Hi.
I'm building a diy power supply intended to supply current to Naim Supernait 1 integrated amplifier.
So far, I've placed transformers in place, along with diodes, capacitors and RC filters. I've bought discrete regulators, relatively expensive, that are connected to the ends of aforementioned RC filters.
However, one of the discrete regulators outputs different voltage. Instead of 24V that are needed for naim circuitry, it's reading +25.2V.
I know that op amps wouldn't be particularly picky about their voltage, but would higher voltage damage the Naim's preamplifier circuitry?
Best regards,
Stefan
I'm building a diy power supply intended to supply current to Naim Supernait 1 integrated amplifier.
So far, I've placed transformers in place, along with diodes, capacitors and RC filters. I've bought discrete regulators, relatively expensive, that are connected to the ends of aforementioned RC filters.
However, one of the discrete regulators outputs different voltage. Instead of 24V that are needed for naim circuitry, it's reading +25.2V.
I know that op amps wouldn't be particularly picky about their voltage, but would higher voltage damage the Naim's preamplifier circuitry?
Best regards,
Stefan
I've measured the voltage under no load - nothing was connected in-between the ends.
Could it be possible that , upon some resistance, it actually outputs the correct number?
Could it be possible that , upon some resistance, it actually outputs the correct number?
Not likely, but why not connect a resistor as a load and see? Try a resistor around 250R at 5W.
What is the mfr rated tolerance on the output voltage? What you have is around 5% too high.
Can you post the schematic? If not, look for the reference voltage device and measure it.
Could be an IC reference chip, or perhaps a current source into a resistor.
Hopefully the regulator input and output nodes have proper decoupling on the board,
so there is no instability.
What is the mfr rated tolerance on the output voltage? What you have is around 5% too high.
Can you post the schematic? If not, look for the reference voltage device and measure it.
Could be an IC reference chip, or perhaps a current source into a resistor.
Hopefully the regulator input and output nodes have proper decoupling on the board,
so there is no instability.
Last edited:
I've got a 5w 1500ohm resistor on hand, for caps bleeding. It's showing the same voltage with that load, even somewhat higher 25.5V.
I've got another power supply for Naim (by the way, from the same manufacturer that also made those discrete regulators!) and all 4 rails show in-between 24.5 and 24.8 volts. We used it to supply the current to Naims for years...
Could I post the schematics of what, discrete regulators?
I've got another power supply for Naim (by the way, from the same manufacturer that also made those discrete regulators!) and all 4 rails show in-between 24.5 and 24.8 volts. We used it to supply the current to Naims for years...
Could I post the schematics of what, discrete regulators?
Last edited:
Yes. There's no good reason for 5% error in the regulator output voltage.
It's easy to get a fraction of 1% error.
It's easy to get a fraction of 1% error.
Ok, it's open loop, with an LED based reference. Noise was a higher priority than precision.
You can try tweaking the P3 at the typical output current drawn, but the voltage will vary somewhat with loading.
It's more a stabilizer circuit than a regulator, though.
You can try tweaking the P3 at the typical output current drawn, but the voltage will vary somewhat with loading.
It's more a stabilizer circuit than a regulator, though.
Last edited:
If the circuit uses 24V, but 25V burns it, you have more problems than just the power supply.
Oddly, there's no mention of the supply output current capability (or any other specs).
Oddly, there's no mention of the supply output current capability (or any other specs).
Should I interpret that as it should be safe to use?
Maybe I should add another RC filter after the regulator as well.
They are speced as 1 amp in their stock form.
Maybe I should add another RC filter after the regulator as well.
They are speced as 1 amp in their stock form.
Yes.
The output impedance is pretty high as it is, being open loop, and more filtering would raise that.
Also the design bandwidth is only available at the output node, and an added filter would narrow that.
Would the preamp circuitry be connected directly to the regulator output?
Or is there further decoupling on the preamp board?
The output impedance is pretty high as it is, being open loop, and more filtering would raise that.
Also the design bandwidth is only available at the output node, and an added filter would narrow that.
Would the preamp circuitry be connected directly to the regulator output?
Or is there further decoupling on the preamp board?
Too much techy stuff for my modest knowledge.
I don't know, folks at Naim are experts in hiding their schematics.
There should be some decoupling, as their power supplies are placed in a separate enclosure as well.
I don't know, folks at Naim are experts in hiding their schematics.
There should be some decoupling, as their power supplies are placed in a separate enclosure as well.
I hear the RCA transistor manual has some of those Naim schematics.
Probably the amp does have further decoupling inside.
This would power the preamp section of an integrated amplifier?
Probably the amp does have further decoupling inside.
This would power the preamp section of an integrated amplifier?
I'll look into it. Why do you mention further decoupling?
It should be supplying current to preamp, and in case of my generation Supernait, possibly even the DAC section.
Naims have rather practical jumper on the back, that connects preamp section to power amplifiers power supply.
It should be supplying current to preamp, and in case of my generation Supernait, possibly even the DAC section.
Naims have rather practical jumper on the back, that connects preamp section to power amplifiers power supply.
nothing to lose sleep about, if those were unloaded rails, expect them to drop some, say 2 volts...
I gotta ask...was there a problem with excessive or even audible noise while using the Naim power supply?
Mike
Mike