So does a MLTQWT actually sound like a TL?

[pinkmouse]

Well, thanks to the kindness of another member here, Jamie F, I have aqquired a pair of classic drivers, Kef B139 SP1044s, in return for a few bottles of ale!

I have run them both through Speaker Workshop to check parameters, and they all match up to the published stats pretty well. I spent the best part of a day running them through MJK's worksheets, and came up with a pretty good design, a single fold box with a line length of 120", tapering from 1.5 Sd down to 0.5 Sd. Conventional, but with a few woodworking twists I might build in.

However, I then had a quick play with the MLTQWT worksheet, and came up with some interesting other possibilities. Normally, I would just build test boxes of both types and compare, but lack of time and funds are prevailing currently.

So, to the $64000 question. I love TL bass, to me it is the only real way to do bottom end, (perhaps dipole is close, but I don't want to get into that at the moment). I have owned and built BRs and sealed, but no matter how optimised, never been totally happy with the results. So, does the ML port on the MLTQWT sound as good as true TL, or do you get those port artifacts typical of BR boxes? Opinions please from those that know what I mean, I don't want this to devolve into a meanless debate about box type, just relevant comment from those that have built and listened to both and can offer valid comparisons.

cheers

al

[planet10]

An ML-TQWT -- ie an expanding TL with a restricted terminus and the driver offset so as to kill off the 1st undesirable resonance uses geometry tricks to get as much low pass functionality before damping as possible... small amount of damping means more bass reinforcement. Left with low damping, you will have the double saddle of a BR, similar group delay, but the big advantage of using th e qaurter-wave resonance to your advantage.

A traditional TL with the driver at the end will need more damping -- add enuff damping and it becomes aperiodic and one of the impedance bumps decreases and you start getting group delay closer to sealed, but less reinforcement of the bottom. Of course you can damp the ML-pipe to be more aperiodic as well.

Did you try anything with steeper taper, shorter, and an offset driver?

dave

[pinkmouse]

Originally posted by planet10
Did you try anything with steeper taper, shorter, and an offset driver?

I suspect I may be too traditional in my approach to what a TL should be to get the best benefit from Martin's wonderful worksheets. I really must try harder to throw away my preconceptions.

The problem with the ML design is as I suspected, the group delay and double impedance peak really will have the negative BR type results I am trying so hard to get away from, so whilst it may suit some, it's not what I want.

Time for me to re-read Martin's paper again and start thinking out of the box...

[planet10]

Originally posted by pinkmouse
re-read Martin's paper again and start thinking out of the box...:

Download the tables... plug the B139 into it and grab the 10:1 line as a starting point...

dave

[Puggie]

We have a set of those Kefs in some old Lentek monitors at work, they are a TL design, damn long 3 fold design, matched with the Kef midrange from the Rogers LS3/5 and T 27 tweet.

[Bricolo]

Hi Al,

Have you tried a ML-TL?

[pinkmouse]

Originally posted by Puggie
We have a set of those Kefs in some old Lentek monitors at work, they are a TL design, damn long 3 fold design, matched with the Kef midrange from the Rogers LS3/5 and T 27 tweet.

Gosh, Lentek, now there's a name from the past! That driver line up is very common in '70s vintage systems, much as the LS3/5 variants became a common feature in most manufacturers catalogues. Personally, I never liked the B110 as a mid much, great for plum voiced 1950s BBC announcers, but no use for music.

[pinkmouse]

Hi Briccolo

I must admit, no. If you have never heard real TL bass it's hard to describe what my point is, but the definition and ambience just put ported designs in the shade. Therefore, my first post. I feared that any kind of ML would affect response, but hoped that it might not be the case, and there was a possibility of TL Nirvana in a small box. Still, seems not to be...

Time to crack on with Dave's suggestions.

[Puggie]

Originally posted by pinkmouse


Gosh, Lentek, now there's a name from the past! That driver line up is very common in '70s vintage systems, much as the LS3/5 variants became a common feature in most manufacturers catalogues. Personally, I never liked the B110 as a mid much, great for plum voiced 1950s BBC announcers, but no use for music.

We have all sorts of old BBC crap knocking about, loads of LS3/5s, 5/8s and 5/9s, Spendors, Genelec 1032s (5.1 setup with sub, very very lame IMHO, not a nice setup) and even some nice speakers (ATC SCM20A, 100A, and 100ASLs in a 5.1 setup).

I'm not a fan of the B110 either, might have some Kef T27s knocking about though if you fancy a completely KEF based project.

[planet10]

Originally posted by Puggie
I'm not a fan of the B110 either, might have some Kef T27s knocking about though if you fancy a completely KEF based project.

In the early 80s i built up a pr of MTM B110 isobariks that i quite liked... way better drivers today thou.

dave