Something Strange Happened to my Tascam Portacapture x8

[Id1212]

Hi All,
Something extremely strange happened today.
We ordered 2 Shure SM7DB (the new version with the built-in pre-amps) to use in the studio).
We opened them, set them up, and connected them to the Portacapture. Initially, we got nothing from the mics.
So we tried anything we could think of - we changed the mode on the mics (pre-amp on and off, turned the 48v on the Portacapture on and off and the connected channels etc., etc.
At some point - not shure exactly when the Portacapture started doing something bizarre all the channels were peeking all the time. so we disconnected the mic - still peaking. We turned the unit on/off - still peaking. We disconnected the top mics - still peaking. We reset the settings on the Portacapture - the same thing. We tried different power sources - still the same.
Upgraded to the latest firmware - still the same.

What is going on here?!
I have so many questions:
1. Did the Portacapture somehow destroy the two SM7DB mics at the same time? (it seems super unlikely - the Portacapture was connected to a power bank I hardly think it had the power to jolt both mics to death but maybe I am wrong (both don't work at all on any device - we tried 4 cables and 3 other recorders - nothing - other mics work fine).
2. Is the Portacapture itself dead - and if so how did this happen from just using it normally? (even if we somehow chose a "wrong" setting this should not happen).
3. It is well past warranty - is there anything that we can do?

If you look at the attached image you can see that nothing is connected to the Portacapture and yet all channels are maxed out (this happens after you connect a mic and then disconnect it - it looks like some sort of internal feedback loop or something).

Any help on this will be most welcome,
Id

 

[Id1212]

Update - even when using AA rechargeable batteries I got the same issue. For the first few sec it seemed OK but as soon as I got a mic connected (any mic) we got this noise (it seems like a pulse going up and down pretty quickly and filling all channels even when nothing is connected (like some sort of feedback).

 

[-mjk-]

I would try a factory reset. From the OM:

1. 15 - 6 Resetting the unit to its factory defaults.

Select the GENERAL SETTINGS screen > SYSTEM page > INITIALIZE item, and conduct initialization.

NOTE
After executing the INITIALIZE function, always use the

/HOLD switch to turn the unit off.

 

[Id1212]

Hi,
Thanks for the answer, however as I said I did that and I still hear the same sound buildup every time I connect a mic (any mic with any cable using any power source) to the unit - other suggestions?

ID

 

[-mjk-]

Oh yes, I apologize. No excuses, but I did read the OP awhile back and I had forgotten that.

No, I am at a loss also, unfortunately. Updating to the latest firmware didn't help either. I think it's time to consult with Tascam directly.

 

[Id1212]

Yeah I guess I have no choice

 

[-mjk-]

I suppose there wouldn't be any harm in reverting to an older FW just to see what happens.

 

[Id1212]

This happened with the old FW so I doubt if this will do anything.

 

[Teak]

Do you have any other interface/mixer/field recorder you can test the Shure mics on? Did you try other mics on the X8? Have you tried using other bitrate settings to see whether it's the ultrasonic noise getting stuck in a feedback loop?

 

[Id1212]

I tried many different mics with the X8 it has issues with all of them - it is like a tone that keeps building a few sec after you connect a mic to any of the XLR inputs - it's very strange.

The mics don't have issues with other recorders.

I did a full factory reset so if it can't work in its most basic mode - then something is certainly wrong here...

 

[-mjk-]

I presume you can record this tone and let us hear it?

 

[Id1212]

Not exactly audio (I am having an unrelated issue with my PC) but a short video - you can see the clicking. I discovered that these fast clicks are actually present all the time even when no mic is connected not even the top mics (I connected headphones and you can clearly hear them - fast tik tik tik).

See here:

Watch Click-x8-2 | Streamable

Watch "Click-x8-2" on Streamable.

streamable.com

 

[-mjk-]

That's no random noise - it is a repeating timed pulse. Some kind of device is causing it and it could even be electro-mechanical (e.g. a relay).

I am completely baffed by one thing though: When you are on the Mixer screen the pulse is slower than it is after you change to the Home screen. That is just weird. Any possible explanation for that?

I spent years as an RFI investigator and pulses like that can come from some very unlikely sources. I had a regular pulse on 20m that wiped out the whole band (I had a triband beam on the roof). I called my pal at the power company and he disconnected the meter on the house across the street. It was his Christmas lights. It's probably too late in the year for Christmas lights, but you get the point. It could be a traffic light. It could be a motion detector. Who knows?

Post #2:

Update - even when using AA rechargeable batteries I got the same issue. For the first few sec it seemed OK but as soon as I got a mic connected (any mic) we got this noise (it seems like a pulse going up and down pretty quickly and filling all channels even when nothing is connected (like some sort of feedback).

Please clarify: You say it seemed OK but as soon as you connected a mic you got the pulse. But in the last sentence you said that it happens "even when nothing is connected." I'm not nitpicking - it makes a huge difference if you see the pulse only when something is connected, or all the time. In the video it looks like you have a mic connected. What happens when you pull the connector?

If you get the pulse on the unit with nothing plugged in it means either there is some overwhelming local source of RFI or the machine itself is malfunctioning as you alluded to. Keep in mind that even with nothing connected, a pulse doesn't necessarily mean the machine is malfunctioning. It could be being overwhelmed with RFI. Determining which is the case is crucial to solving this problem.

If you are getting the pulse with nothing plugged in, take the machine out of the studio and walk around, observing the meters for any change. If it is indeed some local source you might even be able to use the machine to Direction Find (DF) the source. If the pulse remains unchanged, the next thing I would do is to take the machine to a completely different environment and see if you still have it. At some point it will become clear that it is either a local issue or the machine is malfunctioning.

If you only get the pulse when something is connected then you can work with that to eliminate the issue. That might involve verifying/repairing shield connections (perhaps floating them at the source).

The solution is going to take a disciplined and methodical approach to solve. In the end, there might be nothing wrong with either the recorder or your studio setup, but rather that something is overwhelming your site with RFI. Since this is a new issue in your studio, it could mean that this particular piece of equipment is sensitive to RFI. I've had to open up some devices and install tiny chokes on the inputs to eliminate RFI. Many modern devices don't have such chokes anymore whereas the vintage gear seems much more robust in that regard.

After determining that the equipment is not malfunctioning, I would be using a portable AM radio to see if I could hear that pulse on the Medium Wave band. The ferrite rod of a portable AM radio can be used to DF an RFI source. While the problem is a pain in the neck for sure, sometimes sleuthing the culprit can be a fascinating and rather fun exercise.

Please follow up with what you've discovered.

 

[Id1212]

Well - I honestly have no idea where this is coming from.
I tested:
1. two different places connected to USB from AC.
2. different USB and v-mount with USB batteries and even AA batteries.
So I hardly think it's electrical and it's unlikely from other RF sources since I tested it at our studio and home which are about 6-7km apart (plus it doesn't appear on other recorders in the studio).

I just did another test with a different USB battery - initially, nothing connected to a mic it started clicking slowly and then faster. Disconnected, still clicking, turned off and on - no mic, still clicking. Took out the USB (no batteries in) reconnect (no mic) still clicking.

Went outside - turned it on - no clicking - connected a mic - clicking.

When it clicks the mic doesn't work - i.e. you touch the capsule and it doesn't register anything.

I have no idea what is going on.

 

[-mjk-]

I just did another test with a different USB battery - initially, nothing connected to a mic it started clicking slowly and then faster. Disconnected, still clicking, turned off and on - no mic, still clicking. Took out the USB (no batteries in) reconnect (no mic) still clicking.

Do you mean a USB battery bank? A USB cable can introduce all kinds of noise as they are usually not very well shielded. In my studio I have chokes on all my USB cables. But if you have the pulse with only the internal batteries that is not a good sign.

Does it click with any microphone or only the one you're trying to use?

The clicking slower and then faster sounds suspiciously like a capacitor charging.

I think it's time to send the machine to the repair shop.

 

[Id1212]

It clicks with any mic and USB cable (again it's not the first time I have had A/B testing issues).
Yeah, probably. honestly, I am not sure if it's worth it...