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Question: Have you come across anyone with tips on
how to develop the TLS80 - certainly by replacing the drivers as they grow old, maybe
in other ways. They have a wonderful sense of largeness and bass depth, but I confess
the mid range does not now compare with the best of modern speakers.
Besides doing all the "standard/simple" tweaks, the biggest weakness
of the TLS80, which is common to most speakers of that era, is the XO. The next big
weakness would be too many tweeters. Then i'd think about replacing the B110.
Fortunately the enclosure for the B110 is in about the right place unlike the
Atkinson TL -- which uses a B110/B139 and even more tweeters -- and it's mid enclosure
is too close to the floor.
So in order of execution this is the approach I would take.
- "Standard/Simple" tweaks (these are intended as general directions
to go as opposed to specific directions as what to do).
- Better wire.
- Make sure the cabinet is "tight". This might mean extra bracing
(extra bracing has to be done such that it doesn't use up too much space), caulking,
etc. Attention to the baffle might be particularily effective (ie a 1" x 1/2"
strip vertically on the back of the baffle between the B139 and the rest of the drivers)
In the TLS 80 particular attention should be paid to the mid enclosure. The mid enclosure
is a cardboard tube. Impregnate this inside & out with a liquid stiffening material.
One could use something like West System epoxy but probably most convienient and
way less toxic (ie you could do it in the living room) would be a puzzle-coat
like substance. I am using a brand called MOD PODGE which I find in craft stores.
It looks & smells like runny white wood glue. You apply 3 or 4 coats with an
appropriate sized paint brush. (reports back from England confirm that this makes
a substantial difference)
- Duct Seal*. This is the putty-like stuff pipefitters use to plug holes
with. It remains "plastic" forever (I am recycling stuff I first applied
20 years ago). A layer of this should get applied to the baskets of the B139 &
the B110 to damp out parasitic resonances. Apply some to the ouside of the mid enclusure
as well.
*(or plasticine or any of many other damping compounds).
<the above are useful on any
speaker>
- Play with the mid-range enclosure damping. Things like layering from the
back a gradation of damping material to make the mid box more like a TL. dense foam,
less dense foam, wool/dacron mix or fiberglass or miraflex (getting less dense as
you get closer to the B110). A more drastic move would be to extend the entire mid
cabinet out the back of the speaker and leave it open making it into a real TL.
- play with ways of minimizing the grill cloth holder diffractions.
Ideally both the grills and the aluminum inserts to hold them would go away. If this
doesn't meet with SAF then a new grill with minimal structure offset from the surface
of the baffle.
All the above fall into the doesn't cost much, just some elbow grease & ingenuity
required. I have yet to run across a speaker where these tweaks didn't make less
than subtle (usually dramatic) improvements.
The following are in the class of throw money at the problem,
and can make even more dramatic improvements:
- Tweak the passive crossover.
- Multi-amp. This system should be bi-amped at a minimum. And with a fast
XO. The B139 has some nasty resonances that with the 12 dB/octave XO @ 400 Hz decidedly
color the mids. When we were building speakers using the B139/B110 in the late 70s
a 200 Hz 18 dB/octave XO made a huge difference. Nowdays I would use a LinkWitz-Riley
24 dB/octave XO and tune it to the baffle-step frequency (or a little lower), which
in the case of the TLS 80 should be about 225 -250 Hz (baffle width of 18 inches).
- Replace the 2 Coles with a single tweeter. Today there are alot of way
better tweeters available than were available when the TLS 80 was built. ScanSpeak,
Vifa, Focal, Raven, on and on. Take a visit to Bob's
LDGS and go shopping. Now the hard part about this is the XO. If you decide to
tri-amp then no problem, it is easier to integrate the tweeter with the B110. If
not then you would have to design an appropriate XO. That is a much bigger challenge.
A more appropriate approach might be to do 6 and 7 together at the same time and
use someone elses already well worked out passive XO.
- Replace the B110*. If all active XO then just pick a good one. I just
signed up to get some Seas MP14RCs (Tim Garvey chakodile@hotmail.com) that a BASSList
member is trying to get enuff people together for a caselot. There are lots of other
good mids. If you decide to passively XO the mid & top then you should look for
an already designed 2-way minimonitor with a 5" mid/bass and use those for mid/tweeter/XO.
The Vifas in the TLb are a good example (and there is no simpler XO) -- cost of drivers
and XO for both your TLS80s about 125 USD.
* and you could mail those to me ;^).
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