Integrated Pre-amp with Line Driver + Phono + TVA's

[Andrew]

Here they are....the numbering schemes don't correspond, so this is posted to give you an idea, I will fix the numbering when I get chance. Obviously the vero is just one channel whereas the schematic is both channels. On the vero red tracks are the copper traces along and the blue ones are wire links running top to bottom; it should be obvious where to make cuts in the copper tracks.

cheers,

-- Andrew

[izzy wizzy]

Or, as you get used to building them, and if you like them, then build 4 regs one per channel per stage.

Why?

cheers,

Stephen

[Andrew]

Hi Stephen,

OK, its probably overkill, and I don't think its really needed in this case.

But seriously, to my thinking it would avoid having to de-couple each stage as the chances of the signal modulating back onto the PSU across the stages would be eliminated; it just wouldn't be possible.

Similarly, separate regulated supplies would also eliminate the need to have large resistance thus creating a higher impedance supply. Is this worthwhile? Well it does depend upon whether the builder sees a higher Z supply as less preferable, or not, to low Z one.

Cost, is of course, an issue, but they're probably no more expensive than buying a large high voltage cap of decent quality.

My own experience of putting this regulator on a test phono, against an original passive supply, was increased scale, speed and dynamics, I attributed this to the reduced impedance.

cheers,

-- Andrew

[izzy wizzy]

I've been round the houses on this. Way back in the day I started with passive supplies, went through many regulators until I found one I liked. I then went on to dual mono, one reg per stage and with the heaters, a seperate supply and reg for each valve. I lived with that for years and got dissatisifed long term. I then started to rip it all out and the more I removed, the more I liked it from a "good feeling" point of view. I just sat down and listened for longer each time. I then ripped the lot out and went back to basics and made supplies with more iron in them. These passive supplies have stayed around longer than anything else.

If you've found a reg with a sonic signature you are happy with, that's good for you. I never have. You are right about the reg stifling inter stage modulation but that decreases with frequency rising. The passive approach does it the other way round and at a very modest frequency will out perform a reg.

Regs a cheaper, more compact and lighter than an equivalent passive supply. IMHO, a passive supply can beat a reg but it will be at a cost, much bigger and much heavier. I think it's easier to have intial success with a reg.

I think the notion of power supply Z is almost a subject in itself. When you talk about output Z of a regulator, it means something entirely different to the series impedance of a power supply. I may even come down to what is important for you in the sound of the stuff you make. I am now in a camp that hates any electronic interference in my music and so regs, CCS thingies and the like just don't do it for me when there are other alternatives such as iron.

cheers,

Stephen

[simon]

Interesting discussion chaps. I guess it just goes to show how important it is that we try the alternatives for ourselves.

Now when I went from the passive to the valve reg I didn't notice much difference. 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.

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. 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.

I had a little play with decoupling earlier. 390R and 100uF/200uF. The valve reg was set up so I used that, but it's fair to say that the 6080 didn't like it at all. As soon as the HT went on after the soft start of the GZ30 there were a couple of purple flashes inside the valve (this was with 200uF).

I turned off and tried 100uF. This time there was a purple glow instead. Going back to no decoupling the reg worked fine. Tomorrow I'll try the decoupling with the passive supply if I get chance.

[simon]

A couple more thoughts.

Andrew, presumably the regs can all share the same LC, they don't need their own?

Stephen, if you were going to build a passive with lots of iron for this phono what would you start with? I've got a few WKZs and 4 No. 10H chokes coming from AE soon so have a few options perhaps.

[Andrew]

Andrew, presumably the regs can all share the same LC, they don't need their own?

Yes, providing the choke can handle the current.

cheers,

-- Andrew

[Paul Barker]

I am now in a camp that hates any electronic interference in my music and so regs, CCS thingies and the like just don't do it for me when there are other alternatives such as iron.

cheers,

Stephen

Don't ever let the solid state fire brigade put you out.

[izzy wizzy]

I guess it just goes to show how important it is that we try the alternatives for ourselves.

Couldn't agree more on that

Now when I went from the passive to the valve reg I didn't notice much difference.

What was the passive circuit you used?

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.

What was the heater reg? Was there any iron in the passive supply?

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.

Do you mean you will expand the regs as in maybe one per stage? If so, why?

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.

It would be interesting. If you do, the circuit for each needs to be a little different which may make things a little complicated.

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 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

cheers,

Stephen[/quote]

[Nick]

Do you mean you will expand the regs as in maybe one per stage? If so, why?

Maybe because, he just wants to. One of the reasons I set this place up, was it was getting hard work having to justify to others everytime somebody wanted to just see if something worked for them.

[Cressy Snr]

Hi Stephen

What I need to ask is how were your opinions on the question of active versus passive supplies formed?

From your earlier posts it would seem that these opinions were formed through experiment and listening to the results, making modifications based on the outcomes of those experiments until you arrived at your preferred setup, ie the one that gave the most sonic satisfaction.

There is no one here that doubts your expertise as a valve amp builder, similarly no one would doubt that Nick Paul and JamesD know their stuff too.

If one wants to pass on that expertise to the less able members of the forum such as myself. DTB, Simon, Phil, Al et al, then it is a far better policy to explain what you mean to someone contemplating doing something than ask them to justify why they are doing it.

The question is superfluous because they don't know why they are doing it, so are going to have difficulty explaining their reasoning. Often a person learning will do something because it seems like the thing to do. They will make their decisions based on the work of other people whose opinions they respect and who have trodden the same path before them.

For example, JamesD does not post here often due to other commitments but I have had lots of private correspondence with him which in which he has explained carefully why what I want to do is not perhaps the best way of going about things and has made suggestions as to how to do it right and what sort of result I can expect if I do as he says.

Nick has put me right on one or two things and Paul, once you have got inside the meaning of his sometimes bluff comments, has made some great suggestions that have moved my knowledge on from what it was.

So rather than asking the question, "why do you want to do this?", it might be better to say, "this is my view, but have a look at this link here and for an opposite argument look here" In that way the learner can read up on the pros and cons of what they intend to do and be able to go in with their eyes open and at least have an idea of what to expect with each method.

This way the learner can feel that they have ownership of their own learning processes, whilst at the same time being able to feel reasonably safe in the knowledge that they have a pool of expertise on the forum they can rely on if they get stuck. A pool of expertise that is not going to make them feel that they know nothing.

Steve

[izzy wizzy]

I asked why do you want to do it to find out the reason for thinking that way. In this instance, why would you want to regulate more than one stage. It's something I have done and I had reasons. Maybe someone else wants to go that route but for diferent reasons.

What I don't want to do is say one way is better than another because given that people have different opinions on what they want to achieve, their better may not be my better. It might be the case that it is easier to achieve a desired result with a regulator where a passive supply is too big and heavy.

The only real area of valve amp building I've spent any great time in is phono stages. I don't think what is applicable there is equally applicable in say SET power amps or PP power amps.

Fer instance, many people think that going dual mono in a power supply is a good thing. So I ask why? I did it, so I could tell you why I thought at the time, it was a good thing but is that the same reason why another person wants to do it? I did it because I saw manufacturers offering their top products as dual mono; a way of making a distinction between their lower priced product - more bits means it's better right? Well in practice, that didn't turn our being true for me. Just one example.

I am new round here so at present, I only feel comfortable telling people some areas they might want to think about. If they want to ask me why in return, then I'm happy to say so. The whole topic of power supplies is a huge one IMHO and it's possible to go on and on about something and it not being what someone wants to hear. I suppose I was dropping hints and not wanting to derail an existing design or devalue anyones else's suggestions.

I do hear what you are saying and will try to phrase things in a better way

I'll try later to answer your specific question but I'm getting grief about moving stuff upstairs so better go keep my other half happy

cheers,

Stephen

[Paul Barker]

The thing is it's not necessary to conceptualise, or rather to be able to conceptualise. It is enough to try it, without justification, and to report the result.

It is likewise alright to suggest it without justification based on your personal result.

People are free to take it or leave it.

The important thing is to voice it.

When Steve has picked up on a suggestion of mine but would have preferred rationalle or theory it is simply that I can't conceptualise it, I have made a suggestion based on my experience, which is only gained by trying stuff without justification.

[simon]

Sorry Colin, I think I've unintentionally diluted and hijacked your thread so I'll start a new one shortly. That'll probably end the discussion... .

[Andrew]

For my part, I have to say there is absolutely no reason Simon or Colin has to follow what I suggest, I don't fell ownership of this, merely offering to help with their projects and perhaps learn a little along the way.

It's your build Colin, Simon....you must decide what you like.....

cheers,

-- Andrew