"dangling entity" wrote in message
om
"Arny Krueger" wrote in message
...
"dangling entity" wrote in message
om
Wouldn't BagEnd (or something like that) be a better example of the
EQ boosted system you described?
Why do you say that?
Does this name not ring a bell, or are you saying it doesn't fit the
description at all? I was to understand that the product (if I got
the name right, that is) is basically a woofer put into a
smaller-than-usual sealed box, and a complementary bass boost is
applied in the built-in amplification to give the rated frequency
response.
I guess my confusion relates to the fact that you mustn't have seen
Nousaine's post to this thread that discussed this specific product at
length. Further investigation shows that Nousaine's "bag end" post is only
posted in RAO, which means that you're posting from one of the other groups
that this thread is generally cross-posted to.
Here's a link to Nousaine's "bag end" post:
http://www.google.com/groups?selm=20...6%40mb-m23.aol
..com
I think you'll find it interesting.
The Sunfire drive is basically designed to "live" in a small box (in
conjunction with a similarly aspiring passive radiator), inherently.
I don't think so. The box is so small that the system resonance is closer to
50 Hz than 20.
Whether or not there is EQing involved, I'm not exactly sure. It's
really just an extreme take on a conventional vented design, AFAIK.
AFAIK it needs lots of eq.
How does Sunfire do it wrong, btw?
Presumably driver parameters have a lot to do with it. In short, not
enough Xmax. The passive radiator needs to have *enough* Xmax, as
well.
Once upon a time I saw Dumax test results for a larger Sunfire woofer
driver. I can't remember too many details except that at the time,
they were considered to be suboptimal for a product that would be
loud and linear down to 20 Hz.
Well, I wouldn't say Sunfire drivers are exactly lacking in the Xmax
category. When considering 20 Hz output however, just about anything
short of a large diameter driver is going to stress the Xmax
capability at even moderate SPL's.
Not quite. There are some drivers in the ca. 12" category that have soooooo
much Xmax that they can move more air than just about *any* 15 or 18 inch
driver. Here's an example:
http://www.jlaudio.com/subwoofers/pdfs/13W7_MAN.pdf
It's got 1.25 inches of linear Xmax in each direction. 2.5 inches or 64 mm
p-p two-way Xmax. Yup, the cone strokes 2.5 inches with low distortion!
I think the Sunfire subwoofer
products present a sort of odd paradigm between compact form and low
frequency capability. The compact form naturally leads to smaller
driver sizes, but those drivers tend to do well in the low frequency
range where other drivers of similar size would not. The particular
driver parameters in combination with the extreme box loading in a
Sunfire enable a capability that not just any 10" driver (for
instance) could do if slapped into a box of that size. That's one
source of the "mystique", I imagine.
The mystique comes from the advertising.
Here's a fairly detailed review of the sunfire. It says that the drivers are
9 inches in diameter and have 30 mm p-p two-way xmax.
http://www.hometheaterhifi.com/volume_4_1/sunsubre.html.
That said, a lot of people confuse that capability as a means for
"unlimited sub-bass output", regardless of room conditions. What the
Sunfire does, it does fairly well in a *smaller sized room* (which
would unsurprisingly benefit the most from a very compact subwoofer
design). Naturally, if you put it in a medium or larger sized room,
you will need more units to make that 20 Hz-ish range accessible.
That's just plain physics (not that I'm preaching to you), and there's
no way around that- not even for a Sunfire. I imagine a lot of people
had unreasonable expectations for the product when they put just one
in their medium sized room and expected to be palpitated with air
pressure waves. Naturally, just *one* Sunfire unit would find itself
overextended in such a situation, but people were evidently expecting
it to create miracles. That's my take on it, FWIW. 
Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the
permanent magnet circuit of the motor under high current drive
levels (as would likely be encountered with a system that
implements high EQ boosts in the lowest frequency range).
This doesn't seem to be a problem, at least with the Clark
implementation.
It's a phenomenon that effects virtually all VC style speakers.
See item 7 on page 2 of the JL Audio PDF.
Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that care
to expose that sort of information about their product (if they have
even bothered to discern it). I don't believe Clark's Duomax
measurements would necessarily reveal its effects, either, unless
studies are expanded to study (very) large signal inputs, rather than
just standard small signal inputs to determine motor strength.
The Dumax can fully stroke large woofers such as the JL Audio unit above,
which means that it can and does apply relatively large currents to the
UUTs.