet threw me until I read the AES paper. Is that term used by speaker and/or horn designers?

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Thanks for posting this Mike. A very well thought out series of questions. I think it once again proves that Roy Delgado is not only one heckuva an engineer, but his partnership with Mr. Klipsch on the development of the Jubilee was akin to that of Bell and Watson and their work on the telephone.

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The 3.37 meters is the length of a horn of similar flare and throat IF it is designed to work in free space. It is just to show how much shorter the horn can be if designed for a corner. This requires a bit of a close reading, I'll admit.

The figures for length in the table are cumulative length. It is saying, if we measure to B it is so much from A to B, and to point C we have so much from A to C, and if we go to D it is so much from A to D.

The table calculation for flare is based on the cumulative distance from A to the point (B,C,D) and the area at A and the area at the respective points.

The table does not appear to show the flare rate between B and C and C and D. It happens to show the flare rate from A to B because while the distance shown is cumulative, we've started from zero.

At least that is my read.

WMcD

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