MT-ViKI MT-431AV 4 Way Switch Review

[amirm]

This is a review and detailed measurements of the MT-ViKI MT-431AV 4-way audio and composite video passive switch. It is on kind loan from a member and costs US $11 on Amazon:

I wouldn't be able to give you time of day for $11 (including shipping no less!) yet we have a metal box here with four nice/solid feeling selector switches. Back panel brings back horrible memories though:

Composite video! Man, those were the days of horrible picture quality with color decoder errors and lousy resolution. I assume no one uses the video feature in this day and age so let's quickly test the rca switching capability.

Audio Switcher Measurements
Let's start by measuring the performance of the Audio Precision APx555 while looping back internally with 2 volts out:

Immeasurable distortion and SINAD limited by noise. Let's now route the signal through a 6 foot switch to the MT-431AV and then back to analyzer using 3 foot cable:

There is essentially no impact. We do have a bit more 60 Hz which is a given due to much longer shield path of unbalanced RCA connection (I could reduce it a bit but why bother).

Since this is a passive device, we can assume transparency in all the other measurements except crosstalk from unselected input. This can be a serious problem. I have switchers where you can easily hear what is playing on the unselected input. So let's test for that:

The dashed blue line as 0 is the frequency response when the input is selected. The other curves below it are with the same setup but with inputs 2 through 4 selected instead of 1. We see that input 3 is worse than the other two but all three suffer from capacitance that is cross coupling the inputs. The higher the frequency, the worse. Input 3 gets as bad as -32 dB! This could be due to switch itself, wiring or both.

Conclusions
What can you expect for $11? Maybe this is all you can. I like to think though if any attempt was made at measuring, we could do better.

I can't recommend the MT-ViKI MT-431AV. There has to be a better switcher out there...

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[Graham849]

I'm guessing the vote for Great is for the review rather than the functionality of the switch.

 

[daftcombo]

Thanks Amir.

If only one of the four sources connected is playing at a time, no problem though. And that might be the main use case.

 

[Mulder]

Thanks Amir.

If only one of the four sources connected is playing at a time, no problem though. And that might be the main use case.

It would really be useful for me to have a Switch of this sort for switching between different amplifiers. So bad measured performance regarding crosstalk might not be a real problem then?

 

[Graham849]

Which makes me wonder can one use the output as an input for four selectable outputs?

 

[VintageFlanker]

In case there still are dinosaurs using RCA composite video these days... IDK.

But for the price, the passive preamp is acceptable. Thanks, @amirm

 

[JensH]

Were the inputs 2 - 4 unconnected? If so, I would expect a lower crosstalk level by connecting them to a low impedance output/termination.

 

[amirm]

In case there still are dinosaurs using RCA composite video these days... IDK.

I am guessing maybe for old school security camera with audio although that is rare.

Manufacturer Specifications:

Model	MT-431AV
Switches
DIP	Auto Switch ON/OFF
Video Input
Interfaces	4 x RCA interface
Impedance	75Ω
Max. Distance	N/A
Video Output
Interfaces	1 x RCA interface
Impedance	75Ω
Max. Distance	N/A
Video
Max. Data Rate	N/A
Bandwidth	50-5.5MHz
Max. Resolution	N/A
Impedance	75Ω
Connectors	1 x DC Jack
Power	DC5V1.5A
Power Consumption	N/A
Environmental
Operating Temperature	0-50°C
Storage Temperature	-20~60°C
Relative Humidity	10% ~ 90% RH, Non-condensing
Physical Properties
Housing	Metal
Weight(g)	275
Dimensions (L x W x H,mm)	135*84*38

 

[Gounsbairg]

Which makes me wonder can one use the output as an input for four selectable outputs?

You probably can.
Some of these are 'reversible' : https://www.audiophonics.fr/en/source-selectors-c-599.html

 

[wwenze]

Thanks Amir.

If only one of the four sources connected is playing at a time, no problem though. And that might be the main use case.

Then get a switch with 0dB isolation i.e. splitter.

Oh right splitter doesn't work due to shorting sources unless it is a mixer

In that case is -30dB isolation enough to avoid shorting sources?

In case there still are dinosaurs using RCA composite video these days... IDK.

But for the price, the passive preamp is acceptable. Thanks, @amirm

Subwoofer channel

 

[Holy Spirit]

2-way model is even cheaper. For £11 it is most likely the cheapest DIY electronics project box on the market. I am getting one or two for notch filter/low noise amplifier. A fine product.

 

[Mulder]

I am guessing maybe for old school security camera with audio although that is rare.

Perhaps old "Retro" video games.

 

[Hayabusa]

Since this is a passive device, we can assume transparency in all the other measurements except crosstalk from unselected input. This can be a serious problem. I have switchers where you can easily hear what is playing on the unselected input. So let's test for that:
View attachment 340478

@amirm Looks like you measured crosstalk with unconnected open inputs? I assume with at least 'something' connected to these inputs it will look much better?

 

[maverickronin]

I have an 8 channel version of this that I use as a coax S/PDIF switch.

 

[zoink]

Thanks for getting to this one!

This is my unit. The measurements fit with my experience — I've used it to permit additional inputs into an amp with fewer inputs than I have analog sources. I've found I need to turn off my tuner when I'm listening to a different source, as the crosstalk is entirely audible.

To answer @Graham849 and @Gounsbairg — yes, I have used this unit to route a single source to multiple destinations, though I've always used it to route to just a single output at a time.

@amirm Reading this gives me ideas for two measurements possibly worth taking next time you review a passive switch like this: measuring if there is any audible pop in the signal when the input is switched (I don't hear any on this but still seems like something a passive switch might conceivably introduce), and measuring inter-channel crosstalk. The poor performance of crosstalk between inputs doesn't make me feel especially confident it doesn't also have some L/R crosstalk.

 

[ObjectiveSubjectivist]

I'm missing high-end stuff being measured lately. I mean very expensive stuff like used to be measured here like ps audio, totaldac. It was such fun

 

[fgfgfg]

@amirm @zoink teardown by any chance?
Found this one

 

[Noricha]

perfect timing! the publication which arrives right at the time of my search for this type of material (switch from the spdif dac used for the tv and the usb dac for the pc to the only analog input of the volume controller)
It seems acceptable if I handle it carefully taking into account its limitations

 

[Multicore]

Photos of the innards might be real handy for those considering it a platform for DIY projects or for parts.

 

[renaudrenaud]

Anyway after few bad tests maybe it's time for at least one good review this week.