From a technical point of view, I don't think it makes sense.
Fortunately we don't live in a "technical point of view" so you might have a change in SQ using linear depending on your system , grounding etc.
No way to know unless you try..
Fortunately we don't live in a "technical point of view" so you might have a change in SQ using linear depending on your system , grounding etc.
No way to know unless you try..
Well since the ALLO DigiOne provides coaxial s/pdif output which is galvanically isolated from the rPi, that's even less reason to use a linear supply for the rPi.
But as cdsgames has suggested, go ahead and experiment. The current draw of a rPi is quite low - you won't be wasting much extra power by using a linear supply.
But as cdsgames has suggested, go ahead and experiment. The current draw of a rPi is quite low - you won't be wasting much extra power by using a linear supply.
Those regulators I listed earlier are all DIY. You can buy fully built "audiophile" linear supplies from the likes of Paul Hynes, Channel Islands, etc. but these cost hundreds of dollars.
Or on eBay you can find less exotic 5V linear supplies, such as these LT1083/LT1085 based units -
HIFI 25W DC5V linear Power supply with display for USB DAC / Raspberry Pi PSU | eBay
15VA DC5V 2.0A Linear Power supply with USB port HiFi PSU for XMOS 6631 L154-21 | eBay
Or on eBay you can find less exotic 5V linear supplies, such as these LT1083/LT1085 based units -
HIFI 25W DC5V linear Power supply with display for USB DAC / Raspberry Pi PSU | eBay
15VA DC5V 2.0A Linear Power supply with USB port HiFi PSU for XMOS 6631 L154-21 | eBay
Thanks.
My intention was a DIY PSU.
I like the GlassWare LD1085 LV-Regulator, I think that would be a good fit.
What would be a proper transformer for this? Would this one work:
40W R-Core Transformer
As far as I understand, I should have about 6.3V on the secondary winding, and 30VAC should be more than enough for a rPi.
My intention was a DIY PSU.
I like the GlassWare LD1085 LV-Regulator, I think that would be a good fit.
What would be a proper transformer for this? Would this one work:
40W R-Core Transformer
As far as I understand, I should have about 6.3V on the secondary winding, and 30VAC should be more than enough for a rPi.
Just to reinforce your choice of the DIY PSU. I use the Glassware LV Regulator kit configured for full wave bridge. The transformer secondary voltage should be between 7V to 8VAC for a 5VDC output from the regulator. This is mentioned in the user guide which comes with the kit. It is a good quality kit with quality parts.
For my RPi builds, I set the output voltage for 5.1 VDC so this means that the R2 resistor supplied in the kit will need to be changed from 374 ohms to 381 ohms or thereabouts to get your final voltage. I use series resistor combinations to get to 381 ohms.
I use separate 5VDC supplies when I use a HAT DAC / Reclocker combination,I make sure that the power transformer has dual output windings to save on buying a second transformer.
Have fun!
For my RPi builds, I set the output voltage for 5.1 VDC so this means that the R2 resistor supplied in the kit will need to be changed from 374 ohms to 381 ohms or thereabouts to get your final voltage. I use series resistor combinations to get to 381 ohms.
I use separate 5VDC supplies when I use a HAT DAC / Reclocker combination,I make sure that the power transformer has dual output windings to save on buying a second transformer.
Have fun!
Yes that transformer looks good. Be aware that transformer ratings are quoted at their maximum load, and with more modest loads (such as your rPi) that transformer is likely to measure 7.5VAC or so - that's close to the upper voltage specification that ktham just mentioned. After the rectifier bridge that will yield somewhere between 9 and 10.5 VDC. Your regulator will be running warm-to-hot.
This is just my experience. I have a very revealing system and top tier. Using a good linear supply has improved both raspi and digi one. Ive tested all switching, bad. The powerbank is 2nd best but the linear is best.
Btw raspi+digi one with li esr aupply is the best transport ive ever heard. Better than my Cec transport, better than any Mac audirvana , better than aerender server that i ABed yes, true. And better than the hifiberry pro+.
Btw raspi+digi one with li esr aupply is the best transport ive ever heard. Better than my Cec transport, better than any Mac audirvana , better than aerender server that i ABed yes, true. And better than the hifiberry pro+.
Attachments
Get the 2.5" heat sink when you order the LV Regulator kit. Future proofing.
A question about your transformer choice. Do you plan to use the 180VAC CT windings for anything else for this build? Or, are you just looking for low voltage such as the two 6.3V windings?
A question about your transformer choice. Do you plan to use the 180VAC CT windings for anything else for this build? Or, are you just looking for low voltage such as the two 6.3V windings?
Ah yes, I didn't look closely. That 180V-0-180V output is possibly of no use to you.
I recommend Triad's series of dual-bobbin transformers - for you the VPS12-2000 - which is 4amp @ 6VAC (or 2amp @ 12VAC). DigiKey has this transformer for about US$14.
I recommend Triad's series of dual-bobbin transformers - for you the VPS12-2000 - which is 4amp @ 6VAC (or 2amp @ 12VAC). DigiKey has this transformer for about US$14.
Correction, I meant "split bobbin" not "dual bobbin".
Item # VPS12-2000, Chassis Mount Quick-Connect World Series™ Power Transformers On Triad Magnetics
Item # VPS12-2000, Chassis Mount Quick-Connect World Series™ Power Transformers On Triad Magnetics
Glad to hear that the Glassware is a good choice. I also thought about having two secondaries, in case I change my mind later and get a DAC HAT.
Good to hear someone else has also tried the DigiOne.
What is that big "can" inside of your case?
Will do!
I don't know much about transformers. From what I had gathered so far, toroids are generally better for power amps, and for lower-powered stuff like pre-amps and DACs etc., some recommended R-Core transformers.
I don't need the 180V... but I just couldn't find any other R-Core transformer with 6.3V secondaries.
The Triad transformer looks promising.
What would be the advantage of using a split-bobbin vs. a toroid or r-core or E-l transformer?
I also noticed in my vintage pre-amp, that the transformer is entirely covered with a metal box. I am wondering whether that is helpful or even necessary...
I understand that R-cores have good rejection of mains interference, and split-bobbins are even better in this regard. That's why I like split-bobbin.
R-cores are the best in terms of low EMI radiation, EI the worst. The metal shield you describe is most likely unnecessary for an R-core.
With a split-bobbin you might consider a metal shield (or Faraday cage) but I think if you keep your audio circuitry a few centimetres away from the split-bobbin unit you should be fine without.
R-cores are the best in terms of low EMI radiation, EI the worst. The metal shield you describe is most likely unnecessary for an R-core.
With a split-bobbin you might consider a metal shield (or Faraday cage) but I think if you keep your audio circuitry a few centimetres away from the split-bobbin unit you should be fine without.
The big can is a 55,000uf capacitor on the PS. Ive tried all typed of trans. I do not buy into the toroidal. The best is dual c core and i like Ei also.
I'm not familiar with c-core. Does the Hammond 229 series qualify?
Hammond Mfg. - Power Transformer - (229 Series)
Hammond Mfg. - Power Transformer - (229 Series)
For a single output look at the Hammond 166M8 or 166N8. These are 8 VAC output transformers.
For dual output configuration ( Rpi plus HAT DAC powered individually off 1 transformer core) look at the Hammond 266 L14 or the Hammond 266 L16.
Both series are between 25 to 35VA. Both are chassis mount if that is what you want. Have a look at the Glassware LV Regulator schematic and you will see why a 7-8VAC input is required vs a 6.3VAC input when your circuit is under load vs no load.
If you are considering the Kali re clocker as an add on to the Pi and with a Piano DAC the power requirement is for 3 Amps so size your transformer accordingly. That 2.5" heat sink selection for the regulator will come in handy.
I would encourage you to review this power supply forum for more information on DIY power supplies as they relate to RPi and HAT DACS. There are lots of builder feedback and techniques which you might find helpful in your build. Depending on your building experience there are other linear regulator designs somewhat comparable to the Glassware LV Regulator in design but you will have to source all the parts and the PCB yourself. I cannot quantify the cost comparison because all my costs are in Canadian $ and I have my own supplies in house to draw from. I am not a commercial operation.
Send me a PM if you need additional build help.
For dual output configuration ( Rpi plus HAT DAC powered individually off 1 transformer core) look at the Hammond 266 L14 or the Hammond 266 L16.
Both series are between 25 to 35VA. Both are chassis mount if that is what you want. Have a look at the Glassware LV Regulator schematic and you will see why a 7-8VAC input is required vs a 6.3VAC input when your circuit is under load vs no load.
If you are considering the Kali re clocker as an add on to the Pi and with a Piano DAC the power requirement is for 3 Amps so size your transformer accordingly. That 2.5" heat sink selection for the regulator will come in handy.
I would encourage you to review this power supply forum for more information on DIY power supplies as they relate to RPi and HAT DACS. There are lots of builder feedback and techniques which you might find helpful in your build. Depending on your building experience there are other linear regulator designs somewhat comparable to the Glassware LV Regulator in design but you will have to source all the parts and the PCB yourself. I cannot quantify the cost comparison because all my costs are in Canadian $ and I have my own supplies in house to draw from. I am not a commercial operation.
Send me a PM if you need additional build help.
Thanks for all the help.
There is one little issue I need to add to the whole project... I want to be able to squeeze it into a chassis that is about 2.25 inches (about 57mm) tall (the interior space). Otherwise there is plenty of space (width and depth).
Shoot me for being too picky about this, but I really would clone this chassis:
My metal working skills are a lot better than my electronic skills...
Well, after having confessed that, it looks like the Hammond low profile power supplies that linuxfan mentioned would be a nice fit for that. I also like that they have "universal" AC input (115/230).
But I wouldn't be able to use the Glassware PSU with a 2.5" heat sink.
So I guess I must keep looking for another PSU then? Maybe the AMB Sigma 11 is a good choice afterall, it allows several different heat sink mounting options.
There is one little issue I need to add to the whole project... I want to be able to squeeze it into a chassis that is about 2.25 inches (about 57mm) tall (the interior space). Otherwise there is plenty of space (width and depth).
Shoot me for being too picky about this, but I really would clone this chassis:
My metal working skills are a lot better than my electronic skills...
Well, after having confessed that, it looks like the Hammond low profile power supplies that linuxfan mentioned would be a nice fit for that. I also like that they have "universal" AC input (115/230).
But I wouldn't be able to use the Glassware PSU with a 2.5" heat sink.
So I guess I must keep looking for another PSU then? Maybe the AMB Sigma 11 is a good choice afterall, it allows several different heat sink mounting options.
I think one of these transformers would fit the bill:
Triad PC-mount World Series
I found the user guide for the Glassware LV, and I think I will try it with the regular heat sink. If that gets too hot, I must be able to find another, larger, heat sink that can be fitted to that board, shouldn't I?
Of the transformers linked to above, which one would be the most suitable? As far as I understand, 8V on the secondary would be ideal for the Glassware LV. But what VA to choose, I am thinking 30VA, e.g. this one.
Only problem is, I would need to get a PCB to mount the transformer. I have some PCB etching solution, so I may intent to make one myself. This way I could actually add some connectors that would make it easy to switch the input voltage from 115 to 230V (like they do in some vintage amplifiers, like the Accuphase ones).
Any thoughts on this?
Triad PC-mount World Series
I found the user guide for the Glassware LV, and I think I will try it with the regular heat sink. If that gets too hot, I must be able to find another, larger, heat sink that can be fitted to that board, shouldn't I?
Of the transformers linked to above, which one would be the most suitable? As far as I understand, 8V on the secondary would be ideal for the Glassware LV. But what VA to choose, I am thinking 30VA, e.g. this one.
Only problem is, I would need to get a PCB to mount the transformer. I have some PCB etching solution, so I may intent to make one myself. This way I could actually add some connectors that would make it easy to switch the input voltage from 115 to 230V (like they do in some vintage amplifiers, like the Accuphase ones).
Any thoughts on this?
Within that "VPP" PC-mount range the VPP16-1900 is 8.0 V at 3.8 A, and it's 1 9/16 inches high
Item # VPP16-1900, PC Mount World Series™ Power Transformers On Triad Magnetics
but of course once mounted to a circuit board and raised on half-inch standoffs - that's then a total height just over 2 inches, very close to your available 2.25 inches.
Triad's "FP" Flat Pack range is even more compact - the FP16-3000 is 8.0 V at 6.0 A, and is 5mm lower than the VPP16-1900. Also, it's a split-bobbin design.
Item # FP16-3000, PC Mount Flat Pack™ Power Transformers On Triad Magnetics
If you prefer Hammond, the equivalent model is 229D16. Dimensions are identical.
229D16 - Hammond Mfg.
Yes, that's the right way to do things. The rough way is just drill correctly spaced holes in blank circuit board, then solder insulated wires to the protruding pins on the underside.
I estimate you cannot go any higher than the standard 1.5 inch heatsink, so you must go wider, or turn the board vertically, or find a radically different form-factor. This might work -
http://www.altronics.com.au/p/h0669-84-x-24-x-28mm-low-profile-to220-pcb-mount-heatsink/
This wide heatsink has a thermal resistance of 5 K/W, better than the 6.5 k/W of the 1.5 inch heatsink, and almost as good as the 4.5 k/W of the 2.5 inch heatsink.
Thank you so much for your help!
That heat sink is definitely on my short list.
I think I will go for the VPP16-1900 power supply. It seems to be a bit "safer"... don't need any more fires here 🙁. I will build the case last, it wouldn't be the end of the world if I will need to go a 1/4" taller.
For the transformer PCB:
I guess I will put connectors for AC-in and AC-out on each side of the PCB. I wonder if I should use PCB "tabs" or screw-down terminals for the connections.
Oh, one more thing I was wondering about:
Do I need an IEC inlet with EMI filter built-in? The GlassWare LV has an RC filter on board, but as far as I understand that's a different type of noise filter...
So I guess it should be EMI Power Inlet -> Fuse -> Switch -> Transformer, correct?
That heat sink is definitely on my short list.
I think I will go for the VPP16-1900 power supply. It seems to be a bit "safer"... don't need any more fires here 🙁. I will build the case last, it wouldn't be the end of the world if I will need to go a 1/4" taller.
For the transformer PCB:
I guess I will put connectors for AC-in and AC-out on each side of the PCB. I wonder if I should use PCB "tabs" or screw-down terminals for the connections.
Oh, one more thing I was wondering about:
Do I need an IEC inlet with EMI filter built-in? The GlassWare LV has an RC filter on board, but as far as I understand that's a different type of noise filter...
So I guess it should be EMI Power Inlet -> Fuse -> Switch -> Transformer, correct?
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