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Tascam DR-05 ticking noises
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Adrian Tuddenham
Nov 12, 2018, 11:50:19 AM11/12/18
to
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
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
peterw...@gmail.com
Nov 12, 2018, 12:40:00 PM11/12/18
to
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
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
Nov 12, 2018, 2:13:02 PM11/12/18
to
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.
Dave Platt
Nov 12, 2018, 2:46:54 PM11/12/18
to
In article <1ny62dx.1g2jnyleguzpcN%adr...@poppyrecords.invalid.invalid>,
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.
Adrian Tuddenham <adr...@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
>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.
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.
peterw...@gmail.com
Nov 12, 2018, 2:49:18 PM11/12/18
to
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.
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.
Sjouke Burry
Nov 12, 2018, 3:18:58 PM11/12/18
to
Adrian Tuddenham
Nov 12, 2018, 6:18:18 PM11/12/18
to
recorders behave the same way.
Adrian Tuddenham
Nov 12, 2018, 6:18:19 PM11/12/18
to
pf...@aol.com <peterw...@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 :-)
> 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).
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
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.
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
Nov 12, 2018, 8:09:40 PM11/12/18
to
inductances
to vary, take your pic.
Dave Platt
Nov 12, 2018, 10:08:06 PM11/12/18
to
In article <5bea2452$0$25659$e4fe...@textnews.kpn.nl>,
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.
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
Nov 13, 2018, 5:59:41 AM11/13/18
to
comes on after about a second's delay?
Demonstration at:
www.wrightshardware.co.uk/Other/DR0002_0276.wav
...beware loud clicks!
N_Cook
Nov 13, 2018, 7:03:59 AM11/13/18
to
On 13/11/2018 10:59, Adrian Tuddenham wrote:
> Dave Platt <dpl...@coop.radagast.org> wrote:
>
>> In article <5bea2452$0$25659$e4fe...@textnews.kpn.nl>,
>> Sjouke Burry <burrynu...@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!
> Dave Platt <dpl...@coop.radagast.org> wrote:
>
>> In article <5bea2452$0$25659$e4fe...@textnews.kpn.nl>,
>> Sjouke Burry <burrynu...@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
>
>
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
Nov 13, 2018, 11:07:26 AM11/13/18
to
Jeff Liebermann
Nov 13, 2018, 12:17:21 PM11/13/18
to
On Mon, 12 Nov 2018 16:50:02 +0000,
adr...@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
adr...@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?
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 je...@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
Nov 13, 2018, 1:01:04 PM11/13/18
to
N_Cook <div...@tcp.co.uk> wrote:
> On 13/11/2018 10:59, Adrian Tuddenham wrote:
> > Dave Platt <dpl...@coop.radagast.org> wrote:
> >
> >> In article <5bea2452$0$25659$e4fe...@textnews.kpn.nl>,
> >> Sjouke Burry <burrynu...@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
> On 13/11/2018 10:59, Adrian Tuddenham wrote:
> > Dave Platt <dpl...@coop.radagast.org> wrote:
> >
> >> In article <5bea2452$0$25659$e4fe...@textnews.kpn.nl>,
> >> Sjouke Burry <burrynu...@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?
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.
worse until one day I found the cause.
Adrian Tuddenham
Nov 13, 2018, 1:01:04 PM11/13/18
to
Jeff Liebermann <je...@cruzio.com> wrote:
> On Mon, 12 Nov 2018 16:50:02 +0000,
> adr...@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
> On Mon, 12 Nov 2018 16:50:02 +0000,
> adr...@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.
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.
John-Del
Nov 13, 2018, 2:17:04 PM11/13/18
to
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?
> 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.
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
Nov 13, 2018, 2:22:48 PM11/13/18
to
eliminators" to power the recorders?
N_Cook
Nov 13, 2018, 2:27:12 PM11/13/18
to
easily as only low level anyway and doubtful whether anyone would know.
Dave Platt
Nov 13, 2018, 5:59:37 PM11/13/18
to
In article <1ny79x7.wl3ij9kcn7mqN%adr...@poppyrecords.invalid.invalid>,
Adrian Tuddenham <adr...@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
>> >> 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!
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?
Adrian Tuddenham
Nov 13, 2018, 6:31:28 PM11/13/18
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Adrian Tuddenham
Nov 13, 2018, 6:31:29 PM11/13/18
to
John-Del <ohg...@gmail.com> 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?
That is correct - or at least I have never noticed it. I'm guessing it
> 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?
is because:
1) I never use the internal mics for professional work and rarely use
them at all.
2) When I do use the mics, nowhere is quiet enough to show up the
effect.
3) I would record from the mics with the gain at a level where just the
pre-amp noise floor prevented the effect.
>
> What sort of "external circuit" are we talking about?
long, with nothing connected to the far end. The effect also happens
with the same lead plugged into a passive mixer and also on a longer
lead with a built-in 12dB attenuator, fed from a powered mixer
I have also used a passive distribution box with separate L and R inputs
(P.O. 315 jacks) taking line level from the mic pre-amp (floating and
battery-powered) and delivering signals to two 3.5mm output plugs, one
attenuated by 12 dB and one by 24 dB for the two recorders.
>
> If it only happens when recording silence, wouldn't that be easily
> mitigated with post production software?
the clicks by hand. I would rather tackle the problem at source if at
all possible.
> 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.
...or add a sub-audio signal.
...or never turn the recording gain right down and let the pre-amp noise
floor take care of it..
I haven't looked to see if new software is downloadable for that model -
but I suspect this is more likely to be a hardware fault.
Adrian Tuddenham
Nov 13, 2018, 6:31:29 PM11/13/18
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John-Del
Nov 14, 2018, 8:05:48 AM11/14/18
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That's true, but if my solution works, it won't require any intervention to prevent that spurious noise.
Years ago, I had a customer with a Vizio flat TV that would start, run five seconds, and shut down. Turns out it was set to the PC input awaiting a timing signal, and when finding none, shut down as most computer monitors will. There was no way to change the input during the short time it was on. I connected a PC to it, it stayed on, and I put it back on "TV" mode and sent it back with instructions to be careful about switching inputs.
A month later, it was back with the same problem. Seems when switching inputs to watch a DVD, they again paused over the PC input and the TV shut down.
I ended up finding a timing signal on the board, cap coupled it to a transistor, and fed that to the back of the PC jack to fool it to think an active PC was connected. That fixed that. From then on, it would stay on regardless of where the input was set.
A software change would have fixed it, but there was no help from Vizio.
> I haven't looked to see if new software is downloadable for that model -
> but I suspect this is more likely to be a hardware fault.
>
mako...@yahoo.com
Nov 14, 2018, 10:23:52 AM11/14/18
to
> > > > 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.
> > >
slowly drop the level.
at some level the clicks will start.
observe the tone during the clicks for clues. Does the tone change in anyway due to the clicks?
Also with the external input connected to nothing, do the clicks change depending on if the external input is open vs shorted or terminated?
These recorders often apply a few volts of DC power to the input to power mics.
Put a scope on the input line and see if the spikes are actually present on the input line. Or connect the input to another audio input that you can listen to , do the spikes come OUT the audio input?
If you apply a small DC signal to the input through a current limiting resistor , will that stop the spikes? Try both polarities?
Is there a schematic available?
mark
mako...@yahoo.com
Nov 14, 2018, 10:34:10 AM11/14/18
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Also the clicks in the wav file are alternating polarity, up then down then up etc. might mean something to you
mark
N_Cook
Nov 14, 2018, 11:08:38 AM11/14/18
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Can you read the IC numbers relating to preamps, then perhaps find a
generic operational problem with it, outside of Tascam. A datasheet
would let you find the main rails and perhaps there is some space to add
some chip caps across the rails in that arra.
generic operational problem with it, outside of Tascam. A datasheet
would let you find the main rails and perhaps there is some space to add
some chip caps across the rails in that arra.
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