do think I've been writing a lot about
the TJL 3-way. The experiences gained from the
Ekta and Zahra made me even more anxious to get
started. If the latter two constructions hadn't
come along, I would have done the TJL3W a long
time ago. But events took their own course and I
have been pleased with the results of the former
constructions and the TJL3W was very much next.
TJL2W is my favourite among a
number of 2-way floorstanders and you always ask
how to make a good thing better. The TJL shares
the limitations of most other 6" + tweeter
two-ways: Lack of dispersion in the upper
midrange/lower treble due to the bass driver
having to handle everything up into the treble
area despite the low point of crossover around
2500 Hz. When a single driver has to pump the
deep bass and at the same time handle the
delicate upper midrange and lower treble there
are limitations to the loudness we can expect
from such a design. Suitable for most, but it
can't play excessively loud. However, the TJL3W
wasn't made to play loud, rather to play low.
Below some thoughts about crossing over in the
"critical" midrange and some thoughts
on having a uniform power response from our
The zip file contains all large graphics
(back to top)
Don't cross over between
drivers in the critical midrange!
Just to recapitulate:
lower midrange = 160-320 Hz, middle midrange =
320-640 Hz, upper midrange = 640-1280 Hz. Above
1280 Hz we're getting into treble territory and
no wonder we find 6-7" drivers having
trouble here. People are always surprised when I
play a 315 Hz warble tone from a test CD. Is it
really this high?!
So, even 3-4" drivers
can cope with a 300 Hz point of crossover and we
do see middomes taken this low. Does it sound
natural? I case you have an electronic crossover,
preferably 24 dB/octave, try make a 320-1280 Hz
midband and play voices on a 4", a 5"
and a 6" driver. Add a coil to the drivers
in order to make the response reasonably linear.
All drivers on suitable baffles. Try adjust to
the same loudness from the drivers and listen to
voices. Quite some difference. Remarkably
different. I've always found 6" drivers to
give the best lower midrange. It adds a low-end
weight to vocals that smaller drivers cannot do.
However, depending on the woofer below and the
chosen slope of the crossover you can make a
perfect blend of sounds. If you can get away with
a 2nd order filter the results may be very good
indeed. With higher order filters you start
depending very much on the actual performance of
the driver itself and there's no "help from
your friends" here. I've heard excellent
vocal performance from a 6" midrange driver
taken down to 150 Hz with - presumably - 4th
order filters (Von
Schweikert VR4 mkIII).
In large speaker systems
we often see 6" or 8" drivers used for
lower midrange and not seldom a small 4"
driver helping in the upper midrange, e.g. Krell Resolution 1. This is an interesting speaker as
it uses a "low-cost", 4" Peerless
pp midrange. This is a dedicated upper midrange
driver with flat polypropylene surround making a
low-sloped blend with the SEAS W22 around 450 Hz.
Measurements from Stereophile: Blue is
Peerless M122 mid-driver.
(Very nice and smooth slopes, by the way.)
Now, few manufacturers go
4-way due to complexity and overall
costs, but no wonder this approach make it
possible to use a driver with a diameter best
suited for the particular frequency range it has
The compromise - and we're not talking 2-ways -
is to find a 5" driver that will handle
anything from 300 Hz to 3 kHz or even up 4-4.5
kHz and there are a few around. The best example
is the AudioTechnology 4H52
Flexunits or C-Quenze used in
the Stradivari and other constructions. A 4H52
C-Quenze really is a broadbanded driver doing
well up to 4 kHz. If it had to go higher it would
need a smaller voice coil like seen in the larger
Dynaudio speakers with dedicated midrange
I have once tried
making a 2-way from my 4H52 Flex-Unit with a
point of crossover (4th order) at 4.5 kHz and I
wasn't impressed. But making a point of crossover
in an area where the drivers have an easy
one-octave surplus capability is luxury and we
may get the best of both worlds.
Don't be afraid to cross
over in the "critical" midrange!
There are - to my
mind - great benefits to be gained from this
approach, but make sure you have good control
over amplitude and phase when you do so. It's not
particularly difficult to cross over at 800 Hz.
The wavelength is 43 cm here and when you model
the bass and mid in LspCAD, the distance from
drivers to listening position is much less
critical compared to the upper mid-treble
characteristics of loudspeakers.
characteristics of loudspeakers is a
controversial subject and an enormous amount of
written material is published on the web and even
trying to summarise the various opinions
regarding this aspect of speaker performance is
Read an introduction
here from Dick Olsher: http://www.blackdahlia.com/samadhi/cbae.htm:
Although audio magazines continue to make a
living off on-axis frequency response
measurements, it is actually well established
that speakers that measure identically
on-axis in an anechoic chamber sound much
different in a typical domestic
environment. These differences are due to how
these speakers radiate sound off-axis as a
function of frequency. Even at a listening
distance of only 8-feet, the soundfield at the
listening seat is already more than 50%
room reflections in the bass and midrange.
Speakers whose power response is deficient in the
midrange will color the soundfield in the
same direction. For example, a two-way
design with an 8-inch woofer crossing over
to a 1-inch dome at 3 kHz, may measure fine
on-axis (anechoically), but show a 10 dB dip in
the midrange off axis. Such a speaker will sound
recessed and lifeless in a real-world room.
More here at: http://mixguides.com/studiomonitors/products_features/audio-listening-space/
The problem relates to
having and wide and uniform versus a
narrow and - uneven power response. Both the
choice of drivers and the filters used will have
a major influence on what is achieved. What can
be seen from this construction is a uniform
horizontal and vertical sound dispersion and to
get my feet back on the ground, this has one
distinct feature: My writing desk is close to the
door into our living room where the speakers are
located, giving me rich opportunity to the
"listening from another room"
situation. Actually I sit here an awful lot
writing these web pages! With the TJL3W I can
clearly follow what is going on even at low
levels. It's even better than the Acapella SE.
The "flat" ribbons have a nice
horizontal dispersion, but are usually poor in
the vertical plane (The ATD or NDRL ribbons are
exceptions due to their special construction). As
the Acapella SE is more or less optimised for
on-axis listening, the combined upper frequency
power response is probably significantly lower
compared to the TJL3W. This does not say that the
Acap. SE is a crappy speaker, but was balanced to
produce the flattest response on-axis.
A "domed" Acapella
SEas has been made for those
who may want to experiment with this. It makes
quite a difference and there's a lesson to be
learned from this exercise too.
Now, with a speaker
having a wide and uniform sound distribution I
can more fully enjoy the music off-axis, even if
it has to pass a door opening - well, I'm only ½
metre away from that door opening - where a
speaker with a narrow and focused radiation will
force me to pay more attention to details at low
levels - and even sometimes draw me into the sofa
in the living room for some "on-axis"
action - and eventually some power napping, which
Before we start building a loudspeaker we should
really analyse our listening room to get an idea
of whether this room is suitable at all for music
reproduction. At low frequencies we don't have
much choice and we're stuck with the room modes
(resonances) and we can go Linkwitz's route and
use a dipole bass in order to try overcoming this
problem. Going higher in frequency we start
having desirable or undesirable reflections
supporting or distracting the sound images we
"Early reflections ruin perspective" we
read all the time. The Stradivari has nothing but
early reflections, however renders good reviews
and is praised for what it does. How does this
correlate? Not even "reflections"
derived from diffraction seems to disturb our
peace. We praise speakers for their
3-dimensionality despite having loads of
diffraction whether we round our cabinet edges or
My point is that the Ekta,
Zahra and TJL3W due to the combination
of drivers having suitable diameters for the
frequency ranges they have to handle and from the
use of higher order filters produce a more even
power response and are less fuzzy when it comes
to placement. Speakers that have energized my
listening room better than more directional
constructions. Speakers that makes me enjoy the
music also at low levels, that can play louder
due to lack of intermodulation distortion from
overlapping driver's response*, that can play
female vocals much louder due to lack of beaming
- and maybe distortion - in the 1-3 kHz range.
Essentially I get speakers that are "easy to
listen to".... Read here: http://www.troelsgravesen.dk/HES.htm
I have an old pair of HECO P3000
speakers. 3-way (6"+3"+1")
bookshelf speakers from the Seventies. 3"
midrange driver. There are a lot of things these
speakers are not good at, but... they're easy to
listen to and essentially does what a speaker is
supposed to do. Provide enjoyment and relaxation
rather than adding to the daily struggle for
*: By this I mean not trying to
combine a 15-20 grams midbass cone to a 300
milligrams tweeter diaphragm. 5 grams appear to
be much more suitable. No matter what kind of
crossover we use in order to produce the flattest
possible amplitude and phase performance, we
cannot do anything about the fact that where the
drivers have to reproduce the same frequencies, a
tweeter dome of 300 milligrams will rise much,
much faster compared to a 10-15 grams midbass
cone. And I don't care if the whole construction
can reproduce square waves or not. I don't listen
to square waves. I don't think it's an important
parameter. Linear distortion and dispersion
appear to be more important.
back to the TJL3W:
Should you consider
building a speaker like this, keep in mind that
this is a relatively small speaker of 24 litres
net. volume and there are limitations to what a
126 cm^2 bass cone can do. In this construction
you get a decent deep bass (F3 = 40 Hz) and I
render the construction well suited for rooms up
to 25-35 m^2.
The relatively low sensitivity of 84-85 dB is
what we can expect from a 6" driver with a
15 grams membrane weight and a small magnet. The
advantage of this was deep bass from a small
cabinet with a high WAF. All about compromises.
Very much in line with the 2.5 clone but with
much better sound.
I had the cabs made in
June 05 and we're now in January 2006. I
routed the test front panels to be attached by
screws, as I wanted to experiment with both the
W11 and W12 middrivers and the HiQUPHON OWI and
the Fountek JP3 tweeters. The panels seen above
are routed for the OWI and this will be the
initial set-up. For those who may want to upgrade
their TJL, I'll try the JP3 ribbon later.
The frequency response and impedance data files
for all the drivers were made a long time ago and
from time to time I've made a few simulations to
explore the possible crossovers needed to make
the three drivers gel into a - hopefully -
Having the TJL3Ws running
for the first time I used these CDs:
1. Marie Boine: "Unfolding", Verve
2. Siri's Svale Band: "necessarily
so...", Sonor Records, SONCD 2005, and
3. Maddy Prior and The Girls: "Bib and
Tuck", Park Records, PRKCD61.
Thanks again to Finn Dahle in Norway for sending
med the two first CDs: 2_95_finndahle.htm. I would
probably never have found these magnificent
recordings had it not been for you.
Marie Boine sings the most exciting songs I've
heard in a long time and she does it in her
native tongue coming from Samiland (Lappland).
The recording was done in a studio a little North
from where I live, PUK-studio, Denmark. And it's
a great recording. Play track 6 and the TJL3Ws
will shake your guts and tell you that these
speakers will give you a decent sense of what's
below 40Hz. Marie Boine's vocal is recorded a
little too close and dry to my taste, but the
TJL3Ws handle it all very well.
Siri's Svale Band
has been my favourite recoding for a long time
for demonstrating loudspeakers. People may like
or dislike jazz music, but this recording will
leave no one unaffected. Recorded in Trondhjem,
Norway. Excellent! The TJL3W will tell you a lot
of what's going on in the studio. If your speaker
has a good level of transparency, this recording
will make you want to take the few step into the
studio and watch what's going on.
Maddy Prior: I
had this CD from my friend Darryl and it's a
killer! Three female vocals producing narrow
peaks of 10-15 dB in the 700-1000 Hz range. Very
few speakers can handle these vocals without
severe distortion. The Zahra and the Ekta did
these recordings very well and thanks to W12
upper midrange driver, the TJL3W is not left
behind. The Zahra may beat the TJL3W by a small
margin due to higher sensitivity (larger membrane
area) but the TJL3W is more neutral due to the
Well, the very first music I fed the TJL3Ws were
some vinyl stuff, a 45 rpm audiophile recording,
Kei Akagi: New Smiles and Travelled Miles. This
LP comes with a bonus 45 rpm LP. Try this on a
good turntable and who cares about CD when this
is possible? Well, back to the present and ...
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Do I hear
something about a lot of components
here? Well, we're dealing with metal cone drivers
and we need to completely eliminate the cone
break-ups. Basically the crossover between bass
and mid is close to a third order on the acoustic
side. The bass needs a 4th order electric filter
to render this and the benefit of this is we
don't need any notch filter for this driver.
need a 3rd order HP section and a 4th order LP
section. The tweeter section is a bit tricky and
this is basically a 4th order with some minor
equalisation at the inlet.
The placement of the attenuation resistor after
the 13.3 uF cap. in the mid section doesn't leave
much room for adjustment here. However, you can
reduce value to 3R3 without problems to increase
midband level and to reduce midband level you may
ad 47R across mid terminals and 1R0 in series
before the 47R.
Basically I don't think either the midband or the
tweeter will need further adjustments.
The notch filter in the mid section takes care of
a small bump around 2 kHz. I don't think you
should leave it out.
A high order crossover
may seem rather complex, but breaking it up into
the various sections, it becomes quite
manageable. The bass section is placed at the
bottom of the cabinet and consists of only 2
coils, 3 caps and a resistor. I'll make separate
boards for the mid and tweeter sections to
And by the way:
I've recently auditioned the Von Schweikerts VR4
mkIII speakers and if you still think 4th order
filters will kill the music, go listen to these
speakers. If you think paper cone (Aerogel)
midrange drivers lack homogeneity and
transparency, go listen to the VR4 mkIII. If you
think the Vifa XT25TG tweeter is crap, go listen
to the VR4 mkIII. It's not the end of the world,
but a great lesson in doing things clever. Forget
about "Global Axis Integration
Networks" and cascaded 1st order filters -
whatever that is. Common marketing rubbish.
Schweikert uses coils and caps like the rest of
us, so if you use higher order crossovers, do it
right. Well done!
(back to top)
The list of crossover components. Hope it's all there!
The two coils in the bass
section are important. Used cored and very
low-ohm coils < 0.2 ohms DC resistance. We
need all the sensitivity we can get from the W18.
The 4.7 mH coil for the LCR filter can be a
high-ohm cored coil made from thin wire as the
LCR carries a 15 ohms resistor anyway. Don't use
a monster coil for this small circuit.
Complete TJL3W kit
crossover components, vents, terminals, wires,
Not included: HIQUPHON OWI, cabinets and
HIQUPHON OWI tweeter available here.
(back to top)
The question on
placement of drivers is one I often
receive from builders, like: "Can you
explain the reason for placing some of the
drivers off-centre on the front baffle? Are there
any guidelines here or should I just place them
so they look good?"
There's a short
and a long explanation. The long one is found in
this link: http://www.speakerdesign.net/understand.html
The short one is
that the baffle provides an acoustic support for
the soundwaves generated by the drivers. When the
soundwave reaches an edge, it "falls
down" creating irregularities in the
frequency response of the driver. This is
compensated in the crossover to render a flat
response. By off-centering the drivers the
intrinsic response of the drivers is often
smoothed and this makes it possible to make a
less complicated crossover.
So the drivers have to
placed exactly as shown in the drawings,
otherwise the crossover will not work as
The front panel dimensions, width and length, has
to be exactly as on the drawing to render the
frequency response shown.
And don't forget to chamfer the driver holes, in
particular for the midrange driver to allow free
air ventilation from the rear of the driver.
Obviously the tweeter don't need this. The
amount of energy released from the rear of
the driver is exactly the same as from the
More links to understand why:
check this file for a transmission line solution: TJL3W
built by Ingvar/Sweden
The net volume of the mid cabinet is 2.15 litres, a
little more than needed,
but I wanted to experiment with various volumes and
Routing the front panel for drivers. Use a fresh, sharp
router bit when doing solid wood.
front panel with drivers. To the right the SEAS W11 paper
cone. Not a bad option
for a 3-way - and easy when it comes to making
crossovers. The W11 will not be used here.
Damping materials used for TJL3W. The black wavy
polyester foam is used
only right behind the bass driver. Middle: MDM3. Right:
10-12 mm sheep's wool felt.
Damping material behind bass driver.
front panel and cab ready for oil.
(back to top)
The starting point, frequency response and
impedance of drivers:
Impedance of drivers in
cabinet. The chosen vent (Monacor BR60-TR) works
spot on in this cabinet. Vent tuning is approx.
Middriver's basic resonance is at 90 Hz. No
reason to do anything about this as the middriver
is only going to work down to 700-800 Hz.
HIQUPHON QWI resonance is around 900 Hz as
declared. Smooth and symmetrical. How does Oscar
these tweeters? No problem with these tweeters.
SPL response of
individual drivers. Red = W18E001, green =
W12CY001, blue = OWI . This
tweeter is a darling, isn't it. Flat response,
etc. Does everything right - and it sounds great
The W18 break-up is two octaves above point of
high-Q peaks of the magnesium drivers
are hard to overlook. Adding the MLS signal to
the drivers during testing, the sound is
terrible. It shreds your ears. In particular the
W18 having the peak at exactly 5 kHz. The W12
doesn't sound nearly as bad having the peaks from
10 kHz and above. I took special precautions in
the two-way TJL to ensure the W18's 5 kHz would
be gone. Steep filters and a notch filter as
well. But once these peaks are gone, there's a
calm, "dark" and uncoloured sound left.
"Dark"? The magnesium drivers have a
quietness contrary to most other cone materials
and for lack of better words, I call it
"darkness". Reading a review recently
on a high-end speaker using the Accuton drivers,
it appeared that the reviewer almost thought they
were too un-coloured. We're so used to the mixed
blessings of cones breaking up in all sorts of
ways that once we're left with a speaker made
from drivers with significant reduced levels of
cone colouration, we get a little uneasy from not
hearing what we use to do.
The finished speakers:
SPL response of the
finished speaker. An overall smooth response with
the usual minor tilt downwards towards the highs
rendering a smooth presentation of overtones. The
OWI indeed is a fine
Blue is minimum phase.
I'm going to spend some
more time than usual on the dispersion
characteristics of this speaker and show three
measurements on horizontal and vertical
dispersion to display the overall power response.
Obviously a speaker should have a reasonably flat
response measured on-axis as this is where we
tend to place ourselves when doing some
"serious" listening. However, off-axis
response may be just as important and here we go:
What I have done here is to record the vertical
SPL at one metre distance varying the height of
the microphone in 10 cm increments, starting at
between-tweeter-and-mid height. This will
correspond to a listening height of +30 cm to +60
cm above normal listening height at 3 metres
distance. Downwards from 0 cm to -90 cm. Well,
few people may listen from lying under the sofa,
but just to show the extreme.
Red = -90 cm, blue = -60
cm, green = -30, yellow = 0 cm, purple = +30 cm
and black = +60 cm.
I don't think I have to comment the results. An
even vertical dispersion is the most difficult
thing to do and only if you are seriously
"grounded" will you have a -5dB
response around 3 kHz.
Horizontal dispersion is
measured at 1 metre distance and in 10 deg.
The TJL3W is a non-symmetrical speaker as the mid
and tweeter drivers are offset, thus giving
different horizontal dispersion depending on from
"which side" you are listening.
The TJL3W should be set up with the mid and
tweeter towards each other as seen on the
drawing. The measurements shown here were done on
the right speaker turning the speaker to the left
(L) and right (R).
Left speaker turned right
Purple = 40 deg. The rest: Well, take your pick!
Left speaker turned left
Purple = 40 deg. The rest: It doesn't matter.
What can be seen is that due to lack of symmetry
in drivers' placement on front panel, the
response is different depending on listening
What happens if we invert
polarity of the midrange?
In a two-way system you can always find a spot
where the phase tracking is perfect and make a
nice and deep suck-out. At least it has to be
specified where the reading was taken from and
those previously shown have been at listening
height = usually at tweeter height or a little
below. I have also warned you not to put too much
into this, as it's so easy to manipulate to
impressive performance. But if conditions are
specified it may tell that something appear to
have been done right.
A 3-way is more nerve wrecking and reversing the
polarity of the middriver must be the litmus test
for a three-way system when you still place the
microphone at tweeter height.
I have to confess I hadn't done this test before
the crossover was finished because even it hadn't
been as nice as seen above, I wouldn't have
changed the crossover anyway. Now, this all looks
very nice but what happens at 2 metre distance?
Next graph below.
Two metres distance is a
bit tricky because my workshop isn't very big and
the readings are only valid down to 500 Hz.
Red = tweeter level, green = mic lifted 15 cm and
blue = mic lowered 15 cm.
So, despite different listening level, we have a
decent phase tracking between drivers.
Same exercise at 1 metre
Blue = correct polarity of mid.
Red = reverse mid polarity at tweeter height.
Green = reverse mid polarity with mic lifted 10
Yellow = reverse mid polarity with mic lowered 10
Purple = reverse mid polarity with mic lowered 20
Red = same SPL as seen
above: On-axis, 1 metre at tweeter-mid height.
Not valid to lower than 350 Hz due to gating.
Blue = nearfield reading of bass driver showing
decent response down
to 60 Hz and minimum at 35 Hz where the vent will
take over and produce the lowest octave.
Green = vent (response not corrected for actual
Step-response showing tweeter connected with negative
and the mid and bass with positive polarity.
Impedance profile. As
always an interesting measurement giving you an
idea of how tough the speaker will be on your
power amp. Impedance is not below 5 ohms in the
critical bass area and an overall moderate load
to your amplifier. My 50 wpc valve power amp has
no objections running this speaker loud.
Construction of crossover
bass section crossover layout.
Space is a serious
concern in this construction due to a limiting 24
litre cabinet volume and the bass crossover
section is placed at the bottom panel. The two
coils were connected in series and moved around
while measuring the inductance and the shown
placement provided minimum interaction. Placing
the coils in parallel as far apart as possible
did not work despite some 15 cm distance.
The coils used here provide a combined series
resistance of only 0.33 ohm.
Don't be afraid to use an electrolytic capacitor
here in the bass section. These ELKOs from
Intertechnik works great and are often seen in
high-end German speakers.
Use brass or stainless steel screws in order not
to change the inductance of the coils.
mid section crossover layout.
Pretty close to the layout above.
TJL3W tweeter section crossover layout.
Slightly different from the layout above.
TJL3W - Fountek JP3 version.