Tascam DR-05 ticking noises

[Adrian Tuddenham]

I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

The noise only occurs if the recording gain is set low; as soon as it is
advanced, the noise floor of the pre-amp is enough to stop the effect
(it doesn't need to be high enough to mask it). it isn't audible on the
headphone monitoring port, even if that is connected to the input of a
high gain amplifier; it only shows up when the recording is played back.

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[pfjw@aol.com]

This is a SWAG - and based on personal history.

Back in the day, I had a Tandberg 10" machine, TOL for its day. However, and despite two trips to their Armonk, NY service location, it would 'tick' as you describe on the left channel, and in Fast Forward in a dry room, would shoot sparks from static electricity from the tape to the tape head. I actually drove to Armonk and demonstrated the phenomenon that they stated was impossible. Did not matter which tape was used either. I traded it in on a Revox and never looked back.

So, check all your grounding, your patch cords and so forth. That is the best I can suggest off-hand.

Best of luck!

Peter Wieck
Melrose Park, PA

 

[Adrian Tuddenham]

pfjw@aol.com <peterwieck33@gmail.com> wrote:

This is a SWAG - and based on personal history.

Back in the day, I had a Tandberg 10" machine, TOL for its day. However,
and despite two trips to their Armonk, NY service location, it would
'tick' as you describe on the left channel, and in Fast Forward in a dry
room, would shoot sparks from static electricity from the tape to the tape
head. I actually drove to Armonk and demonstrated the phenomenon that they
stated was impossible. Did not matter which tape was used either. I traded
it in on a Revox and never looked back.

So, check all your grounding, your patch cords and so forth. That is the
best I can suggest off-hand.

I've had similar experiences with static electricity on the drive belts
of some tape machines, but this is a hand-held digital recorder with no
moving parts.

It makes the noises even with a short double-ended 3.5mm stereo jack
lead in the input socket and nothing connected to the far end. If the
lead is plugged into a passive mixer, the result is just the same and if
it is connected to a grounded mains-powered mixer, the result is still
the same. I don't think static electricity or anything to do with
grounding can be the problem.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[Dave Platt]

In article <1ny62dx.1g2jnyleguzpcN%adrian@poppyrecords.invalid.invalid>,
Adrian Tuddenham <adrian@poppyrecords.invalid.invalid> wrote:

I've had similar experiences with static electricity on the drive belts
of some tape machines, but this is a hand-held digital recorder with no
moving parts.

It makes the noises even with a short double-ended 3.5mm stereo jack
lead in the input socket and nothing connected to the far end. If the
lead is plugged into a passive mixer, the result is just the same and if
it is connected to a grounded mains-powered mixer, the result is still
the same. I don't think static electricity or anything to do with
grounding can be the problem.

Is it possible to download the resulting digital recording, and
examine the waveform with Audacity or a similar tool?

A ticking sound might be the result of a one-sample error - either a
single bad sample (which would show up as a vertical "tick" on the
waveform), or a missing or duplicated sample (which would show up as a
vertical jump in the waveform, or a sudden flat spot).

In either case, "clocking errors" are what comes to mind for me... a
synchronization problem in the analog-to-digital/storage process.

Years ago, there used to be a fairly common problem of this sort with
long-distance phone calls, where the calls were being transmitted in
digital format between phone switches whose internal
clocks/oscillators were not properly synchronized. One would be
running faster than the other, and occasionally (every few seconds)
the difference between the clocks would cause one audio sample to be
dropped or duplicated.

This resulted in an almost-inaudible "tick" sound. Not a problem for
voice calls, really. However, for modem connections (e.g. V.32) which
were sensitive to signal phase, it was enough to cause a one-bit error
in the data, resulting in a spurious character appearing (most
commonly "}" if I recall correctly). If V.42 error control was turned
on, the error was detected and the data packet re-sent, so you
wouldn't see the bad data, but the retransmission slowed down the
connection significantly.

 

[pfjw@aol.com]

AUTO LEVEL
Using this function, the recording level is automatically
increased when the input sound is too quiet or decreased
when it is too loud. This function is useful for recording
meetings, for example. In this mode, the recording level cannot
be changed manually.

Precautions for placement and use
* The environmental temperature operating range of this unit
is 0–40°C (32–104°F).

* Do not install this unit in the following types of locations.
Doing so could degrade the sound quality and/or cause
malfunctions.
Places with significant vibrations
Near windows or other places exposed to direct sunlight
Near heaters or other extremely hot places
Extremely cold places
Places with bad ventilation or high humidity
Very dusty locations.

* If this unit is placed near a power amplifier or other device
with a large transformer, it could cause a hum. If this occurs,
increase the distance between this unit and the other
device.

* This unit could cause color irregularities on a TV screen or
noise from a radio if used nearby. If this occurs, use this unit
farther away.

* This unit might produce noise if a mobile phone or other
wireless device is used nearby to make calls or send or
receive signals. If this occurs, increase the distance between
this unit and those devices or turn them off.

* To enable good heat dissipation, do not place anything on
top of this unit.

* Do not place this unit on top of a power amplifier or other
device that generates heat.

Beware of condensation
If the unit is moved from a cold to a warm place, or used
after a sudden temperature change, there is a danger of
condensation; vapor in the air could condense on the internal
mechanism, making correct operation impossible. To prevent
this, or if this occurs, let the unit sit for one or two hours at the
new room temperature before using it.

____________________________________________________________

All of the above suggests that this is an acutely sensitive device. You mention that the ticking happens only when something is plugged in, even if that something is inactive or not plugged in itself. Again, just for giggles, try shorting the inputs, left and right (not left to right). The internal architecture may cause these artifacts to favor the left channel over the right, and I actually find it encouraging that both units display identical behavior. But, what it comes down to if a problem is associated with a specific set of conditions - avoid those conditions moving forward. If shorting the not-otherwise-connected input cord make a change, then you have found the problem. If the problem is associated with the AGC (when the mics are off), you have found the problem. And so forth.

Best of luck, again.

Peter Wieck
Melrose Park, PA

 

[Sjouke Burry]

On 12-11-2018 17:50, Adrian Tuddenham wrote:

I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

The noise only occurs if the recording gain is set low; as soon as it is
advanced, the noise floor of the pre-amp is enough to stop the effect
(it doesn't need to be high enough to mask it). it isn't audible on the
headphone monitoring port, even if that is connected to the input of a
high gain amplifier; it only shows up when the recording is played back.

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

Oscillating a bit somewhere?

 

[Adrian Tuddenham]

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:

On 12-11-2018 17:50, Adrian Tuddenham wrote:
I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

The noise only occurs if the recording gain is set low; as soon as it is
advanced, the noise floor of the pre-amp is enough to stop the effect
(it doesn't need to be high enough to mask it). it isn't audible on the
headphone monitoring port, even if that is connected to the input of a
high gain amplifier; it only shows up when the recording is played back.

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[Adrian Tuddenham]

pfjw@aol.com <peterwieck33@gmail.com> wrote:

AUTO LEVEL
Using this function, the recording level is automatically
increased when the input sound is too quiet or decreased
when it is too loud. This function is useful for recording
meetings, for example. In this mode, the recording level cannot
be changed manually.

Never used auto, I'm trying to make proper recordings

Precautions for placement and use
* The environmental temperature operating range of this unit
is 0â€"40°C (32â€"104°F).

Temp around 18C

* Do not install this unit in the following types of locations.
Doing so could degrade the sound quality and/or cause
malfunctions.
Places with significant vibrations
Near windows or other places exposed to direct sunlight
Near heaters or other extremely hot places
Extremely cold places
Places with bad ventilation or high humidity
Very dusty locations.

On a clean table

* If this unit is placed near a power amplifier or other device
with a large transformer, it could cause a hum. If this occurs,
increase the distance between this unit and the other
device.

No power near.

* This unit could cause color irregularities on a TV screen or
noise from a radio if used nearby. If this occurs, use this unit
farther away.

I don't have a television.

* This unit might produce noise if a mobile phone or other
wireless device is used nearby to make calls or send or
receive signals. If this occurs, increase the distance between
this unit and those devices or turn them off.

Nowhere near any other device

* To enable good heat dissipation, do not place anything on
top of this unit.

* Do not place this unit on top of a power amplifier or other
device that generates heat.

Neither of those.

Beware of condensation
If the unit is moved from a cold to a warm place, or used
after a sudden temperature change, there is a danger of
condensation; vapor in the air could condense on the internal
mechanism, making correct operation impossible. To prevent
this, or if this occurs, let the unit sit for one or two hours at the
new room temperature before using it.

It had been in the same dry room for at least 24 hours beforehand.

___________________________________________

All of the above suggests that this is an acutely sensitive device.

Not really, they all say that.

>You mention that the ticking happens only when something is plugged in,
even if that something is inactive or not plugged in itself. Again, just
for giggles, try shorting the inputs, left and right (not left to
right).

I'll try it, but the passive mixer terminated it with around 2 kilohms
to ground on each channel and plugging and unplugging that didn't alter
the amplitude of the noise.

>...what it comes down to if a problem is associated with a specific set
of conditions - avoid those conditions moving forward. If shorting the
not-otherwise-connected input cord make a change, then you have found
the problem. If the problem is associated with the AGC (when the mics
are off), you have found the problem. And so forth.

So far I haven't found any condition when it doesn't occur, other than
when there is a signal on the channel and for one second after that
(that's why it doesn't occur with the internal mics operating, they
increase the noise floor).

The first time it made its presence felt was when I was using both
recorders together, one with a 12dB attenuator in circuit and the other
with a 24dB attenuator as an insurance against overloads when recording
an unrepeatable performance from a mixer that could deliver over +12dBm.
During gaps in the programme, the machine with the lower level recorded
occasional ticking noises, which didn't matter at the time because I had
a clean recording on the other machine.

I've only just had time to investigate this properly and have discovered
that both machines will do it if the signal level is low enough.

 

[Sjouke Burry]

On 13-11-2018 0:18, Adrian Tuddenham wrote:

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:

On 12-11-2018 17:50, Adrian Tuddenham wrote:
I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

The noise only occurs if the recording gain is set low; as soon as it is
advanced, the noise floor of the pre-amp is enough to stop the effect
(it doesn't need to be high enough to mask it). it isn't audible on the
headphone monitoring port, even if that is connected to the input of a
high gain amplifier; it only shows up when the recording is played back.

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.

Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

 

[Dave Platt]

In article <5bea2452$0$25659$e4fe514c@textnews.kpn.nl>,
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:

On 13-11-2018 0:18, Adrian Tuddenham wrote:

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

 

[Adrian Tuddenham]

Dave Platt <dplatt@coop.radagast.org> wrote:

In article <5bea2452$0$25659$e4fe514c@textnews.kpn.nl>,
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 13-11-2018 0:18, Adrian Tuddenham wrote:

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

That could be the sort of thing that is happening - but I wonder why it
comes on after about a second's delay?

Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
....beware loud clicks!


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[N_Cook]

On 13/11/2018 10:59, Adrian Tuddenham wrote:

Dave Platt <dplatt@coop.radagast.org> wrote:

In article <5bea2452$0$25659$e4fe514c@textnews.kpn.nl>,
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 13-11-2018 0:18, Adrian Tuddenham wrote:

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

That could be the sort of thing that is happening - but I wonder why it
comes on after about a second's delay?

Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
....beware loud clicks!

Any chance of cutting a couple of traces and jumpering/swapping left and
right to see if the problem swaps channel or stays the same?

The mystery ticking noise I had long ago was with magnetic tape car
cassette player, no record function, would overlay ticks on pre-recorded
tapes.
A small bit of ferrite/magnet buried in the pinchwheel rubber was the
cause there.

 

[John-Del]

On Monday, November 12, 2018 at 11:50:19 AM UTC-5, Adrian Tuddenham wrote:

I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

The noise only occurs if the recording gain is set low; as soon as it is
advanced, the noise floor of the pre-amp is enough to stop the effect
(it doesn't need to be high enough to mask it). it isn't audible on the
headphone monitoring port, even if that is connected to the input of a
high gain amplifier; it only shows up when the recording is played back.

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Is there a Tascam specific web group? With two of these doing the exact same *weird* and specific problem, sounds like a design issue.

 

[Jeff Liebermann]

On Mon, 12 Nov 2018 16:50:02 +0000,
adrian@poppyrecords.invalid.invalid (Adrian Tuddenham) wrote:

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

I would guess(tm) that the "ticks" are coming from something outside
of the recorder. Try testing it again at a different location. If
the "ticks" go away, look around at your original location for
suitable culprit. Periodic noises are fairly easy, but random is
difficult. For example, I just found a similar problem that was
caused by RF noise from an ultrasonic mouse and rat repeller:
<http://www.victorpest.com/store/rat-control/ultrasonics>
The device produces random ultrasonic noises and whatever was doing
the randomizing was also producing random bursts of RF noise. You
might have something similar happening.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Adrian Tuddenham]

Jeff Liebermann <jeffl@cruzio.com> wrote:

On Mon, 12 Nov 2018 16:50:02 +0000,
adrian@poppyrecords.invalid.invalid (Adrian Tuddenham) wrote:

Can anyone suggest why this is occurring (bearing in mind that it only
affects the left channel) and can anyone suggest a cure?

I would guess(tm) that the "ticks" are coming from something outside
of the recorder. Try testing it again at a different location.

I first noticed it when I was recording a brass band in a school hall
and subsequently a radio play in a small studio - the test recordings
were made on the kitchen table at home. It doesn't appear to be
location-specific.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[Adrian Tuddenham]

N_Cook <diverse@tcp.co.uk> wrote:

On 13/11/2018 10:59, Adrian Tuddenham wrote:
Dave Platt <dplatt@coop.radagast.org> wrote:

In article <5bea2452$0$25659$e4fe514c@textnews.kpn.nl>,
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 13-11-2018 0:18, Adrian Tuddenham wrote:

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

That could be the sort of thing that is happening - but I wonder why it
comes on after about a second's delay?

Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
....beware loud clicks!



Any chance of cutting a couple of traces and jumpering/swapping left and
right to see if the problem swaps channel or stays the same?

I really don't want to go butchering it, I'mrelying on it quite a bit
for location recordings.

The mystery ticking noise I had long ago was with magnetic tape car
cassette player, no record function, would overlay ticks on pre-recorded
tapes.
A small bit of ferrite/magnet buried in the pinchwheel rubber was the
cause there.

I've had that happen with a car cassette player, the tapes got worse and
worse until one day I found the cause.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

 

[John-Del]

On Monday, November 12, 2018 at 11:50:19 AM UTC-5, Adrian Tuddenham wrote:

I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

To be clear, this doesn't happen when using the internal mics?

What sort of "external circuit" are we talking about?

If it only happens when recording silence, wouldn't that be easily mitigated with post production software?

But if it's a design problem, I would try adding an osc signal above audible frequencies at low levels right at the input jack. Should have no effect on the recorded audio and may be enough to keep the phenomenon from happening. If there's no room inside the Tascam, maybe you can add it to the external circuit.

 

[N_Cook]

On 13/11/2018 18:00, Adrian Tuddenham wrote:

N_Cook <diverse@tcp.co.uk> wrote:

On 13/11/2018 10:59, Adrian Tuddenham wrote:
Dave Platt <dplatt@coop.radagast.org> wrote:

In article <5bea2452$0$25659$e4fe514c@textnews.kpn.nl>,
Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:
On 13-11-2018 0:18, Adrian Tuddenham wrote:

Oscillating a bit somewhere?

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

That could be the sort of thing that is happening - but I wonder why it
comes on after about a second's delay?

Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
....beware loud clicks!



Any chance of cutting a couple of traces and jumpering/swapping left and
right to see if the problem swaps channel or stays the same?

I really don't want to go butchering it, I'mrelying on it quite a bit
for location recordings.


The mystery ticking noise I had long ago was with magnetic tape car
cassette player, no record function, would overlay ticks on pre-recorded
tapes.
A small bit of ferrite/magnet buried in the pinchwheel rubber was the
cause there.

I've had that happen with a car cassette player, the tapes got worse and
worse until one day I found the cause.

Do you use batteries or what used to be oddly called "battery
eliminators" to power the recorders?

 

[N_Cook]

On 13/11/2018 19:17, John-Del wrote:

On Monday, November 12, 2018 at 11:50:19 AM UTC-5, Adrian Tuddenham wrote:
I have two Tascam DR-05 recorders and they both exhibit the same
phenomenon: when they are recording complete silence, there are faint
irregular ticking noises on the left channel.

This occurs when using an external circuit which disconnects the
internal mics, but the circuit only needs to be plugged in, not
connected to anything, for it to happen. If there is any sound on the
channel, the noise immediately stops, but re-starts about one second
after complete silence returns.

To be clear, this doesn't happen when using the internal mics?

What sort of "external circuit" are we talking about?

If it only happens when recording silence, wouldn't that be easily mitigated with post production software?

But if it's a design problem, I would try adding an osc signal above audible frequencies at low levels right at the input jack. Should have no effect on the recorded audio and may be enough to keep the phenomenon from happening. If there's no room inside the Tascam, maybe you can add it to the external circuit.

Even if it had to be sub 20K , then it could be knotched out quite
easily as only low level anyway and doubtful whether anyone would know.

 

[Dave Platt]

In article <1ny79x7.wl3ij9kcn7mqN%adrian@poppyrecords.invalid.invalid>,
Adrian Tuddenham <adrian@poppyrecords.invalid.invalid> wrote:

That's what I was thinking, but why only on the left channel? Both
recorders behave the same way.


Spread in components, differences in layout causing parasitic caps an
inductances
to vary, take your pic.

Possibly there's some occasional switching noise on a digital or power
trace, which is coupled more effectively into the left-channel analog
trace going to the ADC? The left-channel trace might actually be
acting to shield the right-channel trace from some of the noise.

That could be the sort of thing that is happening - but I wonder why it
comes on after about a second's delay?

Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
...beware loud clicks!

Looking at that file, I see three sets of noisy impulses... two
negative-going and one positive-going. They're present in both
channels - similar but not identical waveforms in the two channels.
There's a very sharp leading edge (rise time is two or three samples)
and then a much slower fall, with some ringing. The signal takes
about 40 milliseconds to fall back to zero, and then overshoots.

This doesn't look like a one-sample error on the digital-storage side
of things - it's not just a brief impulse. It appears to me that
something is spiking the input to the ADC pretty hard, and that this
glitch is getting into both ADC inputs. The fact that the pulse and
ringing is slightly different, between the two channels, suggests that
it's not just a single sample of bad data in the ADC being blurred out
by the ADC's filters.

Is this .WAV exactly as it came out of the recorder, or did you adjust
it (e.g. gain-boost for visibility) in any way?