hitsware
Posts: 123
Joined: Sat Mar 26, 2016 10:12 pm
Location: sacramento , california , usa
Contact: Website

Simple audio enhancement

Fri Sep 07, 2018 9:40 pm

By using gpio pins 12 and 13 with a slightly modified
( compared to stock ) LP filter , Pi audio can be somewhat
improved .
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Burngate
Posts: 5967
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
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Re: Simple audio enhancement

Sat Sep 08, 2018 8:57 am

hitsware wrote:
Fri Sep 07, 2018 9:40 pm
By using gpio pins 12 and 13 with a slightly modified
( compared to stock ) LP filter , Pi audio can be somewhat
improved .
Not wanting to take the wind from your sails, but in what way is it improved?

Which model are you talking about?
The Pi 3B+ has a low-noise supply feeding the output stage, which yours doesn't have.
Also, in your design, the end result will very much depend on the load it's feeding. The 3B+ has a couple of extra resistors to help control that issue.

hitsware
Posts: 123
Joined: Sat Mar 26, 2016 10:12 pm
Location: sacramento , california , usa
Contact: Website

Re: Simple audio enhancement

Sat Sep 08, 2018 2:18 pm

> in what way is it improved?

1) Twice the output voltage.
Perhaps not needed (or wanted) by all,
but allows me to get the final output I
want without adding a stage.
Besides which extra ' headroom ' is
always an enhancement.

2) Better quality capacitors.
The small size of the stock capacitors
decludes use of audiophile quality
capacitors.

3) Note I did say ' somewhat ' improved.
Not night vs. day, but clear day vs hazy.
Easy to try for oneself to see if applicable.
I suggest an outboard pot to help trim levels.
I use one of these:
http://www.rolls.com/product.php?pid=MX42

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