SPS01 - help with build

[framos]

I will be building a SPS01 power supply for a ClassDAudio SDS-254 amplifier.  The amp is expecting +- 40-50 vdc from the power supply.  The power supply in use with it now is the "heavy duty" ClassDAudio one.

Since I'm not very versed in the technical aspects of power supplies, will the stock build from the BOM supplied with the board give me a power supply I can use with this amp?  If not, how do I go about computing/figuring out what components to change out from the BOM to build the SPS01 so it can drive my amp board?

The existing power supply is currently driven by a 400va 35v toroidal transformer.  The ClassDAudio instructions for sizing the transformer with this power supply say that the "voltage the power supply will put out  can be obtained by multiplying the transformer secondaries by 1.41".  So 35 * 1.41 = ~50v the amp needs.  Does the SPS01 built with the stock BOM part have a similar rule.  I would need to know to purchase the new 800va transformer with the appropriate secondaries voltage for the SPS01.

Thanks in advance for any pointers/help.

[peranders]

It's always 1.4 times the AC voltage.

[framos]

So can I use the SPS01 built with the BOM for this amp board without any changes to the components in the BOM?  Also, that means I should keep the voltage of the new transformer at 35v and just get an 800va one instead of a 400va one?

Thanks again.

[peranders]

You should get in contact with you amp module supplier and see what he recommends. The SPS01 is maximized in most senses and also designed for tube amps. It's up to the designer to judge what is necessary.

You can use the "full monty" according to the BOM if you want.

[framos]

One more question and I will leave you alone, as I get a feeling that my newbie
questions are wearing out their welcome.  Before I talk to the classdaudio
folks, can I get what the "full monty BOM" SPS01 offers in comparison to the
stock power supply I got with the amp?

These are some of the specs for the stock power supply, could you put next to
each line what the SPS01, built to BOM provides.  I'm neither smart nor
knowledgeable enough to figure it out (which is telling me I should have bought an
assembled power supply instead of a pcb...):

Some of the stock power supply specs:

1) +/- 75 volts, can handle up to 85 volts
2) capacitance of 28,200 (14,100 microfarad per side)
3) 3 watt bleeder resistors
4) 8 Amp 800V rectifier

Thanks again.

[peranders]

If you have around 50 VDC you can use 50 or 63 V caps without fear in home environment.

10000-22000 uF per rail is reasonable. You can have more if you'll like.

Bleeder resistors should be 7 watt since they will run a bit cooler but this is a matter of taste.

> 200 V diodes since you will have 130 V peak

[framos]

Thanks a lot for the second set of answers, it's a lot more informative to the untrained like me.  A few more questions about your answers above:

>>If you have around 50 VDC you can use 50 or 63 V caps without fear in home environment.
>>10000-22000 uF per rail is reasonable. You can have more if you'll like.

The caps in the stock power supply are 4700uf 80v.  I should go with the 63v then?

Do I need to populate the  all four slots/rail or can I put two capacitors on each rail to start with and purchase two more later and add them? 

If adding later is ok, the BHC's in the states are ~$29/each for 15000uf 63v.    Also, I found 22000uf 63v Mundorf's for $42/each.  Any preference over going with 2 22000 Mundorf's over three 15000 BHC's to start with?  I have no experience listening to different capacitors, but the few forums/articles I read seemed to rate the Mundorfs the best sounding. 

>> 200 V diodes since you will have 130 V peak

Go to the 300v version of the same diode then?

[peranders]

More voltage is better but more expensive and/or larger caps. If 80 V fits you can choose any and 63 V won't be a bad choice.

Stuff as many caps you want.

300 V diodes is fine.

[framos]

Would one of these work as the 300v diode for the sps01:

1) http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=VS-30CTH03PBF+vishay&x=0&y=0
2)http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=STTH6003CW&x=0&y=0

Any preference of one over the other?  If these don't work, do you have any recommendation for the "> 200 volt diode"?

Also, in your photos of the sps01 you have different size capacitors installed.  Is that just for illustration purposes or is that a "best practice" of capacitor stuffing, using smaller ones mixed with bigger ones?

Thanks again.

[peranders]

The last one fit better. I have footprint for a 2-pin TO220. The last one fits perfectly.

[framos]

Thanks.

Any comments on "in your photos of the sps01 you have different size capacitors installed.  Is that just for illustration purposes or is that a "best practice" of capacitor stuffing, using smaller ones mixed with bigger ones"?

[peranders]

I'll recommend that you read the documentation where you can find the answers. I have made there different pinouts only for flexibility.

[framos]

Thanks.  I did read several times through the build documentation and understand that the different pinouts are there for flexibility in choosing different size/pin layout capacitors.  Since I don't understand enough about electronics, it didn't answer the question of when choosing capacitors, are they normally all chosen to be the same size or mixing different sizes offers some extra electrical benefit that all the same size does not.  I'll just buy all the same size since that's what is in BOM.

Another quick question, can I substitute the  "470kâ,,¦ 0,6W 1% metal film" in the SST01 BOM for the same resistors but 0.5w or 0.75w ones?  The two places where I was able to source all the parts from don't have 0.6w.

[peranders]

When choosing caps you should get in contact with the supplier of your amp and get recommendations from them. The pcb of mine is universal with no particular amp design in mind. As a general rule a general purpose cap will fit you needs. Heavy duty caps may feel better to use but it's necessary only in really heavy duty applications such as switched power supplies.

The reason for to have room different type of caps is only for flexibility. You'll choose the same type for all mounted caps of course even though you could have different types.

SST01: Metal film, 500-600 mW, regular size. The real power in the resistor is only 13 mW.

[framos]

To further show my ignorance of electronic topics, built with the parts listed in the BOM in your website, can this power supply power multiple class d amp boards?  I'm using the classdaudio.com sds-254 and originally was going to build only a single amp (power supply/one amp board), but if this powers multiple boards I may build a 5 channel amp (three amp boards) for my home theater instead.

Thanks again.