Using USB Power Delivery for Squeezebox Duet Receiver

[-Axle-]

Like many others I've been looking for a replacement for the stock 9V DC Power Supply Adapter as many of mine keep breaking (3 so far). I'm going to compile a lot of information here so this will be a long post, I'll do my best to compartmentalize.

GOAL
Getting a replacement 9V Power Supply Adapter to work with the Squeezebox Duet Receiver (and possibly other models)

CHALLENGES

1. Barrel Plug Size is Non-Standard: As many have noted, this can be a tricky thing to accomplish as the DC Barrel plug size Logitech decided to use for the Duet Receiver is NON-STANDARD. The exact measurements are 3.5mm Outer Diameter x 1.05mm Inner Diameter, Center Positive. Many have opted for the "Universal" DC Power Supply Adapters that come with multiple plug sizes but unfortunately none of those are perfect fits despite what some online users may claim. Yes, that's right, I'm all-knowing, all-powerful, and infallible so I know without even looking at their particular adapter that the sizing is not perfect. How? This is because all of those adapters come with standard sized plugs that do not match the aforementioned dimensions on BOTH the inner AND outer diameter. So you may get a snug fit on the outside but not on in the inner diameter or vice versa. They're still "doable", but also sub-optimal. The standard sizes those universal power supplies come with include; 4.0mm x 1.7mm, 3.5mm x 1.35mm, and 3.0mm x 1.1mm. Notice that none of them match the 3.5mm x 1.05mm size of the original.
2. The PSA05R-090-R Spec Sheet is Incorrect: Despite the official power supply adapter model # being PSA05R-090-R, the spec sheet from Phihong states the DC barrel plug as standard @ 5.5mm x 2.1mm, except you'll notice that doesn't match the aforementioned plug. This is why you'll find a lot of Amazon/eBay/etc listings claiming they have a replacement power supply specifically for the Logitech Squeezebox Duet, yet the reviews will often show someone saying the plug didn't fit.

POTENTIAL SOLUTIONS

1. Settling for suboptimal universal power supplies: This is the most common solution you find throughout the forums. These DC Power Supply Adapters have dials so that you can select 9V (amongst others) and then also swap in a plug that happens to fit your device. As noted, none of these DC barrel plugs are exact matches (refer above) despite anecdotes you will hear online of people claiming they fit perfectly. Some users are simply unaware that it's not an exact match and that the other sizes CAN work, despite being different sizes. The 3.5mm x 1.35mm size is the one I found to be the least problematic despite being a little loose (and no surprise since it's the closest to 3.5mm x 1.05mm), but the 4.0mm x 1.7mm and 3.0mm x 1.1mm sizes also work albeit are finickier on connection. The 4.0mm x 1.7mm is the most misleading as the outer diameter feels like a perfect fit when you slot it in, but you may notice as you place the device around, that the connection can be lost by slight movements since the inner diameter has >0.5mm of play.
2. Using USB Power Delivery to replace the power supply: This is something I haven't found as much dialogue in the forums for and what inspired this post. The basic gist of it is that you can use most standard USB Power Adapters that have come with phones ever since the original iPhone 3G to replace the official Logitech Power supply. Most of these adapters you will note are 5V 1A adapters but it's not hard to get them to 9V 0.56A (the spec of the Logitech power supply) since that still fits with the overall power demand (e.g. 5V @ 1A = 5.00W while 9V @ 0.56A = 5.04W, almost identical, and recall that the the device doesn't use the max output so that 0.04W of headroom is not very consequential), but it will require a special USB cable. For added bonus, the official Apple USB Adapters have similar ripple requirements as the Logitech Power Supply so one less thing to worry about. I would not recommend knock-off adapters as those tend to have looser ripple requirements and are more of a gamble. I would explain more but this video does a better job without me having to type it all out (ignore the USB C-type requirement, as that's optional and you can use a standard USB Type A plug)

So in conclusion, search for a "9V USB cable" and you'll see a bunch of results come up. You want to match the barrel plug size for the device you need but I'll defer that challenge to the details below as it's complicated for the Squeezebox Duet Receiver. On the plus size, if you need this for the Squeezebox Touch, that barrel plug is the standard 5.5mm x 2.1mm so it's easy to find. The catch on that one is that it requires 5V @ 3A, and that means a more modern USB charger that goes up to 3A or more (typical was 1A or later 2.1A, which would both fall short).

ADDITIONAL DETAILS ON SOLUTION #2:

• USB Type A or C Cables Work Fine: You don't have to force yourself to use a USB Type C Power Supply Adapter (since those are more recent and less common). If you do go that route, the good news is that most USB Type C power supplies are greater than 5V @ 1A so you easily exceed the Logitech Power Supply requirements. Again, would not recommend you use knock-off power supplies as those tend to have looser ripple requirements. A USB Type A cable works fine provided it has the added chip to convert 5V to 9V.
• Where to buy the cable: As mentioned, USB Type A cables are available with barrel plug ends at Amazon, eBay, etc. What you need to look out for is that it's 9V (as there's also 5V, 12V, etc. variants) and that the barrel plug matches the size we need (3.5mm x 1.05mm).
• Finding the right barrel size (3.5mm x 1.05mm): And here dear reader, we come full circle to trying to solve the same problem. The 3.5mm x 1.05mm barrel plug size is non-standard and a PITA to find online. As far as I can tell, it's non-existent. There's apparently a standard size that is 3.8mm x 1.05mm according to this website (pic below), however, I have been unable to locate such a size online.
  
  
  
  One solution that is handy, is that most 9V USB--> DC Barrel plug cables are 5.5mm x 2.1mm for the barrel plug, and the barrel plug "size converters" all seem to originate at that 5.5mm x 2.1mm size, so once you locate a 9V USB Type A cable at that size, it's just a matter of also getting a barrel size converter to your desired size (e.g. 3.5mm x 1.35mm) and voila, you've essentially got the same solution as the Universal DC Power Supply Adapter except for far less money. That latter piece is the challenging part and you will likely have to settle for 3.5mm x 1.35mm via an adapter (from 5.5mm x 2.1mm) and that is sub-optimal but will get you into the same territory as the universal power supplies.

POTENTIAL IMPROVEMENTS

• The last piece of the puzzle here is trying to find an adapter that matches this darn barrel plug size that would be an EXACT match to the original power supply. If anyone finds a source online, please feel free to share although I suspect because it's non-standard, that it would likely either be far more expensive or simply impractical.
• A good alternative would be the 3.8mm x 1.05mm size which is supposed to be standard. Why? Well, remember how I said that the 4.0mm x 1.7mm barrel plug fits the Squeezebox Duet Receiver quite snuggly? Well, that's because there's some margin there to fit a larger plug. Since the inner diameter would be an exact match at 1.05mm, oversizing the exterior barrel diameter would be inconsequential since you'd simply have a snugger fit on the outside with an exact fit on the inside. Win-win. The catch is that I have been unable to find any barrel size converter that goes to the 3.8mm x 1.05mm size. If anyone does, please feel free to share as this would solve the last piece for an even better solution.

POTENTIAL FEEDBACK

• This seems like a lot of work when the universal power supply is an easier solution overall: No argument there. The plus of using USB Power Delivery is that it's cheaper since most of us already have the actual power supply end of a bunch of chargers lying around. All you need is a cable that can convert the 5V to 9V and you're pretty much done. This is also a more scalable solution where each universal power supply is ~$15 where as each cable is ~$2 (at least where I am in Canada), different markets may differ. Of course, if you don't have spare old power supplies from old phones lying around, this argument goes out the window.
• My plug fits perfect from the universal power supply so this is a waste: RTFM, or in this case, OP
• So you're saving $10 maybe? Is that worth it: In my case, yes, but that's because I have 6 Squeezebox Duets throughout my house plus another 2 Squeezebox Touches. 3 of my Duet power supplies have gone over the years, so now I'm short 3 power supplies and suspect I'll have more dying over time. I've tried placing them behind power surge protectors as I've noticed they often fail after a power outage was experienced, but even those behind power surge protectors have gone as well, so it seems random and with age. As I keep replacing more, it's getting more and more expensive.

Phew, I think that's about it. If anyone has questions, I'll try to update the OP. Hope this info helps someone, particularly into the future as this may become an even more common challenge.

[Spacegrass]

Thanks for the thorough review of the connector issue Axle. My Duet (i think the PSU) just failed, so i am "in the market".

In the previous thread on Duet PSU replacement, a number of owners suggest cutting off the right sized connector from the original PSU and grafting it to a new PSU - do you have any fundamental concern with this option, given your conclusion that an exact replacement is otherwise unavailable?

Also, i have never seen this suggested, but i was wondering if anyone has ever considered replacing the barrel plug port in the Duet Receiver, with a more standard size? I am not an electronics guy so i can't assess this, but it seems theoretically possible.

[-Axle-]

Thanks for the thorough review of the connector issue Axle. My Duet (i think the PSU) just failed, so i am "in the market".

In the previous thread on Duet PSU replacement, a number of owners suggest cutting off the right sized connector from the original PSU and grafting it to a new PSU - do you have any fundamental concern with this option, given your conclusion that an exact replacement is otherwise unavailable?

Also, i have never seen this suggested, but i was wondering if anyone has ever considered replacing the barrel plug port in the Duet Receiver, with a more standard size? I am not an electronics guy so i can't assess this, but it seems theoretically possible.

Yep, those are both options, the catch is how much work you want to put into it.

In terms of your first question/option, it's pretty straight forward since you're only having to connect two leads. If you're good with soldering and have some shrink tubing, it's pretty straight forward so long as you do a good job and have a strong contact to make sure the cable isn't left too thin or with weak contacts. The only part I don't know is if introduces any interference / distortion on the analog outputs since that part of the cable may not be insulated as well. My guess is that the answer is "no, it's fine", since that's the input power portion of the chain rather than something downstream, plus, that's something that would literally affect all other power methods (substitute PSU, USB, etc.) so I doubt it's material in terms of impact, but something I had thought about. If using the digital outs then it's definitely a non-issue.

On the second question/option, same thing, I would imagine it's perfectly possible, just more work and you risk doing damage to the actual receiver (that costs more than a cable) plus have to retrofit it into the case/hole that was smaller originally.

A third option I've been contemplating that would solve a lot of these problems but I haven't come across as I'm not that much of a electronics person (so I'm not sure if it exists), is if there is any such thing as a brass insert ring to extend the outer diameter of any barrel plug. Really, all we need is to maker the outer diameter of the 3mm x 1.1mm plug a little bigger an a lot of problems would be solved. I also say brass because that's what barrel plugs are made of to my knowledge. If there was such a thing, then such an insert ring could be added to the 3mm barrel plug size to oversize the outer diameter to 3.5mm or 4mm and then you'd have a snug fit on the inner and outer diameter (the 3mm plug is 1.1mm on the inside). But alas, I have not come across any such thing.