(I'm hoping that this message will attach itself intelligently to the
thread which begain this past October ...)

As I mentioned, I was able to con some friends in Germany into making
detailed measurements on one of my Royer SF-1s (which was very recently
checked over by Royer, incidentally). In the horizontal plane it does
have a nearly ideal bidirectional pattern, while in the vertical plane
it has a good pattern up below 8 kHz, by which point it has off-axis
losses that distort its pickup pattern.

This fits with what one would expect given the ribbon's shape--in the
vertical, it's like a very large diaphragm while in the horizontal, it's
like a tiny one. That's fine as long as people know about it. I wouldn't
use this type of microphone laterally as the "S" mike in an M/S pair, but
if its body is placed perpendicular to the sound source, it should offer
really precise imaging capability.

All in all the frequency response curves at all angles in the horizontal
plane were smooth and very close to parallel with each other--but that's
just another way of saying that its polar pattern was accurate.

(Pedantic proposal: If anyone here doesn't see why those two facts
relate in that way, it might be worth your trouble to think it through.)

--Having lavished this praise on the microphone, let me point out a few
problem areas. One is that this excellent response extended only to 11
or 12 kHz. Above that, there was a very noticeable rolloff. (It's hard
to interpret Royer's published frequency response graphs since the graph
"paper" isn't divided in any rational way--you sometimes can't tell what
frequency is supposed to be what.)

Another problem--potentially a big one--I mentioned in another thread:
the output impedance of the SF-1 is 300 Ohms as stated--already rather
high for a studio microphone--but this figure applies only in the
midrange and above. At lower frequencies the output impedance rises
until around the resonance point of the microphone (below 100 Hz), it
significantly exceeds 1 kOhm. I don't know by exactly how much, since
the measurement was literally off the chart by then.

For a microphone to have so high an output impedance anywhere in the
audio range is a rather severe problem in my view. It would definitely
be preferable (for reasons of noise and interference as well as the
avoidance of frequency-dependent losses) for the microphone to have a
built-in preamp--assuming that the circuit provided a high enough
impedance at low frequencies.

--One of the main reasons I had for sending this microphone across the
pond was to learn more about the characteristics of ribbon microphones
in general. It is said, for example, that they don't have the off-axis
high frequency peaks which are typical of condenser microphones. I was
greatly interested to know if that was true, because I have heard that
type of peakiness a fair amount, and I consider it a real threat to the
kinds of stereo recording that I am interested in doing.

I think it's fair to say that from the measurements I was shown, this
particular ribbon microphone really is largely free of off-axis peaks.
The frequency response was not extremely flat, but the polar pattern
was highly uniform and that includes a "near-absence" of peaks. For a
dynamic microphone these results were really excellent.

However, I was also shown a set of curves which were run under identical
conditions on a small-diaphragm, single-membrane bidirectional condenser
microphone of a type that I often use--and the same thing could be said
about its response--except that it went up to about 15 - 16 kHz, while
that of the ribbon microphone rolled off above 11 - 12 kHz, as I've said.

For me, this all confirmed the basis for the high opinion which ribbon
aficionados have of good ribbons--but not the anti-condenser rhetoric
which some of those same people emit at times as if by reflex. The
rhetoric may apply with more fairness to large, dual-membrane condensers,
which tend not to have such good polar patterns and some of which have
peaky off-axis response (mixed in with a general drop-off of response
to the sides--e.g. what a U 87 looks like at 90 degrees). But I wish
that people wouldn't take those characteristics to be emblematic of all
condenser microphones; it just isn't so.

Also, the frequency response of the condenser microphone (a Schoeps--no
surprise there) stayed within fewer dB of flat response all across the
main part of the range, where the Royer has more bumping and tilting.
Not narrow peaks--more like anatomical features which correspond to
definite aspects of the ribbon mike's sonic character. Either type of
response may well be considered desirable, but it's interesting to me
that even the most highly touted ribbon microphones (consider for example
the Coles 4038) are never very close to flat, as compared with the
flattest condenser microphones. In fact I'm quite sure that whenever a
Coles 4038 or a Royer is being tested for quality assurance purposes, a
condenser microphone is what's being used as the standard of comparison.

So some day before I die, I would really like to hear and try out the
very flattest possible bidirectional ribbon microphone--or can they not
be made any flatter than this? (I'm just asking.) It seems to me that
until then, we're hearing big frequency response effects mixed in with
whatever might be fundamentally different about "ribbon sound" versus
"condenser sound"--and that's no way to reach reliable conclusions.

David Satz wrote:

So some day before I die, I would really like to hear and try out the
very flattest possible bidirectional ribbon microphone--or can they not
be made any flatter than this? (I'm just asking.) It seems to me that
until then, we're hearing big frequency response effects mixed in with
whatever might be fundamentally different about "ribbon sound" versus
"condenser sound"--and that's no way to reach reliable conclusions.

They can be made much flatter. Try the RCA BK-11.

The Coles 4040 is also worth checking out, although it has a presence peak.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article writes:

For me, this all confirmed the basis for the high opinion which ribbon
aficionados have of good ribbons--but not the anti-condenser rhetoric
which some of those same people emit at times as if by reflex. The
rhetoric may apply with more fairness to large, dual-membrane condensers,
which tend not to have such good polar patterns and some of which have
peaky off-axis response (mixed in with a general drop-off of response
to the sides--e.g. what a U 87 looks like at 90 degrees). But I wish
that people wouldn't take those characteristics to be emblematic of all
condenser microphones; it just isn't so.

I suspect that the reason for this is that most people's experience
with bi-directional mics today is either with the Royers or large
capsule Chinese condensers. There aren't a lot of small diaphragm
bi-directional mics in personal and project studios, and that's where
most of the mics are these days.



--
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