Loudspeaker Designs and Articles for the DIY Enthusiast
|A Design utilizing both
Where should I begin? This started out as a design exercise, and not necessarily a
viable design for popular consumption, but turned out sounding so nicely that I felt
it had some merit. My first thoughts were to use 1st order slopes for the mid and
woofer, but once I had modeled the measurements, I found the required 3 octave
overlap for the 1st order transfer functions would be problematic. I also wanted to
stay away from a complex crossover. (Remember my initial criteria was to stay
below $350.00.) I found I could maintain 1st order slopes for about a octave either side of the center frequency, but then the increased to a higher order
slope. However, by keeping the drivers in phase quadrature, I could obtain a reasonably flat response with little phase variation over a fairly wide frequency
band. This sparked my memory of an article written by John Kreskovesky on Quasi Transient Perfect 2nd order crossovers.
Looking at John’s article and spreadsheet, I found I had inadvertently stumbled onto a variation of this topology in my design. Due to the fact that my design
is not exactly transient perfect for a couple of reasons, (one being the tweeter network) I call mine a Quasi-Transient Perfect design or QTP. However it
does do a more than passable job of passing a 1 kHz square wave relatively unscathed.
For those wanting to try their hand at a ‘full-on’ TP 3 way utilizing the filler driver concept, I’d suggest the Peerless and TB drivers of this design, as well as s
suitably robust tweeter such as the Seas 27TBFC/G would be a good starting point. –These will be at significantly higher costs compared to the Mavericks,
To easily audition the differences between the QTP and a conventional (hereafter designated a NTP) transfer functions of the Mavericks, I designed 2
woofer crossover topologies. The ‘conventional’ design more closely emulates a typical 2nd order crossover and reverses the woofer driver polarity. The
QTP version utilizes the woofer connected with normal polarity. In both cases the tweeter is connected out of phase
While I consider the Mavericks an 8 ohm design, the impedance profile slowly drops in the upper midrange and treble to an impedance minima just below 5
ohms, before increasing back to 12 ohms by 20 kHz. While the impedance phase is relatively benign, the Mavericks impedance may cause some minor
response variations when powered with tube amplifiers, and some experimentation may be required to determine the best impedance tap for a given tube
amplifier. Solid state amplifiers rated for 8 ohm speakers will be unlikely to have any issues driving this speaker.