Croft Polestar III 2 box power amp project

[The Black Adder]

Mmm! If Glenn as the designer and builder (not the aftermarket modder) sees fit to build 2 boxes that's good enough for me - and I've heard the results!

+1

Andrew, I certainly wouldn't go back to the internal stock type. - No way, not a chance, not even if you paid me.

[Arkless Electronics]

As far as the 2 box bit goes, and above a certain "hi-end-ness" quite a bit of gear is 2 box, the erm.. gospel according to Jez on that is

MC phono stages - Very desirable! It's almost impossible to completely ban the last remnants of mains hum with the transformer in the same box, and with all that gain any mains vibration is not good...

MM phono stages - Desirable but not nearly so important as with an MC stage due to lower gain.

Line stages - No real advantage.

Power amps - Not a good idea unless size and weight dictate it. You are using huge transformers etc and then putting the resistance of the cable, and any plugs and sockets used, between this humongous PSU and the bit needing the power.... Not a game ender or anything if the cable and connectors are sufficiently heavy duty and the cable as short as practicable but, technically, not ideal....

YMMV

[Wakefield Turntables]

Yeah, happy for you as well Joe. I'm perfectly happy plodding on with what I have sitting in front of me.

[Wakefield Turntables]

Suppose I better declare my 4-box phonostage then... , I'm not a hater of the two box pre or power amp, and better still if it sounds better in an individuals system.

[The Black Adder]

One of those things to do at a later day maybe.

[Wakefield Turntables]

One of those things to do at a later day maybe.

Me? Nope. Valve regulations for me mate if anything else.

[The Black Adder]

Good move...

[Jimbo]

A question for Jez, would you recommend valve regulation of a power amp to be more important than a large PSU and do you think valve regulation is necessary/ better than non regulated?

[Arkless Electronics]

Suppose I better declare my 4-box phonostage then... , I'm not a hater of the two box pre or power amp, and better still if it sounds better in an individuals system.

It's an MC phono stage so it fits in with the technical philosophy I outlined I certainly don't hate or want to preach about any amount of boxes as a solution! Just saying where, technically, there is an obvious case(sic) for the use of either one box or more than one....

IMHO some hi-end gear is offered as a two box solution purely to allow a suitably hi-end price tag to be applied to it... a second equally bling box with maybe a digital read out of PSU status or something may increase the parts cost by say £350 but allow the asking price to be £12K when the one box version is "only" £7K, and without any genuine technical reason... it's just what "the market" expects and perceives as the next step up from a single box solution maybe?

[Arkless Electronics]

A question for Jez, would you recommend valve regulation of a power amp to be more important than a large PSU and do you think valve regulation is necessary/ better than non regulated?

A can of worms...

I wouldn't recommend valve regulation of a solid state or hybrid power amp under any circumstances! Disaster! I think you mean regulation of the gain stages in the case of the Croft....? A valve regulated supply couldn't supply the sort of current needed by the output stages As to whether regulated or non regulated is better well that could bring forth a range of opinions! Mine is that regulated is definitely better, and can be a lot better, but there is lots of scope for getting it wrong!
As to valve regulator V SS regulator there is simply no contest technically... A good SS regulated supply is better by an order of magnitude or several than a valve one in every respect. To the point that there can be no technical justification for the use of valve regulation under any circumstances! Now as to whether it has any subjective advantages due to some valve magic being imbued to the actual voltage is something that I'm sure could be debated..... I can't see it myself but admit that due to the technical superiority of SS being crushing when it comes to regulators... I've never tried it. Maybe I'm missing out... who knows? It has occurred to me that a valve regulated supply is still better than an unregulated supply and that the obvious reason they are used in valve equipment is to stick to the notion of all valve, "no SS", "no sand" etc for marketing/brand reasons... call me cynical

I did design and build a bench PSU for testing valve prototypes etc in which I used valve regulation purely for its ability to withstand a dogs abuse electrically! Which it did for many years. For powering really sensitive stuff I sometimes had to put a SS regulator in line after the valve one though, which should tell you quite a lot