from Pinterest - - a Karlsonator Six pair w. FE166EN.
https://i.pinimg.com/1200x/6e/ed/b8/6eedb81e7fe8091f9265027313392a08.jpg
https://i.pinimg.com/1200x/6e/ed/b8/6eedb81e7fe8091f9265027313392a08.jpg
I've always wondered something about the K aperture and the recommended builds: wouldn't the horizontal brace going across the K opening cause some diffraction anomalies? Would it be better to have a round bar bracing the two sides?
Edit: or some other way to brace the two sides without interfering with the opening?
Edit: or some other way to brace the two sides without interfering with the opening?
Last edited:
Stuffing in closed end absorbs reflections that cause resonances and makes it sound more neutral. The aperture does have an effect on sound quality but nothing to do with “mass loading”. Mass loading is analogy to how 1/4wave TL has lower resonance frequency like a tuning fork that has mass added to the forks. The mass loading is the introduction of a constriction at the terminus.
one or two Beta 8A might make a punchy K-nator or XKi along with a K-tube.
Since Beta 8 seems only available in 8 ohm, a parallel Beta8A K could present a load near 3 ohms. In its favor is an evenly rising on axis response. which negates having a lowpass filter pull more current for "boost" via a drop in impedance.
I don't think a Beta8A or Beta 8CX Karlaonator should be tuned as low as GregB's "Karlsonator8" which has Fb~41Hz. 50Hz would be better.
Although Karlson's X15 system appeared to be named after that airplane, It;s ok these days to think of X12 and X8 as being basically K12 and K9 with an internal K-tube for two way systems.
btw, Kappa 12A whose curve is shown, is one of my favorites for a Karlson 12 plus K-tube. That combo is jaw dropping on a synth recording and more impressive on the little K12 than my K-horns - - don't think of Karlson's originals as "obsolete".
Since Beta 8 seems only available in 8 ohm, a parallel Beta8A K could present a load near 3 ohms. In its favor is an evenly rising on axis response. which negates having a lowpass filter pull more current for "boost" via a drop in impedance.
I don't think a Beta8A or Beta 8CX Karlaonator should be tuned as low as GregB's "Karlsonator8" which has Fb~41Hz. 50Hz would be better.
Although Karlson's X15 system appeared to be named after that airplane, It;s ok these days to think of X12 and X8 as being basically K12 and K9 with an internal K-tube for two way systems.
btw, Kappa 12A whose curve is shown, is one of my favorites for a Karlson 12 plus K-tube. That combo is jaw dropping on a synth recording and more impressive on the little K12 than my K-horns - - don't think of Karlson's originals as "obsolete".
Attachments
Jordan VTLs I hadn't heard of before, they're beautiful. At least the craftsman build from what I can see of them.
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I like them on their sides with the opening facing out toward the side walls left and right, I think they sound best that way excellent sound stage.
Thanks X.
I find it very dependent on what I am listening to. For example, the soundtrack while playing the movie A Star is Born was incredible earlier today. Plenty enough lower end.
Generally I find the bass is there, it’s just for most music and sources the mid and high ranges are just so dominant. I may try the recommended BSC to see if that better suits my ears.
I am really enjoying them with the tv or a movie as I am hard of hearing and often have problems with dialogue. These produce the voice very clearly.
I find it very dependent on what I am listening to. For example, the soundtrack while playing the movie A Star is Born was incredible earlier today. Plenty enough lower end.
Generally I find the bass is there, it’s just for most music and sources the mid and high ranges are just so dominant. I may try the recommended BSC to see if that better suits my ears.
I am really enjoying them with the tv or a movie as I am hard of hearing and often have problems with dialogue. These produce the voice very clearly.
I am finding them a little 'foam boardy' sounding, but also loving the clarity.
I am also thinking to use them for the tv.
I am not a big film watcher, and these might be ideal for voices.
I still need to go through and make sure it is air tight though.
Plus, I have just realised, I put nothing behind the speaker terminal bit, so it is escaping there.
Plus I don't have the best amps. I am looking forward to tweaking and see what changes it makes.
I am also thinking to use them for the tv.
I am not a big film watcher, and these might be ideal for voices.
I still need to go through and make sure it is air tight though.
Plus, I have just realised, I put nothing behind the speaker terminal bit, so it is escaping there.
Plus I don't have the best amps. I am looking forward to tweaking and see what changes it makes.
Hi Karlsonators - I have been thinking up building a pair of speakers, as an upgrade to my current markaudio based TL's. Getting a bit more cm2 and efficiency, as well as quality stepup. I use a 12w tube amp, that I really like, so efficiency is important, and I do like fast and extended, enjoyed my electrostats back in the days. Room is roughly 6x4m, 3m high, dont mind placing speakers closer to wall if it works well.
Overall thinking as of now is..
Two way, with compression driver horn taking care of the upper, and sitting on a classic box (looked at onkens, but having a hard time finding a comprimise in box size and a working element in it). I will try to make sure the horn is big enough to be crossed at 500-1000 somewhere.
Then I saw the Karlson's, then I saw the Karlsonator's etc. and cannot see a way to "calculate" how they would behave, but it sounds like one of them might be a good choice..
Anyways, finally the question, do you guys have suggestions in if to go for the classic K15 (using something like a Beyma 15p80Fe, or Faital Pro PR400), or Karlsonator, with either a midbass like Beyma 12p80Nd or perhaps the on-paper and hornresp fantastic Fostex fw305, or a "scaled up" Karlsonator with 15". The K15 size is borderline to get wife-approval for, and maybe the Fostex can go as deep in the Karsonator, and maybe the midbass Beyma could be wonderful as Karlsonator - but would it be deep/physical enough ?
Any feedback would be greatly appreciated. I can of course supply specs for woofers in case anyone who can calculate has some spare time...
Regards Henrik
Overall thinking as of now is..
Two way, with compression driver horn taking care of the upper, and sitting on a classic box (looked at onkens, but having a hard time finding a comprimise in box size and a working element in it). I will try to make sure the horn is big enough to be crossed at 500-1000 somewhere.
Then I saw the Karlson's, then I saw the Karlsonator's etc. and cannot see a way to "calculate" how they would behave, but it sounds like one of them might be a good choice..
Anyways, finally the question, do you guys have suggestions in if to go for the classic K15 (using something like a Beyma 15p80Fe, or Faital Pro PR400), or Karlsonator, with either a midbass like Beyma 12p80Nd or perhaps the on-paper and hornresp fantastic Fostex fw305, or a "scaled up" Karlsonator with 15". The K15 size is borderline to get wife-approval for, and maybe the Fostex can go as deep in the Karsonator, and maybe the midbass Beyma could be wonderful as Karlsonator - but would it be deep/physical enough ?
Any feedback would be greatly appreciated. I can of course supply specs for woofers in case anyone who can calculate has some spare time...
Regards Henrik
You might try classic full size Karlsonator and 12in full range like the Fane 12-250LTC. High sensitivity and deep reaching bass.
New 12" Full-Range: Fane 12-250TC
New 12" Full-Range: Fane 12-250TC
Cheers.
How does one generally seal behind terminal cups and drivers?
I assume you don't glue it.
I was going to use that closed cell foam.
K15 isn't terribly particular as to woofer choice. IMO, its good to not have a lot of moving mass. That monster magnet ferrite Beyma has a real 4mm travel ability.
Here's some comments on K15
... Author Topic: Testimonies to the Karlson Faith (Read 1923 times)
freddyi
• Moderator
• Hero Member
•
• Posts: 9302
◦
Testimonies to the Karlson Faith
« on: May 11, 2008, 11:12:34 AM »
got any to add?
Freddyi although I already had K15 laying around from the 1980's I got hooked further when playing with some free and very rough K15's which were a gift from Martin Needleman ("Say G'nite Gracie" kritic) - with EV SP15B (a very high Q >1 wideband), soprano voices would "float" in a 3D fashion like nothing I ever heard from direct radiator or horn. Drums sounded beautiful. My normal C15CX Eminence coaxial do pretty well and play all of Alan Parsons Soundcheck musical tracks nicely - a better HF driver and xover could help. There should be something nicer than PSD2002 Although I've hads anti-K moments, K15 overall has been very good and same goes for K-tubes. K15 with an average 15" coax is better than any of my phoolrange
Steve Schell of Cogent loudspeaker fame
Re: Karlson -- why?
209.178.152.4
[ Follow Ups ] Thread: [ Display All Email ] [ High Efficiency Speaker Asylum ]
Posted by Steve Schell (M ) on September 27, 2004 at 17:21:15
In Reply to: Karlson -- why? posted by serenechaos on September 27, 2004 at 15:42:59:
I sense a bit of serene skepticism in your question. No problem, Karlsons do look pretty goofy at first glance. There is something exceptional in their performance, however, that audio writers and hobbyists have been struggling to explain for 50 years now.
It took me many years to appreciate accuracy in bass reproduction, which is quite different from sheer level or extension. Karlsons are exceptionally clean sounding as well as very extended for their size. It takes a bass horn of considerably greater bulk to outperform them. They impose no limitations on bandwidth- Karlson Associates used to recommend their use with the coaxial and triaxial drivers of the day. I much prefer them loaded with field coil theatre woofers, and big ol' midrange horns and compression drivers sitting on top.
*********************
John Lapaire
Hi Fred,
No scientific study here, but my RS spl meter measured a clear 8-10 db
difference between my old Theater 4s with Mike's Gauss/JBL components and
the Karlsons with either the cheap-*** Eminence or the Gauss. Guess which
had the most punch. These things really do have gain, with a visible
reduction in excursion. The big, full-sounding Theater 4s became suddenly
thin and weak.
We started by listening to his dual-10" 3way all-aluminum setup, which has
beautiful clear deep bass and good volume considering lower eff motors.
Then the Theater 4s with Gauss/JBL, then Eminence-loaded Ks, then swapped
top ends, including the K-tube (great sound, weak lower mids-no surprise).
Then all hell broke loose with crossover swaps, driver swaps etc. At one
point we stacked the Ks (wrong way, but we didn't have enough wire to flip
them!) Finally we wound up with Gauss in one K, Em in the other, 500 hz
crossover to JBL HF, cranked up the JBL lpads to match the Ks. This
arrangement actually shook dirt out of the ceiling/floor joists.
Mike's incredible OTL monoblocks each have 7 pairs of tubes running in
parallel, easily pushing the Ks up over 120 db at 1 meter, occasionally
pegging the meter over 126 db (I was wearing hearing protection). We
didn't do any sine wave tests, just music: rap, rock, jazz, but watching the
needle jump left no doubt about what frequency range was being energized.
One surprise was the difference between the $400 Gauss and $50 Em - or lack
of difference. Mike compared them in the Th 4 boxes, and we compared them
in the K boxes. Similar in tone and sensitivity, the Gauss slightly edged
out in control/detail IMO.
The Ktube did well enough to pursue further. Gotta get it down a little
lower without losing the top end.
I got some photos before running out of memory, they're on the hp site.
Don't want to publish Mike's equipment, suffice to say the quality of the
signal producing chain can probably not be improved on.
John Lapaire
*************************************************
Lars Moseholm
Subject: Some K15 observations - workings and principles
Dear Group
My sister’s vest is some useful equipment. Can I borrow some…. Hmm..
Take care out there and do not forget to enjoy the nice outdoor summer days and have some fun! Next week I go with my family to Lithuania of all places. It's a rather unic mix of old Northern and Baltic way of life behind all the late Eastern European Communist fixes. Wonder if John Karlson ever was in Europe?
Lars
A K15 BASS GUITAR KARLSON
Date: 07/18/02 11:13:19 AM
Name: Lars Moseholm
Email:
Subject: Some K15 obserþ£S‚. °T›
2 à=Ð/ LARS BUILDS A K15 BASS GUITAR KARLSON
Date: 07/18/02 11:13:19 AM
Name: Lars Moseholm
Email:
Subject: Some K15 observations - workings and principles
Dear Group
My sister’s boy wanted an enclosure for his bass guitar - a low cost and efficient one. I proposed to build a K15, and so we did, using the original x-15 dimensions. We used a 15” guitar speaker from Monacor we had in hand (the SP-385G: Fs=35Hz, Qts=0,4 modified, Vas=260 l, EBP=60).
First some observations without the tapered panels. The resulting back chamber vol. was 95 l without stuffing. We tuned it to 42 Hz using one 15-cm diameter port of length about 15 cm using nearly 65 vol-% stuffing. Unfortunately, we had to tweak the vent somewhat resistive in order to lower the box Q to get rid of some + 3 dB booming due to too small K15 back-chamber vol. for the given speaker. This turned the box into a hybrid between an aperiodic closed-box and a vented-box with an increased f0 near 60 Hz and a Qts of 0.7. It sounded really good. Dry bass and everything.
The speaker Z-plot revealed a major resonance at 61 Hz and a minor one at 315 Hz (the major front chamber parallel side walls resonance, there was no top-bottom resonance due to the titled speaker board, shelf and tilted top board). The port gave useful output between 40 – 120 Hz (-9 dB down on both sides). The speaker output was fairly flat (+/- 2 dB) down to about 60 Hz followed by the usual 4th order vented drop off.
The above results without the panels were all expected and fit with the usual TS box calculations.
With the tapered panels in place the front chamber was 55 l (behind the panels) and tuned to 150 Hz by an acoustic efficient tapered opening of 1320 cm2 (less than the nominal of the tapered opening of 1560 cm2 – not all area takes part in the tuning probably due to the tilted speaker board). With the tapered panels in place the usual K15 speaker terminal impedance top at 150 Hz showed up (other measurements have show 160 Hz), and other changes took place:
a) The back chamber port really took over. At 15-25 Hz the port output increased from 8 to 2 dB. The 2 dB increased output continued up to 40 Hz, and further increasing to 3 dB at 50 Hz. The vented port output dropped 9 dB from 50 to 120 Hz as mentioned above, however, the total K15 output was constant up to the 120 Hz (showed no drop). The K15 port further revealed a +4 dB top between 120 and 170 Hz, thereafter sharply dropping to meet the vented output at 250 Hz. So, the speaker drove the front chamber through the back chamber port!
b) The speaker output dipped at 200 Hz. The speaker output increased about 2 dB from 25 Hz to 80 Hz, and was the same as for the aperodic box in the range 80 – 100 Hz. That was followed by +1-3 dB up to 140 Hz. Between 140 to 300 Hz the speaker output suddenly dipped 10 dB at the near field, but that dip was somewhat compensated (but not fully) by the increased port output in that range.
We observed another constant 8-10 dB dip at 500 Hz (between 350-750 Hz), but that could be due to the guitar speaker itself. However, Fred also have measured the dips at 200 and 500 Hz recently using the Eminence and the JBL 2220H in his posting of 29th of June, and others as well. I also remember some curves showing a big K15 dip at 400 Hz.
c) Overall SPL increased. The nominated speaker SPL was 96dB. The measured K15 SPL was larger than 100 dB. Estimated total output was close to 120 dB. That speaker box really could punch out dry bass with practically no speaker movements.
How to make some sense out of this?
I modelled our K15 using standard 6th order band-pass set-up. This is a combination of a 4th order high-pass vented function, and a 2nd order front chamber low-pass function. This assumes output from the two ports only. The results clearly showed the observed increase in SPL, and the 200 Hz high-pass cut off.
However, the K15 also had output form the speaker itself at frequencies above the front chamber low-pass cut-off due to direct radiation. That could evidently explain the 200 Hz “dip”.
In a usual band-pass the two ports radiate into the environment. In the K15 the port from the back chamber radiates directly into the front chamber, but the two filter functions would not necessary significantly interfere with each other. Any additional mass loading from the front chamber on the back chamber port in our ported design would be small compared to the amount of port mass set into motion. This may not be the case in the original design.
The area between the shelf and the back wall is larger (and in our case definitely shorter, but that is not the case in the original design) than the port, and the same can be said about the opening between the front shelf and the tapered panels. In accordance, we saw no significant interference from the shelf on box resonance’s.
I think the K15 is what Freddy calls a series band-pass box. A more precise term could be that the K15 is a direct radiator 6th order series band-pass.
The coupler seems not to do any ¼ wave mass loading (no high-pass filter function). The right experiment to do would be to replace the tapered panels with a panel with a circular hole of similar effective size, and measure the acoustic filter response. If the same response was seeing – the tapered design means nothing for the filter function (but still a lot for the off-axis dispersion and some front chamber resonance's – I know). Unfortunately, the boy drove off with the box before I could do that small experiment. But now my own son got interested into this design after hearing the K15 box given full blown rap-music for the benefit of our neighbouring area. So, I think time will come for that panel shape experiment also.
The high efficiency is inherent to the band-pass and is – among other things – determined by the difference between the two Helmholtz frequencies. The Helmholtz resonance’s also explains the small diaphragm movements even for the high outputs.
The sound “colour” of the K15 was clearly determined by the balance between the direct radiated sound and the front chamber resonance’s and high-pass filter function. Also the diffraction of waves from the narrow part of the tapered opening was important.
It is not possible to specify a usual alignment for a band-pass. However, using the K15 dimensions and a front chamber tuning of about 150 Hz, the optimal driver parameters seem to be within the following ranges: Qts near 0.3, fs around 40-45 Hz, and Vas 400 – 450 l for a fairly flat frequency response. Does that fit with the early fifties good quality speakers?
A flat response is not so important in the bas range, so a large degree of flexibility should be allowed in practise (“the K15 fit many speakers”). It should also be possible to come up with some “cookbook” design rules for given drivers – or to justify the use of specific drivers. A lower front chamber resonance (140 Hz ?) may also help to smooth out the response (a smaller flare rate, tractrix curves)
Changing the diameter of the speaker – all other things equal – will only change the two “port” sizes in order to keep the proper tuning. However, Vas will also change as a function of sq.(Sd), so no simple scaling of dimensions exist.
In summary:
1. That a speaker box shows a tapered opening does not mean that the effect of that opening is the same for any box. The tapered opening in a ¼ wave pipe works in a very different way compared to the opening in the K15 (high-pass filter versus a low-pass filter, respectively!).
2. The K15 is a viable design, and it can basically be understood in usual engineering terms. However, in particular it’s on- and off-axis output cannot be easily predicted at present from TS-parameters.
3. The cabinet seems fairly robust to a range of speakers.
4. No simple scaling of the dimensions of the K-cabinet according to the speaker diameter can be recommended.
If one focuses at the need for total absence of resonance’s and a flat on-axis response in a speaker-box people should go for other designs. If one goes for high efficiency, low frequency punch, good dispersion and some work in the area of the unknown, so choose a Karlson. In fact, the K15 seems quite well behaved and a very interesting design.
I would like personally to thank the group for blowing new interest into this bass-box. After I build a dissapointing K12 35 years ago, I now understand that the K15 is different. I also think I understand why. But there is no way around the fact, that in order to build a broad recognition of the value of the design among the speaker community, things have to be justified in terms of TS-parameters and basic acoustic principles.
Further, I’m not sure I understand the seemly disagreement between the claim of usual degraded transient performance from a band-pass and my own - and certainly others at this forum observations of the “dry punch” from a K15. Can anyone enlighten me here without referring to some Karlson magic.
Best regards,
Lars
************************
Willem Norloos
Sorry Fred it took so long to answer, been busy rearanging and cleaning out my workplace (>20 bags of once "must have" garbidge went out).
As i said before, i like to use the K. as it was designed originally, however, i use it only for low up to 500 Hz. I build my first K's (12") when i was 14 years old and i got stuck with them ever since. On the other hand i spent most of my working years in the professional audio business (i took a job as a graphic designer in the 90's because of back-problems). I never used any K's in pro-audio, not because they are no good, but because other types of enclosures are usually better suited for the jobs on hand. In the end it is quality AND SPL's that counts.
For the big venue systems (mostly 4 to 6-way) we had a choice of 2x15" (raelly big) RCA bins, Cord-bins, several types of Cerwin Vega (L36, sensurround, etc) JBL and Martin-bins. The K is a rather broadbanded enclosure, it will work from 25 to whatever the woofer can do, where the other (horn systems) give more SPL in their narrow band, wich is a good fit to the 4 and more-way systems. In our studio i could never convince anyone to try anything else than their trusted JBL's (4343) and Altec's (don't remember the type but is was 2-way with a funny 90 deg. bent horn).
Last year i decided to make an active 2-way system for home use.
Before i made any choices i wrote down the design parameters and worked along those lines. I wanted reasonable flat response from 30-20kHz, constant dispersion of no less than 90 deg., and max. SPL of 115 dB over the entire band without ANY sign of stress or compression.
The upper part was really very easy, i have heard enough makes of drivers to vote for JBL or Altec without looking further. There are only a few types capable of starting at 500hZ and giving acceptable high's. JBL 2441 (Diamond pattern) would do fine. I found a pair of 2445 wich are also oke, just need a bit more EQ to lift 16kHz. The JBL 2380 horn was the obvious choice for this driver.
For the low end i looked at a few horn designs (Klipsch, Altec) but they were either too big or needed a corner to stand in, i do not have suitable corners.
I had my doubts about cone-control at high output levels with the normal vented boxes, so in the end there really was no competition left for the Karlsons.
I am happy to say, they do all that i expect from them!
At the moment i use the Cetec-Gauss 4583XR. The specs are:
Fs 31Hz
Qms 2.5
Qes 0.33
Qts 0.30
Vas 10.00
Highest Xo 800Hz
Xmax (lin) + & - 0.250"
Xmax (max) + & - 0.375"
RMS 400W
Flux 12000 Gauss
Eff. 97dB 1W@1m. (swept from 30 - 800Hz)
XR stands for:
- Kevlar reinforced cone
- High temp. VC
About the dips (400-500 region) you mentioned, they do not show up with the impedance measurement! There is only one (small) resonance at 140Hz. The peaks i found with reponse measurement were at 125 and 350Hz but they are probably room related.
About measuring from the slot:
I expect you measure with warble tones within one octave at the time. D.B. Keele (Electro Voice) has researched measuring nearby pressure fields (within the loudspeaker piston-range!) and found the results to be in good agreement with more traditional methodes (AES Anthology nr. 1). I would place the mike very close to the slot (1"), warble one octave and move the mike up and down for max. readout, and use this maximum. The max should be the same for each octave.
I never tested Karlson's claim for 120 deg. dispersion up to 10kHz because i do not use them that high. Maybe someone using a coax can verify the claim?
Well, i hope i have been of some help
Regards,
Willem
**********************************
Paul Searce builds a Karlson Ultra-Fidelity
Date: 09/27/02 11:18:59 PM
Name: Paul S.
Email: nscearce@citlink.net
Subject: University Karlson
I have just completed my first Karlson enclosure and loaded it
with a University UXC-123 driver. To these ears it sounds great.
I used the plans listed in the Oct. 1955 issue of Radio-Electronics,
slightly modified to allow a thicker back and tapers.
I listened and took some measurements with, and without the tapers in place.
Without the tapers there was a noticable peak in the mid bass as one would expect
from this driver in a 3.5 cu ft ported box.
With the tapers, bass is less peaked, and seems deeper. Hasty measurements show 3-6 dB
increase from 30Hz to 70Hz.
I wasn't sure how well the University would work in a Karlson, but it seems to be a decent match.
From what I have been reading here, I expected good things from the Karlson, and I'm not dissapointed.
Thanks everyone.
Paul
« Last Edit: May 12, 2008, 06:25:47 AM by freddyi »
Here's some comments on K15
... Author Topic: Testimonies to the Karlson Faith (Read 1923 times)
freddyi
• Moderator
• Hero Member
•
• Posts: 9302
◦
Testimonies to the Karlson Faith
« on: May 11, 2008, 11:12:34 AM »
got any to add?
Freddyi although I already had K15 laying around from the 1980's I got hooked further when playing with some free and very rough K15's which were a gift from Martin Needleman ("Say G'nite Gracie" kritic) - with EV SP15B (a very high Q >1 wideband), soprano voices would "float" in a 3D fashion like nothing I ever heard from direct radiator or horn. Drums sounded beautiful. My normal C15CX Eminence coaxial do pretty well and play all of Alan Parsons Soundcheck musical tracks nicely - a better HF driver and xover could help. There should be something nicer than PSD2002 Although I've hads anti-K moments, K15 overall has been very good and same goes for K-tubes. K15 with an average 15" coax is better than any of my phoolrange
Steve Schell of Cogent loudspeaker fame
Re: Karlson -- why?
209.178.152.4
[ Follow Ups ] Thread: [ Display All Email ] [ High Efficiency Speaker Asylum ]
Posted by Steve Schell (M ) on September 27, 2004 at 17:21:15
In Reply to: Karlson -- why? posted by serenechaos on September 27, 2004 at 15:42:59:
I sense a bit of serene skepticism in your question. No problem, Karlsons do look pretty goofy at first glance. There is something exceptional in their performance, however, that audio writers and hobbyists have been struggling to explain for 50 years now.
It took me many years to appreciate accuracy in bass reproduction, which is quite different from sheer level or extension. Karlsons are exceptionally clean sounding as well as very extended for their size. It takes a bass horn of considerably greater bulk to outperform them. They impose no limitations on bandwidth- Karlson Associates used to recommend their use with the coaxial and triaxial drivers of the day. I much prefer them loaded with field coil theatre woofers, and big ol' midrange horns and compression drivers sitting on top.
*********************
John Lapaire
Hi Fred,
No scientific study here, but my RS spl meter measured a clear 8-10 db
difference between my old Theater 4s with Mike's Gauss/JBL components and
the Karlsons with either the cheap-*** Eminence or the Gauss. Guess which
had the most punch. These things really do have gain, with a visible
reduction in excursion. The big, full-sounding Theater 4s became suddenly
thin and weak.
We started by listening to his dual-10" 3way all-aluminum setup, which has
beautiful clear deep bass and good volume considering lower eff motors.
Then the Theater 4s with Gauss/JBL, then Eminence-loaded Ks, then swapped
top ends, including the K-tube (great sound, weak lower mids-no surprise).
Then all hell broke loose with crossover swaps, driver swaps etc. At one
point we stacked the Ks (wrong way, but we didn't have enough wire to flip
them!) Finally we wound up with Gauss in one K, Em in the other, 500 hz
crossover to JBL HF, cranked up the JBL lpads to match the Ks. This
arrangement actually shook dirt out of the ceiling/floor joists.
Mike's incredible OTL monoblocks each have 7 pairs of tubes running in
parallel, easily pushing the Ks up over 120 db at 1 meter, occasionally
pegging the meter over 126 db (I was wearing hearing protection). We
didn't do any sine wave tests, just music: rap, rock, jazz, but watching the
needle jump left no doubt about what frequency range was being energized.
One surprise was the difference between the $400 Gauss and $50 Em - or lack
of difference. Mike compared them in the Th 4 boxes, and we compared them
in the K boxes. Similar in tone and sensitivity, the Gauss slightly edged
out in control/detail IMO.
The Ktube did well enough to pursue further. Gotta get it down a little
lower without losing the top end.
I got some photos before running out of memory, they're on the hp site.
Don't want to publish Mike's equipment, suffice to say the quality of the
signal producing chain can probably not be improved on.
John Lapaire
*************************************************
Lars Moseholm
Subject: Some K15 observations - workings and principles
Dear Group
My sister’s vest is some useful equipment. Can I borrow some…. Hmm..
Take care out there and do not forget to enjoy the nice outdoor summer days and have some fun! Next week I go with my family to Lithuania of all places. It's a rather unic mix of old Northern and Baltic way of life behind all the late Eastern European Communist fixes. Wonder if John Karlson ever was in Europe?
Lars
A K15 BASS GUITAR KARLSON
Date: 07/18/02 11:13:19 AM
Name: Lars Moseholm
Email:
Subject: Some K15 obserþ£S‚. °T›
2 à=Ð/ LARS BUILDS A K15 BASS GUITAR KARLSON
Date: 07/18/02 11:13:19 AM
Name: Lars Moseholm
Email:
Subject: Some K15 observations - workings and principles
Dear Group
My sister’s boy wanted an enclosure for his bass guitar - a low cost and efficient one. I proposed to build a K15, and so we did, using the original x-15 dimensions. We used a 15” guitar speaker from Monacor we had in hand (the SP-385G: Fs=35Hz, Qts=0,4 modified, Vas=260 l, EBP=60).
First some observations without the tapered panels. The resulting back chamber vol. was 95 l without stuffing. We tuned it to 42 Hz using one 15-cm diameter port of length about 15 cm using nearly 65 vol-% stuffing. Unfortunately, we had to tweak the vent somewhat resistive in order to lower the box Q to get rid of some + 3 dB booming due to too small K15 back-chamber vol. for the given speaker. This turned the box into a hybrid between an aperiodic closed-box and a vented-box with an increased f0 near 60 Hz and a Qts of 0.7. It sounded really good. Dry bass and everything.
The speaker Z-plot revealed a major resonance at 61 Hz and a minor one at 315 Hz (the major front chamber parallel side walls resonance, there was no top-bottom resonance due to the titled speaker board, shelf and tilted top board). The port gave useful output between 40 – 120 Hz (-9 dB down on both sides). The speaker output was fairly flat (+/- 2 dB) down to about 60 Hz followed by the usual 4th order vented drop off.
The above results without the panels were all expected and fit with the usual TS box calculations.
With the tapered panels in place the front chamber was 55 l (behind the panels) and tuned to 150 Hz by an acoustic efficient tapered opening of 1320 cm2 (less than the nominal of the tapered opening of 1560 cm2 – not all area takes part in the tuning probably due to the tilted speaker board). With the tapered panels in place the usual K15 speaker terminal impedance top at 150 Hz showed up (other measurements have show 160 Hz), and other changes took place:
a) The back chamber port really took over. At 15-25 Hz the port output increased from 8 to 2 dB. The 2 dB increased output continued up to 40 Hz, and further increasing to 3 dB at 50 Hz. The vented port output dropped 9 dB from 50 to 120 Hz as mentioned above, however, the total K15 output was constant up to the 120 Hz (showed no drop). The K15 port further revealed a +4 dB top between 120 and 170 Hz, thereafter sharply dropping to meet the vented output at 250 Hz. So, the speaker drove the front chamber through the back chamber port!
b) The speaker output dipped at 200 Hz. The speaker output increased about 2 dB from 25 Hz to 80 Hz, and was the same as for the aperodic box in the range 80 – 100 Hz. That was followed by +1-3 dB up to 140 Hz. Between 140 to 300 Hz the speaker output suddenly dipped 10 dB at the near field, but that dip was somewhat compensated (but not fully) by the increased port output in that range.
We observed another constant 8-10 dB dip at 500 Hz (between 350-750 Hz), but that could be due to the guitar speaker itself. However, Fred also have measured the dips at 200 and 500 Hz recently using the Eminence and the JBL 2220H in his posting of 29th of June, and others as well. I also remember some curves showing a big K15 dip at 400 Hz.
c) Overall SPL increased. The nominated speaker SPL was 96dB. The measured K15 SPL was larger than 100 dB. Estimated total output was close to 120 dB. That speaker box really could punch out dry bass with practically no speaker movements.
How to make some sense out of this?
I modelled our K15 using standard 6th order band-pass set-up. This is a combination of a 4th order high-pass vented function, and a 2nd order front chamber low-pass function. This assumes output from the two ports only. The results clearly showed the observed increase in SPL, and the 200 Hz high-pass cut off.
However, the K15 also had output form the speaker itself at frequencies above the front chamber low-pass cut-off due to direct radiation. That could evidently explain the 200 Hz “dip”.
In a usual band-pass the two ports radiate into the environment. In the K15 the port from the back chamber radiates directly into the front chamber, but the two filter functions would not necessary significantly interfere with each other. Any additional mass loading from the front chamber on the back chamber port in our ported design would be small compared to the amount of port mass set into motion. This may not be the case in the original design.
The area between the shelf and the back wall is larger (and in our case definitely shorter, but that is not the case in the original design) than the port, and the same can be said about the opening between the front shelf and the tapered panels. In accordance, we saw no significant interference from the shelf on box resonance’s.
I think the K15 is what Freddy calls a series band-pass box. A more precise term could be that the K15 is a direct radiator 6th order series band-pass.
The coupler seems not to do any ¼ wave mass loading (no high-pass filter function). The right experiment to do would be to replace the tapered panels with a panel with a circular hole of similar effective size, and measure the acoustic filter response. If the same response was seeing – the tapered design means nothing for the filter function (but still a lot for the off-axis dispersion and some front chamber resonance's – I know). Unfortunately, the boy drove off with the box before I could do that small experiment. But now my own son got interested into this design after hearing the K15 box given full blown rap-music for the benefit of our neighbouring area. So, I think time will come for that panel shape experiment also.
The high efficiency is inherent to the band-pass and is – among other things – determined by the difference between the two Helmholtz frequencies. The Helmholtz resonance’s also explains the small diaphragm movements even for the high outputs.
The sound “colour” of the K15 was clearly determined by the balance between the direct radiated sound and the front chamber resonance’s and high-pass filter function. Also the diffraction of waves from the narrow part of the tapered opening was important.
It is not possible to specify a usual alignment for a band-pass. However, using the K15 dimensions and a front chamber tuning of about 150 Hz, the optimal driver parameters seem to be within the following ranges: Qts near 0.3, fs around 40-45 Hz, and Vas 400 – 450 l for a fairly flat frequency response. Does that fit with the early fifties good quality speakers?
A flat response is not so important in the bas range, so a large degree of flexibility should be allowed in practise (“the K15 fit many speakers”). It should also be possible to come up with some “cookbook” design rules for given drivers – or to justify the use of specific drivers. A lower front chamber resonance (140 Hz ?) may also help to smooth out the response (a smaller flare rate, tractrix curves)
Changing the diameter of the speaker – all other things equal – will only change the two “port” sizes in order to keep the proper tuning. However, Vas will also change as a function of sq.(Sd), so no simple scaling of dimensions exist.
In summary:
1. That a speaker box shows a tapered opening does not mean that the effect of that opening is the same for any box. The tapered opening in a ¼ wave pipe works in a very different way compared to the opening in the K15 (high-pass filter versus a low-pass filter, respectively!).
2. The K15 is a viable design, and it can basically be understood in usual engineering terms. However, in particular it’s on- and off-axis output cannot be easily predicted at present from TS-parameters.
3. The cabinet seems fairly robust to a range of speakers.
4. No simple scaling of the dimensions of the K-cabinet according to the speaker diameter can be recommended.
If one focuses at the need for total absence of resonance’s and a flat on-axis response in a speaker-box people should go for other designs. If one goes for high efficiency, low frequency punch, good dispersion and some work in the area of the unknown, so choose a Karlson. In fact, the K15 seems quite well behaved and a very interesting design.
I would like personally to thank the group for blowing new interest into this bass-box. After I build a dissapointing K12 35 years ago, I now understand that the K15 is different. I also think I understand why. But there is no way around the fact, that in order to build a broad recognition of the value of the design among the speaker community, things have to be justified in terms of TS-parameters and basic acoustic principles.
Further, I’m not sure I understand the seemly disagreement between the claim of usual degraded transient performance from a band-pass and my own - and certainly others at this forum observations of the “dry punch” from a K15. Can anyone enlighten me here without referring to some Karlson magic.
Best regards,
Lars
************************
Willem Norloos
Sorry Fred it took so long to answer, been busy rearanging and cleaning out my workplace (>20 bags of once "must have" garbidge went out).
As i said before, i like to use the K. as it was designed originally, however, i use it only for low up to 500 Hz. I build my first K's (12") when i was 14 years old and i got stuck with them ever since. On the other hand i spent most of my working years in the professional audio business (i took a job as a graphic designer in the 90's because of back-problems). I never used any K's in pro-audio, not because they are no good, but because other types of enclosures are usually better suited for the jobs on hand. In the end it is quality AND SPL's that counts.
For the big venue systems (mostly 4 to 6-way) we had a choice of 2x15" (raelly big) RCA bins, Cord-bins, several types of Cerwin Vega (L36, sensurround, etc) JBL and Martin-bins. The K is a rather broadbanded enclosure, it will work from 25 to whatever the woofer can do, where the other (horn systems) give more SPL in their narrow band, wich is a good fit to the 4 and more-way systems. In our studio i could never convince anyone to try anything else than their trusted JBL's (4343) and Altec's (don't remember the type but is was 2-way with a funny 90 deg. bent horn).
Last year i decided to make an active 2-way system for home use.
Before i made any choices i wrote down the design parameters and worked along those lines. I wanted reasonable flat response from 30-20kHz, constant dispersion of no less than 90 deg., and max. SPL of 115 dB over the entire band without ANY sign of stress or compression.
The upper part was really very easy, i have heard enough makes of drivers to vote for JBL or Altec without looking further. There are only a few types capable of starting at 500hZ and giving acceptable high's. JBL 2441 (Diamond pattern) would do fine. I found a pair of 2445 wich are also oke, just need a bit more EQ to lift 16kHz. The JBL 2380 horn was the obvious choice for this driver.
For the low end i looked at a few horn designs (Klipsch, Altec) but they were either too big or needed a corner to stand in, i do not have suitable corners.
I had my doubts about cone-control at high output levels with the normal vented boxes, so in the end there really was no competition left for the Karlsons.
I am happy to say, they do all that i expect from them!
At the moment i use the Cetec-Gauss 4583XR. The specs are:
Fs 31Hz
Qms 2.5
Qes 0.33
Qts 0.30
Vas 10.00
Highest Xo 800Hz
Xmax (lin) + & - 0.250"
Xmax (max) + & - 0.375"
RMS 400W
Flux 12000 Gauss
Eff. 97dB 1W@1m. (swept from 30 - 800Hz)
XR stands for:
- Kevlar reinforced cone
- High temp. VC
About the dips (400-500 region) you mentioned, they do not show up with the impedance measurement! There is only one (small) resonance at 140Hz. The peaks i found with reponse measurement were at 125 and 350Hz but they are probably room related.
About measuring from the slot:
I expect you measure with warble tones within one octave at the time. D.B. Keele (Electro Voice) has researched measuring nearby pressure fields (within the loudspeaker piston-range!) and found the results to be in good agreement with more traditional methodes (AES Anthology nr. 1). I would place the mike very close to the slot (1"), warble one octave and move the mike up and down for max. readout, and use this maximum. The max should be the same for each octave.
I never tested Karlson's claim for 120 deg. dispersion up to 10kHz because i do not use them that high. Maybe someone using a coax can verify the claim?
Well, i hope i have been of some help
Regards,
Willem
**********************************
Paul Searce builds a Karlson Ultra-Fidelity
Date: 09/27/02 11:18:59 PM
Name: Paul S.
Email: nscearce@citlink.net
Subject: University Karlson
I have just completed my first Karlson enclosure and loaded it
with a University UXC-123 driver. To these ears it sounds great.
I used the plans listed in the Oct. 1955 issue of Radio-Electronics,
slightly modified to allow a thicker back and tapers.
I listened and took some measurements with, and without the tapers in place.
Without the tapers there was a noticable peak in the mid bass as one would expect
from this driver in a 3.5 cu ft ported box.
With the tapers, bass is less peaked, and seems deeper. Hasty measurements show 3-6 dB
increase from 30Hz to 70Hz.
I wasn't sure how well the University would work in a Karlson, but it seems to be a decent match.
From what I have been reading here, I expected good things from the Karlson, and I'm not dissapointed.
Thanks everyone.
Paul
« Last Edit: May 12, 2008, 06:25:47 AM by freddyi »
re: cheapass $50 Eminence 15 that John Lapaire mentioned, I believe that's Eminence's Delta 15A. Look at its nice rising response. That probably offsets its somewhat weak motor.
Eminence Delta 15A speaker. The Eminence Delta 15A is a 15" 8 ohm speaker. Delta-15A is a 400 watt RMS 12" woofer.
A Karlsonator 12 could be a nice option. A K-tube mounted either on top, or internally with the compression driver mounted in the "stub" above the woofer.
Re:FW305 - the dreaded foam surround. If direct radiator midrange presence is sufficient for your situation, then Beyma's old 12CX whose woofer extends pretty high could make a nice Karlsonator 12 setup. It sells for $199 these days in the US.
Beyma Coaxial Speakers - Beyma 12CXX coaxial speaker - Beyma 12CX 200 watt 12" coaxial speakers for all 2-way applications. Beyma 12CX coxial speaker and other Beyma 12" coaxial speakers here.
In Karlson's K12, I like Eminence's Kappa12a woofer.
Perhaps a CD waveguide or simply "horn"
Eminence Delta 15A speaker. The Eminence Delta 15A is a 15" 8 ohm speaker. Delta-15A is a 400 watt RMS 12" woofer.
A Karlsonator 12 could be a nice option. A K-tube mounted either on top, or internally with the compression driver mounted in the "stub" above the woofer.
Re:FW305 - the dreaded foam surround. If direct radiator midrange presence is sufficient for your situation, then Beyma's old 12CX whose woofer extends pretty high could make a nice Karlsonator 12 setup. It sells for $199 these days in the US.
Beyma Coaxial Speakers - Beyma 12CXX coaxial speaker - Beyma 12CX 200 watt 12" coaxial speakers for all 2-way applications. Beyma 12CX coxial speaker and other Beyma 12" coaxial speakers here.
In Karlson's K12, I like Eminence's Kappa12a woofer.
Perhaps a CD waveguide or simply "horn"
Last edited:
Thanks X and Freddi!
I did not have a coax in mind, even though I did plan a 70l "Onken", with a fullrange 8 inch Sonido SWR, before I got cold feet over 2mm xmax (SPL etc.) and efficiency with my limited power, as it would probably be similar to the markaudio TL I have now. Would feel better to have more of a step up, especially as I will not build every year. Having a fullrange/coax as close to the ground as in a Karlson feels strange (without hearing one of course, I am probably way off), and I don't mind the extra horn on top, if that can bring great music.
So therefore the main idea as of now is a Karlson cabinet with the high frequences above, probably as CD&Horn ( I have a friend with a CNC and we are toying with the idea to build Yuichi a-290 wood horns that allow 300-500 Hz cross), but could be a full range, if that would be "better".
Thanks Freddi for the statements of the K15, and I think I understand it to work with most old school 15" with low mms and strong motor. Not sure if a newer Beyma "monster" 15p80 or 20 year old JBL 2220 or similar would work "best", but I guess both would in slightly different ways. I have seen discussions about some kind of "dip" around 300Hz in K15, is this a problem that makes the Karlsonator a better choice? (I cannot cross lower than that using CD, otherwise it sounds like it would work fine for the bass side of a 2 way, crossing somewhere 500-1000Hz)
For the Karlsonator, I am not as sure what would be a wise choice, I understand it would go deeper, even with a 12", and act more like a TL. Not sure how linear it would be up to 1000 Hz, but as you use it for full range, then it should be fine.? Maybe you have looked at it before, but it would be excellent to hear how a Beyma 12P80ND would behave in such a cabinet (or if not a similar low mms&strong engine 12") - as that would allow it to cross higher if needed, and as they are considered as great midbass drivers, but kind of hard to hard to use as woofers. Or even to put the larger 15p80 or Faital Pro FR400 or ? in a scaled up (wider only?) karlsonator. The eminence I had not considered before, but maybe I should with the low mms..
And you probably figured, I have never heard either Karlson, so your guidance is king, obviously, especially as I cannot use some kind of calculator for these..
The Beyma 12p80ND has these specs in case you guys can have a look..
Fs 50 Hz
Re 5.1 ohm
Qes 0.17
Qms 4.25
Qts 0.16
Vas 65 L
Efficiency 4.65 %
Calculated efficiency 4.59 %
Xmax 7.5 mm
Mms 67 gr
Le 0.75 mH
EBP (Fs/Qes) 294 Hz
Vas/Qts² 1.67 L
..and thanks for the heads up regarding the Fostex foam surround- I guess that could mean trouble, not sure I want trouble
I did not have a coax in mind, even though I did plan a 70l "Onken", with a fullrange 8 inch Sonido SWR, before I got cold feet over 2mm xmax (SPL etc.) and efficiency with my limited power, as it would probably be similar to the markaudio TL I have now. Would feel better to have more of a step up, especially as I will not build every year. Having a fullrange/coax as close to the ground as in a Karlson feels strange (without hearing one of course, I am probably way off), and I don't mind the extra horn on top, if that can bring great music.
So therefore the main idea as of now is a Karlson cabinet with the high frequences above, probably as CD&Horn ( I have a friend with a CNC and we are toying with the idea to build Yuichi a-290 wood horns that allow 300-500 Hz cross), but could be a full range, if that would be "better".
Thanks Freddi for the statements of the K15, and I think I understand it to work with most old school 15" with low mms and strong motor. Not sure if a newer Beyma "monster" 15p80 or 20 year old JBL 2220 or similar would work "best", but I guess both would in slightly different ways. I have seen discussions about some kind of "dip" around 300Hz in K15, is this a problem that makes the Karlsonator a better choice? (I cannot cross lower than that using CD, otherwise it sounds like it would work fine for the bass side of a 2 way, crossing somewhere 500-1000Hz)
For the Karlsonator, I am not as sure what would be a wise choice, I understand it would go deeper, even with a 12", and act more like a TL. Not sure how linear it would be up to 1000 Hz, but as you use it for full range, then it should be fine.? Maybe you have looked at it before, but it would be excellent to hear how a Beyma 12P80ND would behave in such a cabinet (or if not a similar low mms&strong engine 12") - as that would allow it to cross higher if needed, and as they are considered as great midbass drivers, but kind of hard to hard to use as woofers. Or even to put the larger 15p80 or Faital Pro FR400 or ? in a scaled up (wider only?) karlsonator. The eminence I had not considered before, but maybe I should with the low mms..
And you probably figured, I have never heard either Karlson, so your guidance is king, obviously, especially as I cannot use some kind of calculator for these..
The Beyma 12p80ND has these specs in case you guys can have a look..
Fs 50 Hz
Re 5.1 ohm
Qes 0.17
Qms 4.25
Qts 0.16
Vas 65 L
Efficiency 4.65 %
Calculated efficiency 4.59 %
Xmax 7.5 mm
Mms 67 gr
Le 0.75 mH
EBP (Fs/Qes) 294 Hz
Vas/Qts² 1.67 L
..and thanks for the heads up regarding the Fostex foam surround- I guess that could mean trouble, not sure I want trouble