Doug Von Gausig wrote:
> At 05:30 PM 10/14/2002, the highly esteemed Walter Knapp wrote:
>
>
>>Having used both consumer minidisc and pro minidisc recorders, I've got
>>some feel for the difference. Consumer minidisc does not have as good a
>>mic preamp as a pro minidisc does,
>
>
> Hey Walt,
>
> Would you mind giving us a short primer on just what the better pre-amps=
> give us that is lacking in consumer recorders? Lower noise, better
> "headroom", less overloading - what's it all mean from a practical
> perspective in the field?
You do want me to stick my neck out.
I should note here that I'm in the process of sifting my entire
collection of frogcall recordings looking for pieces for a CD to be
produced. In the course of that I'm listening to recordings done with a
Sony MZ-R30, with a number of mics (Shure BG4.1, Sony ECM-MS957, my
homemade parabolic, a Telinga Pro V and some rare others). And to more
recent recordings done with the HHb Portadisc, with the Sony, the
Telinga, a bit from Lang's setup, and a tiny bit from my newer mic
setups. I'm not just listening a little, but dissecting them in detail.
The clearest change points in the quality of recording I could do are
the jump to the Telinga, which occurred first, and then the move to the
Portadisc. I've had a couple seasons recording with the Portadisc. The
most dramatic difference is stereo vs mono. I don't expect to do much
mono from here on. But that's about mics.
Note also, my portadisc is out of the very first shipment into the US,
has a version number of it's software lower than any other I've come
across. It does not have the problems with software that people
attribute to Portadiscs. I sometimes wonder if they are even talking
about the same machine. I won't talk about pro machines in general, just
the one machine I'm most familiar with.
You should note it's a system, it's not a higher quality pre grafted
onto a consumer recorder, the changes go throughout. It is not a highly
expensive pre like the MP2 with the rest compromised to keep the price
down, so yes, as a pre the MP2 is a little better. It's a pretty
balanced system. You will not get anything like a Portadisc just using
a external pre on a walkman.
When I first started using the Portadisc, the sound change that was
immediately noticeable was that it was much cleaner sound in lots of
small ways. When I needed to turn up the gain, it would come up with
much less noise, or the other way of looking at it was that I could turn
up the gain a lot more and still get good sound. And that clipping was
less disruptive.
Let's take your list one at a time. Lower noise? Well, I can put my
Portadisc into record with nothing connected to the inputs, crank the
gain to the peg, crank the headphone amp to the peg and what do I hear?
Nothing, no noise whatsoever coming from the headphones. The level meter
has only the bar at minus infinity, no twitching toward the -60 which is
the next step. At least with either of my MZ-R30's if I do this I get
considerable hiss. Even at lower settings the MZ-R30's are never fully
as quiet.
Now what would happen if you plugged a couple MKH 40's into the inputs
with those settings? On a night like I've been having lately, mostly
fairly quiet insects? Extreme pain, the quiet insects would be a painful
scream, the meter would peg out, massive clipping, your headphones would
not even be happy to say nothing of your ears. You would need to crank
the gain down by at least a quarter, and would want the headphone level
down to half or less.
Do the same thing with a bunch of cable hooked into the Portadisc
inputs (Canure star quad, of course) and the result is the same unless
you touch the bare contacts with something metal, providing a loud hum.
Note if you put the Telinga down on the rug so as to cut off as much
noise as possible from it and repeat the full gain experiment, you will
hear the self noise of the Telinga. Or most of the MKH's I have if you
can muffle their pickup enough.
In other words, the noise in the Portadisc is quite low. This gives you
quite a bit of flexibility in recording.
Better "headroom"? Well, this is primarily a function of your gain
settings, but the Portadisc has a wider usable dynamic range due to it's
quiet circuits and a softer clip. So you can record at pretty low levels
without much problems or being as likely to run into the noise floor (if
using quiet mics). And, of course, at the other end, slight clipping is
almost ok. It's rated at above 120 dB dynamic range.
Less overloading? You can overload the standard mic input of the
Portadisc, but it's harder to do, like feed it the output of the MP2
into it's mic input setting with no attenuation and a pretty strong
signal. And you have effective attenuation options of -15 dB and -30 dB
as well as the line option. The Telinga can fairly easily overload the
pre of a walkman MD, the Portadisc will not be unhappy at all with it.
At the other end of the scale, you can work with mics with less output
than you could with the walkman.
Now, overloading can include clipping. Clip on the Sony MZ-R30's, even a
little bit and it's awful, trashy scratching sounds, etc. Push the
Portadisc into clipping, soft clipping up to a few dB can often be hard
to detect, stronger clipping does mess up more and more, but not so much
the trashy sorts of things. Sound goes mushy, fuzzy, with more and more
nasty overtones. Obviously the A/D in the Portadisc is different as this
is where this sort of thing happens. (and note if you use a external pre
with a walkman you are still depending on the A/D of the walkman)
The short summary is that in several ways you get more options in your
settings that still get good recording. You get more usable gain. With a
walkman you have this narrow range between self noise and overloading,
little wiggle room. And even at the optimum setting a walkman will not
give quite as clean a sound. Of course how much your room to wiggle is
expanded is highly dependent on your mic too.
What's it like to record with the Portadisc in the field as compared to
a walkman MD?
Well, to start with, it's much heavier and larger. Put a neck strap on a
walkman MD and walk around with it on your neck and you would hardly
know it's there. Not so with the Portadisc, you will know it's there,
and if using the original strap will probably find it uncomfortable
after a while. My modification to a new 1 1/2" soft webbing strap does
make it fine for fairly long periods. I can even carry it plus a MP2 off
that strap, though in the long run I'll probably make a custom combo
pack for the pair. Note that when I recorded with the MZ-R30's, I
usually just juggled them in my hands while recording. With the
Portadisc on it's strap, I've got both hands free for the mic.
Next, it can be run one handed for most functions. My experience working
with a walkman MD was that it took two hands to pin it down and work the
tiny buttons, usually with the tip of my fingernails, one slip and it
would easily squirt out of my hands. You had to anticipate what you
wanted to do a lot longer ahead than with the Portadisc and get it into
a holding grip, which was often complicated by juggling the mic as well.
The Portadisc has full size controls, even starting it into record pause
I normally do one handed. That leaves the other hand free for the mic. I
don't have trouble with making noise that gets into the buffer starting
a record going. Many of my walkman recordings have unwanted noises at
the beginning or end. Most settings in the Portadisc are settable even
while recording if you wish. And it's menus are not that multi level.
Easy to get to all settings quickly.
The level display is large and seems pretty accurate. It has a peak hold
function that's useful. It's got a counter that will give you record
time or remaining time, also a display option to read headroom
numerically on the fly. It's also got switchable illumination, a
important consideration for me as most of my recording is done in the
dark. The illumination color is bug light yellow, does not attract
insects. One of the problems using the MZ-R30 was that I'd have to
switch on my headlamp, instantly attracting insects that were not only
annoying, but bumped into the mic.
The drive inside the Portadisc is a Sony pro level drive, and is
virtually silent when recording. No problems picking it up even with
sensitive mics. Only when it uncouples from the disk when stopped does
it make a audible click.
Compared to a walkman, you do have to be more aware of the batteries.
Though you would be fairly hard pressed to get into trouble with a
single disk starting from fully charged, unless you ran around a long
time in pause. The battery indicator is designed for the voltage profile
of alkaline batteries, so with rechargables you only get about 20
minutes warning when it finally drops off the 99% indication.
The 6 second prerecord can just about eliminate cut off calls at the
beginning of a recording. And it's enough time to make a quick judgment
if it's worth recording. It will not stay indefinitely in record pause,
but will drop into play pause after a while.
What does the combo of the MP2 and the Portadisc do that's different? As
far as sound, it extends the available gain a bit more. And the sound
you get will be somewhat cleaner than with just the Portadisc, probably
because both will be loafing at part gain, not sweating it out at fuller
gain. I've not had the MP2 long, am still experimenting with optimum
matching to the Portadisc. I'm currently leaning toward going into one
of the attenuated mic settings with a -15 dB attenuating cable rather
than using the line input. I get more setting options on the Portadisc
that way, and the sound seems a little fuller to me. MP2 into line with
the Portadisc is not much different than can be had with just the
Portadisc. It's clear it's probably not worth using the MP2 unless you
have the quality mics to match. And, of course, for me there's the MP2's
capabilities for MS stereo. I'm also beginning to like the MP2's limiter
a little, need to do a lot more to know on that one.
What would MP2 give you if combined with a walkman MD? Your available
gain would be better primarily due to the lower noise floor of the MP2,
assuming your mics were up to it. I'm doubting it would help the harsh
clipping much, as I said that's a function of the A/D. The A/D has a lot
to do with the headroom issue as well. You would get rid of the
overloading of the walkman pre by a hot mic, but might find it's just
returned in the interface between the MP2 and the walkman. It would feed
a pretty hefty dynamic range to the MD. I've not tried feeding my
walkman a MP2 signal yet. You would gain some in the cleanness of the
sound, but remember you would still be feeding part of the analog
circuit of the walkman and the A/D, so not as much as a dedicated
system. And you would be tied to two lumps to juggle, and still have all
the handling problems of the tiny MD recorder. You'd certainly have to
put the MP2 on some kind of shoulder strap so as to have hands free to
run the MD while juggling the mic.
MP2 pre vs Portadisc? Both are not perfect. The things I said about
noise, headroom, overloading, pretty much are the same for the MP2. It's
clean sound will stand up to a little stronger output levels than the
Portadisc. Drive it high enough with either and you won't get the best
sound. I think the MP2 limiter may be a bit better than others I've met.
It's high pass filters don't do as good a job cutting out low stuff as
those of the Portadisc. It's phantom power does seem as good as the
Portadisc. Runs the mics, does not add noise. It's battery life on
internal batteries is pitiful. Though I'll admit so far I've been
running it mostly on some old nicads as I'm not really in the field and
only running a few minutes at a time. Unless it improves a lot on full
capacity NIMH, I'll probably end up having to make a battery pac for it.
I don't know if that's what you had in mind, it wanders a lot beyond
just the pre because it's a system you use. There is a great gulf
between piddling around with a recorder at home and tromping through the
bushes with one.
Walt
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