[[email protected]]

Hi there people,

I have recorded some fairly high spl with a sennheiser 414, put a 20db
pad on the preamp inside a tascam portable DAT recorder, inadvertantly
had the limiter on the recorder enabled. The sounds have recorded OK,
but for some wierd intermittent distortion. I transferred the original
single channel recording using spdif on a different tascam da-30 deck
to computer via sound card.

The wave form appears continuous except when zoomed right in to view
individual samples. Some sample values are duplicated (repeated). This
sounds like impulse noise, and happens about once every half second or
so, randomly. I suspect it's sample errors on the tape, but I'd expect
the error values to be random impulses rather than duplicated values
of whatever the previous (correct) value was. It happens more
frequently the higher the amplitude, and so sounds above say -6db have
many of these errors per second, while amplitudes below about -30db
are clean.

My question is what might be the origin and the cause of this, and how
can i fix it? Has anyone come across this before? It's very
annoying... I need to clean up the recordings and I can't go back and
re-record. Any advice much appreciated.

Thanks in advance- Terry

[Mark]

On Sep 13, 6:55 am, wrote:
Hi there people,

I have recorded some fairly high spl with a sennheiser 414, put a 20db
pad on the preamp inside a tascam portable DAT recorder, inadvertantly
had the limiter on the recorder enabled. The sounds have recorded OK,
but for some wierd intermittent distortion. I transferred the original
single channel recording using spdif on a different tascam da-30 deck
to computer via sound card.

The wave form appears continuous except when zoomed right in to view
individual samples. Some sample values are duplicated (repeated). This
sounds like impulse noise, and happens about once every half second or
so, randomly. I suspect it's sample errors on the tape, but I'd expect
the error values to be random impulses rather than duplicated values
of whatever the previous (correct) value was. It happens more
frequently the higher the amplitude, and so sounds above say -6db have
many of these errors per second, while amplitudes below about -30db
are clean.

My question is what might be the origin and the cause of this, and how
can i fix it? Has anyone come across this before? It's very
annoying... I need to clean up the recordings and I can't go back and
re-record. Any advice much appreciated.

Thanks in advance- Terry

can you post a small section of it that we can listen to / look at
Mark

[[email protected]]

Rather than subjecting you to bad ASCI art, if you could imagine a
smooth sinusoidal waveform, which every now and then remains in the
present by 1 sample extra, so you get a momentary DC signal 2 samples
long, like a sample-and-hold. The resulting discontinuity sounds like
a click. It's random, and takes ages to actually find in the waveform
display because it is hidden in the overall form of the wave, rather
than sticking out like an impulse, but it sounds just as bad. If an
impulse noise is like a mosquito bite, this is a bit like an itch--
just don't know how to scratch it!

Terry

[Scott Dorsey]

wrote:

I have recorded some fairly high spl with a sennheiser 414, put a 20db
pad on the preamp inside a tascam portable DAT recorder, inadvertantly
had the limiter on the recorder enabled. The sounds have recorded OK,
but for some wierd intermittent distortion. I transferred the original
single channel recording using spdif on a different tascam da-30 deck
to computer via sound card.

Sounds good.

The wave form appears continuous except when zoomed right in to view
individual samples. Some sample values are duplicated (repeated). This
sounds like impulse noise, and happens about once every half second or
so, randomly. I suspect it's sample errors on the tape, but I'd expect
the error values to be random impulses rather than duplicated values
of whatever the previous (correct) value was. It happens more
frequently the higher the amplitude, and so sounds above say -6db have
many of these errors per second, while amplitudes below about -30db
are clean.

If you listen directly to the analogue output of the DAT machine, do you
hear the same noise? Or is it only on the digital transfer?

How does it sound? Does it sound like a whining noise?

My question is what might be the origin and the cause of this, and how
can i fix it? Has anyone come across this before? It's very
annoying... I need to clean up the recordings and I can't go back and
re-record. Any advice much appreciated.

Use the DA-30 error rate function to see if the error rate on the tape
playback is excessive.

When were these machines last aligned? If you let the machines go for
too long without alignment, they will drift apart and you will have problems
with interoperability. You will know that this is the issue when the error
rate on playback becomes high.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Sep 13, 11:03 pm, (Scott Dorsey) wrote:

If you listen directly to the analogue output of the DAT machine, do you
hear the same noise? Or is it only on the digital transfer?

Its past my bettime so I'll check it out tomorrow.

How does it sound? Does it sound like a whining noise?

No whining, just subtle but nevertheless ruinous clicks.


Use the DA-30 error rate function to see if the error rate on the tape
playback is excessive.

I'll ahve to get the manual out for that one

When were these machines last aligned?
Yes its been a while.

If you let the machines go for
too long without alignment, they will drift apart and you will have problems
with interoperability. You will know that this is the issue when the error
rate on playback becomes high.

Thanks, will investigate.

[Scott Dorsey]

wrote:
On Sep 13, 11:03 pm, (Scott Dorsey) wrote:

If you listen directly to the analogue output of the DAT machine, do you
hear the same noise? Or is it only on the digital transfer?

Its past my bettime so I'll check it out tomorrow.

How does it sound? Does it sound like a whining noise?

No whining, just subtle but nevertheless ruinous clicks.

Use the DA-30 error rate function to see if the error rate on the tape
playback is excessive.

I'll ahve to get the manual out for that one

When were these machines last aligned?
Yes its been a while.

If you let the machines go for
too long without alignment, they will drift apart and you will have problems
with interoperability. You will know that this is the issue when the error
rate on playback becomes high.

Thanks, will investigate.

Sounds to me like you will need to get back the original portable machine
(was it a DA P-20 or one of the newer ones?) and see if the tape plays
correctly there. It does sound like an alignment issue even if it isn't
breaking out into squeals yet.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Nono]

On 13 sep, 15:35, wrote:
On Sep 13, 11:03 pm, (Scott Dorsey) wrote:


Use the DA-30 error rate function to see if the error rate on the tape
playback is excessive.

I'll ahve to get the manual out for that one

If you find that function, please let me know; I cannot find it in my
manual.

Thanks,
Norman.