Build Thread K-Slot Rear Loaded Horn for Tangband W8-1772

[freddi]

"IF" 1772 behaved as per the AJ sim, then that alone could have been pretty bad. did Zob try any other fullrange in them?

a regular K12 Karlson if the vent were tweaked might sound pretty good - I liked 1772 in a little "SK8" better than the 1954 Karlsonette - never mounted 1772 in the slit vent K12.

 

[xrk971]

Impulse response of this speaker is what kills it. Huge group delay and multiple peaks make it very "tomb like". It may have something to do with the fact that the end of the horn mouth is a flat wall - reflection from end?. It may improve things to taper it down so that the CSA goes to zero as the K-slot grows to max width. I would also flip it around so that the large mouth aims at the floor for enhanced bass coupling to the floor. A major redesign for sure.

See the impulse response calcs here:

http://www.diyaudio.com/forums/attachments/full-range/371784d1379472562-fe168e-fe208e-sigma-project-ideas-k-12-w8-1772-freq-1m.png

 

[xrk971]

"IF" 1772 behaved as per the AJ sim, then that alone could have been pretty bad. did Zob try any other fullrange in them?

a regular K12 Karlson if the vent were tweaked might sound pretty good - I liked 1772 in a little "SK8" better than the 1954 Karlsonette - never mounted 1772 in the slit vent K12.

The W8-1772 appears to be a fine performer in a K15 scaled by 12/15. It reaches 60 Hz and has a flat response in the high to mid 90's dB out to 1.2 kHz.

 

[freddi]

can you easiy truncate the 12/15 k15's vent to half height? (and area) - just wondering if it can lose vent area, flatten the bottom, and not lose the nice midrange. I'd like to find someone to cut some 0.8 scale K15s.

 

[zobsky]

"IF" 1772 behaved as per the AJ sim, then that alone could have been pretty bad. did Zob try any other fullrange in them?

a regular K12 Karlson if the vent were tweaked might sound pretty good - I liked 1772 in a little "SK8" better than the 1954 Karlsonette - never mounted 1772 in the slit vent K12.

If I recall, I did try my fostex FE-166E in the K-slot horn, using an adapter plate. It actually sounded a bit better than the 1772 in the bass, though I still like the overall tone of the 1772 better.

 

[zobsky]

The W8-1772 appears to be a fine performer in a K15 scaled by 12/15. It reaches 60 Hz and has a flat response in the high to mid 90's dB out to 1.2 kHz.

Dang. gave away my K-15 (yes, I built one of those too), to a friend who uses a vintage altec in them. Kenpeter still has a classic K15 that he uses ocassinally for bass guitar purposes. Right now, it's running an eminence 18 that we somehow managed to shoehorn in, but as I recall, his most positive impressions were with the eminence delta pro 12 .

Fun box, for all its faults in the midrange. I tried university C-15 W in it as a pseudo sub - down to about 50 Hz and managed to bounce my upstairs floor. When I ran it as a fullrange, I used Stephens trusonic C-15W

 

[PreSapian]

would a driver like 1772 be able to handle complex electronica such as this song?

Chris Clark - Shonny - Ceramics Is The Bomb - YouTube

shallow bass i can live with but faithful instrument separation is a must. lowther horn i tested this track out on crapped out when the bass started playing.

 

[kenpeter]

The baffle in my K15 is replaceable for an 8", or whatever.
Giant pain to do so, but was made to slide out. A blockoff
plate for the 18" hole would involve considerably less time
and effort than the nightmare of getting that baffle out.
I did not properly plan for tool access, thus it has not been
the convenience that I envisioned.

Besides, I think that graph was for K15 scaled 12/15 size.
Not for original size K15 or K12. We tried in slit vent K12,
and was OK in that tuning but not amazing...

 

[freddi]

hi Pre-Sapian - If I can move a Karlson 12 loaded with 1772 closer to an amp I could try that track and see. You really might be better off with an added sub and fullrange with passive line level highpass on the fullrange speaker.

I'd love to hear a Lowther in a Karlson coupler around K12's overall bulk or the Karsonator - that would probably maximize its useful bass.

I had one 1772 in a tiny Karlson 8 - very little rear chamber volume and tuned high - here's how that sounded on flute and drums - it had no real bass so would need a sub

Karlson 8 cabinet from ~1955 with Tangband 1772 - YouTube

 

[PreSapian]

hi freddi, thank you i'd appreciate that greatly.

sorry i got confused between the two songs- the one below would be much more excruciating trial for bass

http://www.youtube.com/watch?v=sqHIqX8KB-E

the song 'shonny' sounds effortless on my wayne parham's 4pi atm., but i can't help wanting to build something more 'pure' whenever i visit a thread like this.

 

[xrk971]

K15 scaled to 12/15 and 8/15 in width with Lowther PM6C and TB W8-1772

I'd love to hear a Lowther in a Karlson coupler around K12's overall bulk or the Karsonator - that would probably maximize its useful bass

Freddi,
Your question about putting a Lowther in a Karlson probably makes some Lowther-centric fans shudder at the thought. However, I have never tried a Lowther in any of my models before, so I thought what the heck? Doesn't cost me anything other than typing 10 lines of T/S params.

Well, as it turns out... the PM6C was almost made to be in a scaled down K15. I scaled the height by 12/15. left the depth alone at 15/15, and scaled the width by 8/15 - so it will look kind of tall, deep, and skinny compared to a normal Karlson box. It needed the volume reduction - similar to your earlier question about the W8-1772. The W8-1772 is also ideally suited for the same box as you will see. Given the cost disparity - the W8-1772 could be called a "budget" Lowther - though it is debatable if a $230 driver should ever be called "budget". The W8-1772 also has the Lowther beat on being an easier load to drive as the impedance curve is smoother and not as peaky. We are now able to achieve usable bass extension down to circa 45 Hz (at 90 dB). The real beauty of this speaker is the transient response as shown by the nearly ideal impulse function which looks like it is operating in a sealed cabinet. The attack and decays, kick drums, etc will be amazing with this speaker.

SPL vs Freq for Lowther PM6C in cabinet with 12/15 width

SPL vs Freq for Lowther PM6C in cabinet with 8/15 width

Impedance for PM6C with 8/15 width

Cone Displacement for PM6C with 8/15 width

Impulse Response for PM6C with 8/15 width

SPL vs Freq for TB W8-1772 with 8/15 width

Impedance for W8-1772 with 8/15 width

Cone Excursion for W8-1772 with 8/15 width

Impulse Response for W8-1772 with 8/15 width

So, when are you going to build a skinny K15 scaled to 12/15 and 8/15W? This looks really promising.

 

[IG81]

Thanks xrk971 for doing the sims.

I think I agree with kenpeter that the Fulmer/K-slots might be better suited to straight or decreasing cross-sections. Having the CSA increase along with the slot probably just removes any kind of load otherwise afforded by the line. It's probably not such a bad think on Bill's K-horn, where this onlyl happens to the last ~5th (?) or so of the line. I kind of view Karlson front-chambers or the 1" TPC Tube device as "anti-horns", where the impedace match is done with a progressive leak to outside air instead of an increasing amount of contained air. Seems to work well for a K-Tube at least, as there are no apparent reflections, HOMs or redundant peaks on the Z response.

About the RCA-fan K-horn, we also have to remember that it was designed to replicate the sound of certain RCA theater horns of old, which I don't doubt it does. As for technical perfection under modern design paradigms, it should probably not be expected to be the last word. At least this is how I understand it without having it directly from Bill's mouth.

IG

 

[xrk971]

IG,
You are welcome. I am scratching my head as to how to model a K tube tweeter driven by a CD. I don't have a way to make a curved radiator - I may have to approximate with flat segments which form a round tube - an octagon?

 

[IG81]

IG,
You are welcome. I am scratching my head as to how to model a K tube tweeter driven by a CD. I don't have a way to make a curved radiator - I may have to approximate with flat segments which form a round tube - an octagon?

IMO, the way you model a Karlson front chamber might work, main difference is that it would now be apex-driven and the CSA is constant other than the slot gradual opening.

IG

 

[xrk971]

IG,
Your idea off starting with a simple flat radiator like how I model the K15 front chamber is certainly the first step. This begs the question has anyone made a K tube tweeter using a square cross sectional tube? Folded cardboard with a K slot might work - this is certainly something those of you with existing K tube tweeters can easily try out and report back on how it sounds.

 

[IG81]

IG,
Your idea off starting with a simple flat radiator like how I model the K15 front chamber is certainly the first step. This begs the question has anyone made a K tube tweeter using a square cross sectional tube? Folded cardboard with a K slot might work - this is certainly something those of you with existing K tube tweeters can easily try out and report back on how it sounds.

Square K-Tube =~ Klam. Maybe use your Klam model and don't constrict CSA as a function of length.

Typical K-Tube response is not awfully different from that of the driver on a PWT, other than the mass roll-off above 3kHz is not as pronounced. It's probably more resistive than reactive as the Z plot displays ~ the driver's profile and nothing else much on top.

IG

 

[freddi]

Weiss mini-klam K-lens which goes with his patent - try it using cardboard

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one of Carl's test K - should be Lowther friendly

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mic on floor measurement of AN10 in K15 with 30.5 sq.in. vent to compare to akabak

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parameters for that AN10

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little SK8 with fast flare aperture - try this and compare
-- it sounded good with 1772

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[xrk971]

mic on floor measurement of AN10 in K15 with 30.5 sq.in. vent to compare to akabak

Freddi,
I was looking all over the Web for the T/S params for the AN10 and duh, realized that you had measured it and posted it below the picture. Why doesn't Common Sense Audio post the T/S params??? Too much variability in manufacture?

Anyhow, I put it in the K15 model and WOW this thing Rocks! 100 dB sensitivity and smooth as butter. Reaches 93 dB at 50 Hz - not bad at all.

SPL vs Freq (far away from walls - like in a stadium)

Impedance

Cone Excursion

Impulse Response

SPL vs Freq (48 in away from back wall and measured at ground plane)

 

[freddi]

AN10 sounded much better overall in K15 than a reflex. Its rather rough as a reflex and had very little power handling. Putting it in K15 kept output good within the plus and minus 1mm xmax spec. It could play some hiphop bass without bottoming out plus vocals ranging from Mario Dwhiel Monaco to Porter Wagoner were very nice. Its too bad the Karlson wasn't picked up by the fullrangers -- they seem fascinated by pipes and reflex and consider those holy while not being able to grasp that all speakers are flawed one way or another and that the Karlson approach has some useful virtues . K15 sounds great in general on harpsichord, sax, piano - about anything. I would like some new K's which are smaller than K15 - and perhaps something similar to K15 sans the front shelf. I need a cabinet builder!

 

[xrk971]

Freddi,
The Karlson, I believe suffered from some initial bad PR. I think some of the lack of interest by the full range crowd may have to do with the fact that there was not a model of it that folks could play with and optimize, or more importantly, 'test out' new drivers and T/S parameters without having to physically build it. I for one, will be building a Karlson (probably a slightly modified K15) as my next box as soon as I have a shop with a table saw. I am getting a little impatient and may just go ahead and prototype with 3/4 in thick XPS foam sheathing and 1/8 in chip board reinforcement to see what it sounds like. Right now I need some CD's and a XO to go with my coaxials as I don't have something like an AN10 or W8-1772 to try out as a full ranger. I am hoping that 2013 is the year that the Karlson makes a comeback as it really is a special box that deserves another look by many who discounted it for really a lack of understanding what it can do. You are right that all speakers are compromises and all have limitations. Within the 50 Hz to 1.5 kHz bandwidth, it will be tough to find another alignment with as good efficiency, dispersion, and dynamics afforded by the clean impulse response.