Dayton Audio MK-442T Floor-standing Speaker Review

[TLS Guy]

Got 'ya. One of the regrets I have in coming to this hobby late in life is that I never built a pair of speakers myself. Everything I own is off the shelf.

It is never too late to start!

Anyhow, my new workshop is taking place. I hope it will be functional by the end of the week.

Once I get settled I should have time to develop and test some cost effective designs. I won't be running a huge lake place, maintaining tractors, boats and maintaining rural roads. I do have some interesting projects, but not test built and tested.

 

[tn001d]

Anyone have any opinions on how these compare to the pioneer SP-FS52 Andrew Jones Designed Floor standing Loudspeaker ?

 

[Ponzio]

Starting to edumacate myself about crossover's.

Now if I could only stop staring at his ears. Looks painful.

 

[Ponzio]

Part II of crossover design.

 

[NeilBlanchard]

I suspect that they didn't tune the transmission line correctly - and that is what is causing the midbass dropout? This is actually closer to a Voigt tube - the "dead end" section of the chamber (on the front, below the two woofers) is resonating, and is not really part of the transmission line. For it to be a transmission line, the drivers would have to be at the closed end, and the entire length of the transmission line would extend to the opening.

So, it would have to be reconfigured to be a "proper" transmission line. Don't judge transmission line designs by this one - they generally have wonderful bass - they combine the reduced loading of an open baffle with the greater bass extension from smaller woofers, of sealed or ported designs.

 

[ryanosaur]

This is actually closer to a Voigt tube

No. A voigt pipe has the closed end tapered to a surface area of zero and flaring to the open end. This is a classic Voigt Pipe, not folded.

Note, Voigt himself thought this a flawed design.
Weems designed his line on the Voigt Pipe, but found having a small surface area at the narrow closed end improved performance:

For it to be a transmission line, the drivers would have to be at the closed end, and the entire length of the transmission line would extend to the opening.

What you describe has been called Transmission Lines, true, but the most efficacious way of placing the drivers is along the length of the line preferably at the node of the Third Harmonic, then again at the node of the Fifth Harmonic if using a second driver. These placements help neutralize those more destructive harmonics in a manner that Damping/Stuffing the line does not.
Also of note is that having the driver at the end of the line, rather than along the length, borders on the design actually being a Rear-Loaded Horn, especially if it flairs toward the open end.
Lowther Horns are a prime example:

Most modern Transmission Lines tend to be either Mass Loaded designs or built as Tapered Quarter Wave Tubes with the closed end being wider and tapering to the Terminus (see G. Augspurger, M. King).
This post from a forum member shows his TQWT Subwoofer based on Augspurger's program.

 

[NeilBlanchard]

Thanks for the clarifications. There are a lot of variations on transmission lines. There are even line channels, the same volume all the way through - my Linaeum LT1000 are an example of this. There are tapered channels - some get larger toward the vent opening, and others that get smaller.

And another variation is where the woofer(s) are located within the line channel - having the driver at the closed end, is the "simplest" and therefore I like to think of that as a transmission line. The MK442T has the drivers at *about* 2/5ths from the closed end, and that "dead end" portion is going to resonate (whether or not it is straight or tapered), and therefore it is adding an additional element to the idea of a transmission line.

The ideal transmission line (in my opinion) does several things:

* Prevents the reflection of the backwave from the cone - from "bouncing" off the back of the cabinet, and then coming back out through the cone
* Has minimal cabinet pressurization, which minimized structural resonances
* Prevents bass cancellation - this is the main job of any cabinet - it gets more bass from a smaller woofer
* Extends the bass by mass loading the woofer at the lower end of its response with the air / damping within the transmission line

I agree that widening the line channel toward the opening is closer to a folded bass horn. I think tapering it smaller toward the opening is the better way to go. At the top of its range, the woofer acts similar to an open baffle, and as the frequency drops, it transitions gradually to having more and more mass loading. So the bass response is more even, with no drastic change like a ported design can have.

Transmission line designs are the best of all worlds: clarity and speed of open baffle, but better bass from smaller drivers, like sealed and ported designs.