Hey Andy! Where would you put 'em?

[pm1961]

Hi Andy,

I've put this on the forum because (hopefully) more people might be asking the qusetion.........

I've finally got round to building your s/regs...... and I always intended to build a prefix clone with your regs in the T/T.

Before that however, I've started to build my DIYcaps. I'm building three, but still debating what regs to put in them. My feeling is that I'll get most VFM from using a standard 317/329 reg in the Cap and using your s/reg at the point of use.

Finally, my questions!

Is it correct that any reg is of most value adjacent to its point of use? Secondly, is there any value in cascading your s/regs? i.e. one in the Cap and then one at the point of use? Or does the law of diminishing returns takeover?

Cheers,

PM

P.S. Any news of a complementary -ve s/reg? I wouldn't mind having a go at supplies for some analogue output stages that require a +/- supply.

Failing that, can the 329 ref be used in a 337 type -ve reg?

 

[Andrew L Weekes]

PM,

Before that however, I've started to build my DIYcaps. I'm building three, but still debating what regs to put in them. My feeling is that I'll get most VFM from using a standard 317/329 reg in the Cap and using your s/reg at the point of use.

I think I would support that view, generally.

Is it correct that any reg is of most value adjacent to its point of use?

Generally yes, but the dominant factor to sonic performance (which I'm not prepared to reveal publicly at present) has benefits even if on the end of a cable. This is how Naim get away with doing this.

Secondly, is there any value in cascading your s/regs? i.e. one in the Cap and then one at the point of use? Or does the law of diminishing returns takeover?

I do this in some applications, my 112 has a SNAPS feeding internal reg's. The effect of an external supply is clearly audible, but I'd be happy with a simpler LM317 feed for a first attempt. In conjunction with a friend we did a 32 running from a wall-wart style supply a while back, and got excellent results, but a better PSU made a difference.

Cascading regulators can have an effect on stability, if one is not careful. Keeping things simple is certainly easier and requires less analysis. This is the reason that I suspect Naim rarely cascade reg's in analogue applications, but it can be done, quite easily, if one analyses the problem.

An approach I'd like to try, which may be more elegant, is to get the rectifier / caps into the same box as the reg's and analogue circuitry, leaving just the transformer external. Some care with twisted pair wiring and some screened cable should result in little EMI to consider and would get the impedance of the supply lower at the point of interest.

P.S. Any news of a complementary -ve s/reg? I wouldn't mind having a go at supplies for some analogue output stages that require a +/- supply.

These have been available for some time, contact me via PM for details.

Failing that, can the 329 ref be used in a 337 type -ve reg?

Yes it can, it's only a diode, just reverse it's direction and you're there!

Andy.