Sb3

[t.]

Hi,

Has anybody modified or have any comments on the Squeezebox 3? Wondering if they had any potntial regarding tweaks.
I've a few modified cdp's and a diy dac and was thinking of buying one of these SB3's to have a play about with.
Only things I've seen is a better external 5v supply and bypassing the output op-amp with a coupling cap.
Is it worth going further with these units

[Clipper]

Hi T

I'm currently planning to mod my SB3. Having spent lots of time looking around the web for ideas, I have a list of tweaks I want to try and am currently collecting parts. I plan to use my SB3 without a DAC, so my tweaking will focus on improving the analogue outputs. I've read lots of good things about modded SB3's and i'm hoping after modding to retire my Arcam CD92T.

1) I already built a linear 5V supply to replace the stock supply. This bought some slight improvement, but for me it wasn't the step improvement i'm looking for.

2) I'll be removing the output opamp and coupling the DAC output to RCA sockets via Blackgate/Sonicap Platinum caps. I expect this to bring the biggest single improvement (fingers crossed!)

3) I'll upgrade the DAC to the "KE" version

4) I'll swap out the internal DAC supply caps for Panasonic FC/Blackgates.

May also remove 12.28Mhz oscillator (used to upsample low bit rate radio stations). This has been shown to lower jitter marginally.

For analogue out, I think that's about all there is to tweak. The only other stuff I've seen is to do with re-routing DAC power feeds to avoid internal switching supplies. Also one report of using an external TentLabs clock.

Hope this helps

[t.]

Hi Clipper,

thank you for your reply, I'd have thought modding these SB3 would be more popular.

How do you currently rate the sound of your SB3? I have a few modded cdp's including a highly modified Arcam Alpha5 which sounds excellent, Ideally I'd like to replace it with a SB3 if it has the potential.
If not I'll use the SB3 with my diy Pedja dac.

I was planning on running separate super regs to each of its supplys, instead of totally removing the op-amp I may build an output stage using something like an LM4562 or AD827 and feeding it a +/-v supply instead of the single +v supply as used in the SB3.
I may also remove the 12mhz clock and fit a tent based XO for 11.2896mhz
I have a PCM1748KE chip already unfortunately when I ordered the SB3 there was none in stock so I'm waiting for another delivery

[Clipper]

Agreed. There doesn't seem to be much DIY modding of these going on. Lots of talk however about professionally modded units (from Bolder or Red Wine Audio etc) on SlimDevices.com forum and AudiCircle.com. Lots of happy people using modded units in very high-end systems.

The stock SB3 sound is far from shabby. When you consider the price of these things it's pretty impressive what they've achieved. Since I got mine, i've used it pretty much exclusively, only really using the CD92T occasionally for comparison. As you'd expect, the SB3 stock sound isn't as nice as my CD92T. It's less detailed, and gives a flatter presentation (in terms of soundstage, rather than dynamics) and is a little bright. That said, I still find it a pleasing listen. I'm sure using your stock SB3 with an external DAC would improve these areas. So you "stock" sound may be better than I currently get.

I too have a few PCM1748KE, so that one is a no-brainer. Super-regs is fairly major surgery and is further than I want to go at the moment. Although I would be very interested in your implementation of this (and the Tent XO) for a possible phase 2 set of mods!

A lot of folk with pro-modded units where the op-amp stage is removed use the analogue outs directly to a power amp. I was keen on removing the op-amp partly to get the resulting output level drop. A potential downside of this however is that it introduces a phase inversion. Not sure if this is something I will hear.

[t.]

Ideally I didn't want to use an active pre-amp going to my amp so I'm searching around trying to find a decent circuit that would be suitable for the PCM1748 output stage, if I can't find anything I'll just build something based on op-amps.
I think one of the older downloads is supposed to invert the signal so should be suitable to use if you remove the op-amp and fit a coupling cap

My modified CDP has already seen off enough non modded units so the SB3 needs to be made to sound at least as good before I'd consider using it as my main source.

Hopefully we can get a few more interested in modding these units

[Clipper]

There have also been requests for Slimserver to implement a switchable phase setting. The new Transporter supports this feature, but it hasn't yet been adapted for the SB3.

One other potentially exciting option with the SB3 is the Digital Room Correction plugin that a guy named Inguz has developed. Its early days but a few users are reporting good results. I'm trying to track down the bits needed to give this a go.

[t.]

Originally posted by Clipper
There have also been requests for Slimserver to implement a switchable phase setting. The new Transporter supports this feature, but it hasn't yet been adapted for the SB3.

One other potentially exciting option with the SB3 is the Digital Room Correction plugin that a guy named Inguz has developed. Its early days but a few users are reporting good results. I'm trying to track down the bits needed to give this a go.

Digital room correction, I've not heard of that for the SB3, should be interesting.
The switchable phase setting would certainly be worthwhile, I'll have a look on the slimdevices forum to see if I can find anything

[GaryB]

Hi,
I modified my SB3 almost a year ago and reported the results over on the slim devices forum. It's gotten buried in all the traffic since then but you can take a look here:

http://forums.slimdevices.com/showthread.php?t=19822

Since writing this up, I've changed the external power supply to an HP lab supply I picked up off of ebay and it represented another step up in performance.
I can also report that there seems to be a big variation in preference for the digital out of the squeezebox vs. analog outs from system to system. In my system, I now greatly prefer an external dac. But I've taken it over to other people's houses and there the internal dac was better. But the mods I did improve both the digital and analog outputs so you get to experiment for yourself.
Have fun.
---Gary

[I_Forgot]

The analog circuits in the SB3 are powered from the DC-DC converter that provides high voltage for the display. I would think that biggest bang for the buck modification would be to cut the analog section's power free of the DC-DC converter and replace it with an analog regulated source.

I_F

[Clipper]

Hi I_F,

Good idea.

t. mentioned using super regs with external feeds for analogue circuit power. This would be the best solution, but I was wondering about an internal alternative.

The SB3 has a linear regulated 3.3V for the headphone amp derived directly from the 5V input.

Anybody got thoughts on borrowing this, together with a line from the main 5V input to power the DAC?