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For a special project, I would like to create a 1kHz sine wave DSD signal using a MCU (in C). Can someone give me some pointer of how best to do it? Many thanks 🙂

This is not the right one, this is SMPS. Need the original one.

People ask how does it sound? It actually sounded ok, better than the generic SMPS, more refine sound and less glare. But overall no match for more advance power solutions, for example the iFi iPower or ZERO-ZONE SUPER -PSU.

Aqvox USB Low Noise Power Supply is just a very generic old style linear wall wart power supply, both filtering and regulator used are nothing to write home about, but it is better than generic SMPS power supply out there, so a score of 60 ? 1. 95 9V alkaline battery 2. 93 iFi iPower 9V SMPS 3. 90 ZERO-ZONE SUPER-PSU 4. 80 TeraDak TeraLink X2 5. 65 Breeze Audio DC-1 / S.M.S.L Panda dual 9V (both flawed) 6. 60 AQVOX USB Low Noise Power Supply 6. 55 Apple charger 7. 50 Xiaomi 10040mAh battery bank

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 ( 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

I will do an Aqvox post in the next couple of days "How to improve the Aqvox?".? The simple answer is Aqvox is not really a match for iPower, but that's not the point. Something else very interesting came up during the review.

I heard the Lite CT3 too, it's quite a colored phono stage IMHO, may be because it has a lot of coupling caps in the signal path (c.f. iPhono2 that is direct coupled, no coupling cap), and each additional coupling cap adds a different sound; also the MC stage was quite noisy for my taste. Comparing to the iPhono2 will be quite difficulty I would say, it's like Fish Curry vs Sashimi (I like both), the Lite CT3 is the Fish Curry, the iPhono2 is the Sashimi?

I found the new iGalvanic3.0 really help with USB grounding issue, it really took the system up a few notches.

I would use an iFi dual head USB cable.

We man needs toys, don't we I guess the ANC circuit inside the iSilencer clean up my PC USB ports one by one and lower the overall system noise, as all USB ports are connected to the main motherboard. But agree with you, most of the time one will be enough ...

Tests all done, but didn't have time to do the write ups. For a short summary, all those small USB gadgets they all worked in various ways. Both Bonnes Note Dressing (what a name) and the AQ Jitterbug is USB2.0 device; both iFi iSilencer and iDefender is USB3.0 devices. Bonnes Notes Dressing (US$55) and the AQ Jitterbug (US$49) The 2 Bonnes Notes Dressingand the Jitterbug does make the sound a bit more organic, but not on the same class as the iSliencer (seems like their ANC actually works). I tends to prefer the BoneNote slightly more than the Jitterbug, the BoneNote just gave a touch more fineness in sound. iFi iSilencer (US$49) The most significant is the iSilencer, it really lower the background noise and make the background darker, sound (especially the mid range) is defectively more organic, also the treble is quite a bit smoother. Use Multiple of them? (on the same PC on different USB ports) 2 x Bonnes Notes: didn't have much improvement at all over the single one, this is a bit weird. 2 x Jitterbug: a small additional improvement was heard when the 2nd one is installed, a little bit more organic sound. 2 x iSilencer: again a small but quite nice improvement was heard, dark background still, it makes the music notes jump out to you. I now have 3x iSliencer plugged in on the same PC, the first one gave the most improvement, however each additional one does bring another nice but small improvement. Lastly, nearly forgot, the iDefender is for a different purpose: to add external power input when there is none. I am using it with iFi iPower to create a really nice low noise supply. So far this combination has already better my AQVOX USB power supply and a couple other Linear Power Supply. Scores (out of 100): 60 Jitterbug 65 2 x Jitterbug 65 1 x Bonnes Notes Dressing 65 2 x Bonnes Notes Dressing 80 iSilencer 88 2 x iSilencer Note: As those are much cheaper gadgets, the points scale is not the same as the original USB hug devices tested.

Li-Po voltage is normally 3.7-4V, in order to give a 5V output, a SMPS is needed.

I sent him a few power supplies to test, he told me new tests will be up next few weeks , stay tuned

I have similar experience too, USB3.0 works better than USB2.0 ports for audio (more compatible and better audio performance), even for running USB2.0 devices.

I would suggests wait for the iGalvanic for normal use (basically a all-in-one USB fix), for the ultimate and cost no object people, go for the iGalvanic + micro iUSB3.0, I am awaiting the iGalvanic to be launched and will report back