I even found an open frame type 15VDC / 1A, Meanwell RS15-15, which is even cheaper at EUR 8.80 plus shipping. Two of those would allow a +/- 15VDC symmetrical switching PSU of 1A output capacity...
http://cdn-reichelt.de/documents/datenblatt/D400/RS-15-SPEC.pdf
They are available from Mouser too... http://www.mouser.de/ProductDetail/Mean-Well/RS-15-15/?qs=%2fha2pyFaduhTgKandwNLmsBPFkvDXycwJ5WVIcxF%2f9zmuUVxUTrxOQ%3d%3d
And another open frame one, Meanwell PD-2515, which supplies both +15VDC and -15VDC at 0.8A each from one unit. Almost same price compared to two of those above.
They are available from Mouser too http://www.mouser.de/ProductDetail/Mean-Well/PD-2515/?qs=sGAEpiMZZMsPs3th5F8koEQpGtpkXN6kckxdQHLrinA%3d
This one seems to feature lower noise but somewhat less amperage.
http://cdn-reichelt.de/documents/datenblatt/D400/RS-15-SPEC.pdf
They are available from Mouser too... http://www.mouser.de/ProductDetail/Mean-Well/RS-15-15/?qs=%2fha2pyFaduhTgKandwNLmsBPFkvDXycwJ5WVIcxF%2f9zmuUVxUTrxOQ%3d%3d
And another open frame one, Meanwell PD-2515, which supplies both +15VDC and -15VDC at 0.8A each from one unit. Almost same price compared to two of those above.
They are available from Mouser too http://www.mouser.de/ProductDetail/Mean-Well/PD-2515/?qs=sGAEpiMZZMsPs3th5F8koEQpGtpkXN6kckxdQHLrinA%3d
This one seems to feature lower noise but somewhat less amperage.
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Hi Xavier,
It seems that my shipment is lost somewhere on the way from London to ???
I contacted a local mailing service and this was their (translated) response:
"Regarding your request, we want to inform you that the said consignment is not arrived in Croatia.
Therefore, please contact the sender, about the possibility of starting the inquiry process."
Therefore, I would be grateful if you could look at what happens to my parcel.
Attached Thumbnails
It seems that my shipment is lost somewhere on the way from London to ???
I contacted a local mailing service and this was their (translated) response:
"Regarding your request, we want to inform you that the said consignment is not arrived in Croatia.
Therefore, please contact the sender, about the possibility of starting the inquiry process."
Therefore, I would be grateful if you could look at what happens to my parcel.
Attached Thumbnails
Attachments
I ordered a couple of those Meanwell RS15-15 (15VDC / 1A) open frame PSUs as mentioned above, which have been delivered today.
I checked, if in- and output potential are isolated against each other and against PE, which they did. Therefore one could stack them for a symmetrical (+15.5VDC) - 0 - (-15.5VDC) power supply by just bridging one (+) to one (-) on the other PSUs output, using this as common GND. Adjustment range of the output voltage should be sufficient for fine tuning the supply voltage to the Hypex regulators.
The data in the datasheet from Meanwell are worst case specs, meaning that an average unit should be within specs with a safety margin: https://www.meanwell-web.com/en/download_datasheet.php?products_id=RS-15-15&type=2
To improve HF filtering on the input side of the PCB I am going to add some 0.1uF / 50VDC SMD (1206) ceramic capacitors across those 1000 uF / 25 VDC electrolyts whilst soldering them and feed the PCB power supply wires through an additional ferrite inductor. Judging by the block diagram from Meanwell the PSU supply side has an EMI filter installed already.
For an LDR type gain adjustement (replacing the linear pot) one could easily add another RS 15-XX PSU (i.e. 5VDC) of the same size side by side. They are really very compact in size: (LxWxH) 62.5 mm x 51 mm x 28 mm and shielded already.
Any comments ?
I checked, if in- and output potential are isolated against each other and against PE, which they did. Therefore one could stack them for a symmetrical (+15.5VDC) - 0 - (-15.5VDC) power supply by just bridging one (+) to one (-) on the other PSUs output, using this as common GND. Adjustment range of the output voltage should be sufficient for fine tuning the supply voltage to the Hypex regulators.
The data in the datasheet from Meanwell are worst case specs, meaning that an average unit should be within specs with a safety margin: https://www.meanwell-web.com/en/download_datasheet.php?products_id=RS-15-15&type=2
To improve HF filtering on the input side of the PCB I am going to add some 0.1uF / 50VDC SMD (1206) ceramic capacitors across those 1000 uF / 25 VDC electrolyts whilst soldering them and feed the PCB power supply wires through an additional ferrite inductor. Judging by the block diagram from Meanwell the PSU supply side has an EMI filter installed already.
For an LDR type gain adjustement (replacing the linear pot) one could easily add another RS 15-XX PSU (i.e. 5VDC) of the same size side by side. They are really very compact in size: (LxWxH) 62.5 mm x 51 mm x 28 mm and shielded already.
Any comments ?
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I semi-finished two of those pre amp modules yesterday, but skipped the linear pot, input switch and the power connector, because I haven't decided yet what to include / use. Next will be testing the assembly hooked up to my lab power supply.
How hot are the Hypex Regulators getting during "normal" use. Do they need to be heat sinked (SMD transistor at top) ?
I am looking for a BPBP case which matches the NCore 400 cases by Ghentaudio (or Hypex). Those are the amps I am using right now... Any idea ?
Only a few builds for the pre amp have been documented as far as I can tell, but there doesn't seem to be a common idea about what cases to use for this. Especially the cut out for the power inlet and the XLR (male/femal) connectors are cumbersome to do although I probably have the the skills to do it, but it wouldn't look quite "professional" because one would see rough edges etc in my opinion. And silk screen lettering would be missing too...
PS.: Should we consider a GB for a case ?
How hot are the Hypex Regulators getting during "normal" use. Do they need to be heat sinked (SMD transistor at top) ?
I am looking for a BPBP case which matches the NCore 400 cases by Ghentaudio (or Hypex). Those are the amps I am using right now... Any idea ?
Only a few builds for the pre amp have been documented as far as I can tell, but there doesn't seem to be a common idea about what cases to use for this. Especially the cut out for the power inlet and the XLR (male/femal) connectors are cumbersome to do although I probably have the the skills to do it, but it wouldn't look quite "professional" because one would see rough edges etc in my opinion. And silk screen lettering would be missing too...
PS.: Should we consider a GB for a case ?
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Many thanx !
Will have a look at my Hypex regulators and what I might be able to use...
PS.: What power connector is that green one visible in your pictures ? Phoenix Contact type ? What RM does it have ? What the order code for it ?
I checked at Mouser.com for that suggested JST-B3P-VH connector but they don't seem to have it stocked...
Will have a look at my Hypex regulators and what I might be able to use...
PS.: What power connector is that green one visible in your pictures ? Phoenix Contact type ? What RM does it have ? What the order code for it ?
I checked at Mouser.com for that suggested JST-B3P-VH connector but they don't seem to have it stocked...
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Soldering small copper straps to it conducts heat a lot better, but i don't like to solder to a finished module although I got some "big" soldering irons to handle the job. I fear damaging them... after I had a look at those regulators.
I am thinking now about a common small heatsink stripe affixed across the body of those two transistors, because they are electrically isolated.
How about that ?
the thermal resistance of the plastic package is likely to be too high to effect much cooling.
The big mistake in my view was taking the relay coil supplies from the regulated rails.
He could very easily have taken the ~15Vdc after the smoothing and used a current saver to operate the coils and the regs would then run much cooler. One reg is passing an extra 12.5mA, the other one is passing an extra 12.5mA, or 25mA, depending on which channel is being processed. Nearly clean relay DC along a close coupled pair from the unregulated side would not pass much emi into the audio circuits.
I will have a further look at the PCB and see if current saving and pre reg supply can be implemented on my second board. But I am using 317/337 with heatsinks so the need is not so important.
The big mistake in my view was taking the relay coil supplies from the regulated rails.
He could very easily have taken the ~15Vdc after the smoothing and used a current saver to operate the coils and the regs would then run much cooler. One reg is passing an extra 12.5mA, the other one is passing an extra 12.5mA, or 25mA, depending on which channel is being processed. Nearly clean relay DC along a close coupled pair from the unregulated side would not pass much emi into the audio circuits.
I will have a further look at the PCB and see if current saving and pre reg supply can be implemented on my second board. But I am using 317/337 with heatsinks so the need is not so important.
The "problem" seems to be, that Putzey's preamp design (probably) was only to demonstrate his stated principles and not meant to be a "real" preamp for everyday use. Thus not much thought (probably) went into optimizing the power needs for the Hypex regulators. He just used them because his company Hypex has been selling them 
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