View Full Version : Squeezebox Classic Low noise power supply build
Hi Guys,
This is a follow on from the 5v Linear power supply designs (http://theartofsound.net/forum/showthread.php?t=5225)thread.
Following some discussion, I have agreed to build a PSU to replace the std wall wart for Chrism.
I would like to start by pointing out that this build is a favour while I'm off work recovering from knee surgery (gives me something to do other than watch mindless drivel that is daytime tv!!!:lol:). I will ensure that sufficient information is shown in the thread to enable anyone who is interested to build their own should they choose. I will not be able to build any further units :(. At this point, Chris has paid me by cheque for parts with a small amount of head room for sundries like heatshrink, cable ties and standoff's etc. I should like to also disclose at this time that Chris has included as payment for my effort, a couple of beers which I thank him for! :cool: I've disclosed this now as I do not want to be tripped up on it later.
The design specification has been discussed with Chris and I will only deviate from out agreed design with his permission.
The breif is to create a linear 5v PSU unit capable of outputting up to 2A. The supply should be significantly superior (in terms of supply quality) to the existing unit. As I am a home modder, I cannot measure the noise on the new supply. I can however comment from experience with the selected devices and supplier specifications.
I will test the supply under dummy load and whilst connected to a 5v supply rail within my own CD Player. Again although this is clearly not a scientific test it should demonstrate the PSU's potential. I'm sure Chris will add his findings to the thread when he receives the unit.
The unit is based on the design I listed in post 13 of the afore mentioned thread http://theartofsound.net/forum/showpost.php?p=96778&postcount=13
The component list is attached.
The main pcb has arrived today. I will be popping to Maplins a bit later to buy the case placing an order for the other electronics later.
I'll get some photo's as soon as a few bits have been layed out.
Should be quite interesting to see what this unit will doe when the build is complete :)
Ali Tait
15-02-2010, 15:04
Interesting stuff Ian.Have a Touch on preorder,so might build one for when I eventually get it!
Covenant
15-02-2010, 15:37
Ali, I read on the Squeezebox forum that the design of the Touch meant that there would be no advantage in getting an improved supply.
As a user of a linear supply I will be interested in your findings Ian. There has been many people say that it is of no benefit due to the internal switching
design but I noticed a significant improvement with mine.
I'm really hoping this PSU isn't held back by any internal regs.
I'm encouraged by the couple of responses to suggest that improvements have been noticed with an upgraded PSU! :)
Ali Tait
15-02-2010, 15:53
Aye I read that myself,but for all the cost of the parts,it's worth a try.If there's no difference,I'll find another use for it.
Thanks Ian,
I can confirm that as I am a true Yorkshire Man I have only allowed Ian 2 pints of standard bitter in the costings. Spillage will be at his own cost!
Was going to build it myself but Ian very kindly offered as he is off work and asked if he could.
I am very much looking forward to giving it ago (although I am one who thinks the internal SB regs will prevent it doing it's job) and will post my findings accordingly.
Regards
Chris
The supply arrangement in the SB2/3 is different, because of the display. It takes the incoming supply, and kicks it up to 55 V or so, for the display. It derives all of the other voltages, from that supply rail. The Duet, and presumably the Touch, won't have that problem to wrestle with.
The stock SMPS for all of them generates tons of noise. If you look at their output on a spectrum analuser, you will see harmonics of the mains frequency for a looooooong way out. A rudimentary linear supply would only have the mains frequency, and its first few harmonics coming out of it.
Does any of this matter? When used as a transport, someone who has fancy equipment can see the mains frequency, as sidebands of the SPDIF signal. When you apply a clean supply to the clock and SPDIF stages, the sidebands go away.
Can anyone hear any of this? You have to decide that for yourself. To be honest, there is a pretty fair chance a lot of folks may have a hard time discerning the difference. Which leads to "An outboard supply doesn't sound any different", vs "The difference is day and night. You are daft if you can't hear it."
The truth probably lies somewhere in the middle.
As I mentioned before, be prepared to supply 0.83 A on a continuous basis.
Ali Tait
15-02-2010, 19:38
2A plenty then.
OK then.... most af the parts are here now.
As with most little projects, all is not as simple as expected!!!
The 1st problem I've encountered is that what seemed like a purfect case, is somewhat a little snug!! This is mainly due to the fact that I didn't take into account the space needed for the sockets (mains and DC) inside the case.:doh:
I've looked for a suitable alternative thats a bit larger but I can't find one thats mains rated with ventillation for anywhere near the price. Having discussed the options with Chris, we've agreed to hard wire the mains side.
The other problem is the height of the selected TSUP capacitor. The maximum height I can use inside the case is 40mm. This has meant that I'll need to select a slightly lower cap. There are a couple of possibilities here and I'll make the final selection following listening tests.
Anyway, I'll try to get a few bits bolted up and soldered early this evening and post the steps and pictures later :cool:
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5784.jpg
Don't worry about the Elna cap! Just in to show size :lol:
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5787.jpg
Ready for bolting up and soldering
Oh yes and please don't laugh at the table cloth :lol:
A few bits together now
New mounting hole marked for the Transformer and the original mains in terminals need to be removed. The PCB is designed to accept low va encapsulated transformers directly on board for clock PSU's.
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5790.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5791.jpg
PCB drilled and Transformer mounted.
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5792.jpg
The secondaries are in parallel to use the full output for a single rail. The leads are to be cut for a tidier mount onto the PCB. Because the fly leads are enamelled copper wire (the ends of the windings) they need to be stripped and tinned. The enamel was scraped off with a stanley knife.
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5793.jpg
The secondaries are soldered in place. The Cap and Hexfreds added
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5795.jpg
And finally it offered up the the base.
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5798.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5799.jpg
I'll be re-mounting the Hexfet output of the regulator to the side of the PCB to allow the space required for the output connector. But thats a job for tomorrow! :cool:
Hi Ian,
Yes time for a pint I think! I see what you mean about being snug. Nice workmanship.
Regards
Chris
Just a quick update,
The unit was assembled last night ready for testing. Upon power up the transformer got hot and there was no output! :steam:
I metered the TX and one of the secondary windings is short circuit. I replaced the transformer with a lower VA just to ensure that all was correct with my part of the circuit and all is fine!
New transformer (FOC replacement) is on its way as I post so I'll be refitting and testing at the end of the week!:doh::doh:
Thanks Ian,
Looking forward to giving it ago.
Regards
Chris
twelvebears
16-03-2010, 17:35
OK, I'm going to ask publicly a (potentially stupid) question that I've already posed to Ian privately.
Assuming that the internal voltage regulation in a Squeezebox is reasonably robust, and that the main problem is noise being passed through from the nasty SMP supply, are them any massively obvious problems with powering it from a 6 volt lead acid battery?
Being a relatively low current draw device, it would be able to run for hours on a decent size battery without causing any singificant voltage droop, and presumably, a battey must be pretty much noise free?
Thoughts?
Hi steve,
I'm fairly certain that I've read about trying batteries as a replacement but I'm sure I read that there are some issues.
Whilst it looks good on paper, I'm sure I read that the sonic characteristics are poor?! I'll try to dig out the article.
Generally with respect to the increased voltage, assuming all circuits are regulated inside the SB, it won't be a problem. However if some circuits are expecting external regulation to 5v, then there may be issues. I'd guess that there wouldn't be any issues at 4.8v tho?! (4x1.2v cells) Also remember that a typical load of just under 1A will drain smaller cells fairly fast!
I'm back at work now full time and its been a bit manic catching up! No one did my work while I was of for a month!!!! lol! This has meant that I've not spent the time on Chris's supply that I'd have like to. Also there have been a few issues.....
The PSU being built here has had a few issues. Mainly due to the heat dissipated at regulation over 1 amp. The case is a little 'snug' for sure! A larger case and heatsink will resolve these issues for sure. The SB draws about 900mA constant consisting of approx 400mA for the display and 500mA for the rest. I've been talking with chris about splitting these rails out in the SB and running 2 PSU's. This low noise one on the 500mA digital side and original on the display. SHoule be very good!
That said, a bigger case and heatsink would work for the whole unit but its going to get hotter than i'd anticipated! I'd be interested to know how warm the Teddy reg units run (Audiocom - Mark?) I'd suspect that it would be pretty warm!
Yes, those displays hog a fair bit of current, wouldn't setting the display to go off after a few seconds when not in use help? it then comes back on briefly when changing tracks
I have the Duet Receiver powered up all the time, it lacks the SB3's display and the psu heatsink only feels warm so I'd imagine yours would be fine too once the display is no longer hogging the juice, actually makes sense separating the display because its noisy as hell!
SB Classic has a lower noise emission with display at the highest level, and the highest noise when display is off.
The noise affects both digital and analog outs. It has been measured, the difference is quite impressive (although I don't remember exactly how much it was).
It has to do with the SB3 internal topology.
Looks like he'll need some meaty heatsinks and aluminum case then
SB Classic has a lower noise emission with display at the highest level, and the highest noise when display is off.
The noise affects both digital and analog outs. It has been measured, the difference is quite impressive (although I don't remember exactly how much it was).
It has to do with the SB3 internal topology.
It will definately be a large improvement if the SB is modded to accept 2 supplies with 1 dedicated to the display then!!! :)
Looks like he'll need some meaty heatsinks and aluminum case then
I'd say if you are looking for a single supply, you'd need a bigger aluminium case and some pretty heavy heat sinks. I was going to try a CPU cooler minus the fan next. I noticed you used a copper block onto the heatsink in one of you're supplies Leo. Where do you get the coppet blocks from? I quite like the idea of mounting the OP device to copper then hte copper to the heatsink. I guess this allows for better dispersion accross the aluminium sink.
It will definately be a large improvement if the SB is modded to accept 2 supplies with 1 dedicated to the display then!!! :)
This is quite possible Ian. I can't find the measures though... they must have been archived. :(
If I remember properly the processor+display need to be separated from the rest. But I don't have the details, unfortunately.
Perhaps Pat (ar-t) has some details. Iknow he had made several measures on the SB and Duet and had a perfectly neat view of what has to be done at various levels. You could try sending him a PM.
Hi Ian,
The copper block came with the PH PR3 , I just added an additional heatsink I got from ebay
cheers
I have been discussing various options with Ian about the new PS and have decided to go the split rail solution. Ian's new 5v Spower reg PS will do the digital (tested to 900ma and does not get to warm) and my Maplins linear regulated will do the display (can be set at 6.0v, 4.5v and 3.0v and can do up to 1200ma (gets warm at this level though).
Ian is also going to do a little cap swapping as well.
Was contemplation trying to remove the switcher on the digital but looks a bit tricky.
Regards
I've recently been sent a SB3 to play with, I tried it first as stock using stock psu, seriously chaps I was extremely disappointed ! My modified Duet walks all over it in all honesty (used to supply the external dacs) I remember the Duet was a little pants (IMO) as stock so hopefully Chris your upgraded psu should at least bring some noticeable improvements
twelvebears
23-03-2010, 07:19
I've recently been sent a SB3 to play with, I tried it first as stock using stock psu, seriously chaps I was extremely disappointed ! My modified Duet walks all over it in all honesty (used to supply the external dacs) I remember the Duet was a little pants (IMO) as stock so hopefully Chris your upgraded psu should at least bring some noticeable improvements
Hi Leo.
My SB Classic came from Mark at Audiocom and has his L2 digital mods and upgraded clock BUT (and I know this is poor) I'm still using the horrible stock PSU.
For someone without your or Ian's electronics skills, is there any stop-gap improvement short of one of the pricy Teddy Pardo units?
Have tried looking around but can't seem to find any non-switched ready made supplies....
I've recently been sent a SB3 to play with, I tried it first as stock using stock psu, seriously chaps I was extremely disappointed ! My modified Duet walks all over it in all honesty (used to supply the external dacs) I remember the Duet was a little pants (IMO) as stock so hopefully Chris your upgraded psu should at least bring some noticeable improvements
Where do you think the problem lies Leo?
In the SB3 there are several rails tapped at about 13v from the middle of the voltage multiplier fro the display. These are use to power the analogue out and the DAC itself.
In Chris's unit, I have seperated the rail to the voltage multiplier and the rest of the unit. I have also removed the DAC from the derrived rail and connected it to the new clean 5v supply.
This now means, if you are only using digital out, the display should no be compromising the audio. In fact with an external DAC, you can remove the PSU used for the display completely leaving unpowered!
If I was to do this again with a requirement for analouge out to be improved, i'd add an additional 3rd supply at 12v for the analogue side so that it too has a clean supply.
I'm interested in the differences in the duet. Is it the fact that is doesn't have a screen and therefore much cleaner rails that makes the difference or is it using a different architecture?
Also, I posted on another thread but the "ipeng" app for iphones and ipod touch makes control of the SB3 excellent!
I've recently been sent a SB3 to play with, I tried it first as stock using stock psu, seriously chaps I was extremely disappointed ! My modified Duet walks all over it in all honesty (used to supply the external dacs) I remember the Duet was a little pants (IMO) as stock so hopefully Chris your upgraded psu should at least bring some noticeable improvements
Hi Leo,
I have only ever used the SB3 with a cheapo regulated linear PS into a Beresford DAC via SPdif so no idea what it's like through it's own DAC. The SB3 into Bersford is on a par with a Naim CDS1 I used to own, so much so that the CDS1 was sold on.
I suspect that the Duet and SB3 into an external DAC will be very similar being a digital signal out only. The experiment Ian and I are working on is only that and I don't expect much of a change but according to Ian I am in for a pleasant surprise with the new PS/tweaked SB3.
Interestingly I have compared USB/Caiman direct from my PC vs the wireless unmolested SB3 (with linear supply)/Caiman using the same music file and I cannot detect any difference.
Regards
Chris
Hi Chris,
The SB3 and modded Duet was tried with both the Caiman and Modified ES9018 Sabre dac. I don't use the analogue output of the Duet or SB3 in the main system.
Bear in mind I only used the stock psu with SB3, next I will be trying a nice psu with the SB3, I then may have a look at the internals of the SB3 too, its not mine so we'll see what happens
BTW I find the stock SB3 sounds slightly fuzzy, flatter and lacking the detail of my modded Duet, Belden 1505A cable was used as a SPDIF lead going to the Caiman and Sabre dac
I hear differences with the spdif sources no matter what external dac is used
Cheers,
Leo
Where do you think the problem lies Leo?
In the SB3 there are several rails tapped at about 13v from the middle of the voltage multiplier fro the display. These are use to power the analogue out and the DAC itself.
In Chris's unit, I have seperated the rail to the voltage multiplier and the rest of the unit. I have also removed the DAC from the derrived rail and connected it to the new clean 5v supply.
This now means, if you are only using digital out, the display should no be compromising the audio. In fact with an external DAC, you can remove the PSU used for the display completely leaving unpowered!
If I was to do this again with a requirement for analouge out to be improved, i'd add an additional 3rd supply at 12v for the analogue side so that it too has a clean supply.
I'm interested in the differences in the duet. Is it the fact that is doesn't have a screen and therefore much cleaner rails that makes the difference or is it using a different architecture?
Also, I posted on another thread but the "ipeng" app for iphones and ipod touch makes control of the SB3 excellent!
Hi Ian,
It would have been more fair to compare a stock Duet against the stock SB3, my Duet uses a better clock, the spdif and clock are now separated from the single hex inverter, the hex inverter has its own separate reg, I added some additional filtering to the Duets DC input, It also has a Bybee on the SPDIF which made quite a noticeable improvement after run in, these with the Paul Hynes PSU gives the Duet an unfair advantage, its still nice to see the mods was not a waste of time even using when using it as a spdif source:) Theres more things I want to try yet
Cheers,
Leo
Edit, I'll know more with the SB3 after having a poke around inside
What else have you got up your sleeve then!!!! :)
My SB3 should arrive friday and the 1st thing i''ll do (over what I've already done for Chris) is to clock it. I'm going to try clocking the DAC at 24.576Mhz. The reason being, I want to run the left justified direct into the new AD1853 DAC i'm building and share the clock! (the clock will run on the DAC ultimately)
I'm not sure if it will work (the datasheet says it will run at 24 as opposed to 11) but I'm not sure how it will effect the rest of the SB. I'd really like a diagram!!!!
If all else fails, I'll use an 11Mhz on the SB.
Well I have the "modded" Squeexbox Classic up and running through a Caiman and it sounds fantastic! Bit strange plugging two power supplies into the SB - Ian's Spower ( PSU board and built in regulator is Brent's at audioupgrades) based linear PS for the digital side and a Maplins cheap Linear for the display.
Ian also changed some caps inside the SB with Rubycon ZA's amd Oscon SEPC's as advised by Brent.
The kit is still warming up but the change to the sound is quite staggering. Much more vibrant and exciting than before and the overall sound is bigger somehow. Realism and clarity has taken a good step forwards.
Really big thank you Ian for all your help and time with the mods. I think that I must owe you quite a few pints!
Regards
Chris
Glad it's all finally coming together! It was run constantly at mine for a few days since fitting the caps so it should have a few hrs under it's belt. I'll make time to go through what was done and where I had the problems as soon as I get time. Needless to say, if something could go wrong, it did!!!!! Should be miles more friendly now chris, I'll starting the same work on my own sb next week!
Right! I thought it was about time I let you all know what went right and what went not so right (well wrong actually) with this PSU build.
Firstly the design was in essence unchanged but the implementation migrated due to technical limitations.
When all the parts arrived, it was evident that the fit was snug :doh: What I had failed to take into consideration was the various sockets would take up space inside the box!!! A change to hard wired mains resolved this issue.
I assembled the components to discover a fault with the supplied transformer. RS replaced the transformer and the psu was tested.
It was clear that the std heatsink on the board was never going to cope with the current being drawn (constant approx 1A) for any legnth of time. Bigger heatsinks were ordered! When these arrived they did a better job but still not good enough! I next tried a graphics card sink with a fan. This worked very well however both Chris and I were unhappy about a fan inside the PSU. It was apparent that the case would not be capable of housing a suitable heatsink :(
After some research and discussion, I suggested to Chris that we seperate the supply to the SB display as this account for about half of the current drawn. This way, 2 supplies could be used. The origianal SMPS for the display and new low noise linear PSU for the rest (There is a bit more to the rail seperation but more on that later).
This is the final configuration. 2 supplies, one for the display, and 1 for the rest. The unit runs warm (as expected) supplying about 600mA to the control, wireless and digital side of things.
I carried out a few other mods whilst inside the SB too! OsCon SEPC's on the digital rails and Rubycon ZA's on the analogue rails. I also addressed the digital supplys to the DAC that are derived from the voltage multiplier that drives the display.These nor run from the 5v supply from the new linear PSU. I'll let Chris describe the changes to the audio but here are the pics!!! The cable was finished with overbraid which is not shown as I didn't take a photo of the finished lead!!!!
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5918Custom.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5917Custom-1.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5920Custom.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5921Custom.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5925Custom.jpg
http://i497.photobucket.com/albums/rr332/Trunky1812/Low%20noise%20Squeezebox%20PSU/IMG_5939Custom.jpg
I just noticed! The PSu looks like its using a single regulator device!!!!! Its not! The device mounted on the heatsink is a Hexfet. The feedback parts to the circuit are all smt under the pcb!
A few internal pics of the SB3 mods (hope that's ok Ian).
1690 1691 1692
Soundwise what a transformation! The overall sound is bigger and dynamic and has improved clarity on well recorded stuff. Much more enjoyable and addictive to listen to than before (and I liked it before).
I feed the modded SB into a modded Caiman (Murata's and Rubycon caps) with a nice linear supply and I have not enjoyed a set up more.
Hoping to tinker with reclocking the SB soon as Ian thinks that this will produce even more gains. Thanks Ian you have done a great job.
Regards
Chris
A few internal pics of the SB3 mods (hope that's ok Ian). NP ;)
You may laugh but I've not changed a single component in my SB yet! I've been to busy with work and had a few other bits to sort out too (Centre and rear channel amps and mains cable for a start!) Add that to 5 new chests of drawers in the bedroom (thats 20 drawers I assembled) a new bigger TV stand (all m gear is on that due to room constraints & about 3 hrs "sorting" the cabling) and I must have done about 6 weeks work in the last 2!!!
I will shortly be looking at clocking (as soon as my SB is in a similar state of tune you yours ;) ) I'll be sure to let you know when i've complete my clock testing!!!!
Also.......you'll never need a SBtouch if you get iPeng app on the iPhone/iPod touch! Its awesome. Full coverflow type remote for all the SB's in your house from you hand! :eek:
Glad you're enjoying the changes Chris :cool::cool:
Ali Tait
16-04-2010, 19:19
Yeh,but the Touch is just soo sexy.. :eyebrows:
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