Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

[We received our first shipment of M-Audio MicroTrack 24/96 flash memory
recorders this past Monday. I've been posting my impressions to the
PenComputingAudio group on Yahoo, and thought that this groups might
appreciate them too. -- LM]

As I work my way through what the MicroTrack 24/96 can do, I've found
some more interesting and unexpected things:

First, as I noted before, its phantom power voltage is 30 Volts and not
the usual 48. I haven't measured how many milliAmps per channel it can
supply.

When recording an S/PDIF data stream, MicroTrack 24/96 is currently
limited to making 16-bit recordings. That really clinches my initial
impression that it's really a 16-bit recorder. Its Mic and Line inputs
are limited to roughly 16-bit dynamic range (despite the option to
record that to file in a 24-bit format), and the digital input is also
16-bit only. Perhaps the next firmware release will extend it to
24-bit?

Also, while the level meters operate when recording from the S/PDIF
input, the headphone output (and presumably the Line outputs too, since
they are probably driven from the same analog signal source) does not.
So you can't monitor on headphones while recording from a S/PDIF source.
(You can monitor on 'phones when recording from the TRS and 1/8-inch
analog inputs.)

Another surprise is that MicroTrack 24/96 is currently a stereo-only
recorder. It can not record in mono, though there are indications that
it will be added in a future release of the firmware.

There are a fair number of bugs, most of which do not "sink the ship",
but are pretty weird and annoying. Like what? Like imagine you
recorded three files from the S/PDIF input. You simply can't get it to
play back the first file in the file system. If you try to play back
the first file, it simply won't play. If that weren't enough, it also
causes a condition that you then can't play *any* of the files. But if
you first play back the second or third file, it works fine unless you
then try to play the first: that breaks it and you have to cycle power
to get it back.

The workaround (not surprisingly) is to record a few short files and
then delete the first file -- then you'll always be able to play the
rest of the files.

Weird.

There are others like that. And then there are the ones that can sink
the ship. Like the one that I haven't quite figured out yet. It makes
the file system act like the CF card has no more space for recording.
If you check the time remaining for recording, it's a negative number.
But when you check the directory to list the files that are there, there
aren't any files! If you've made a recording, it's gone and in some
cases unsalvageable. The only way I've found to get back into business
is to reformat the card in a PDA or a PC and start over.

I'm keeping M-Audio informed of what I find.

I'll post more as I dig deeper.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
moskowit@core-sound.com Tel: 201-801-0812, FAX: 201-801-0912

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Len,

Thanks a ton for this review. I've been waiting for months for this
exact type of info.

Personally, I almost expected firmware bugs, that can be fixed in later
revisions. What I'm mostly worried about is the sound quality itself.
Any impressions on the overall sound quality as compared to the R1 or
PMD660?

One major flaw seems to be the weak phantom power. IMHO, this could be
grounds for a recall....while I realize that phantom power specs are
often overrated by a few volts, there is a huge difference between 30v
and 48v. I really doubt 30v would provide enough capacitance to properly
drive most condenser mics.

Anyhow, any word on the overall sound quality, or better yet, some .wav
or flac clips would be great! Thanks a ton Len!

Jonny Durango

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Thank you Len for this information
On Thu, 22 Sep 2005 05:19:56 +0200, Len Moskowitz wrote:

> As I work my way through what the MicroTrack 24/96 can do, I've found
> some more interesting and unexpected things:
>
> First, as I noted before, its phantom power voltage is 30 Volts and not
> the usual 48. I haven't measured how many milliAmps per channel it can
> supply.

Fore some, I don't think many, microphones this could be a problem. I've
checked some of my microphones. The documentation of my Shure microphones
says: "Phantom Supply Voltage 11 to 52 Vdc Current Drain 2.0 mA max at 52
Vdc". AKG writes: "The phantom powering standard covers nominal values of
12, 24, and 48 volts dc. The tolerance on the values is broad enough so
that many AKG condenser microphones can be powered anywhere from 9 volts
to 52 volts, making them adaptable to a wide range of operating
conditions. Some of the studio models such as the older C414EB/P48 will
work only on 48 volt powering." So for this device the 30V choice may not
be too bad. I've checked the circuit diagram of my AKG C480. I think 30V
will do.

> When recording an S/PDIF data stream, MicroTrack 24/96 is currently
> limited to making 16-bit recordings. That really clinches my initial
> impression that it's really a 16-bit recorder. Its Mic and Line inputs
> are limited to roughly 16-bit dynamic range (despite the option to
> record that to file in a 24-bit format), and the digital input is also
> 16-bit only. Perhaps the next firmware release will extend it to
> 24-bit?

The S/PDIF should be corrected. As for the dynamic range. If the specified
100dB is met, I think it will do for most location recordings. Just for
reference: the equivalent noise level of my microphone ia 11dB (much lower
than ambient noise for location recording), the sound level of a piano at
a propper recording distance is less than 100dB. So 100dB dynamic range
should be quite sufficient.

... (several software? bugs snipped)

> I'm keeping M-Audio informed of what I find.
>
> I'll post more as I dig deeper.

Please do!

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Jonny Durango wrote:

> Personally, I almost expected firmware bugs, that can be fixed in later
> revisions.

Has our existence come to this, that we EXPECT bugs? Shame on you,
Johnny! I guess we've pretty much come to expect bugs in software,
particularly when that software isn't sure what environment it will be
running in, but this is a piece of hardware that functions as a piece
of hardware. It can, and should, be completely predictable. There's no
excuse for any of the things that Len reported, except perhaps for the
low voltage phantom power (clearly not a bug) which was cleverly absent
from any of the advance literature.

Oops, there's a little software bug in your car. The anti-lock brakes
lock up when you press Radio Button 5 when moving at speeds between 37
and 42 mph. How would that be?

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Chel, by coincidence you examined two brands of microphone which allow
for non-standard phantom powering. Please don't conclude, or lead
others to conclude, that many other high-quality microphone
manufacturers are following a similar approach. Some are, especially in
electret microphones. But in general, most serious international
manufacturers of traditional condenser microphones assume standard
phantom powering according to DIN EN 61938 in their designs.

For example, in transformerless Neumann microphones such as the KM 180
series, a DC/DC converter is used to obtain the polarization voltage
for the capsule. This circuit uses an oscillator whose frequency varies
with the supply voltage. If the supply voltage is too low, the
converter won't reach its intended output voltage. The sensitivity of
the microphone will decrease along with the maximum SPL. Meanwhile the
equivalent noise level rises, and the frequency of the oscillator
itself can even fall into the audible range, or perhaps just into the
range of some people's preamps and A/D converters if they go for
extended frequency response and high sampling rates.

This isn't something to fart around with. If a microphone clips or is
noisy during a recording, you're in serious trouble; why invite that?
Why spend thousands of dollars on microphones and undermine them to
save a lousy few bucks in the power supply? It's nice if a microphone
can tolerate wider deviations than the standard allows, but only a
power supply which conforms to the standard can be presumed to support
all 48-Volt phantom-powered microphones correctly.

--best regards

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

In rec.audio.pro Mike Rivers <mrivers@d-and-d.com> wrote:
>
> Jonny Durango wrote:
>
>> Personally, I almost expected firmware bugs, that can be fixed in later
>> revisions.
>
> Has our existence come to this, that we EXPECT bugs? Shame on you,
> Johnny! I guess we've pretty much come to expect bugs in software,
> particularly when that software isn't sure what environment it will be
> running in, but this is a piece of hardware that functions as a piece
> of hardware.

Firmware IS software.


--
Aaron

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

On Thu, 22 Sep 2005 16:26:22 +0200, David Satz wrote:
>> I've checked the circuit diagram of my AKG C480. I think 30V will do.

> For example, in transformerless Neumann microphones such as the KM 180
> series, a DC/DC converter is used to obtain the polarization voltage for
> the capsule. This circuit uses an oscillator whose frequency varies with
> the supply voltage. If the supply voltage is too low, the converter
> won't reach its intended output voltage.

The AKG C480 has about the same design. The phantom power is go through a
voltage regulator circuit to get a stable DC voltage. This DC voltage is
not very high i asume, as the first stage of the preamp is on this DC
supply. The DC/DC converter to generate 62V polarising voltage.
http://www.akg.com/mediadatabase/p [...] b41250.pdf

This design, together with AKG's statement "many AKG condenser microphones
can be powered anywhere from 9 volts to 52 volts", make me think that the
30V will not give problems for me. I do think Shure and AKG are "serious
international manufacturers of traditional condenser microphones"

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:1127394079.523849.253440@g44g2000cwa.googlegroups.com...

> Oops, there's a little software bug in your car. The anti-lock brakes
> lock up when you press Radio Button 5 when moving at speeds between 37
> and 42 mph. How would that be?

Better:

Vendor: "Hello ... is that Tim ... we're having a problem with your card
payment, it seemed to go through, so we hiopped the goods; but when we look
in out account, the money isn't there."

Tim: "Yes, that's a bug in my card payment software. The first payment gets
lost; the second or third payment go through OK, unless you try to obtain
the first payment, when *none* of the payments will go through ... oh, you
know already?"

Tim

Tim

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Tim Martin wrote:

> "Mike Rivers" wrote...

> > Oops, there's a little software bug in your car. The anti-lock brakes
> > lock up when you press Radio Button 5 when moving at speeds between 37
> > and 42 mph. How would that be?

> Better:

> Vendor: "Hello ... is that Tim ... we're having a problem with your card
> payment, it seemed to go through, so we hiopped the goods; but when we look
> in out account, the money isn't there."

> Tim: "Yes, that's a bug in my card payment software. The first payment gets
> lost; the second or third payment go through OK, unless you try to obtain
> the first payment, when *none* of the payments will go through ... oh, you
> know already?"

Badadah BAM!

Tim Martin, folks; he'll be here all week.

Excellent.

--
ha

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

David Satz wrote:

> Chel, by coincidence you examined two brands of microphone which allow
> for non-standard phantom powering. Please don't conclude, or lead
> others to conclude, that many other high-quality microphone
> manufacturers are following a similar approach. Some are, especially in
> electret microphones. But in general, most serious international
> manufacturers of traditional condenser microphones assume standard
> phantom powering according to DIN EN 61938 in their designs.

> For example, in transformerless Neumann microphones such as the KM 180
> series, a DC/DC converter is used to obtain the polarization voltage
> for the capsule. This circuit uses an oscillator whose frequency varies
> with the supply voltage. If the supply voltage is too low, the
> converter won't reach its intended output voltage. The sensitivity of
> the microphone will decrease along with the maximum SPL. Meanwhile the
> equivalent noise level rises, and the frequency of the oscillator
> itself can even fall into the audible range, or perhaps just into the
> range of some people's preamps and A/D converters if they go for
> extended frequency response and high sampling rates.

> This isn't something to fart around with. If a microphone clips or is
> noisy during a recording, you're in serious trouble; why invite that?
> Why spend thousands of dollars on microphones and undermine them to
> save a lousy few bucks in the power supply? It's nice if a microphone
> can tolerate wider deviations than the standard allows, but only a
> power supply which conforms to the standard can be presumed to support
> all 48-Volt phantom-powered microphones correctly.

Thanks, David. When one's recording fails, excuses for mediocrity in kit
won't fix it.

And there's likely more to excellent phatom power supplying, as I heard
David Jospehson at AES in SF last year ask Grant Carpenter about the
noise floor of the Gordon preamp's phantom supply. Aaaaah, the details!

--
ha

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Chel, there is a subset of phantom-powered microphones which will work
properly when the phantom supply voltages are non-standard. And I don't
mean to downgrade the importance of AKG or Shure. Your microphones may
indeed work with the piece of recording equipment which is the subject
of this thread. If so, you may consider yourself lucky, if you like.

But then again, they may not. We have mainly been talking about
open-circuit voltage, but some AKG mikes with the 9 - 52 Volt
arrangement (such as the old, original C 451) draw as much as 6 mA
apiece. I wouldn't assume that so much current is necessarily available
for each microphone from this new device. I've seen plenty of portable
preamps that can't even put out 4 mA per microphone input--the supply
drops out of regulation first.

When the standard is followed, P48 microphones are correctly powered by
P48 inputs, end of story. It is a very bad idea to release new
equipment with non-standard phantom powering, because so many people
have the types of microphone which depend on conformance to the
standard.

--best regards

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

but then we are talking about 350$ box with allot of compromise in between
to build better powering circuit might be one of these things( with allot
others ) which bring not develop the product at all
might be that the mkh or sanken users wouldn't love it ,but if they can
afford the mikes- they obviously can afford the dienekey ps-2 :-)

best
--
Oleg Kaizerman (gebe) Hollyland

> When the standard is followed, P48 microphones are correctly powered by
> P48 inputs, end of story. It is a very bad idea to release new
> equipment with non-standard phantom powering, because so many people
> have the types of microphone which depend on conformance to the
> standard.
>
> --best regards
>

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

Chel van Gennip wrote:

> This design, together with AKG's statement "many AKG condenser microphones
> can be powered anywhere from 9 volts to 52 volts", make me think that the
> 30V will not give problems for me. I do think Shure and AKG are "serious
> international manufacturers of traditional condenser microphones"

Well, let us know what you think of your Micro-Trak when you decide to
upgrad to something like a Shoeppes. But then there isn't much point to
that if you're only doing 16-bit recording. I'm sure your AKG mic will
do fine.

I'm not knocking your choice of mics, I'm knocking your calm acceptance
of a device that limits your choice of mics. But then I guess I'm happy
with a PC even though it won't run Mac software.

Archived from groups: rec.audio.pro,rec.audio.tech (More info?)

whats wrong with schoeps cmc6 or ccms which run 12-48,?

--
Oleg Kaizerman (gebe) Hollyland

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:1127421956.037858.122680@z14g2000cwz.googlegroups.com...
>
> Chel van Gennip wrote:
>
>> This design, together with AKG's statement "many AKG condenser
>> microphones
>> can be powered anywhere from 9 volts to 52 volts", make me think that the
>> 30V will not give problems for me. I do think Shure and AKG are "serious
>> international manufacturers of traditional condenser microphones"
>
> Well, let us know what you think of your Micro-Trak when you decide to
> upgrad to something like a Shoeppes. But then there isn't much point to
> that if you're only doing 16-bit recording. I'm sure your AKG mic will
> do fine.
>
> I'm not knocking your choice of mics, I'm knocking your calm acceptance
> of a device that limits your choice of mics. But then I guess I'm happy
> with a PC even though it won't run Mac software.
>