[zybar]

What are the mods?

What are the improvements?

What are the costs?

I am most interested in ways to make the digital better (not really interested in the analog output).

George

[JohnnyLightOn]

Mods would be great, but what is there to compare them to?  I haven't even read a decent, detailed user review yet that compares the SB2's output to a good quality transport or to a modified previous-gen SB.  It seems like they should have made great strides with this new unit, but were are the audiophile reports on it?

I've read the SlimDevices forums, and there haven't been reliable reports posted yet.

[JoshK]

George, here is a thought. My platter is pretty full atm, but supposing I could clear it up, here is an idea, or an idea to other more clever DIY'ers like tiangus, et al.

You buy two SB2's.  Send them to me (or other DIYer) and I experiment on one of them, even I have a few tricks up my sleeve on how to improve such things.  Since I am local, you come down, or I come up and we do a shoot out of the original vs. the modded.  Notes are taken and maybe some more mods are done.  Iterations are done until we acheive a very satisfying result.  The then modified unit can become the reference and the original flipped back on the market.   In my case I have one already, so only one extra would be needed.

I know Larry & BobM have both done some DIY'ing in the digital realm so they may have more ideas on what parts work best where.  Probably best to illicit someone local so personal input can be added to the end result.

The two very obvious places to start would be PSU upgrades, which really matters, especially in digital circuitry, and with the clock circuit.  There are numerous DIY clocks available on the market, even some high performance, reasonable cost solutions like the TentClock, Kwakclock, etc. Then lastly examining the digital circuitry and bypassing unneccesary or unneeded options, cleaning up and improving decoupling.

Then again you could just send it into a hired modder but where would the fun be in that?  

[brj]

I have to admit that I'd be interested in what mods might do this this unit....

The two very obvious places to start would be PSU upgrades, which really matters, especially in digital circuitry, and with the clock circuit.

Except for maybe the vacuum display, I would guess the rest of the unit would have rather low power requirements... I wonder if a SLA battery might be simpler/easier/better than modding the power supply?  This assumes you are willing to recharge it, of course, but I imagine time between chargings would be rather long...

Just a thought...

[JoshK]

... I wonder if a SLA battery might be simpler/easier/better than modding the power supply?  This assumes you are willing to recharge it, of course, but I imagine time between chargings would be rather long...

Just a thought...

That is a very good point.  I thought of that too, but I think my Felicia will suffice plenty and is more convenient.  You isolate the VFD from the rest of the supply, assuming it doesn't have it's own (not likely) I would add a small inductor.

[audioengr]

I have to admit that I'd be interested in what mods might do this this unit....

The two very obvious places to start would be PSU upgrades, which really matters, especially in digital circuitry, and with the clock circuit.

Except for maybe the vacuum display, I would guess the rest of the unit would have rather low power requirements... I wonder if a SLA battery might be simpler/easier/better than modding the power supply?  This assumes you are willing to recharge it, of course, but I imagine time between chargings would be rather long...

Just a thought...

If it runs on 12VDC, I have a battery supply that would work.  I use it for the Off-Ramp.  BTW - the power supply/power delivery needs modding even with battery.....

[Wayne1]

I have done some mods on an original Squeezebox.

The 2 is supposed to be more "mod-friendly"

The power supply does need work. I modded an external PS. I replaced the digital outptu connect and modded some of the digital circuitry.

Please contact me through PM or e-mail if you are interested.

[Occam]

It might be appropriate to first examine what the Squeezebox 2 says about itself -
http://www.slimdevices.com/pi_specs.html

Power
Power input
5.0V DC, regulated
Center positive, sleeve ground
Connector: 2.5mm ID, 5.5mm OD, 11mm long
Min supply rating: 1000mA

 Power supply
Switching power supply included
Input voltage range and plug style specific to shipping destination
Power supplies are small, efficient, and do not get hot
One of four styles is included depending on country

Soooo, examining the supplied overbuilt switching wall carbuncle, one might posit that it might bear improvement. (this is not to say that excellent switching supplies for audio do not exist, and will become more common in the future. I'm simply stating that the supplied unit isn't one of them.
Offhand, you've two options -
1.Use a 6v SLA/charger and drop/filter the voltage
2. Put in a proper linear 5vdc regulated powersupply, no wretched toroidal transformers, but a proper split bobbin transformer. A typical 3amp regulated supply with overvoltage protection is rather generic, and at the typical retail of $35, one might be tempted to scratch build for increased peformance, but I happened to see a bunch fall off the back of a truck & for less than $10, its a 'Sarah Lee'. And Felicia-cizing would certainly improve upon that. As you're already using a proper 'back end' transformer (the linear supplies), one additional appropriate transformer with flitering cap(s) and Bob's yer uncle.

This is the non-invasive $35 first cut. Obviously if you're willing to crack the box, further joys await. If someone would send that squeezebox to JoshK, I'm sure we could work something out....

Two dedicated linear power regulators for DAC and line-out stages
Full 6.0Vpp line-level signals

This confuses me a bit. If both those linear regulators are the expected 3 pin jobbies providing <5Vdc, the only way the line-level could provide 6Vpp is if the output stage were a BTL, bridge tied load achitecture. or
There is a voltage stepup in the box to provide either a split rail, of a higher single rail to provide the stated p-to-p output swing......
Anyone have any info on this?
In any event, if one is willing to open the box, the inevitable output electrolytic coupling caps should be upgraded, the generic 3 pin linear regulators could be upgraded, better ps caps and Saints Preserve Us, ERS could be appropriately applied.....

Regardless, providing a proper 5VDC, whether via the wall or a battery is the maximal bang for the buck, non-invasive, easy mod whether for digital or audio output.

Josh - normally I'd agree with you on simply front ending it with a Felicia, but I had the advantage of seeing the external ps, and yes, size can be decieving, Its a testament to miniturization and the economy of mass production, but that is simply not a proper ps to work with.
FWIW

[Occam]

Zybar,

Iff'n you'll loan one of your RSA power conditioners to PhilNY's Rave on June 25th, I'll give you a proper regulated 5Vdc powersupply  

[JoshK]

Paul,

Thanks for the good info.  I fully expect to mod mine out, including cracking the box open.  But first things first for now in terms of my system priorities.

[zybar]

Zybar,

Iff'n you'll loan one of your RSA power conditioners to PhilNY's Rave on June 25th, I'll give you a proper regulated 5Vdc powersupply  

I won't be able to attend the meeting and I use both of the RSA units in my main system.

So thanks for the offer but it won't work out.

George

[Occam]

The innards of the Squeezebox 2-
http://www.slimdevices.com/photos/inside_squeezebox2/
an NJM2041m dual bipolar opamp for audio output (a 'low noise version" of the ubiquitous NJM4558)
BB1748 DAC
one generic radial 3300uf 15v electolytic  for ps? duties which could be replaced by a Panny FC, FM, Nichicon UHE, or whatever; and scads of smt electolytics, including coupling on the audio outs.
Those 3 pin linear regulators for DAC and Audio line outs, and a bunch of switching regulators for other duties....
Dang! Thats alot of very sophisticated technology for not much money by audiophile standards.

FWIW

[doodlebug]

and will be upgrading the power supply first.  I'll be using an HP/Agilent lab supply with *lots* of voltage regulation for the project.

That little wall-wart is surprisingly small for the 5V it produces.  I'll check some of the power supply regulation now that I've finally got a scope again.

I'm also running an M-Audio Audiophile USB outboard DAC and, frankly, these 2 units pretty much run neck-and-neck, sonically - both in stock form.

Cheers,

David

[Occam]

The SB2 Powersupply topology -
http://forums.slimdevices.com/showpost.php?p=43304&postcount=3

posted by Sean Adams, Slim Devices CEO
Its quite refreshing to the CEO being so supportive and open with those seeking to enhance his product.

So you've gots to get an external powersupply that provides regulated 5vDC and 14vDC. (or that 14vDC could be changed to a charger for a 12v SLA, assuming the dropout voltage of the 2 linear regulators it would feed [to the analog circuitry] allows it. You've got to cut a trace  to route your 14vDC in, and void the SB warranty....

So you need a multibobbin power transformer, not a toroid, bridge(s) [and doubler depending on transformers secondary], ic or discrete regulators and caps.... As you're using a proper transformer with low capacitve leakage and limited bandwidth, you might as well front that with a single small balancing transformer and appropriate capacitive filtering between, and drop the noise going in, and out.