2. digital
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Filter tweak for digital backwash?

As my system improves, it’s easier to hear anomalies. The search is now on for a tweak to filter only digital backwash in my AC. The culprit is the regulated transformer power supply (120vac/19vdc converter) to the dedicated laptop for streaming.

The balanced power conditioner has separate outlets for analog and digital. The digital outlets already have built-in filtration for backwash. They work well. But, I need even more. When the laptop is running on its internal battery, the music is very smooth. Unfortunately, the battery life is short. When the laptop is running on the power supply, there’s a slight stridency. When the power supply is plugged in anywhere else, there is huge stridency. So, I’m looking for some gizmo to clean up the digital backwash in-between the conditioner digital outlet and the power cord to the regulated power supply.

I’m not looking for an overall line purifier. The balanced power conditioner does a pretty good job already. Any suggestions?


steakster
erik_squires
16,922 posts
 
The least expensive unit I recommend, based on a lot of research this one:

http://amzn.to/2h9R4Z4

Series mode power surge suppression also includes noise reduction that works down to about 3kHz, and that noise reduction is bi-directional.  Most noise supression is too expensive, or doesn't work below 100kHz. These units are perfect for isolating a noise source. For $30 more this one adds their linear filtering technology, which works too, not sure you need it:

http://amzn.to/2gMitgC

Of course, more expensive Furman units include multiple different filter banks. I haven't tried them for bank to bank isolation though.


Best,


Erik
erik_squires
16,922 posts
 
OH! Almost forgot to mention, it has been shown that a lot of the noise from a laptop or PC isn't "noise" so much as a ground loop. Obviously, it looks like noise, but the fix is entirely different.

For these you need a ground loop isolator. Here is one designed for medical instruments, so it's a lot cheaper than audio-grade but works every bit as well. :)

http://amzn.to/2hgqSfU

I would try this first, then try a power supply strip like the Furman.

Best,


Erik
erik_squires
16,922 posts
 
And, just a little rant.... Stereophile KNOWS this but still tests DAC's with battery powered laptops. Gahh!
randy-11
1,913 posts
 
Why aren't the engineers designing expensive audio gear dealing with these problems?

I thought it was pretty easy to deal with noise injection(?)
georgehifi's avatar
georgehifi
10,312 posts
 
I thought it was pretty easy to deal with noise injection(?)
Not when smp is involved.

Cheers George
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