Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone

195.99.125.204

Posted by Thorsten on June 15, 2001 at 07:53:41

In Reply to: Power Supplies for the TDA1541 DAC-Thorsten, anyone posted by Ryan on June 15, 2001 at 02:05:46:

Hi,

>For the record, I had teh following setup:
>
>1. 300W toroid feeding fast soft recovery rectifiers
>2. This was smoothed by 40 000uF (4x 10 000uF) caps

Nice enough....

>3. This then fed two regulators (fixed) 7815 and 7915
>4. From the 7815, I derived teh +5V via a 7805 reg
>5. From the 7915, I fed the DAC -15V and derived the -5V
>with a 7905 reg.

Now that is about as piss poor as it can get. Sorry.

When I refer to the Supplies I'm actually on about fast, low noise regulators (shunt type ideally) combined with suitable wideband decoupling. Using 78XX/79XX type regs is worst than using discrete transistor/zenner combos, a lot worse.

>These voltages were fed to the DAC where the relevant power
>supply pins were decoupled by a 100uF Oscon, bypassed with
>a 0.22uF polyester and a 0.001uF poleyster.

In digital bypassing film cap's tend to have too much inductance. The 100uF Os-Con is still way too small to do anything about the noise from the regulator or about the nonlinear output impedance.

>When this setup was compared with a DAC being fed off the CDPs
>built-in Powersupply, there was no real discernable difference.

Not surprised at all.

Check PSU line noise levels with a fast 'scope and minimise these by optimising decoupling, block all ways out/in in the PSU per in with HF Chokes and Ferrite Beads, so that noise from one pin cannot interact or feedtrough to any of the others etc.

Later T

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Follow Ups Full Thread

Topic - Power Supplies for the TDA1541 DAC-Thorsten, anyone - Ryan 02:05:46 06/15/01 (12)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Elso Kwak 11:19:28 06/16/01 (0)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Thorsten 07:53:41 06/15/01 (6)

Ps.... what I think of as good supply..... - Thorsten 08:10:03 06/15/01 (5)

Re: Ps.... what I think of as good supply..... - Terry Demol 12:59:57 06/15/01 (4)

why does everyone rave..... - Thorsten 13:15:54 06/15/01 (3)

Re: why does everyone rave..... - Terry Demol 22:51:04 06/15/01 (2)

Question for Terry regarding transistor shunt - Hartono Tandjoeng 05:17:46 06/16/01 (1)

Re: Question for Terry regarding transistor shunt - Terry Demol 00:49:43 06/17/01 (0)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Lesha 05:37:47 06/15/01 (0)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - AT 02:49:45 06/15/01 (2)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Ryan 07:44:47 06/15/01 (0)

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Tazo 05:42:03 06/15/01 (0)

Follow Ups

Re: Power Supplies for the TDA1541 DAC-Thorsten, anyone - Thorsten 07:53:41 06/15/01 (6)

Ps.... what I think of as good supply..... - Thorsten 08:10:03 06/15/01 (5)

Re: Ps.... what I think of as good supply..... - Terry Demol 12:59:57 06/15/01 (4)

why does everyone rave..... - Thorsten 13:15:54 06/15/01 (3)

Re: why does everyone rave..... - Terry Demol 22:51:04 06/15/01 (2)

Question for Terry regarding transistor shunt - Hartono Tandjoeng 05:17:46 06/16/01 (1)

Re: Question for Terry regarding transistor shunt - Terry Demol 00:49:43 06/17/01 (0)

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