NVA substitutes?

[Marco]

Spot on (as usual) Clive

on a more hair shirt, SQ at all costs design I'd be ok with phase inverting...

Croft amplifiers are as 'hair shirt' as they come and designed solely with one goal in mind: the best possible audio performance for the least possible financial outlay. In stock form, and particularly when older designs are judiciously modified, they are incredibly satisfying music-makers!

Marco.

[hifi_dave]

Yes I agree, however, I suspect that the veritable 'night & day' difference I heard when Glenn made the change I mentioned in my system, was primarily due to him exploiting the sonic benefits of the amp's phase-inverting circuit (minimising active stages used), than anything relating to what you've described.

That is why I can clearly hear significant sonic benefits with ALL the recordings I own, not just those that are "polarity coherent".

Like I said too, you now have an answer for why Glenn designed his amps to phase-invert the signal. Knowing him well, and the design goals he values, it’ll have been all about minimising the amount of active stages needed, and hence simplifying the signal path, in order to maximise sonic performance

Marco.

Just spoken with Glenn and he says " Every amp I make inverts phase except the phono stages. It's system and source dependant whether it's audible. If you use a pre-amp and power-amp combo, you don't have to bother."

As I am aware, quite a few products invert phase, it's not just Croft.

In my estimation, the differences are subtle to say the least and vary with product and the recording. When I have played around with inverting phase, I have found that certain images in a sound-stage will move slightly forward whilst others move slightly back. Reverse the phase and the opposite happens. Which is correct ? Tiny differences which, to my ears, are not worth bothering with but maybe, it might be more obvious with different recordings and/or equipment.

[Marco]

Thanks for that, Dave. The info is useful

Like you say, the sonic effect of the phase-inverting, in terms of how obvious it is, will vary from system to system.

As I said, in mine (and perhaps it's because I'm using a non-standard, heavily modified vintage Croft preamp), the different between how my system performs when the polarity of the speaker cables (and thus phase) is reveresed, or not, is extremely significant - and I mean in a fundamental musical satisfaction sense, not in terms of prosaic hi-fi considerations, such as issues relating to tonality.

Like I said before, quite often, due to a lack of concentration, I've connected up my speaker cables the 'wrong way' and sat there thinking: 'my system sounds rather 'off' today', only to look behind my power amp and see the cause of the problem... Then sort it and listen again, and bingo - the magic is back!!

Marco.