Matrix MPS-3033X 3-channel 198W Isolated PSU - REVIEW (UPDATED WITH CONTENT!)

[radensb]

I was able to get around to putting together what I felt was a proper review of this product. Note: I have never reviewed a PSU before and took hints from some of Dave's videos reviewing programmable linear supplies like the Rigol DP832 and Atten.

The Matrix MPS-3033X looks to be a clone of the BK Precision 9130B (or equivalent) and has (on paper) the same spec claims, so I used one for comparison. I also used a BK Precision 8600 programmable load and an in calibration Fluke 289 DMM.



I got this unit from Amazon for $299 with a 25% off promotion (retails for $399).

Lets get into it.


Initial observations:

• The BK Precision is listed at a 30V@3A/30V@3A/5V@3A for CH 1/2/3 respectively. However, the unit actually lets you set 31V@3.1A/31V@3.1A/6V@3.1A.
• The Matrix is also listed as 30V@3A/30V@3A/6V@3A for CH 1/2/3 respectively. However, the unit actually lets you set 32V@3.2A/32V@3.2A/6.2V@3.2A
• The Matrix has a larger and brighter display
• The software is nearly identical (how the unit is controlled, the menu, the features). The only difference I have seed so far are subtle things like setting change confirmation messages.
• Both units have the same IO (USB, RS232, and sense for all three channels), except the BK also has a GPIB port.
• Form factor is identical and dimensionality is identical.
• The Matrix has louder relays and didn't use the standard 0.750" post separation (for BNC adapters) 
• The banana cables it comes with are ok, but the alligator ends are not great.

For my comparison, I tested the following:

• Supply Power Up transients before outputs are enabled (no load) - DEPRECATED, SEE SECTION NOTE
• Supply Power Up transients before outputs are enabled (10Ω) - DEPRECATED, SEE SECTION NOTE
• Open Circuit Voltage Accuracy
  
• Loaded Accuracy (indicated vs measured)   
  100mA
  1A
  2A
  3A
• Open Circuit Power up ramp measurement
  1V
  5V
  10V
  20V
  30V
• 1Ω stress test and recovery (Dave's favorite)
• Pk-to-pk Open Circuit voltage noise
• CC (1.3A) for 40W transient power ramp
• Time to transition to CC mode (4A load)
• Channel Off Transients (30V, 1.3A load)
• Supply Off Transients (30V, 1.3A load)
• Supply Off Transients (5V, 1.3A load)
• Supply Off Transients (3.3V, 1.3A load)
• Supply Off Transients (3.3V, 5V-30V AC Coupled in 5V increments, 1.3A load)

1. Supply Power Up transients before outputs are enabled (no load): BK Precision on Left and Matrix on Right

There looks to be some trivial activity on the outputs of both units when they are powered up (outputs off), but the amplitude is very low and only lasts a few hundred nanoseconds.
NOTE: As another member below has pointed out, these are EMI spikes from the supply and not on the output. I will leave the content to maintain the list, but I think this can safely be dismissed.

2. Supply Power Up transients before outputs are enabled (10Ω load connected): BK Precision on Left and Matrix on Right

Again, similar results with an active load connected.
NOTE: As another member below has pointed out, these are EMI spikes from the supply and not on the output. I will leave the content to maintain the list, but I think this can safely be dismissed.

3. Open Circuit Voltage Accuracy:



4. Loaded Accuracy:


5. Open Circuit Power-up Ramp: BK Precision on Left and Matrix on Right (Note - BK ramps much slower so time base is 10ms vs Matrix 1ms)

Above shows the ramp for a 1V output.


Above shows the ramp for a 5V output.


Above shows the ramp for a 10V output.


Above shows the ramp for a 20V output.


Above shows the ramp for a 30V output.

6. 1Ω Stress Test and Recovery: BK Precision on Left and Matrix on Right

Both units went into constant current mode and did not oscillate between CV and CC mode. I even made sparks by shorting the channel out with banana leads over and over again. It would immediately click into CC mode and drop to ~50mV. 

7. Pk to Pk Open Circuit Noise: BK Precision on Left and Matrix on Right

Both units went into constant current mode and did not oscillate between CV and CC mode.

8. 1.3A (~40W) Constant Current Power Up Transient: BK Precision on Left and Matrix on Right

Both units went into constant current mode and held there when I used the constant wattage mode on the programmable load, so I used a CC of 1.3A. This comparison also shows the difference in ramp up rate.

9. Time Delay to Transition from CV to CC mode: BK Precision on Left and Matrix on Right

Both units went into constant current mode in 800us.


The Matrix had a slightly more aggressive drop in voltage.

10. Channel Off Transients (30V, 1.3A): BK Precision on Left and Matrix on Right

The channel output is about the same between the two units when enabling and disabling the channel with the BK being a bit more consistent as the slope doesn't change, but that doesn't matter. Both units have a safe channel power off transition with no spikes or concerning transients.

11. Supply Off Transients (30V, 1.3A): BK Precision on Left and Matrix on Right

The channel output with powering off the entire supply (while under load) is a bit different between the two units, however both have very fast and clean power drops.

12. Supply Off Transients (5V, 1.3A): BK Precision on Left and Matrix on Right

The Matrix seems to ramp up an additional 0.2V (over ~23ms) before discharging when active shutdown occurs with a 5V output which is not present in the Matrix.

13. Supply Off Transients (3.3V, 1.3A): BK Precision on Left and Matrix on Right

The BK seems to have a small transient just before discharge at 3.3V that is not present in the Matrix.

Below is a zoomed in view of the short transient present on the BK during the active 3.3V shutdown


14. Supply Off Transients (3.3V, 5V - 30V AC Coupled in 5V increments, 1.3A): Below shows the AC coupled power transients of the Matrix supply to get a better look.

• 3.3V: No transient detected.
• 5V: 26.4ms ramp up to 162mV overshoot
  
• 10V: 22.8ms ramp up to 152mV overshoot
  
• 15V: 48.2ms ramp up to 244mV overshoot
  
• 20V: 48.2ms ramp up to 276mV overshoot
  
• 25V: 49.8ms ramp up to 284mV overshoot
  
• 30V: 54.4ms ramp up to 288mV overshoot
  

The Matrix supply ramp up lasted ~26ms to ~55ms depending on the output range and ramped up to ~160mV to  ~290mV depending on the output range (> 5V).

Below is a plot summary of the voltage overshoot peaks based on the output voltage to interpolate the intermediate values. (3.3V is at 0V overshoot)


This was masked in the section 11 testing due to the voltage range of the signal and DC coupling it. This characteristic is something to keep in mind, but I don't think its a concern. Also, keep in mind that I measured the overshoot peak, which is not the active level during the entire ramp up time. Please comment if you disagree!

Overall, I am pretty impressed. There are a few things that I think I could evaluate better. If anyone has any suggestions, I would be happy to experiment further!

[radensb]

After using this supply for a few weeks now, I have noticed no discernible issues. I did see one typo in the menu "Chunnel Select" ... 

Otherwise, this seems to be a solid sub $400 unit with sense (one thing I hated that the Rigol's are lacking in this price range, along with a standard number pad...)! I haven't messed with the USB or RS232 interface yet, but that is next on the list when I get some time.

[nctnico]

Those 'power up' transients are due to the EMI from the power switch. These aren't actually on the output. Look at the time scale on your oscilloscope! As a rule of thumb: only spikes lasting longer than several tens of us (microseconds) are likely to come from the regulation circuits. Better turn on the 20MHz bandwidth limit for these measurements. Typically there is a capacitor across the output with at least tens of uf of capacitance so extremely narrow spikes have no chance reaching the load.

What is missing from your test is the behaviour when the PSUs are switched off with the outputs on. Some cheap PSUs can show really nasty spikes in that case.
Edit: overlooked that shutdown behaviour was part of the test and the supply passes with flying colors. Early mornings 

[Berni]

That is a pretty nice looking PSU for a impressive price. I like the front panel and form factor more than the Rigol i got.

What is the boot time like?
How loud are the fans at no load and full load?
Does the USB interface work properly with SCPI? (I seen some chinese programmable PSUs have half broken PC interfaces)

[radensb]

Those 'power up' transients are due to the EMI from the power switch. These aren't actually on the output. Look at the time scale on your oscilloscope! As a rule of thumb: only spikes lasting longer than several tens of us (microseconds) are likely to come from the regulation circuits. Better turn on the 20MHz bandwidth limit for these measurements. Typically there is a capacitor across the output with at least tens of uf of capacitance so extremely narrow spikes have no chance reaching the load.

What is missing from your test is the behaviour when the PSUs are switched off with the outputs on. Some cheap PSUs can show really nasty spikes in that case.

Thanks! I had not considered the power up transients to be an EMI, but due to the time base, this makes perfect sense. It also explains why this was the most inconsistent measurement! Thanks for the rule of thumb. I'll keep that in mind for the future.  I also updated the original post to include two more tests/comparisons. Section 10 is the power down curve of both PSU's by disabling the output channel (turning it off) while loaded with a 40W load. Section 11 is the power down curve of both PSU's when shutting them off (on/off switch) while loaded with a 40W load. I believe the latter is what you suggested directly in your post? Both situations looked pretty clean to me.

That is a pretty nice looking PSU for a impressive price. I like the front panel and form factor more than the Rigol i got.

What is the boot time like?
How loud are the fans at no load and full load?
Does the USB interface work properly with SCPI? (I seen some chinese programmable PSUs have half broken PC interfaces)

• Boot time is ~1.8 seconds.
• When there is no load, the fans are off (or so quiet I cannot hear them). I ran a test with the programmable load set to 3A and ran it for ~10min. From 1 foot away, the Matrix fan noise was ~35dB (whisper) level. It was very quiet. Much more so than the programmable load!
• I have not tried the USB interface, but the unit did pop up immediately under Device Manager as a USB to Serial device with a COM port# without any drivers needed.  The manual states that it accepts SCPI commands, but I am not familiar with that style of control ... yet

[Berni]

• Boot time is ~1.8 seconds.
• When there is no load, the fans are off (or so quiet I cannot hear them). I ran a test with the programmable load set to 3A and ran it for ~10min. From 1 foot away, the Matrix fan noise was ~35dB (whisper) level. It was very quiet. Much more so than the programmable load!
• I have not tried the USB interface, but the unit did pop up immediately under Device Manager as a USB to Serial device with a COM port# without any drivers needed.  The manual states that it accepts SCPI commands, but I am not familiar with that style of control ... yet

Very nice. Might consider getting one of these.

The boot time on the Rigol is unreasonably long for just a power supply and the fans are loud as heck even on idle (Swapped the fans out in mine to fix that)

[simba15]

Any one seen any current links to purchase one?

Sure looks like alot of ques came from the Keithley. Personally I like the 2U half rack design.

That non standard probe spacing tho..... not sure if I can live with that.

[pope]

For some reason most Matrix products are not available in Europe. At least I can't find them anywhere.

I've been looking into their LCR series and only one (older?) model can be purchased by Eleshop and that's about it really.

[mawyatt]

The GW Instek and Siglent Linear Power supplies we have are barely audible unloaded. The fans are rotating but very little air movement, wish the other instruments we have were this quite!!

At the other end of the fan noise spectrum is the Hioki IM3536 LCR meter, this sounds like a jet engine yet only consumes ~25 watts!! No it's not defective, evidently they all are this noisy!!

Best,

[radensb]

What is missing from your test is the behaviour when the PSUs are switched off with the outputs on. Some cheap PSUs can show really nasty spikes in that case.
Edit: overlooked that shutdown behaviour was part of the test and the supply passes with flying colors. Early mornings 

Nope! I added that content to the OP after I read your comment! 

[radensb]

Any one seen any current links to purchase one?

Sure looks like alot of ques came from the Keithley. Personally I like the 2U half rack design.

That non standard probe spacing tho..... not sure if I can live with that.

This is the Amazon link: Matrix MPS-3033X

I hear you about the post spacing. I just got boards in to fix that! Its an adapter board that mounts to the binding posts and provides an offset positive terminal that is the proper 0.75" spacing from the return terminal. (please ignore the marring on the screen - I haven't removed the protective film yet because I'm that guy...)


I havent installed the post for the offset positive hole, but the below shows how it would line up.


I am planning on buying these: https://www.digikey.com/en/products/detail/keystone-electronics/6096/316533
Ill probably have to turn the back hex head down to make it a bit thinner to fit behind the board, but then I can lock it in place with the nut and keep the exposed threaded section insulated with some red shrink wrap. 

[kmike]

It looks like the Itech IT6322:

https://www.welectron.com/ITECH-IT6322A-Labornetzteil

[kilobyte]

For the Turn Off Transient it would be interesting to see what happens if the output voltage is set to a low voltage like 3V/5V as there some Power Supplys like the R&S HMP2xxx/4xxx Series where the output voltage jumps up if mains power is switched off.

[Kean]

It looks like the Itech IT6322:

Yep, a BK 9130B (mentioned by OP) is rebadged ITECH IT6322.
Based on the pricing and slightly different front panel this Matrix unit looks like a copy/clone rather than a rebadge...

[radensb]

For the Turn Off Transient it would be interesting to see what happens if the output voltage is set to a low voltage like 3V/5V as there some Power Supplys like the R&S HMP2xxx/4xxx Series where the output voltage jumps up if mains power is switched off.

Thanks for the recommendation! I added this content as sections 12, 13, and 14 to the OP. I was able to measure a small amount of voltage overshoot when an active output driving a load was shutoff by shutting the supply off (main ON/OFF switch). This behavior was hidden from my previous testing because its so small and I was DC coupling a 30V signal. I have provided AC coupled measurements over the 30V range to provide a better picture of what is happening in this scenario.

[Frex]

It looks like the Itech IT6322:

Yep, a BK 9130B (mentioned by OP) is rebadged ITECH IT6322.
Based on the pricing and slightly different front panel this Matrix unit looks like a copy/clone rather than a rebadge...

Hello,

I own the ITECH IT6302, and according to the pictures found on the internal view of the Matrix MPS-3033X,
The design have nothing in common with it expect front panel appearance.

IT6302  = https://www.eevblog.com/forum/testgear/itech-it6302-power-supply-any-teardownsreviews/msg1755776/#msg1755776

Matrix MPS-3033X = https://m.media-amazon.com/images/I/81hQHQmU0zL._AC_SL1500_.jpg


Frex

[paerley]

Fun fact for the thread: If you e-mail their support asking if they have sent any units out for review (I specifically asked if there were any youtubers they had sent one to), they link you to this thread.