http://www.atrj13.dsl.pipex.com/images/ ... _rev_d.pdf
I've had a dig around and found this. It was cobbled together from the few bits I had. I actually also added 4 No. 1R 3.3uF RC sections which aren't shown; two per stage, one per channel.izzy wizzy wrote:What was the passive circuit you used?
The passive was a simple pi filter, so something like 4700uF small R 4700uF. No iron. I tried it mostly to find out how much hum was coming from the AC heaters, and it made little difference.izzy wizzy wrote:What was the heater reg? Was there any iron in the passive supply?simon wrote:Going from AC heaters to DC heaters using a simple PI filter made little difference also, but going to the reg heater supply surprised me just how much of an improvement there was.
I haven't tried chokes in heater supplies, guess I've got bigger nuts to crack at the moment . I'm guessing you like them? CLC or something like that? Have you been able to use a smallish last C of nice quality rather than the usual cheap large 'lytics?
The heater reg is a bog standard Morgan Jones type jobbie with an LM338 for a little more current capacity than an LM317. This is pretty much it though I've bypased the Schottkies now, and added a small R on top of the 1uF.
Yeah, to find out how it sounds, especially as I haven't built a SS HT reg yet .izzy wizzy wrote:Do you mean you will expand the regs as in maybe one per stage? If so, why?simon wrote:Next to try is the SS HT reg. Once I've built two channels I'm sure I'll want to build two more, unless I really don't like the sound they're making.
Why not? Serious question.
Yes, one never has enough iron and decent caps . It's also difficult to do a "definitive" comparison as who's to say I will have built the best of each variant (I won't have). But it might be interesting to get a "feel". But I do agree with you that with some of these things I need a long time to decide which is better and which is merely different.izzy wizzy wrote:It would be interesting. If you do, the circuit for each needs to be a little different which may make things a little complicated.simon wrote:What might be interesting is to have a passive, a valve reg and a SS reg supply ready for Owston to see what people think.
That's not too different from what I ended up with in the end. I used a couple of smallish 10uF caps for the first 2 Cs as this modelled best in PSUD. I didn't have any big caps spare to try then - I have some WKZs now I could try, though with the final Cs being decent-ish films maybe the WKZs would be wasted here?izzy wizzy wrote:It's hard to design a passive supply without it being an integral part of the audio circuit i.e. they are not seperate things. Fer instance, a passive supply has decoupling at each stage. It can be daisy chain config as in feed the 2nd stage and then the first is RC decoupled from that or the two stages can both be fed RC decoupled from a common source.
In my phono, I've tried numerous configurations and in the end have liked rectifier-LCLC. Call this last C a common point. then one LC for stage 1 then RC to each channel and from the common point, LC then RC to each channel. The last C is right on the audio circuit to close the AC loop for that stage.
The heater reg was my first reg, the valve the second so I'm just starting out with them to find out how they differ for myself. Regs do seem to be a rather personal taste though.izzy wizzy wrote:The thing I like about passive supplies vs the active stuff is the ease and lack of a kinda mechanical sound in the presentation. I think regs do sound impressive at first. IMHO, when using regulators, the sound of the circuit becomes dominated by their signature. Each reg has its own sound just like an audio circuit; maybe even more so. My preference is to have the PSU as benign as possible rather than the star of the show