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Thread: Squeezebox Duet

  1. #1
    leo's Avatar
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    Default Squeezebox Duet

    First we'll start with the external psu, supplied with the Duet comes a cheap plug in SMPS , I decided to try a well filtered linear based PSU using LM1086 to see if it offered any performance boost in this particular application, I found it slightly improved SPDIF and analogue output, because I felt the move from SMPS to linear improved performance I decided to go a little further.
    Apart from Paul Hynes I don't know of any other alternative upgraded psu's in the UK for the SB's so I tried one of his PR3 modules, this required a small 12v transformer which I already had , other bits needed like the case, cable etc came from Maplin

    Heres the PR3 installed in the Maplin case



    If you don't want to go the diy route Paul sells complete Squeezebox and Duet Receiver upgraded psu's called SR1 which can be found here http://www.paulhynesdesign.com/page7.html

    So how does the PR3 compare against my diy linear? In all honesty it was noticeably better! What was very interesting is that the Receivers analogue out didn't sound bad at all now! Its quite surprising what influence psu's have on a units performance , I'd say the analogue out was on par with most decent mid priced cdps I've heard where as before with the SMPS it was more like a cheap DVD player

    The next stage was some internal mods, the first round is going to be basic stuff easy for most to try if they wish, nothing new here
    Heres the standard Duet pcb



    First thing was to replace the filter cap on the input DC socket, the standard one is a general purpose SMD type which is probably next to useless especially if using the external SMPS, I replaced it with a Oscon , any low ESR should be ok here, stability using low ESR in this position was fine



    The 74HCU04D is part of the SPDIF and XO circuit , its supply comes from the onboard 3v3 switcher used to supply other various bits and bobs, ideally you want a clean supply here so separating the line and giving it its own regulator is worthwhile ,for now I fitted a basic VBE supplying a 3v3 reg, this will be upgraded to something better later (I'll post results) .
    I may also try using separate Hex inverters instead of the one shared for XO and SPDIF but the reg mod alone is certainly worthwhile for both analogue and mostly SPDIF out


    Instead of butchering the track I lifted the supply leg and ran the new regulator straight to it
    Warning, this is fiddly, its very easy to snap off the leg



    With reg installed



    The Receiver also uses SMD ferrites on both the SPDIF out and analogue out, probably there to help filter possible noise because of the SMPS, A guy called ART posted some interesting measurements on Audiocircle about these ferrites used in the SB3 (only used in the SPDIF output for the SB3) , the SPDIF measured better without it so I also decided to bypass both the SPDIF one and also the pair on the analogue out



    What I intend to do later is make use of the internal I2S lines in the Receiver but for now I wanted to see what improvements could be done to both the SPDIF out and the internal dac

    The dac is a cheap WM8501 , not exactly state of the art , these don't even require an additional active output stage
    Datasheet can be found here http://www.wolfsonmicro.com/uploads/.../en/WM8501.pdf


    I next changed the output coupling caps which was a pair of general purpose 10uf SMD's, you can use what you like here as long as theres room in the case, I just used what I had to hand, a pair of Panasonic for audio (metallic blue sleeve) with a Wima film cap strapped across them, I'll faff about comparing alternatives later



    Theres a small 5v SMD reg for the WM8501 dac, this would certainly be worth upgrading too if your using the Duets analogue outs, I'll change this later along with decoupling caps and post results.
    Theres more to try yet so will update as soon as I can, this will mainly be internal regulation.
    I'm currently running in the Receiver but initial impressions are very promising
    Cheers,
    Leo

  2. #2
    Join Date: Oct 2008

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    I'm Jerry.

    Default

    Hi Leo,
    As usual your ability and confidence is to be admired.
    I am glad you noticed a difference with a linear supply-I certainly did with my SB3 classic yet the designer says it does nothing-strange.
    Do your mods improve both the analogue and digital output?
    Jerry
    Hifi: IPL transmission line floorstanding speakers, Squeezebox Touch, Soncoz SGD1 DAC, DCB1 Pre-amplifier, Croft Series 7 power amp.
    Custom Hifi cables HA10SE headphone amplifier and Hifiman HE-400 headphones.
    AV system: LG 55B7, Denon AVR -x2300w receiver, Quad 12L (front) 11c Centre and 11L rear . Velodyne DD15 subwoofer.

  3. #3
    leo's Avatar
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    Default

    Quote Originally Posted by Covenant View Post
    Hi Leo,
    As usual your ability and confidence is to be admired.
    I am glad you noticed a difference with a linear supply-I certainly did with my SB3 classic yet the designer says it does nothing-strange.
    Do your mods improve both the analogue and digital output?
    Thanks
    It improved both SPDIF and analogue out to my ears, more so with analogue out imo, also the range in noticeable improvement with spdif varies depending on what external dac was being used so I guess mileage will vary.
    The upgraded linear supply on its own is a good start, the other bits will be mainly tune ups
    Cheers,
    Leo

  4. #4
    Join Date: Oct 2008

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    I'm Jerry.

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    Thought you might like to see my homemade (not by me) SB3 power supply. Its in a wood box that used to house knives and forks! The Virtual Dynamics power cable had to be disconnected because being a garden hose it doesnt bend very well.
    I thought the linear supply was a good upgrade for 100 but its full potential is probably hampered by the SB3's internal regulators.
    Attached Images Attached Images
    Jerry
    Hifi: IPL transmission line floorstanding speakers, Squeezebox Touch, Soncoz SGD1 DAC, DCB1 Pre-amplifier, Croft Series 7 power amp.
    Custom Hifi cables HA10SE headphone amplifier and Hifiman HE-400 headphones.
    AV system: LG 55B7, Denon AVR -x2300w receiver, Quad 12L (front) 11c Centre and 11L rear . Velodyne DD15 subwoofer.

  5. #5
    leo's Avatar
    leo is offline Circuit Junkie & DIY Room Forum Leader
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    Quote Originally Posted by Covenant View Post
    Thought you might like to see my homemade (not by me) SB3 power supply. Its in a wood box that used to house knives and forks! The Virtual Dynamics power cable had to be disconnected because being a garden hose it doesnt bend very well.
    I thought the linear supply was a good upgrade for 100 but its full potential is probably hampered by the SB3's internal regulators.

    Looks good!
    The internal regs in the Squeezebox's are obviously cheap but I think its that external smps which lets the performance down most.
    One of the problems with SB3 is that noisy display polluting the things
    Cheers,
    Leo

  6. #6
    leo's Avatar
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    Just an update, I removed the wireless card out of the Receiver , the sound doing this has definitely improved some more (slightly but noticeable)
    The only snag is the front led flashes pink continously , it thinks it has a fault
    Cheers,
    Leo

  7. #7
    Join Date: Apr 2009

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    I'm John.

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    well done Leo,
    You certainly are a circuit Junkie - what external DAC are you running this into - Sabre?

  8. #8
    leo's Avatar
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    Quote Originally Posted by jkeny View Post
    well done Leo,
    You certainly are a circuit Junkie - what external DAC are you running this into - Sabre?
    Ta

    I use it with several different dacs, obviously these things are limited especially with higher res formats but their pretty convenient in use and don't sound bad once modded
    Cheers,
    Leo

  9. #9
    Join Date: Apr 2009

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    I'm John.

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    How does it sound with the Sabre? I'm interested in how the Sabre's ASRC handles the jitter that this SB puts out? Any better than sounding than into other DACs?

    I'm attracted to some network solution like this & I was thinking along the lines of a Network Media Tank (NMT) device like the Popcorn Hour. Now these are primarily for video playback so their clock arrangements are not the best so I wondered just how good the Sabre is at handling jitter & would it make one of these into a decent playback device?

  10. #10
    leo's Avatar
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    Quote Originally Posted by jkeny View Post
    How does it sound with the Sabre? I'm interested in how the Sabre's ASRC handles the jitter that this SB puts out? Any better than sounding than into other DACs?

    I'm attracted to some network solution like this & I was thinking along the lines of a Network Media Tank (NMT) device like the Popcorn Hour. Now these are primarily for video playback so their clock arrangements are not the best so I wondered just how good the Sabre is at handling jitter & would it make one of these into a decent playback device?
    It sounds pretty good , actually jitter from Duet isn't bad compared to a few CDP's
    I've never tried one of those Network Media tanks so can't comment on those, even though Sabre is reported to use some fancy patent Time Domain Jitter Eliminator I can still tell the difference with the sources used, I actually tried feeding it from a cheap DVD player and found it sounded noticeably worse than from the Duet

    I tried a separate clock using Tent XO with the Duet, tbh I didn't think results was worth the effort, I'll look into it later for better options

    Biggest most noticeable gains so far for me was from the supplies
    Cheers,
    Leo

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