Picture of SB2 power line

Wayne1 · « **on:** 25 Sep 2005, 05:28 pm »

Here is a poor photo of what the stock SB2 power supply does to ALL the DC power lines to the chips.

This is taken from the 5 volt line feeding the DAC. All of the DC power lines look pretty much the same using the stock power supply

Here is what it looks like with the linear power supply in place

I am sorry for the poor quality of the photos. It should give you an idea about what sort of hash is caused by the stock PS and how the sound can be improved by using a linear supply (or battery

)

zybar · « **Reply #1 on:** 25 Sep 2005, 05:48 pm »

Good to see there is some science behind what I am hearing.

Thanks for the post Wayne.

George

TriodeGuy · « **Reply #2 on:** 26 Sep 2005, 01:10 pm »

Wayne, the guys who run slimserver's forum have some questions regarding the test setup you used for your measurements...

Would you mind posting the time div and amplitude scales your scope was set to in these photos?

Also could you tell us what scope was used and where you connected the probe's ground clip?

B.T.W. I'm not affiliated with slimdevices in any way. I'm a new owner of an SB2 and am thinking of having it modded.

Thanks - Chuck

Wayne1 · « **Reply #3 on:** 26 Sep 2005, 05:59 pm »

The 'scope is a Tektronics 475. The probe is a TEK P6109

The settings were .5 volts per division and the time base was .5 u sec.

The points measured were across C61. The photos were of the same points and same settings with two different power supplies.

The SB2 under test was stock that arrived last week from Slim Devices.

Sean Adams (Slim Devices CEO) stated that:

What you're measuring is noise coupled onto your probe from the digital side (which _will_ be quieter with a linear supply).

If you measure right across C61 with better/shorter leads, you will not see a significant difference.

Occam · « **Reply #4 on:** 26 Sep 2005, 11:31 pm »

Wayne - Sean Adam's comments aside (it must be wonderful to not have to actually listen and use empirical verification in order to opine whether something is or isn't an improvement), what specific linear supply produced the second oscilloscope picture?

TIA,
Paul

Wayne1 · « **Reply #5 on:** 26 Sep 2005, 11:45 pm »

Paul,

The other supply was the one I build. EI core 4 amp transformer, IXYS 8 amp Hexfreds in a full wave bridge and Panasonic FC caps before and after the LT-1086-5 regulator.

Wayne

Occam · « **Reply #6 on:** 27 Sep 2005, 12:10 am »

Wayne,

Thanks. A nicely implemented linear supply. Thank goodness there are vendors who know to use a 'retro' EI core when appropriate

.

-Paul