Ok, hope I help....
The adjusting pin of the regulator wil always be 1.25V from the output (in ideal world)... So if you used 220ohm to bias it... you have put 1.25V/220 = 5.6mA
So at that point between the 2 resistors the voltage is 1.25V and the current is 5.7mA... but you want more of course....
So you use ohm's law, lets say you want 12.5V at the output....
12.5V/.0057A = 2192ohm to be too specific... lol
but remember now, this is from one point to the other .. over both resistors... we know the total resistance, and we know part of it is 220R... so the other resistor should be 2192 - 220R = +-2k..
Now go do your own sums ... use the closest resistor for now... these things eat trimpots...
If you used protection diodes make sure of orentation....
The adjusting pin of the regulator wil always be 1.25V from the output (in ideal world)... So if you used 220ohm to bias it... you have put 1.25V/220 = 5.6mA
So at that point between the 2 resistors the voltage is 1.25V and the current is 5.7mA... but you want more of course....
So you use ohm's law, lets say you want 12.5V at the output....
12.5V/.0057A = 2192ohm to be too specific... lol
but remember now, this is from one point to the other .. over both resistors... we know the total resistance, and we know part of it is 220R... so the other resistor should be 2192 - 220R = +-2k..
Now go do your own sums ... use the closest resistor for now... these things eat trimpots...
If you used protection diodes make sure of orentation....
I am planing on building Micks new PSU. In his tutorial on his site he has used a pair of 10V 75VA toroidals and says that they are perhaps a little over powered. I cannot find a 10V in my cataloges, so I was wondering.
Out of this list, which would be best?
2 x 9+9V 20VA toroidal, each run in parallel.
1 x 12+12V 160VA toroidal, and use one secondary for each voltage.
2 x 9V 30VA chassis mount.
Thanks in advance.
Out of this list, which would be best?
2 x 9+9V 20VA toroidal, each run in parallel.
1 x 12+12V 160VA toroidal, and use one secondary for each voltage.
2 x 9V 30VA chassis mount.
Thanks in advance.
I wouldn't go with less than 12V.
But what do I know? I can't even get 3.5V out of 8V (10 after rectification) and 60VA!
Contrary to what Mick reports, it's my 7.6V SPU that gets scolding hot. I will get 6 or 8 5W resistors on Monday. They will be paralleled 3 or 4. Might be difficult to fit a 10W, much less 20W resistor on my PCB. Might need a bigger heatsink as well. Apparently 25 grams are not enough. The PSX consumes a mere 12W!
The 3.5V resistor does get warm, but so far nowhere near hot.
By the way, the 7.6V PSU seems to work well now. But I can only get 1.6V from the other. I will give it a final crack on Monday or Thuesday when I will replace the resistors and heatsink. Either it works or it ends up in the trash. Seriously, this is too stupid. I feel like a stupid idiot and I do not like it one bit. I have tried the stupist things to get it to work. After I had tried all the non-stupid options there were only stupid ones left.
But what do I know? I can't even get 3.5V out of 8V (10 after rectification) and 60VA!
Contrary to what Mick reports, it's my 7.6V SPU that gets scolding hot. I will get 6 or 8 5W resistors on Monday. They will be paralleled 3 or 4. Might be difficult to fit a 10W, much less 20W resistor on my PCB. Might need a bigger heatsink as well. Apparently 25 grams are not enough. The PSX consumes a mere 12W!
The 3.5V resistor does get warm, but so far nowhere near hot.
By the way, the 7.6V PSU seems to work well now. But I can only get 1.6V from the other. I will give it a final crack on Monday or Thuesday when I will replace the resistors and heatsink. Either it works or it ends up in the trash. Seriously, this is too stupid. I feel like a stupid idiot and I do not like it one bit. I have tried the stupist things to get it to work. After I had tried all the non-stupid options there were only stupid ones left.
Yes, the LM317, or rather LM1084, has metal back. I checked. No short.
And that's the problem. I have double checked everything and then double check that. I even disconnected the other secondary winding, which should make no difference whatsoever. As said, I've tried everything. Still the best I can get is 1.8V, and that's when the output of the LM1084 is 7.5V! That's a 5.7V drop!! It's not real.
And that's the problem. I have double checked everything and then double check that. I even disconnected the other secondary winding, which should make no difference whatsoever. As said, I've tried everything. Still the best I can get is 1.8V, and that's when the output of the LM1084 is 7.5V! That's a 5.7V drop!! It's not real.
What is that 220R resistor you are talking about? You say R2, so is this the serial resistor between the Caps making up a low-pass filter i.e. R2 /R9 in my schematic?
If so, the value you chose is FAR too high. You will have a tremendous voltage drop over it so there will be not enough voltage left for the regulators' dropout (i.e. it will not regulate) AND it will get very hot.
The resistance of this serial R should be in the few ohms range. (Cf. my schematic).
Mick
If so, the value you chose is FAR too high. You will have a tremendous voltage drop over it so there will be not enough voltage left for the regulators' dropout (i.e. it will not regulate) AND it will get very hot.
The resistance of this serial R should be in the few ohms range. (Cf. my schematic).
Mick
I use about 15Ohms for R2 right now--22Ohms + a bunch of paralleled 220Ohm resistors.
But 220Ohms is no problem in my case. I have more than enough voltage as it is, roughly 10VDC for the 3.6V.
The problem is that even when I have 7.5V after the voltage regulator, it still drops to 1.8V once I connect it to the PSX. It's not because of insufficient voltage or too small trafo.
Also the 7.6V doesn't really work. Sometimes I get 5.5V, other times 7.6V and other times 10V! I have tried it on two consoles.
But the problem isn't that it doesn't work. The problem is that I cannot see any reason for it not to work.
Anyway, I have dropped the PSU. I will try another design. I have spent too much time and money on this to drop the linear PSU without giving it one more chance.
But 220Ohms is no problem in my case. I have more than enough voltage as it is, roughly 10VDC for the 3.6V.
The problem is that even when I have 7.5V after the voltage regulator, it still drops to 1.8V once I connect it to the PSX. It's not because of insufficient voltage or too small trafo.
Also the 7.6V doesn't really work. Sometimes I get 5.5V, other times 7.6V and other times 10V! I have tried it on two consoles.
But the problem isn't that it doesn't work. The problem is that I cannot see any reason for it not to work.
Anyway, I have dropped the PSU. I will try another design. I have spent too much time and money on this to drop the linear PSU without giving it one more chance.
I bypassed the resistor.
The secondaries jumped to around 3.8 and 7.8V. But nothing really changed. When I hook it up to the PSX, the 3.8V becomes 1.5V and the 7.8V becomes anything between 9 and 13V.
As I have said all the time: I do not get it. It makes no sense at all to me. I wouldn't have believed this stuff if it hadn't happened in front of my eyes.
Edit: I will probably post a question on the PSU Forum. This is just too strange to me.
The secondaries jumped to around 3.8 and 7.8V. But nothing really changed. When I hook it up to the PSX, the 3.8V becomes 1.5V and the 7.8V becomes anything between 9 and 13V.
As I have said all the time: I do not get it. It makes no sense at all to me. I wouldn't have believed this stuff if it hadn't happened in front of my eyes.
Edit: I will probably post a question on the PSU Forum. This is just too strange to me.
Here's the thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=95749
Now we can only wait and see.
Now we can only wait and see.
Seems Nordic might have been right after all.
Anyway, I thought I should post my impressions of the linear PSU as well.
As Mick says, the bass is significantly improved. I tested with my three bass-heaviest albums: Herbie Hancock: Dis Is Da Drum; Ashes of Time; and Once Upon a Time in China (they use those Chinese drums the size of minivans on the last track; you know the ones they beat on with big, heavy sticks). The bass is disgustingly good.
I can't say for sure about the other things Mick mentions. But I sure wouldn't want to be without the PSU.
Anyway, I thought I should post my impressions of the linear PSU as well.
As Mick says, the bass is significantly improved. I tested with my three bass-heaviest albums: Herbie Hancock: Dis Is Da Drum; Ashes of Time; and Once Upon a Time in China (they use those Chinese drums the size of minivans on the last track; you know the ones they beat on with big, heavy sticks). The bass is disgustingly good.
I can't say for sure about the other things Mick mentions. But I sure wouldn't want to be without the PSU.
Hi to all Fans of the incredible PSX-CDP,
i have so far modified one of three different ps1 and i like the sound-improvement. i can recommend micks output-stage tuning to every one who's in to this. Sadly, i took no pictures, next time. In the next step i will change the PSU as well.
@Mick: Your homepage is very nice, thanks for your work and very nice photos. May i ask you a question about your linear PSU, where exactly did you get your RKTs from? just curious
.
with regards
Patrick
i have so far modified one of three different ps1 and i like the sound-improvement. i can recommend micks output-stage tuning to every one who's in to this. Sadly, i took no pictures, next time. In the next step i will change the PSU as well.
@Mick: Your homepage is very nice, thanks for your work and very nice photos. May i ask you a question about your linear PSU, where exactly did you get your RKTs from? just curious
.with regards
Patrick
Power Supplies and PSXs...
I've always considered the power supply to be the under-valued part of any piece of audio gear... I've never made a change to a PS that was not audible... and not always an improvement! As always, it's important to LISTEN!
Mick, thanks for your inspired PS and as always, your clear and lucid instructions. Hopefully that will inspire more big-boxes feeding PSXs.
As for bass and the PSX, made two changes that had a large impact on the bass on mine... one was when I bypassed the output stage per Mick's instructions. I initially used a 3uf film cap, moved it up to 6uf and noticed an increase in bass extension, power, and definition (and it wasn't a better cap, just parallelling a 2nd on each output to double the value). That tells me not to skimp on the size of the output cap.
The second was when I did upgrades to the stock switching supply. I replaced the input diode bridge with high-speed, soft-recovery diodes. the main PS filter cap with a larger Jensen 4-pole cap, and all the other caps with similar-sized (or slightly larger) Rubycon ZL/ZA series, with significant bypassing at the AC input and diode bridge. Altho it took FOREVER to break-in (over four weeks constant running!), the bass was immediately MUCH more powerful. After run-in, I had a smoother, more articulate, yet more dynamic mids and highs too.
I don't feel the switching supply upgrade I did will be the equal of a well-done linear... but really won't know that until I find the time to make one on my own and compare. (Of course, I balance this with the knowledge that my current amps, the EVS500M from www.tweakaudio.com, use switching supplies!)
But upgrading the switching supplies are an easy evening job once you've secured the parts, a much quicker mod than the full-blown linears. And a plus (in my book) is that you can't fit the top back on after fitting the Jensen 4-pole cap, and have to run the unit topless, which is another significant improvement in my experience.
I also am a model airplane flier and have a supply of high-current/high-capacity lithium-polymer packs that I intend to try out as a battery supply for my PSX someday.
Greg in Mississippi (used to be Minneapolis)
I've always considered the power supply to be the under-valued part of any piece of audio gear... I've never made a change to a PS that was not audible... and not always an improvement! As always, it's important to LISTEN!
Mick, thanks for your inspired PS and as always, your clear and lucid instructions. Hopefully that will inspire more big-boxes feeding PSXs.
As for bass and the PSX, made two changes that had a large impact on the bass on mine... one was when I bypassed the output stage per Mick's instructions. I initially used a 3uf film cap, moved it up to 6uf and noticed an increase in bass extension, power, and definition (and it wasn't a better cap, just parallelling a 2nd on each output to double the value). That tells me not to skimp on the size of the output cap.
The second was when I did upgrades to the stock switching supply. I replaced the input diode bridge with high-speed, soft-recovery diodes. the main PS filter cap with a larger Jensen 4-pole cap, and all the other caps with similar-sized (or slightly larger) Rubycon ZL/ZA series, with significant bypassing at the AC input and diode bridge. Altho it took FOREVER to break-in (over four weeks constant running!), the bass was immediately MUCH more powerful. After run-in, I had a smoother, more articulate, yet more dynamic mids and highs too.
I don't feel the switching supply upgrade I did will be the equal of a well-done linear... but really won't know that until I find the time to make one on my own and compare. (Of course, I balance this with the knowledge that my current amps, the EVS500M from www.tweakaudio.com, use switching supplies!)
But upgrading the switching supplies are an easy evening job once you've secured the parts, a much quicker mod than the full-blown linears. And a plus (in my book) is that you can't fit the top back on after fitting the Jensen 4-pole cap, and have to run the unit topless, which is another significant improvement in my experience.
I also am a model airplane flier and have a supply of high-current/high-capacity lithium-polymer packs that I intend to try out as a battery supply for my PSX someday.
Greg in Mississippi (used to be Minneapolis)
I found these trafos in the Junk. They are very silent and well made. I dont recall the brand printed on their label, but I recall that it was some well known (in Germany) brand.
Greg, thanks for your thoughts. I also believe that switching supplies can be very good in audio, but they have to be well constructed. The efforts to get it noise free etc. are high. The stock SMPS of the PS1 is not particularly well made, therefore the improvement by modifiying or replacing it can be huge.
Mick
Not sure if anyone has posted this before...
Has anyone seen the comments on the PS1 over at arstechnica.com? The author was writing to convey what we know as an excellent CD player, but the comments were rather harsh. Mick's site was mentioned in the article for the mods.
http://episteme.arstechnica.com/eve...&f=697008143731&m=323001791831&r=323001791831
Has anyone seen the comments on the PS1 over at arstechnica.com? The author was writing to convey what we know as an excellent CD player, but the comments were rather harsh. Mick's site was mentioned in the article for the mods.
http://episteme.arstechnica.com/eve...&f=697008143731&m=323001791831&r=323001791831
I was going to post a rather inflamitory response...
But thought better of it.
kec wrote: "... but the comments were rather harsh."
As long as I've been involved in audio, I've observed two dominent camps... the subjectivists and the objectivists. That group was definitely a strong set of objectivists.
I'm in the other camp. And I find my PS to be a fine-sounding CDP, ugly and clunky as it is.
Heck, a lot of people still prefer non-oversampling DACs using NOS TDA1541's!
Greg in Mississippi (ustabe Minneapolis)
But thought better of it.
kec wrote: "... but the comments were rather harsh."
As long as I've been involved in audio, I've observed two dominent camps... the subjectivists and the objectivists. That group was definitely a strong set of objectivists.
I'm in the other camp. And I find my PS to be a fine-sounding CDP, ugly and clunky as it is.
Heck, a lot of people still prefer non-oversampling DACs using NOS TDA1541's!
Greg in Mississippi (ustabe Minneapolis)