Hello Duke,
You
bring up a problem about first order crossovers that is technical
enough but one that any speaker designer worth their salt should be
able to solve with the array of currently available computer based measurement
systems (I use MLSSA, LMS, and CLIO) by running simulations.
With
regard to the driver configuration of the Starship SE, it is not
inspired by “the
four-woofer, tweeter-in-the-middle cluster from the bass cab world.”
The bass cab world is not a part of my orbit. Instead the Starship SE design is a result
of step by step research and development that dates back to the
1990s.
The
provenance of the Starship SE has its origin in the NSM Audio Model 5
that was reviewed by Soundstage back in 1999 That review can be found
here.
Note the drivers used in the Model 5 and their configuration. Having
successfully used a SEAS concentric driver in my NSM Audio 20M also
reviewed by Soundstage here,
I consulted with the SEAS engineers at CES in the 1990s as to whether
or not they had a free standing version to the tweeter used in the
concentric driver that would allow me to simulate the close coupling
of woofer and tweeter approximating the relationship in the coax.
They suggested the tweeter used in the Starship series which I imported
directly from SEAS because it was not available in the US. Subsequently it was distributed by Madisound.
The
first speaker designed in the Role Audio Starship Series—a modular
line of speakers-- was the Kayak, which was based on the Model 5 and
had the same driver configuration. The Windjammer is the transmission
line version of the Kayak. Note something very important: I am using
drivers that work well in both acoustic suspension and in my
transmission line designs. Next came the Discovery. The Enterprise is
the transmission line version of the Discovery. To develop the
Enterprise I had to solve the technical issues involved in mating two
transmission lines – a configuration I had not seen before or
since. So the Enterprise is essentially two Windjammers in one
cabinet. Later on came the challenge of designing a speaker with
twice the power of the Enterprise – the Starship SE. The first
speaker with four transmission lines, to my knowledge. If you draw a
vertical line down the center of the Starship SE you can see that it
is essentially two Enterprises or four Windjammers. The Starship SE
tweeter is different to accommodate the increased sensitivity of the
Starship driver configuration. Note in the Starship SE the drivers
are spaced even closer together than in the Enterprise. The pedigree
of the Starship SE is well established in the series of reviews of
the Kayak, Discovery, Windjammer, and Enterprise.
Now
onto a different issue. No! I am not using mid-woofers in the
Starship that
have “the most powerful motors” you “have ever seen in such a
small woofer whose other parameters are good for making bass.”
Quite the opposite. What I am using is a different transmission line
technology. The motor of the woofer is not
“more
like what you might see on a good 6" or 7" woofer.”
And the design is absolutely not
“very
demanding of the drivers.” Quite the contrary, compared to ported
or acoustic suspension designs at a similar SPL these woofers are
hardly moving. Reduced cone motion and reduced distortion at similar
SPL is one of the hallmarks of transmission line designs.
I
think this misunderstanding of my designs is what led to your earlier
comments about the NSMT Chorus and your disbelief that the “Chorus
has a sensitivity of 96 dB, bass extension to 35 Hz, and an internal
volume of about 1/2 cubic feet.” That level of performance inheres
from the short transmission line technology and TL-ABC port tuning
that I have developed.
There
are several reviews of Role Audio speakers with even smaller internal
volume: the Sampan FTL (.12 cubic feet), Sampan (.13 cubic feet), and
the Windjammer (.36 cubic feet) that have 35 Hz to 20 kHz frequency
response. A Google search of the smallest speaker, the Sampan FTL
which weighs 4.5 pounds and is 8
X 4 X 9.5 inches, will show an image of a composite MLSSA
measurement of the TL-ABC version
that is +/- 3.5 dBs from 35 to 20kHz. Hard to believe but true. The
Sampan FTL was first shown at AudioKarma
Fest ‘07 and
there are comments online about its performance from that showing.
The
imaging, soundstaging, and bass performance of the Starship SE should
not be surprising to anyone who owns or has read the reviews of the
Windjammer and Enterprise, considering the Starship is essentially
four pairs of Windjammers or alternatively two pairs of Enterprises.
