[DigitalMana]

After this upgrade:

Better ripple rejection (15dB more)
Better output filtering
Better transformer (better DC noise resistance)

How to:
 
Buy an Iomega ZIP Drive 15W AC ADAPTER R4W005-100 for US$10 either on ebay or google search “R4W005-100” and will come up many results, for example:

http://genuine-ac-adapter.com/zip-r4w005100-ac-power-supply-charger-adapter-p-5725.html

and swap the DC connector with AQVOX USB connector, then bin the AQVOX power supply😂

NOTE: the R4W005-100 is 120V  input, so for people with 220V mains, you will first need a step down transformer.

For those who doesn't want to throw out their AQVOX, I will suggest some mods at the end of the post too. Now the juicy part….
 
Background

Previous power supplies reviews https://www.audiocircle.com/index.php?topic=149059.0

When I unboxed the AQVOX, a sense of déjà vu hit me, I have seen this thing before, I have owned this thing before.  After 10 mins of search through my carton of power supplies collected over the years (I’m everyone have a big box of those), I found it, the Iomega ZIP Drive power supply!

Ok now the juicy bits … uncensored hardcore comparison

1. Outside





all I can say is they are very similar, one is with cable, one is a direct plug-on type.

2. Inside






They look 90% the same, but there are some differences:

a. The ZIP R4W005-100 uses Sharp PQ30RV21 regulator, the AQVOX uses PQ30RV11.

From here: http://www.sitsemi.ru/analog/pq30rv1_e.pdf

The PQ30RV21 is rated 2A and the PQ30RV11 is rated only 1A; also the PQ30RV21 has higher ripple rejection performance (15dB better), so the PS with the PQ30RV21 will have much less noise.

b. The ZIP R4W005-100 uses 6800uF filtering capacitor regulator, the AQVOX uses 4700uF only,

So the ZIP R4W005-100 will have less ripple on the output and can withstand current spike better, ~50% better.

c. The ZIP R4W005-100 has an extra filtering capacitor before the Sharp regulator

C(IN) in the schematic, the little blue cap in the photo; this increase performance and stability of the regulator.  It is recommended in the Sharp datasheet, but the AQVOX one doesn't have it.
 


d. ZIP R4W005-100 has a better transformer



The core of the ZIP R4W005-100's transformer is alternatively stacked, the AQVOX one is butt stacked. Usually butt stacked is cheaper to make and has lesser performance.

e. ZIP R4W005-100 has a newer version of the main PCB
 


 
ZIP R4W005-100's PCB version is "33-00485-2 REV1", AQVOX's PCB version is "33-00485-0".  Seems ZIP R4W005-100 has a newer PCB version, hence the additional small blue filtering cap.

more on the ZIP R4W005-100 at the end.

3. The connector
 



Obviously the ZIP R4W005-100 comes with a DC connector, the AQVOX comes with a homemade USB male and female connector.

AQVOX did add 2 ferrite beads to the power lines and gold plated the connectors, good on them. Other then this, it appears that the USB connector was made up of one male and one female, with USB Data pins directly solder together, then hot glued and applied heat shrink tube over.     

4. The R4W005-100

After some googling, seems the R4W005-100 is made in China by this Taiwan company:

http://www.sac-ontop.com.tw/

However, their current site doesn't show any linear PS anymore, so those will be old stock.  From another site, it does keep their old product page:

http://php2.twinner.com.tw/site/product_detail/land-ctop-2/index.php?Product_SN=77564&PHPSESSID=loemnib94gthhd2oqhnkibrij6&Company_SN=5697&Product_Site_Classify_SN=29649

So seems like AQVOX is clearing out their old stock.

5. Conclusion

AQVOX USB Power Supply is an older and lesser version of the Iomega ZIP R4W005-100.

AQVOX charging US$100 for a lesser version that can be get online for US$10 is very clever business. But I think there are justifications for this, they did glue a homemade USB plug onto it and add 2 ferrite beads to the power lines, and labour in Germany is very expensive as we all know.

At the end of the day, neither the R4W005-100 or the AQVOX is anything special, they are just generic linear power supply.  If you only have a budget of US$10, get one and replace the generic SMPS you have, they will bring an improvement over the generic SMPS.

But for serious listener, go for something like the iFi iPower, it's light years ahead of those.

P. S.

If one does want to mod the R4W005-100 or AQVOX, here is what a DIYer can do:

1. replace the 2 diodes with schottky diodes to eliminate diode switching noise.

2. replace the big filter car with the lowest ESR and highest capacity you can find, looking at the space, a 10000uF/16V may be able to be fitted there.

3. Add the C(ref) back in if not there.

4. change the Sharp PQ30RV11 to Sharp PQ30RV21, this is a drop in; even better, change to a LT1085, this need circuit change ... if you go to this length, get something else that will be much better