Ditto.
Tom
Tom
.... I used the Ghent Audio case, but modified it slightly by adding in a fuse, following some advice on these pages. I really don't understand why they don't include a fused mains inlet, the cost difference is marginal....
Technically the Hypex SMPS1200A400 power supply is already fused (12A slow-blow fuse), but since it soldered to the PCB, it not considered replaceable.
Personally I would be tempted to add an external 8A or 10A slo-blow fuse, that is easily replaceable. Most people do not need full power output. If one needs full power, one can always put in a higher current (12A) slo-blow fuse externally .
View attachment 154621
Example 0977012.MXEP Littlefuse Slow Blow fuse curves: Time vs Current: https://www.mouser.com/datasheet/2/240/Littelfuse_Fuse_977_Datasheet.pdf-1317309.pdf
View attachment 154627
I've read this mentioned elsewhere. What is the theoretical and measured impact of using an inlet with a Y cap filter?
From what I can see I doubt it is a real issue, for measured impact I suppose you can compare one of the measured VTV amp and the Eigentakt. The VTV amp had more visible noise (Amir called it "ugly" but that's relative) in the FFT but they don't seem high enough to have audible effects. Chance are good that the amp will still be the quietest one in your signal chain.
SINAD may differ by a few dB, that's about it.
Thanks. Even there, we have multiple possibilities for root cause:
With the EVAL1, the banana connectors are directly soldered to the buffer board and no part of the signal path appears to come close to the power supply.
- power filter
- buffer boards
- long speaker wire path
- speaker wires crossing over one of the power supply feeds to a buffer board
- one of the speaker wires crossing over a power supply
- trigger next to a buffer board, trigger wires crossing over buffer boards
- Loose, poorly intertwined inlet power wire from inlet to power supplies across entire width of case
- Two SMPS instead of one, positioned such that they bracket the buffer boards
- combination of above factors
My Purifi is a DIY in a Ghent case so it doesn't have the power inlet filter. My Hypex 252 is a VTV and does have the power filter.
Separate question: some sources I've read suggest that a power line filter is required as much to prevent outbound HF from the device. Do the Hypex power supplies already provide EMC filtering? If not, is it something to consider in selecting components like inlets?
That mains hum may not be due to a Y capacitor. It could just as easily be caused by crappy chassis layout ... or a ground loop.From what I can see I doubt it is a real issue, for measured impact I suppose you can compare one of the measured VTV amp and the Eigentakt. The VTV amp had more visible noise (Amir called it "ugly" but that's relative) in the FFT but they don't seem high enough to have audible effects. Chance are good that the amp will still be the quietest one in your signal chain.
That mains hum may not be due to a Y capacitor. It could just as easily be caused by crappy chassis layout ... or a ground loop.
Tom
The only advantage of having a fuse on the chassis wall is that if the wiring from the IEC inlet to the SMPS fails and shorts to ground, the fuse on the chassis wall will blow.Fuses are not for overload protection in this case, but I am sure you know that already, so I assume your goal is to "protect" the onboard fuse. In that case, even using an external 8A slow blow of the same type (as shown on the attached TTC curves) would not be a sure bet. If the fault current is high enough both will still blow. Even if the board 12A one managed to survive it could have been weakened if it started to melt but not blow in the one fault event. No harm doing it though but I would probably just leave it.
The only advantage of having a fuse on the chassis wall is that if the wiring from the IEC inlet to the SMPS fails and shorts to ground, the fuse on the chassis wall will blow.
Given that many DIYers (and some manufacturers - see Amir's pictures above) use single-insulated wire that is simply resting within the case I always recommend the fuse on the chassis wall when asked.
Tom
Where to find more info on that microaudio SMPS? my HYPEX SMPS1200 died today and hypex as usual won't help, they ask to send the unit back for repair, which i cannot do because of shipping cost and also bad support.First - Thanks for a great forum!
I think I have read all 123 pages to find an alternative to the SMPS1200A400 as it is not in stock anywhere. The only thing I have found is a SMPS1K-PFCR2 from Micro Audio. The problem is just that it is not sent from the EU and it therefore becomes too expensive.
Is there an alternative to the two, which are PnP and which are sent from the EU? (I'm from Denmark)
Thanks in advance