TJLs from Kevin, Arizona, US
Hello Troels,
I recently finished building a pair of your TLJ
loudspeakers and wanted to send you some comments on both
the construction and their sound. Sorry this is
rather long, but I wanted to give you the best feed-back
I could.
First, I would like to thank you for your extraordinary
generosity in sharing your designs with others. I
also want to mention that I appreciate your extended
discussions on the genesis of your designs- what works,
what does not, and how you addressed these
problems. Combined, you provide valuable insight
into both the variables of loudspeaker design and your
own preferences regarding sound reproduction.
Building these speakers was straightforward, but I made a
few changes to your design that may be worth
considering. First, I increased the thickness of
the front baffle and the back to 1 ½ inches, rather than
your indicated 1 and 3/4 inches respectively. I did
this because I wanted a slightly stiffer baffle, and I
was concerned about the material's thickness at the base
after cutting the ½ by 3/8 inch reveals at the top of
the base. I also had only a limited amount of ½
inch MDF. Secondly, I slightly raised the base (1
½ inch) to help accommodate the crossovers. I
compensated for these changes by increasing the depth of
the cabinets, keeping the internal volume the same.
The bitumized felt, mass-loading panels proved a problem
where I live ( a small town in rural Arizona, USA), and
the auto-parts offerings seemed rather expensive. I
solved the problem by using a product called
"Whispermat", a 1/8 inch rubberized base bonded
to ½ inch acoustic foam. The Whispermat was attached to
all interior panels with adhesive- not brads or
staples. According to some on the web, Whispermat
provides 90% of the effectiveness of "Black-Hole
5" at a small fraction of the cost, you may want to
try this product.
To accommodate the crossovers, I increased the depth at
the base for the crossovers, and built a modified plinth
around the cabinets, thus providing a little more
space. This plinth is composed of 1 ½ inch square
pieces with a 30 degree miter on the tops, beginning 1/8
inch wide of the cabinet sides. This miter helps
reduce the chunky look of squared sides. I did not simply
build a solid base and attach it to the bottoms of the
speakers because again, I wanted as much depth to the
crossover compartment as I could get. From an aesthetic
perspective, I really like your treatment of the base,
with a shadow space between the cabinet walls and the
base, but implementing your idea was a problem.
As for the rest of the construction, all went as you
advised. I cut ellipses in the braces, but then
rounded them over and sealed the edges with wood-workers
glue diluted about 25%. I also rounded-over the
inner woofer cut-out as you suggested, and sealed the end
grain. By the way, this sealing of end-grain in
internal panels is suggested by George Short of
"North Creek". In addition to the
Whispermat, I also mounted polyfil to the tops, bottoms,
and behind the woofer, and added some loose batting in
the top chamber behind the tweeter, behind the woofer,
and in the chamber below the port. For the port, I used a
3 inch tube, and adjusted for the greater diameter by
shortening the length slightly.
Fitting the crossovers inside the bottom of the cabinets
was a major concern. I wanted to use foil
inductors, and the 2.2 Mh inductor is nearly 3 ½ inches
in diameter, while the .68 is only marginally
smaller. I basically followed your drawing, but
turned the largest inductor 90 degrees to provide a
little more space. This explains my changes to your
design in order to provide more depth in the bottom of
the cabinet, and why I built the plinth the way I
did. Because of size constraints, I used 14 G Alpha
Core for the LP and 16 G for the tweeters. I also
used Mills resistors and Solen caps.
The finished cabinets are veneered in Pau Ferro, a
Bolivian hardwood, with black lacquered bases. 3/4
inch brass cones are mounted under the base, and improve
image focus. The narrow baffle, relatively modest
height, and depth makes an attractive addition to our
home.
I have included 2 attachments to this email with pictures
of a finished speaker and the crossover.
Okay, so how do they sound?
I have spent over 100 hours breaking the drivers in and I
can finally offer some comments.
First, I had a problem with the cabinet stuffing.
The speakers, while exhibiting extraordinary
soundstaging, depth, and imaging, as well as a wealth of
detail, seemed to be constricted. Dynamics were not
what I expected, and there was a recess in the upper bass
through the mid-range. This was noticeable on
instrumental music, especially where the cello played a
prominent role, and continued up through soprano
voices. The speakers were quite listenable, and in
most respects excellent, but there was something
wrong. Finally, I removed the loose polyfill from
the cabinets- there were only a few ounces in each, and
the transformation was quite dramatic. The speakers
opened-up and the missing dynamics suddenly made an
appearance, as well as a substantial increase in upper
bass and lower mid-range weight. With this simple
change, I now had a better appreciation of your speaker's
potential.
Tonal balance is excellent, perfect for my own personal
preference. As mentioned above, bass is solid and
articulate, full without being flabby. The
orchestral foundation is well reproduced.
Mid-range, especially voice is palpably reproduced.
In a darkened room, the recreation of voices is
spooky. On several occasions, my dog thought
someone was hiding inside one of the speakers!
Treble is clear and relaxed- violins sound wonderful,
while triangles and cymbals have a believable
shimmer. Brass has the proper combination of rasp
and weight, something difficult to describe but readily
apparent. You are quite correct in describing these
speakers as suitable for jazz, rock, classical, or
chamber music, but I get the sense that they become a
little congested with large-scale classical
recordings. On the other hand, I have never heard a
better vocal reproduction, especially female singers!
Soundstaging and imaging are first class. These speakers
are replacing a sub-satellite system consisting of Vifa
P13/OW1 monitors and a sealed 15 inch subwoofer. I
am pleased to find a sub unnecessary with these
speakers. The previous combo had very precise
imaging and very deep bass. With the TLJ, even
though they do not reproduce the bottom octave, images
appear larger- every part of the presentation is bigger
and fuller. Soundstage is very wide, with
appropriate recordings extending beyond the outside edges
of the speakers. Depth is sensational, nearly as
good as I have ever experienced. At first, imaging
did not seem as precise, but with familiarity I believe
the images are much more three-dimensional and recreate
real bodies in an acoustic space, rather than the
relatively one-dimensional but pinpoint imaging of my
monitors. The drivers you selected are very
detailed and I believe make a significant impact on both
their imaging and musical satisfaction. Nuances of
orchestral scoring are clearly reproduced here in a
totally effortless manner. This is not hyper-detail
like one finds in certain ribbons or older metal cone
drivers, but rather a believable recreation of the
musical event. I used to think that the lowest
octave played a key role in reproducing space and
ambience, but with these speakers, I now see that detail
on the micro-dynamic level is at least as
important. Even without the full bottom octave,
these speakers provide a compelling sense of the
recording venue.
I have only one, rather small problem with these speakers
and that concerns their efficiency. Although I have
not made any measurements, I guess their efficiency is in
the low 80s db. range. I am pushing my 60 watt tube
amp to its limits on orchestral passages, and although I
have not audibly clipped it yet, I need to be
careful. At 60 watts, the speakers certainly fill a
moderately sized room, but there is simply not enough
head-room to play at concert-hall levels.
Unfortunately, I can not even consider trying these
speakers in triode mode, with only 30
watts/channel. This is a shame because these
speaker's palpability would probably be even more
dramatic with the sweetness of triode. For those
running solid-state amps, they will probably want around
200 watts to play at high levels. I should put this
into context, since according to my family, these
speakers play very loud already!
While on the topic of ancillary equipment, I want to
share a few other observations. First, the detail
these speakers possess make them a fine analytical tool
for evaluating up-stream components. For example, I
have been experimenting with different NOS tubes in my
amp, and the speakers clearly respond to the different
brands. After finding a good match for my
equipment, the NOS tubes substantially increase the image
focus, soundstaging, ambience, and palpability of these
speakers. I also tried different AC cables on my
pre-amp- a component I have lived happily with for nearly
fifteen years, and the improvement was readily
apparent. Until now, I had been convinced that
power cords were over-hyped tweaks- not anymore.
Although I have decent equipment, I doubt I have reached
the limits of what your speakers are capable of.
Now a few questions for you. I recently noticed on
your website that you are working on a 3-way version of
these speakers. What are your goals for this
project? What are you trying to improve? I
assume you are trying to address the occasional mid-range
congestion, is this correct? Would this new
configuration improve sensitivity, or does the
sensitivity of the W18 limit this? Also, I have not
found any information on the mid-driver you use, not even
on the SEAS website. Is this brand-new, or is there a
different catalog number? My best guess is that it
is an Excel 4.5 inch. metal mid. Is this
correct? How is the project coming? I like
building cabinets in my spare time, and would consider
building a pair if the improvements justified the costs.
In closing, I want to thank you once again for your
generosity in sharing your talents and efforts, I am
thrilled with these speakers and you should know that I
think of you whenever I play them.
Kevin Reid
Flagstaff, Arizona
USA
Comments to Kevin's TJLs:
Thanks a lot to Kevin for a
thorough review of the TJL loudspeaker. And thanks
for allowing me to publish your response on my website.
You are the first person to respond this way to the TJL,
actually I have no idea if anyone ever build it, despite
a substantial amount of mails and questions.
To
your questions at the end of the mail:
Any speaker is a compromise in terms of cost and
performance and no wonder the commercial two-way
floorstander concept is popular - simplicity and
relatively low production costs compared to the more
elaborate three-way. I was/am a bit worried about
releasing the magnesium driver constructions. Despite
very low production tolerances on the SEAS drivers
compared to e.g. Scan-Speak, the fine-tuning of the
needed notch-filters to eliminate cone break-up is
mandatory to get the best from the set-up. One of the
problems that are shared by most 6" +1"
two-ways is the need to crossover to the tweeter around
2500-3500 Hz, where really any 6" driver will start
beaming when the wavelength equals the diameter of the
cone. Most 6" drivers will have a membrane diameter
of some 14 cm = 2460 Hz and apparent compression on
more complex material will start making a noticeable
impact on performance. Thus the - almost retro - idea of making a
three-way with a 6" + 4" + 1", maintaining
the same drivers but adding the W11 or W12 SEAS magnesium
drivers for midrange at around 800 Hz. I have had a pair
of W11 very cheaply and will use these for my final TJL3W
construction - but at the same time implement the
W12, which is destined for a coming 4-way construction. The only apparent
difference between the W11 and W12 is the chassis - which
may have a minor impact on sound, but shouldn't
affect technical performance or require any changes to
the crossover. I expect them to be readily
interchangeable but sound slightly different. We'll see.
In
the Seventies we wouldn't hesitate to add a 4"
driver for the upper midrange and lower treble, simply
because this is the optimum size for a driver handling
this frequency range. The drivers may have been more
tolerable and crossovers were often simple 1st orders.
Making a point of crossover around 800 Hz is difficult -
or was difficult - but with the availability of PC-based
measuring systems and not least great simulation
programmes, this has become much less time consuming. And
for the diy people, we have all the time needed to do the
work and adding a mid-driver doesn't add considerably to
the overall cost. Whether it will be worth while will
have to be seen - and heard. My first step in
this direction was the SP38/13 where I used the 3806/8200
driver, a 38 mm tweeter, easily handling up to
above 10 kHz. This allowed me to take the point of
crossover down to 1600 Hz with improved sound compared to
the SP95 or SP98. So, the purpose of this 3-way exercise
will be to gain a little more speed and sparkle from the
upper midrange/lower treble and enhanced
dispersion characteristics.
The overall sensitivity will not rise due to this change
and it's one of the TJL's compromises. I could have
used the W18EX001 and get an extra dB or
two but with the sacrifice of low-end extension. I have no
problems with the 2 x 60 W Copland valve power amp, but
agreed, these speakers need a sturdy amplifier to get the
best of it. A 2½-way TJL was also considered, but then
the impedance easily falls below 3 ohms and this is
not valve territory either. The Acapella SE has the sensitivity needed
for most valve amps around 40-60 watts but size, cost and
complexity is another issue here. Compression on
large orchestral works? Hmm.... I went to a HIFI show
recently to hear the mega-buck B&W Diamond and yes,
they have an incredible bass performance but I was
disappointed to hear compressed midrange from the 6"
kevlar mid-driver. I mean, how much membrane area does it
take to get midrange right and reproduce a symphony
orchestra? I've heard the second biggest Focal speakers
and they come close having 2 x 6" for midrange.
I case you want to contact Kevin: kevinsreid@att.net
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