Mini Karlsonator (0.53X) with Dual TC9FDs

xrk971 · 2014-05-11 12:00 am

I agree, that is a beautiful picture and a beautiful day to measure a K outside. The UMM-6 is what I use and works well. Measurement at different heights will yield different HF profiles. The HF response is best when in a line parallel to axis of angled driver.

freddi · 2014-05-11 12:26 am

another way to put it - draw a perpendicular from the center of the driver on the K's tilted baffle - that is the line the mic points through.

the X15 is interesting, the highest F's pretty much go straight down the tube (tilted 12 degrees down), the slot faced "up", a lot of energy perpendicular to the slot's long axis fired up into the reflector system where re-emitted out the aperture. X15 sounds very "fast"

regular Karlson can sometimes benefit from de-Q-ing holes along with their regular vents
- this decreases the ability to play strict sine wave but can make the subjective sound "faster".

here's a reasonably close copy of the X15 with the larger diameter K-tube to illustrate the arrangement

An externally hosted image should be here but it was not working when we last tested it.

here's detail of that K-tube - another X15 turned up with a smaller diameter tube so
we know Karlson was experimenting with things. The wood bracket was not part
of the original setup. The tube pressed-fit into the reflector panel and the threaded
phenolic block held a University Sound compression driver and the wafer held
the transitional piece with the sliced end.

An externally hosted image should be here but it was not working when we last tested it.

freddi · 2014-05-11 6:37 am

will W8-1772 (which I have) play right in the Karlsonator 8?

Greg B. suggested using 1/4" plywood for Karlsonator's 8 top section to enlarge the vent,
raise tuning and allow some tweaking of tuning.

Bob Brine's WT2 averages for two W8-1772

Re ohms 7.28996
Fs Hz 42.59512
Zmax ohms 28.85236
Qes 0.44508
Qms 1.31602
Qts 0.33256
Le mH 0.04414
Diam mm 165.5
Sd mm^2 21512.25
Vas L 72.76948
BL N/A 7.4432
Mms g 12.6453
Cms uM/N 1106.912
Kms N/M 905.7046
Rms R 2.57074
Efficiency % 1.1911
Sensitivity dB(1 watt) 92.76138
Sensitivity dB(2.83 volt) 93.166

thejessman · 2014-05-11 6:55 am

I'd be worried you would get nasty panel flex with 1/4" plywood. I guess you could be fairly aggressive with bracing and you might be OK. I'd still be concerned though.

freddi · 2014-05-11 7:00 am

it would just be the little top piece for the stub - 6mm Baltic birch is pretty stiff and might work in the Karlsonator 8 - it'll be interesting to see what the Karlsonator 12 can do with a 12" coax and a reasonably powerful amp.

mctavish · 2014-05-11 10:38 am

Greg B said:
Is that a Fostex craft book hiding beneath your amplifier??

Indeed it is; there is some crazy stuff in there

xrk971 · 2014-05-11 9:15 pm

Greg B. suggested using 1/4" plywood for Karlsonator's 8 top section to enlarge the vent, raise tuning and allow some tweaking of tuning.

I have played with enlarging this by as much as 2.3x and it doesn't change tuning frequency as much as amplitude of the bass. You might actually get more tuning to deeper bass by making it smaller as it would behave like a constriction in a MLTL - at the expense of bass amplitude of course. Making the K aperture go to a cusp vs a slot has more effect on bass extension than changing this channel gap.

EddieT · 2014-05-12 1:35 am

I have a pair of K4s scaled directly from original k12 measurements. At present I have some low wattage cheap 4 inchers installed. If I were to move up to TC9FDs does anyone recommend any mods?

xrk971 · 2014-05-12 1:57 am

EddieT said:
I have a pair of K4s scaled directly from original k12 measurements. At present I have some low wattage cheap 4 inchers installed. If I were to move up to TC9FDs does anyone recommend any mods?

When you say K4 do you mean a scaled down Karlsonator or a K15 bandpass? A Karlsonator scaled to 0.4x works great with a single TC9FD. About 90 Hz bass extension - great all around sound though. A K15 scaled to 0.4x will not work well at all though.

EddieT · 2014-05-12 3:05 am

xrk971 said:
When you say K4 do you mean a scaled down Karlsonator or a K15 bandpass? A Karlsonator scaled to 0.4x works great with a single TC9FD. About 90 Hz bass extension - great all around sound though. A K15 scaled to 0.4x will not work well at all though.

Bandpass but not K15. I thought I had just scaled the measurements of the first Karlson 12 (the term Karlsonette had not yet been coined) however a double check reveals that I have a hybrid so I had better leave them as is and start over. For some reason I ran the 45 degree piece all the way to the vent, probably because the pieces were getting a bit small to work with. My K8 was truer scaling of the same K12.

xrk971 · 2014-05-12 3:16 am

The band pass K designs really don't have much bass when taken below 12 inch scale. It has to do with the fact that it is a multi chamber reflex with a bandpass output (driver front has feedback from rear). You really need to do a 3 chamber band pass simulation to size the volume and interconnect vents properly to get the tuning low. A very basic 3 chamber reflex with two interconnecting vents and a "tapped horn" on the output can be used to first order to optimize the box volume and vent CSA. I should model this one day so we can all make tiny 4 inch K4's that reach 55 Hz!

EddieT · 2014-05-12 3:50 am

xrk971 said:
The band pass K designs really don't have much bass when taken below 12 inch scale. It has to do with the fact that it is a multi chamber reflex with a bandpass output (driver front has feedback from rear). You really need to do a 3 chamber band pass simulation to size the volume and interconnect vents properly to get the tuning low. A very basic 3 chamber reflex with two interconnecting vents and a "tapped horn" on the output can be used to first order to optimize the box volume and vent CSA. I should model this one day so we can all make tiny 4 inch K4's that reach 55 Hz!

Thanks for your response, I suspect the TC9FDs might sound better than whatever I now have but not worth the effort to replace them. Maybe I'll give the Karlsonator a try. For durability maybe 1/2" OSB for the box, wings and speaker baffle and insulation foam board for the rest of the interior pieces.

freddi · 2014-05-12 4:39 am

i think just a bit smaller than K12 is kind of the lower limit for a regular coupled-cavity Karlson to really punch - - here's a "K10" next to one of my K15 - a K-tube would be an improvement overall to a CD-waveguide in such a setup.

An externally hosted image should be here but it was not working when we last tested it.

Delta10A - good value, some coloration I think due to its large dustcap

An externally hosted image should be here but it was not working when we last tested it.

Greg B · 2014-05-12 5:47 am

xrk971 said:
I have played with enlarging this by as much as 2.3x and it doesn't change tuning frequency as much as amplitude of the bass. You might actually get more tuning to deeper bass by making it smaller as it would behave like a constriction in a MLTL - at the expense of bass amplitude of course. Making the K aperture go to a cusp vs a slot has more effect on bass extension than changing this channel gap.

Yeah, i just rechecked my old models. They agree with this strongly, and basically duplicated Jesse's measured results. Enlarging or shortening the vent doesn't change the Fb much at all. Obviously I did not remember my target Fb correctly.

My cruder model cannot duplicate the slot at all. I approximated it with a rapidly flaring conical section to the approximate geometrical mean of the aperture. Still, it agrees, and more closely than I would have expected.

freddi · 2014-05-12 10:11 am

Greg B. "Father of the Karlsonator"

many thanks!!!!!

IG81 · 2014-05-12 2:00 pm

EddieT said:
I have a pair of K4s scaled directly from original k12 measurements. At present I have some low wattage cheap 4 inchers installed. If I were to move up to TC9FDs does anyone recommend any mods?

Classic form-factor Karlsons are more of a novelty item below 8" sizes in the end, IMHO. I made a K5 myself, scaled from the 1960 K8 plan and used it with Pioneer A11, Fostex FF125K and a Vifa C13. High-aspect ratio approaches such as the Karlsonator might work better for going smaller. Linear scaling did not work in an ideal fashion for the bandpass boxes and I suspect it might not be ideal with the modern approach too.

EddieT said:
Bandpass but not K15. I thought I had just scaled the measurements of the first Karlson 12 (the term Karlsonette had not yet been coined) ...

I think the term "Karlsonette" was actually the official name of the first K12 (~1956? freddi?). I built a pair of these as well.

Does not go very low, but decent enough for many types of music and very punchy/dynamic.

The smallest classic form-factor Karlson I've found to work decently was the SK8. It is actually a K10 is you scale-down from K15/K12. Fostex FF225WK worked well enough for me in there and it all remained very punchy. Freddi likes both FE206EN and TB W8-1772 in there AFAIR, correct me if I'm wrong. It benefited from a bit of EQ to extend bass. I think the SK8 design could work well if linearly scaled-up to 10", 12" or 15" drivers. A lot of things went right in the design as I largely failed to improve upon anything when tweaking my pair. Hats off to GregB here again!

Karlson's later (last?) 15" model, the X15, with internal K-Tube, was somewhere between K12 and K15 in dimensions. Most Karlson derivatives (licensees AFAIK)) built in the 70ies seem to have used this as a starting point for their designs. Some of these were Transylvania Power Company, it's not entirely clear whether they actually produced a bass enclosure commercially, but their 1" K-Tube is excellent, I have a pair. LEECH in UK had a sub-license from them and did produce the KHYBOE bass enclosure and used the 1" Tube. Others were Acoustic Control's 115BK, KK-Audio, J&J Audio, Westwood. Maybe I'm forgetting one or two and I'm not entirely clear of a few of these anyway.

The KHYBOE, along with the new Karlsonator are what mostly hold my interest in all things K. I don't rule-out building either to pair-up with my set of TPC "The Tube" somewhere down the road.

IG81 · 2014-05-12 2:35 pm

xrk971, do you think you could plug in the following drivers in you Karlsonator model?

First is a bit of an oddball and perhaps not an ideal candidate, but I'm just "wondering out loud" here. That would be for a full-size 12" K'ator.

Isophon PH2132E. Roughly a 8"x12" vintage German coaxial. Very high Qt, good for OB. I measured some of the following parameters and guesstimated a few.

Re: 2.9ohm (4ohm nominal)
Fs: 58Hz
Qms: 6.3
Qes: 1.05
Qts: 0.9
Sd: 360cm^2
BL: 4.55 N/A

Philips AD7060. Roughly a 6" fullrange driver with whizzer. I'm not certain which Karlsonator size it would do better in and which have already been layed out. How easy would it be to adjust your model's various dimensions to find the "optimum" K'ator for this one? This driver tends to want large Vb's for a 6". It has a very "hot" top-end plateau à la AD9710 and is easily bright enough to be behind a K-aperture IMO.

Re: 7.7 ohm
Fs: 44 Hz
Qms: 3.01
Qes: 0.62
Qts: 0.51
Vas: 50 liters (a bit fudgy to measure, should be close enough IMHO)
BL: 4.75 N/A (WinISD extrapolation)
SPL: 90.4dB/W/m (WinISD extrapolation)

Thanks!

EddieT · 2014-05-12 3:14 pm

Actually I never heard the term Karlsonette before the days of forums. Allied Radio and BA called them Karlson 12s as did the Karlson brochure as late as 1966. Does anyone have a reference for the first use of Karlsonette in print?

By the way as a Karlson fan since 55-56 I feast on every word in these Karlson threads. I built a K15 (with a 12" cut-out and driver) in the late 60s using the RTN article plans. It was my first woodworking attempt I used a jig saw attachment on a 1/4" drill motor. Not many straight lines, I used a lot of bondo, wood glue and fabric overlays to fill and seal gaps. I covered it with walnut veneer and put in a gold grill cloth hiding all the diy and it looked and sounded great.

IG81 · 2014-05-12 3:39 pm

EddieT said:
Actually I never heard the term Karlsonette before the days of forums. Allied Radio and BA called them Karlson 12s as did the Karlson brochure as late as 1966. Does anyone have a reference for the first use of Karlsonette in print?

By the way as a Karlson fan since 55-56 I feast on every word in these Karlson threads. I built a K15 (with a 12" cut-out and driver) in the late 60s using the RTN article plans. It was my first woodworking attempt I used a jig saw attachment on a 1/4" drill motor. Not many straight lines, I used a lot of bondo, wood glue and fabric overlays to fill and seal gaps. I covered it with walnut veneer and put in a gold grill cloth hiding all the diy and it looked and sounded great.

I suppose Freddi would know best and could pull the correct ads/flyers to (dis)prove it.

I think I remember the word Karlsonette on a print, but you have me questioning that now. But I think this first K12 was produced for a comparatively short time versus the second K12. The third K12 is a bit more of a mystery AFAIK.

freddi · 2014-05-12 3:48 pm

it was the Karlsonette for a brief while - until the K8 arrived - I'm not sure if the old pamphlet scan before the K8 is still on the net as Imageshack loses everything --

here's the time of the first K12 - hopefully most of the pages
are still with Imageshack - - K12 was introduced I think in 1954

Fall of 1955 - one can see by Mr. Karlson's comments that the K8 had been introduced. Julian Hirsch was a very famous technical reviewer.

a preview from the 1954 show gave high marks to the Karlson exhibit
- Julian seemed to lean towards the AR speaker as a standard and it
was quite a useful development.

An externally hosted image should be here but it was not working when we last tested it.

Mini Karlsonator (0.53X) with Dual TC9FDs

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