PWK research and development in the later years

[mikebse2a3]

I know PWK sometime in the 90s and later years worked on returning the Klipschorn to a 2-way which led to the Jubilee KPT-KHJ-LF and he was also working on developing extreme slope passive networks.

 

If anyone could please share with us more details and stories about his work on them as well as anything else that kept his interest in this later period of his amazingly long career and life I would really love to hear about them.

 

 

Thanks,

miketn

[Travis In Austin]

Mike,

 

Great question, I will make sure JRH the Historian sees this.

 

As you know, Roy is one primary source on this, but Jim never cease to amaze me on documents he has stashed away.

 

Travis

[JRH]

Correct on the pursuit of a two-way K-horn.  The steep filters he seemed to be obsessed with are referred to as "M-derived".  Some of this work slipped into the KP-600 crossover, as well as other behind-the-scenes contributions.  Roy "made the most" of PWK's never-ending engineering curiosity.  I'm sure he could add much to this dialog.

 

Also, the thesis of John Post on Tractrix horns was the turning point on his enthusiasm for this taper rate. 

[mikebse2a3]

11 hours ago, JRH said:

Correct on the pursuit of a two-way K-horn.  The steep filters he seemed to be obsessed with are referred to as "M-derived".  Some of this work slipped into the KP-600 crossover, as well as other behind-the-scenes contributions.  Roy "made the most" of PWK's never-ending engineering curiosity.  I'm sure he could add much to this dialog.

 

Also, the thesis of John Post on Tractrix horns was the turning point on his enthusiasm for this taper rate. 

 

Thank you for taking the time to respond to my questions and I will do some research on the M-derived filters.

 

Roy has been very generous to share some information like this in the past and I hope maybe he will find time in the future to share more about this time period with PWK.

 

For anyone interested in reading the John Post Thesis that Mr. Hunter is referencing and Roy had mentioned also to some of us in the past.

post_thesis_ut94.pdf

 

 

 

[dBspl]

 

As I recall PWK had at least three different projects that he spent a lot of time on.  There was of course the extreme slope filters that he was preoccupied with most of time.  There was the HF horn design for a two-way Klipschorn.  And then there was the 3" compression driver design that was originally conceived by PWK as using the "Cone-dome " diaphragm geometry. It didn't work, but it transitioned to a more traditional design that later became known as the K-1132.

 

Kerry  

[mikebse2a3]

On ‎10‎/‎25‎/‎2016 at 7:58 PM, dBspl said:

 

As I recall PWK had at least three different projects that he spent a lot of time on.  There was of course the extreme slope filters that he was preoccupied with most of time.  There was the HF horn design for a two-way Klipschorn.  And then there was the 3" compression driver design that was originally conceived by PWK as using the "Cone-dome " diaphragm geometry. It didn't work, but it transitioned to a more traditional design that later became known as the K-1132.

 

Kerry  

 

Thanks for your time Kerry..!

 

I assume your speaking of the K403 Horn which I have been fortunate to have listened to on the Jubilee LF thanks to Roy and I thought it was an excellent design while having collapsing vertical polars.

 

I've owned the K-1132/K402 combination and when combined with the K510 HF Grand I was extremely impressed with the clarity..!!!

 

I'm curious, do you know what didn't work out about the "Cone-dome" for PWK..? What was he looking to achieve/improve with the design..?

 

Thanks,

miketn

[dBspl]

By the time I left engineering in 1994 the K-403 didn't exist yet. I believe it came much later. PWK was still experimenting with exponential horns over the period I was working in the lab.

 

The "cone-dome" diaphragm was basically the shape of an inverted loudspeaker cone.  The problem was that the diaphragm side-walls were way too flimsy and there really wasn't much we could do to improve it. 

 

PWK wanted a 2-way Klipschorn, but of course it had to be an improvement to the current 3-way design. I'm pretty sure PWK didn't believe there was a sufficient horn/compression driver combination available, at that time, that would fit his requirements. So he embarked on his own horn & compression driver designs.  

 

Kerry

[Chief bonehead]

actually the k-403 as paul called it later on, was designed in the early nighties.  since the late 80's, paul had mentioned to me that he had been wanting to find out if the klipschorn could be taken back to a 2 way.  so a did a various designs for paul back in the early nighties and one of the those was taken and was suspposed to become the hf horn for the jub hf, the k-403 horn.  once that got figured out, paul wanted an lf design to go higher than the 400-500 cutoff of the current klipschorn.  that led to the jub lf.  

[mikebse2a3]

Thanks Jim, Kerry and Roy for taking the time to answer my questions...!!!

 

miketn

[seti]

On 11/1/2016 at 4:47 PM, Chief bonehead said:

actually the k-403 as paul called it later on, was designed in the early nighties.  since the late 80's, paul had mentioned to me that he had been wanting to find out if the klipschorn could be taken back to a 2 way.  so a did a various designs for paul back in the early nighties and one of the those was taken and was suspposed to become the hf horn for the jub hf, the k-403 horn.  once that got figured out, paul wanted an lf design to go higher than the 400-500 cutoff of the current klipschorn.  that led to the jub lf.  

 

The K403 is my favorite horn. Always good to learn a little more about the history 

[Travis In Austin]

The Audio Article by Jim, Roy and Kerry Re: Tractrix: 

 

 

tractrix_horns_03-1991.pdf

[JRH]

PWK was certainly human, and did make a mistake or two.  He was quick to say "That was another great idea that didn't work!"  The cone dome was one of them.  We still have the tooling for the cone-shaped diaphragm that may go on display some day with another mistake.  That was the choice of chemistry used for the very early K-5 horn series.  They became brittle and basically cracked and fell apart.  Sherman Fairchild's chemists put him back on track!