Voltage Regulation and Converter stop working

Hi all,
I'm trying to debug an issue I have in my home studio and I would like to check it with you as I do not know where to smash my head.

MY SETUP
- two Myteks 8x192 are connected via MADI to a RME MADIFX
- a FerroFish A32 is connected via MADI to the RME MADIFX
- one Mytek 8x192 provides clock to the other Mytek, the Ferro and the RME MADIFX
- all converters (and the PC as well) power inlets are connected to a Furman m-10lx (that's a practical way to ensure star ground).
- the FerroFish has a cheap external power supply (same as a laptop).
- the Mytek has a big toroid with linear internal power supply.

THE ISSUE
From time to time (unpredictable, sometimes twice each 4 ours) my two Mytek 8x192's stop passing audio (and disappear from the RME MADI control panel).
At the same time a third converter (FerroFish A32) is NEVER EVER affected.
If you are doing the take of your life using the Mytek's this can be really a pain in the ass.

HOW TO SOLVE
Each unit can be restored to normal operations:
- by power cycle
- by switching its metering from AD to DA or viceversa.
- by switching the clock mode

PERFORMED TESTS
- I was able to reproduce the issue also with each 8x192 individually with NO other converter and NO clock cable just the optical MADI and even with the ground lift.
- No matter if I connect via Optical or BNC
- I was able to observe it also with the studio heat pumps switched off (I suspected they could cause spikes).
- I still suspected main voltage fluctuations (I know I have low voltage in my area) so I've bought an AVR (APC Line-r 1200).
I've put the AVR between the Furman and the socket and instead of improving I've got more occurrences.
What I have noticed is that each time the converters stop passing the sound it was coincident with the AVR switching from "normal" to "boost".
- The FerroFish always works, also with the AVR as well as all the rest of my equipement.

NEXT STEP
One option will be to send the two Mytek to be checked, however I'm concerned that they are going to pass bench tests with steady voltage and what I'm getting is the result of a design choice (weak filtering or regulation?)

Which checks would you suggest?
Would you rate as normal that the 8x192 can't cope with voltage fluctuations like the rest of my equipment (e.g. the FerroFish)?

Thanks a lot.

mudseason said:

Would you rate as normal that the 8x192 can't cope with voltage fluctuations like the rest of my equipment (e.g. the FerroFish)?

Click to expand...

Yes. If your mains are getting too low this is the downside of the linear PSU in the Mytec.

If it is power-related then you could try running all the kit off a UPS. APC make some decent rackmount UPS and they show up regularly on eBay, etc.

Budget for new batteries if you buy secondhand. There are plenty of third-party battery suppliers for brands like APC

Nick Froome

Dears,
thanks a lot for your replies.
I had to sell a kidney to buy those converters as my studio is just for myself and I don't rise any money from it and the fact they fail it is a bit frustrating to say the least.

Obviously most of my gear (the 50% of which is DIY) has a linear PSU, none is showing a deficiency, but they are analogue devices.

Please forgive my ignorance, why is it a downside of linear vs switching?
Woudn't be possible to design a quality more roboust PSU?

I was thinking about the UPS too.
As I already have an APC AVR which makes everything worse* wouldn't be NECESSARY to go with a double conversion-online UPS?
In that case the UPS solution would not be a cheap one .

* I fear the AVR (being line interactive) is working that way:
- set the target (say 230V)
- when the Votage is below 230-23 (10%) boost it to 230
- the boost then creates a step of >23V  which stresses the Mytek PSU.
- the Mytek PSU (the voltage regulation stage) cannot smoothly regulate that step causing a general malfunction (e.g. protection mode).
does it make sense to you?

mudseason said:

Obviously most of my gear (the 50% of which is DIY) has a linear PSU, none is showing a deficiency, but they are analogue devices.

Click to expand...

Yes, standard analogue audio circuits won't restart or reset anything when having short dropouts.

mudseason said:

Please forgive my ignorance, why is it a downside of linear vs switching?

Click to expand...

Most switching PSUs accept 100 - 240V mains.
Linear PSUs don't. Some may accept 230V with 20% tolerance, some with 10%, some with 5%.
Your Mytec is obviously on the low side.

mudseason said:

Woudn't be possible to design a quality more roboust PSU?

Click to expand...

I think a mains transformer with higher secondary voltages would make it more robust.
But this is a guess without seeing any schematic etc.

Have you talked to Mytek about this? Its an expensive converter, I would expect it to work properly or get your money back.
Do you have mains problems? Low voltage? Then use a good UPS.
Presumably you have multiple in/outs that you need such flash converters. If you cant afford this stuff, then dont buy it and take up a cheaper hobby!
A recording studio is a large hole in the ground that you pour money into hehe!

You don't say what country you're in, but you say you have low voltage. You may find a proper online UPS solves the problem but you'd have to test to find out

When testing I'd connect all the digital equipment to the UPS - interfaces, computer, etc, but the computer monitor could be fed off the ordinary supply

An online (aka double-conversion) UPS generates a stable 220 V 50 Hz - or, I suspect in your case, 110 V 60 Hz - all the time and connected equipment runs from the generated output, not from the wall supply

Another test would be to try your setup, including your cables, in a location with good power. That should pin down where the problem lies

Nick Froome

pvision said:

When testing I'd connect all the digital equipment to the UPS - interfaces, computer, etc, but the computer monitor could be fed off the ordinary supply
Nick Froome

Click to expand...

If you are putting a UPS in it is normal to put the monitor on it too.  That way you can see what you're doing if you have to shut the computer down in the event of a power failure.

pvision said:

You don't say what country you're in, but you say you have low voltage. You may find a proper online UPS solves the problem but you'd have to test to find out

When testing I'd connect all the digital equipment to the UPS - interfaces, computer, etc, but the computer monitor could be fed off the ordinary supply

An online (aka double-conversion) UPS generates a stable 220 V 50 Hz - or, I suspect in your case, 110 V 60 Hz - all the time and connected equipment runs from the generated output, not from the wall supply

Another test would be to try your setup, including your cables, in a location with good power. That should pin down where the problem lies

Nick Froome

Click to expand...

I'm from Italy (230V 50Hz).

I get you right that you think I should not connect analogue stuff to the UPS?
Would you still recommend not to use it on analogue gear even in case its output is a pure sine?

The issue is very sporadic and is NOT always occurring while voltage is low (probably the problem are the switching transients). The voltage can be as low as 195V and still the two converters work as expected.
I tried also keeping the heat pumps off and other devices still the problem is there.

I'm trying to figure out which is the external factor since one month.
However being a seldom unpredicatable event (there are days where everything works fine) it is really a challenge.

The only achievement that I was able to reach is that using an Automatic Voltage Regulator I can rise the frequency of the issue to 3 or 4 time a session as most of the time the AVR starts pumping the converters crash.
After the transient is gone, even if the AVR is pumping, the converters work fine.

radardoug said:

Have you talked to Mytek about this? Its an expensive converter, I would expect it to work properly or get your money back.
Do you have mains problems? Low voltage? Then use a good UPS.
Presumably you have multiple in/outs that you need such flash converters. If you cant afford this stuff, then dont buy it and take up a cheaper hobby!
A recording studio is a large hole in the ground that you pour money into hehe!

Click to expand...

Oh, so my wife's nick is radardoug.
Jockes apart, yes, I have Low voltage: 195-220 instead of 230.
However the issue is not (or not only) the absolute value.

Actually I need also the 32 in/outs of my FerroFish in addition to the 8+8 of the two 8x192, but luckly I'm reaching the saturation point and my mains are telling me "hey, no more juice, stop pouring your money in that bunker".

I will follow the suggestion, but first let me check that f*** UPS.

I've contacted Mytek and they are really nice and are willing to check the converters, but I have the impression the converters perform as expected as it happens on both converters individually.

As said I do not have perfect mains and Mytek are probably the only units suffering for this.

Rob Flinn said:

If you are putting a UPS in it is normal to put the monitor on it too.  That way you can see what you're doing if you have to shut the computer down in the event of a power failure.

Click to expand...

That's a good point. In many setups there's not enough UPS capacity to run everything and monitors are fairly power-hungry. At least CRTs ones were

If you have the capacity to run the analogue gear from the UPS do so. But my point was not to mix & match the digital gear - have it all on the UPS

Nick Froome

Just a thought...

Have you considered what's causing the brownouts?

If it's some industrial equipment causing those, it might also be sending strong interference up the line. Any welding equipment, traction motors or frequency regulated motors in the vicinity?

I had a case several years ago, where a studio that was next to a railroad shunting station occasionally had a high DC voltage coming in over the ground wire. The traction locomotives used 550V DC and when the weather was dry for longer periods, the studio lost it's own ground connection. Having DC on a ground wire plays strange tricks on audio equipment, like meters moving without signal and equipment dying while it wasn't even switched on.

Took a while before I realised what was going on, as no cause showed on tests because we were called when the weather was wet.

Obviously, you could also complain to the power company, but I don't know if that'll do any good.

Although I wasn't running a audio gear, we had issues with a neutral return. The power company decided to deal with the issue after the neighbour had to call for ambulance twice, my wife once because they got electric shocks when touching tapware or light switches; and finally when the neighbour's powerboard caught fire. The power company replaced the problem components at the power poles including insulators, the neighbours power board and all cables and tethers to every house on the street. It had all been neglected for 30 years.