Did You solve this problem? It seems like I meet the same...Oh, OK, thanks again!
Did You solve this problem? It seems like I meet the same...Oh, OK, thanks again!
Whoever I was conversing with gave me the gerbers to order some PCBs to build a filter. I built one for another project that had similar voltage rails.Did You solve this problem? It seems like I meet the same...
I don’t even bother with multi output modules usually. I just buy single outputs and roll my own grounding as needed.
It's easy to get a GSSL hum-free with a linear PSU mounted off-board with a CRC filter in front of it. And following Rane grounding rules for the balanced connectors. I wouldn't bother with a SMPS in this case.For a console PSU, I imagine that works great. Might still go multi-output switcher or linear for something like a GSSL, though the thought of cramming all these switchers into a 3U GSSL is pretty funny
Exactly what I'm saying. An SMPS per rail is somewhat excessive unless it's a bigger use caseIt's easy to get a GSSL hum-free with a linear PSU mounted off-board with a CRC filter in front of it. And following Rane grounding rules for the balanced connectors. I wouldn't bother with a SMPS in this case.
I built an 8 channel API-312 clone with a linear PSU inside the same chassis. It worked great but I’m starting to notice EMI in the channels closest to the PSU. I would like to swap out the toroidal for one of these:
3-Rail Switch Mode Power Supply +/-16v and +48v
I am curious as to how the actual load affects the filter response and component value choices. In the example the load can be as much as 2 amps at 16V which is equivalent to an 8 ohm load. For a tube HT supply, the values might be 300V and 300mA which is equivalent to a 1K load.The filter recommended on the page that sells this PSU has ~160Hz cutoff with a 30dB peak at 160Hz.
Adding some resistance to the choke, say 0.5 Ohm (which could be the DCR of the Coke) will critically damp this resonance.
An LC lowpass shows 40dB/decade roll-off, so at 16kHz the filter will knock the noise down to 1/10,000, which should be fine.
Thor
Ian, your reasoning does not apply as the output voltage is fixed. You would not be connecting a load that demands 200V operation to a power supply that provides 16V.I am curious as to how the actual load affects the filter response and component value choices. In the example the load can be as much as 2 amps at 16V which is equivalent to an 8 ohm load. For a tube HT supply, the values might be 300V and 300mA which is equivalent to a 1K load.
Cheers
Ian
I think we are talking at cross purposes. What I meant was that the components of the example filter were chosen for a specific output voltage and current. What I wanted to know was how these values would change for a different SMPS which could output 300V at 300mA.Ian, your reasoning does not apply as the output voltage is fixed. You would not be connecting a load that demands 200V operation to a power supply that provides 16V.
However, altering the load resistance/impedance will alter the output current and this will change the filter inductor/capacitor size.
I am curious as to how the actual load affects the filter response and component value choices.
In the example the load can be as much as 2 amps at 16V which is equivalent to an 8 ohm load.
For a tube HT supply, the values might be 300V and 300mA which is equivalent to a 1K load.
I think we are talking at cross purposes. What I meant was that the components of the example filter were chosen for a specific output voltage and current.
What I wanted to know was how these values would change for a different SMPS which could output 300V at 300mA.
Yes and no, I suspect they were chosen on sufficient suppression of switching residuals, voltage and current are more related to practicality of available components.
The same values will work the same. Same resonance frequency and roll-off, DC current and voltage do not change that.
OK, help me out here. This is basically an RLC circuit. Various elements make up the R including capacitor ESR and inductor DCR. But another element of it must be the resistive component of load itself. How is that accounted for in the calculation of Q?
Using switcher mofules with inbuilt power factor correction adds another level of (different) noises to the DC output as modules
I use LC filtering then a LOW dropout Linear regulator ( half a volt at however many amps are needed) to clean up the resultant DC AND offer remote sensing in the 'linear' domain (at the expense of a little bit more wasted heat).
A replacement supply MUST give overall performance as quiet as an original properly functioning supply so in general terms less than say 5millivolts measured DC to 500KHz
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