Tom, I am following your experiments with much interest, but your last two =
posts have contained Picasaweb links which give me problems (like the one b=
elow) - they say simply "Sorry, that page was not found." Is it just me bei=
ng daft ?
Chris
--- In "tk7859" <> wrote:
>
>
>
> --- In "tk7859" <g0sbw@> wrote:
>
> > I had completely overlooked that the MX391 is, in fact, a Wl183 already=
mounted on a very small boundary and does therefore might have some bounda=
ry effect benefit as is. I wonder by what amount the effect is increased b=
y increasing the size of the boundary - to 5 1/2 inches square in my case?
> >
> > This thought raise a second question. Will my EM172 capsules perform =
in a similar way to the MX391s if I reduce the size of their boundary to sa=
y, a 3 inch diameter disc. My limited knowledge suggests they will, but I =
do not have the skill or equipment to test this.
>
> Hi All
>
> On the other hand I could just build one and give it a try.
>
> So I did that.
>
> I planned to use 3 inch plywood discs because they would make a good fit,=
supported by rubber bands, inside the modified poly pipes mentioned in my =
previous post. However, I came across a couple of 3 inch diameter plastic =
tops from Cringle crisp/chip tubes. The EM172s were easily fitted onto the=
se and suspended at the ends of the poly pipe. The sixth, seventh, eighth,=
ninth and tenth photos, in the "two into one blimp" album start with the n=
ew rig fully clothed and follow its undressing thereby demonstrating how it=
was put together. The album is here:
>
> https://picasaweb.google.com/G0SBW.PM/TwoIntoOneBlimp
>
> The next job was to test it against a well performing largish boundary ar=
rangement. I chose the lightweight Shure MX391 equipped boundary (which pe=
rformed OK in comparison with a similar AT3032 equipped boundary. Photos =
11 and 12 in the above album show the rigs as tested.
>
> The weather forecast for early this morning was reasonable; so 4 am found=
me setting up the test in my back garden. The weather was not perfect as =
there was a 10/12 mph wind with gusts. Because both the rigs under test we=
re PIP powered I used a HiMD minidisc for the MX391s and the LS-10 for the =
small barrier EM172s. Both recorders operating 44.1/16
>
> Recording started at 4:30, while still dark, and continued for just over =
an hour. Because of the darkness, and lack of a flash light, recording lev=
els were set with more luck than judgement. As it happens, the recording l=
evel was fairly evenly matched on both recorders (the settings were "15" on=
the HiMD and "high 4" on the LS-10). Other than picking a suitable snippe=
t, adding fade-ins and fade outs and then converting to 320 MP3 the recordi=
ngs are as taken. There is a little wind rumble in places but, thankfully,=
no aircraft noise - there are few flights at this time in the morning. Th=
e comparison recording is below with the MX391 recording being the first 4 =
minutes followed by the same 4 minutes as recorded by the EM172
>
> http://soundcloud.com/g0sbw/new-blimp-test-mx391-vs-em172
>
> The recordings are not vastly different. To my ear the EM172 small bound=
ary rig sounds a little more detailed and smooth? The last two photos in t=
he Picassa album above show the spectrogram and the waveform for the .WAV f=
ile.
>
> Prolonged listening might throw up more differences, but for now the new =
smaller boundary rig gets my vote. It is also some 3 to 4 ounces lighter t=
han a similarly set up EM172 larger, square boundary, rig. It currently i=
s my chosen handheld rig for the nightingale walk. Apparently the smaller =
boundary size makes little difference?
>
> Any comment, critical or otherwise, is welcome
>
> Cheers, TomR
>
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