Tascam DR-05 ticking noises

This is a SWAG - and based on personal history.

Back in the day, I had a Tandberg 10" machine, TOL for its day. However, an d despite two trips to their Armonk, NY service location, it would 'tick' a s you describe on the left channel, and in Fast Forward in a dry room, woul d shoot sparks from static electricity from the tape to the tape head. I ac tually 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 be st I can suggest off-hand.

Best of luck!

Peter Wieck Melrose Park, PA

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.

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

• 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 men tion that the ticking happens only when something is plugged in, even if th at 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 r ight, 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 spec ific 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 o ff), you have found the problem. And so forth.

Best of luck, again.

Peter Wieck Melrose Park, PA

Oscillating a bit somewhere?

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

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

Temp around 18C

On a clean table

No power near.

I don't have a television.

Nowhere near any other device

Neither of those.

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

Not really, they all say that.

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.

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.

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:

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.

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

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: 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.

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.

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

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

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 mitigate d with post production software?

But if it's a design problem, I would try adding an osc signal above audibl e 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 happe ning. If there's no room inside the Tascam, maybe you can add it to the ex ternal circuit.

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

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.

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?