[aos]

I"ve noticed dramatic improvements in sound quality, especially bass, when using even the cheapest 78L12 regulator. A friend of mine considering buying a headphone amp was over last weekend and commented how it was incredible to notice such a big difference in bass by just adding a regulator (and granted, a pair of Elna Cerafine and Black Gate capacitors on their output) to batteries.

Older regulators were not stable with low ESR capacitors. Modern are much more tolerant - generally any capacitor will do as long as it's larger than so many uF (10 is a usual number), but the datasheet is always the right place to consult on that and any other matter.

Normally, there shouldn't be any audible hiss with regulator - unless it has become unstable and oscillates, as ppl pointed out. Impact of relatively high levels of noise are much more likely to be subtle - loss of detail, rather than actual audible noise.

From datasheets it seems like some of the replacements for 3-pins, at least those that are in TO-92 format - are much better than the old originals. Some of them have 10 times less noise for example.

 

[ppl]

aos> have you ever found neg regs to match those you like in your P-DAC. 7818 reg's Yuck i would rather have reduced bass that hear what these do to the Sound thay blur the mids and make the Higs totaly undistinguishable. the LM-317 7 LM-337's are alot better than these but evean these are not what i would use in High end equipment. I don't think I am alone on this but realy don't care if i am. The reason the bass is better through the regs than on batteries is the regs have an impedance of 0.1 ohms and the EL-2001 used as i VGD has about 8 ohms. this places most of the demand upon the caps. I have investigated tthis and Found the LT-1210 used as a unity gain follower for the VGD will give the best of boath worlds the Noise free operation of batteries and the Low impedance of reg's Contrary to popular belief it is not the Voltage regulation that Keeps the ripple out it is the Low impedance. however eveybody has a different view on this. if you really want a low impedance and quiet supply and are willing to fo go safty then using the Center tap of AA or Bigger NI-MH or Ni cad's are the Best however you must recharge way before the weakest cell is discharged or you will lose one half of your supply and place several Volts of DC upon the Output

 

[aos]

ppl, no I haven't found anything as good as what Analog or TI has to offer in positive supplies. I did find something that does look reasonably decent - LT1964 - which I am going to use. At least its noise is very low and in SOT-23 form factor I can afford to use 4 of them.

I haven't really noticed loss of resolution - maybe your hearing really is extremely good. Anyway I was refering to 78L12, not 7812 - that "L" makes all the difference. Those are TO-92, and there are many versions by a lot of manufacturers. Lots of them are much better than what originals were - after all, aren't the originals at least 30 years old?

I am expecting a lot from Diden-Jung which has very low impedance and very low noise. But they are not well suited for portable equipment (size and power consumption).

 

[ppl]

aos. To-92 versions better Humm.. have to check these out as i was refering to the TO-220 versions from ON semiconductor. Thanks for the tip on the LT-1964. That and it's compliment look good and the ability to use low ESR caps will remove the requirement of adding the series output resistor i posted about above. the Diden-Jung Regulator is nice I used this several years ago in a Preamp for RIAA mag Phono sounded good to me. this was from a project in the AA years ago. this regulator makes me think that just going all Discreet component is just as mutch work.

 

[CaptBubba]

Ok, well I built the first section of the PS today with 2900uF of capacitance total across the two rails. There is a bit more capacitance in the form of a few small value (<300nF) film caps. Here is what I get from it:

mains voltage: 120.5V AC
Pre-rectification: 12.7V AC
Output (no load): 20.07V DC
Output (200ohm load): 17.5V DC
Output ripple (loaded): .079V AC
+ to gnd (loaded): 8.75V DC
- to gnd (loaded): -8.73V DC

Not bad at all. Yes, 79mV ripple is still high, but I expected much worse for this amount of capacitance. zzz's formula states I should be getting about 280mV ripple for this setup. The difference must come from how I have it laid out.

I have a 4nF cap across the transformer outputs. After the bridge rectifier I have a low-value choke (scavenged so I don't know the actual rating), followed by 2x2200uF caps in series across the rails with a resistor divider (1k) to give me a ground. After that is a much higher value choke, followed by 2x560uF, 1x680uF, 1x100nF, and 1x38nF, all across the +/- rails, not to ground.

I may add another choke/cap stage to it and see if I can't get a bit more ripple out of it, with a lot of low value films plus a few elec caps. The amp itself will be heavily decoupled with films.