[Builder Brad]

Happy new Year Vinnie!

I have now been using the upgraded SB2 and battery power supply for just over 1 month and would like to say how pleased I am with the improvements to this piece of kit. I would not have been able to live with the standard SB2, so your upgrade for me is very worthwhile and I will be placing and order for another modded SB2/3 in the very near future.

I have a couple/ a few observations:

The mods to the SB2 have changed the unit into something that does not seem related to the standard SB2, it is amazing to hear the differences between a modded and an unmodded unit. I still think that my Arcam Cd player is a little punchier in the bass, but then this may not be the true sound and the bass on the SB2 is less tiring and certainly more musical.

I am a little surprise to not observe an improvement when using the battery power supply. I am only using a basic linear 12v power supply for my comparisons which is rated at 500ma (my SB2 is drawing 380ma) and I am unable to hear an improvement over this when I switch to the SLA supply. I have considered upgrading the 500ma pwr supply but have hesitated because it seems to be performing as well as the battery supply.

I wonder if your USA customers gain the most when using the SLA upgrade because of the 110v mains ect.

I have also powered the 5v regulator with another separate 12v supply via a switch and really noticed an improvement especially on vocals, have you tried this with the 5v reg?

I am wondering if it is possible to upgrade the 5v regulator, or isolate it from the main 12v supply, and see if that improves the sound. Is it possible that this regulator is contaminating the main 12v supply?

Is there any audible benefit in using heavier hookup wire in the SLA power supply?

as always trying to improve/tweak everything!

Thank you

Bradley

[zybar]

Unplug all electrical connections to the battery when using it in battery mode and report back if you hear any improvement.

Many of us have heard improvements when doing this.

George

[Vinnie R.]

Hi Brad,

Happy New Year to you too and thanks for posting your impressions.  

would not have been able to live with the standard SB2, so your upgrade for me is very worthwhile and I will be placing and order for another modded SB2/3 in the very near future.

Thanks!  Glad you are enjoying it.

Just for clarification for those who are reading this, Brad had the RWA basic mod package performed on his SB2 (analog output mods only, no RWA battery conversion).

Regarding your observations:

The analog output voltage of your modded SB is most likely lower than that of your Arcam CDP (~2Vrms vs ~1Vrms of the SB).  When using the modded SB, you probably already found that you need to turn up the volume a little more than with the Arcam.  For A/B comparisons, level matching will be tricky and you'd probably need an SPL meter.

As for power supplies...

Are you sure that your SB2 is only drawing 380mA?  This seems lower than I remember measuring it to be (which was close to 1000mA at full brightness for a wireless SB).  Is yours a wireless SB2?

What 5V regulator are you using?  Have you measured its output voltage under load?  What heat-sinking?  After playing for a while, is it too hot to touch and what is the output voltage under load?  How about for the SLA battery that you are using (size of battery?, output voltage under load)?

For the battery conversion, I use the 12V SLA to feed both a 5V regulator and I also send the 12V into the SB to replace the internal switching regulator that generates ~12V to the regulators that are used for the dac.  In other words, I send BOTH 5V and 12V into the SB with the battery conversion mod and am very please with the results in doing it this way.

I use a large SLA that has BIG output current capability...much larger than what a 12V, 1000mA AC power adapter can deliver.  However, the SB does not draw more than 1000mA, so having a supply with huge power isn't needed (I use the large SLA for long playtime, NOT because its big output current is needed).  It is the cleanliness of the power supply that is most important.  The dac chip itself only needs ~ 25mA of current to operate and drive your preamp.  Afterall, the SB is not a power amp     I cannot see how huge capacitor banks or anything like that would be needed for increased dynamics, punch, etc. when the dac will only be consuming very low power.... but that is a topic for a later discussion.  

Regarding using larger hookup wire, it depends on how long are your wire lengths.  With the SB ON, you should measure the 5V at the input to the SB as well as at the output of the 5V regulator.  How much of a voltage drop are you getting?  If the voltage drop is significant, use thicker wire (which will have less series resistance).  

Also, is your switch rated for the current that you are sending through it?  Is there voltage drop across the switch?  

Keep us posted!


Hi George,

Good idea!  ....especially if noise from the AC line is contaminating the battery circuit via a shared ground...


Cheers!

[Builder Brad]

george,

thank you for the ideas, I initially started to use the SLA supply without a charger and separate Dc supply - i charged the SLa after every couple of hours use with an old auto battery charger. i still use the SLa battery supply with everything dissconected and can defianately hear a difference to the audio quality when the battery harger is pluged into the Battery pack, even though the switches on the RWA SLA should dissable this.

Vinnie,

thank you - I have the Full RWA upgrade including teh SLA battery, all those SB3 deals you did before the new year have frazzled your brains, I believe!.

I do find that the 5 volt regulator makes a negative contribution to the overall  
performance and that the battery upgrade does not live up to my expectations.

bradley

[Vinnie R.]

Vinnie,

thank you - I have the Full RWA upgrade including teh SLA battery, all those SB3 deals you did before the new year have frazzled your brains, I believe!.  ...

I couldn't agree more!      

I had you mixed up with another Brad (who only purchased the analog output mods).

[Builder Brad]

Vinnie,

Given your confusion, I am also now confused by your answers, as they did not deal with the issues raised.

What are your thoughts?

Bradley

[Vinnie R.]

Vinnie,

Given your confusion, I am also now confused by your answers, as they did not deal with the issues raised.

What are your thoughts?

Bradley

Hi Bradley,

Let me try to clear up your confusion:

I am a little surprise to not observe an improvement when using the battery power supply. I am only using a basic linear 12v power supply for my comparisons which is rated at 500ma (my SB2 is drawing 380ma) and I am unable to hear an improvement over this when I switch to the SLA supply.

The battery enclosure that I make for you has a built-in 5V regulator.  The 12V SLA battery feeds this 5V regulator (used for the 5V input of the SB2), and the 12V also passes directly into the SB2 (I bypass the internal switching 12V supply with the 12V SLA).

You also have a dc input jack and a switch on the battery enclosure so you can  use you own 12Vdc power supply instead of the internal 12V SLA battery.  I believe you should be using at least a 12Vdc, 1000mA linear regulated power supply.

Here are some questions for you:

When you switch from SLA power to the external 12V supply, are you sure you know which of the two is actually being used?  Are you sure that your 12V SLA is fully charged.  Have you ever accidentally drained it down?  If you did, it might not be able to hold a charge anymore and in that case, the external 12V supply will be the better supply.  

I have also powered the 5v regulator with another separate 12v supply via a switch and really noticed an improvement especially on vocals, have you tried this with the 5v reg?

Are you talking about the 5V regulator that is inside the battery enclosure?  When you say "via a switch," I assume you mean the switch that is built into the enclosure I made, correct?

I am wondering if it is possible to upgrade the 5v regulator, or isolate it from the main 12v supply, and see if that improves the sound. Is it possible that this regulator is contaminating the main 12v supply?

I can't see how the 5V regulator can contaminate the 12V supply.  The output of the battery enclosure is 12V, 5V, and GND.  The 12V is either from the SLA battery or from your external 12V supply.  Either way, it passes to the output and it sent to the SB2 (to replace the internal 12V switching supply).  The SB2 also requires 5V, so that 12V also feeds a 5V regulator inside of the battery enclosure, and this 5V is passed to the SB2.

I hope this clears up the confusion, but if it does not, please feel free to email me and I will try to make it more clear.  

Thanks,

[Builder Brad]

Thank you Vinnie,

The regulator I am refering to is the one inside the case and there was a distinct improvement to the sound when I run this from another 12v battery via a toggle switch similar to the one fitted to the battery enclosure.

I have never let the battery run down completely, I have only listened to the battery in 1-2 hour periods with the charger dissconnected.

a/b listening tests are very easy in this situation because you just switch the RHS switch up for battery pwr and down for external connected power.

bradley