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WK446
2005-07-29, 22:40
Prior to my joining the forum, I was very interested in researching possible modifications/updates to the SB2. I had contacted Vinnie at Red Wine Audio after reading his post about a battery-based power supply. Recently, he sent me a link about some interesting stuff coming down the pipe. This link is for the *audiophile nutters.*

http://www.redwineaudio.com/SB2_Mods.html

Cheers,
Dennis
P.S. I am not affiliated with ANY manufacturer. But if they want to send me free stuff, that's ok! (:

JJZolx
2005-08-03, 19:16
It's interesting that a guy who would charge $500 to mod your $300 Squeezebox2 would advocate using the internal digital volume control.

Other than that, he may have something, but who can tell? No mention of adding RF shielding, and all of the electronics are still crammed and stacked on top one another in that little plastic box.

WK446
2005-08-03, 19:56
To a certain extent, I agree with you about the pricing, but there are many other modification specialists that also charge as much or more for the modifications than the product itself. For example, modifications to the Benchmark DAC1 from Empirical Audio or Reflection Audio.

I just thought the link would be interesting as it shows some potential for our beloved SB2!

Dennis


It's interesting that a guy who would charge $500 to mod your $300 Squeezebox2 would advocate using the internal digital volume control.

Other than that, he may have something, but who can tell? No mention of adding RF shielding, and all of the electronics are still crammed and stacked on top one another in that little plastic box.

radish
2005-08-03, 20:31
I just thought the link would be interesting as it shows some potential for our beloved SB2!
I think you'll find there's always the potential to spend money :) Whether it's justifiable is a whole other story...

pfarrell
2005-08-03, 20:56
On Wed, 2005-08-03 at 19:56 -0700, WK446 wrote:
> modifications to the Benchmark DAC1 from Empirical Audio or Reflection
> Audio.

Wow, Empirical Audio has a base price of $1050 for their mod
to a $900 Benchmark, and additional options can add another grand.
Clearly I need to find a Santa.

tricking out a $190 SB2 with $3000 worth of DAC
would probably require $1,000 interconnects?

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Aylwin
2005-08-04, 01:28
Thanks for the link! Looking at the mod specs and procedure, the price seems reasonable to me. I might be willing to order the mod myself if I can find a way to get the stuff over here afterwards.

Personally, I'm a big fan of player mods. They allow low-to-moderately priced equipment to compete with the "big boys" costing 5K USD or more. I have a an old modded Sony DVD/SACD player. The mod itself costs more than double what I paid for the actual player. But the result is an SACD player with an exceptional price-performance ratio. And quite simply, I think it's one of the best SACD players you can get for any price.

As for the SB2 mod, if it's good enough so I can get rid of my external DAC then why not. Less cables and boxes is always better.

cliveb
2005-08-04, 01:52
It's interesting that a guy who would charge $500 to mod your $300 Squeezebox2 would advocate using the internal digital volume control.
I don't read it as actually *advocating* it. What he actually says is: "for those of you who want to use the built-in 40-step volume control (performed digitally before the internal DAC), this reduction in voltage allows for a more usable range in the volume control". To me, that isn't saying that you should use it, but that if you do then you'll be able to use a greater range of adjustments due to the lowered output voltage.

But your comment brings up an interesting question: what's wrong with using the digital volume control? Many audiophiles here seem to just take it as read that you shouldn't, but it's by no means clear-cut. The digital data (both internally and as delivered out the SPDIF port) is 24 bit. With the volume control at VC=40, you get a theoretical 144dB of dynamic range. How loud do you want to listen? Let's say you want to listen at a maximum of 120dB. Setting things up so that VC=40 gives 120dB, the theoretical noise floor is 24dB below 0dB (ie. definitely, without a shadow of doubt, inaudible). Now say you want to turn it down a bit, let's say down to 96dB (ie. 24dB down). To achieve this, you'll need to sacrifice 4 bits of resolution, which brings the dynamic range down to 120dB. And where is the noise floor now? It's *still* 24dB below 0dB. And this holds for *all* volume settings - the theoretical noise floor remains at the same inaudible level, regardless of the setting.

This is the beauty of digital level control: distortion and noise increase as the level goes down. This is exactly what you want: at lower volumes, distortion+noise can be allowed to increase, because it remains below the threshold of audibility. Contrast this to a traditional analogue potentiometer, where the tracking gets decidedly vague at very low settings, resulting in undesirable image shifts as you turn things down very low.

*If* you have 24 bit signals to play with, then level adjustment is best done digitally (provided it's done properly, of course, which I'm sure is the case with the SB2). Those of you with high-end 24 bit DACs fed from a fixed SB2 digital output and subsequently feeding an analogue preamp should experiment with connecting the DAC directly to the power amps and using the SB2's digital volume control. The results may surprise you. (Hint: my preamp is currently for sale on eBay as a result).

styx
2005-08-04, 02:22
*If* you have 24 bit signals to play with, then level adjustment is best done digitally

Then again, Red Book is 16 bit... You recommend converting all files to 24 bit for improved dynamic headroom?

Btw, are the signals re-dithered after the SB2 digital volume control has done its business? Improper dithering is actually quite audible if you know what to listen for.

cliveb
2005-08-04, 02:41
Then again, Red Book is 16 bit... You recommend converting all files to 24 bit for improved dynamic headroom?
Yes and no. For sure, the 16 bit signal needs to be extended to 24 bit prior to the digital level control, but there is no need to convert the source files to 24 bit. This bit length extension happens automatically within the SB2 (ie. it adds 8 extra bits to the LSB end of the 16 bit words).


Btw, are the signals re-dithered after the SB2 digital volume control has done its business? Improper dithering is actually quite audible if you know what to listen for.
I don't know, and in fact I don't care. Yes, improper dithering of 16 bit digital is audible, but the quantisation noise of 24 bit signals is so vastly beneath the audibility threshold that it really doesn't matter.

Patrick Dixon
2005-08-04, 02:42
Btw, are the signals re-dithered after the SB2 digital volume control has done its business? Improper dithering is actually quite audible if you know what to listen for.If you have an SB2 I guess you can quite easily answer your own question then.

styx
2005-08-04, 02:54
Yes and no. For sure, the 16 bit signal needs to be extended to 24 bit prior to the digital level control, but there is no need to convert the source files to 24 bit. This bit length extension happens automatically within the SB2 (ie. it adds 8 extra bits to the LSB end of the 16 bit words).


Ah! I wasn't aware of that, thank you :)


If you have an SB2 I guess you can quite easily answer your own question then.

Touché ;) Yes, I have got an SB2, but I don't trust the combination of lacking listening experience and my current setup to reveal such detail. Ask again in a year, and I'll tell you what I hear!

Aylwin
2005-08-04, 02:57
Ask again in a year, and I'll tell you what I hear!Or don't hear. ;)

Vinnie R.
2005-08-04, 18:18
I don't read it as actually *advocating* it. What he actually says is: "for those of you who want to use the built-in 40-step volume control (performed digitally before the internal DAC), this reduction in voltage allows for a more usable range in the volume control". To me, that isn't saying that you should use it, but that if you do then you'll be able to use a greater range of adjustments due to the lowered output voltage.



Hi cliveb,

Thanks for your insightful and meaningful post...nice to read this.

I actually like the digital volume control of the SB2 a whole lot! The sound of battery powered and modded analog output stage of the SB2 sounds great directly feeding my amp. There is no preamp, no analog potentiometer...nothing!

Honestly, I simply don't care if some audiophiles think digital volume controls are bad. IMO, it all comes down to the implementation, and most importantly, how it sounds to me. The digital volume control of the SB2 must be implemented very well, because it sounds very good...period.

I tried using the fixed analog output of the modded SB2 into my amp using a stepped attenuator volume control (a very good one BTW), and using the digital volume of the modded SB2 directly into my amp (no external pot or stepped attenuator). I prefer the digital volume control in the modded SB2. I do extensive listening, I trust my ears, and I mod, tweak, evaluate, and repeat the process until I am extremely satisfied what I hear.



Other than that, he may have something, but who can tell? No mention of adding RF shielding, and all of the electronics are still crammed and stacked on top one another in that little plastic box.

Hi JJZolx,

-- I guess you really can't tell until you hear it for yourself. Until then, it is hard to comment on the value of the mods. I will be posting customer feedback on my website as it becomes available. I have a handful of SB2s on they way for mods.

-- Regarding RF shielding... I don't hear any RF related noise issues, so I didn't waste time and money on this.

-- Regarding the stacking of electronics, I'm simply stacking the SB2 (in that little plastic box) on top of an enclosure that houses a battery...what's the big deal? I'm just trying to figure out where you are coming from with this. This configuration works very well, and is nice and simple. I suppose a power cord extender can be make to allow the SB2 to be mounted away from the battery enclosure, but I can't see what one would gain by doing this, except for added placement flexibility...

Thanks,

Vinnie

Patrick Dixon
2005-08-05, 00:31
Honestly, I simply don't care if some audiophiles think digital volume controls are bad. IMO, it all comes down to the implementation, and most importantly, how it sounds to me. The digital volume control of the SB2 must be implemented very well, because it sounds very good...period.
It sounds OK to me too - I tried it through a Naim pre-amp and I think it is fractionably less dynamic at half volume than full; but very passable.

I've also built some chipamp based power amps and run them directly from the SB2 using the digital volume control. The only problem with this approach is that the SB2's output level, at about 6V pp, is way too high for comfortable listening, unless the fixed gain of the amp is significantly reduced. Obviously, since your mods bypass the SB2's 2x output gain stage completely, you probably wouldn't suffer this problem.

I haven't tried a battery based psu, but I have replaced Sean's 'Big Ass' PSU technology with a more 'British' approach to psu design. I'm very happy with the results so far, but I just 'know' there is more to come.

Vinnie R.
2005-08-05, 05:45
The only problem with this approach is that the SB2's output level, at about 6V pp, is way too high for comfortable listening, unless the fixed gain of the amp is significantly reduced. Obviously, since your mods bypass the SB2's 2x output gain stage completely, you probably wouldn't suffer this problem.
.

Hi Patrick,

Yes, the 6Vpp output is too high, but the mods bring it down to 3Vpp, which allows for a much more useful range of the 40-step volume control.

You can try to attenuate the output with resistors until you find the level of attenuation that works best with your chipamps. Could be fun... :-)

Robin Bowes
2005-08-05, 08:00
Vinnie R. wrote:
> Patrick Dixon Wrote:
>
>>The only problem with this approach is that the SB2's output level, at
>>about 6V pp, is way too high for comfortable listening, unless the
>>fixed gain of the amp is significantly reduced. Obviously, since your
>>mods bypass the SB2's 2x output gain stage completely, you probably
>>wouldn't suffer this problem.
>>.
>
>
> Hi Patrick,
>
> Yes, the 6Vpp output is too high, but the mods bring it down to 3Vpp,
> which allows for a much more useful range of the 40-step volume
> control.
>
> You can try to attenuate the output with resistors until you find the
> level of attenuation that works best with your chipamps. Could be
> fun... :-)

Vinnie,

Would you consider posting details of your mods so that those of us who
can wield a soldering iron can have a go ourselves?

R.

PS. This post on the Red Wine forum made me smile:

http://www.audiocircle.com/circles/viewtopic.php?p=182552#182552

:)

Aylwin
2005-08-05, 22:04
PS. This post on the Red Wine forum made me smile:

Maybe a bit more than a smile from me. :D

jasonthegreat
2006-09-28, 14:59
If you want to block out RF signals that cause interference such as cell phones and computers. you need an RF shield box you can get one here at this web site http://www.rfshieldbox.com/

mac
2006-09-28, 19:09
Maybe a bit more than a smile from me. :D

Most of VR's make me feel the same way. :-)