Input Impedance of NVA Passives?

[Dr Bunsen Honeydew]

I've never understood any of it. Even the explanations above seem to make my head hurt. Interesting subject though, because pre/power pairings are probably one the most unpredictable things in hifi. I'm sure the knowledge will be invaluable to anyone who can understand it. As for me, I guess it will still be trial and error :D

Exactly Andrew, and you are the one who is right, not the egocentric bullshitters. An active circuit both as output and as input is a complex load, yet for some reason people think it is just the last or first parallel resistor the signal hits or leaves - it is not. So the only way is use your ears and listen for synergy.

I believe all this nonsense has come about because of the forum valve pushers who push SUTs on everyone at the same time. It again is lack of knowledge and the ego based desire to be seen as experts that has created this stupidity. Their chosen equipment is so bad it is incapable of driving or receiving a load unless it is exactly matched and is then an indictment to the out of date and incapable technology involved, so they make up for it by inflicting it as some sort of law on the rest of us when it make bugger all difference.

BTW arguing this with the biggest "know it all" knowledgeless egotist of the lot Marco is what got me booted first time from AoS.

[Dr Bunsen Honeydew]

Here's me jumping in where perhaps I shouldn't, but in practise for domestic audio, the rule I believe is to have the output impedance of a source component as low as possible and the input impedance of the other end as high as possible. Some ss designs (and I think many/most valve designs) do this and don't seem to offer much of an issue with different sources and interconnects, but there are some ss amps which offer very low input impedance of 10k or less. It was my feeling that many sources may not work so well into such a load.

Apologies in advance if the above is garbage. Keen to get it straight in my mind

If you feel you have to follow a rule then that is probably the most likely to be right. But it is simplistic and potentially confusing like all objective parameters that are not understood by enthusiasts and pretend experts who then re-write it into crapology so they have something to talk about to try and make themselves look clever.

[Andrew]

You mean he actually argued with you about amplifier design? That's very ..........

And also very

[Dr Bunsen Honeydew]

It is all in the archive at AoS right back when the forum started.

[Dr Bunsen Honeydew]

He stated the *ONLY* way to accurately match and amplify a MC cart was with a SUT and then a valve phono stage, I argued with him very much on the terms as here that a good solid state circuit is load rejecting and was unquestionably far better *electrically* and IMO musically. I had no one on my side in the argument, even people there who claim to be technical like Anthony TD, they all crawled up Marco's arse. BUT quite simply I was right, so stood my ground and was booted, allowed back later then booted again, and allowed back later and booted again - other stories involved with those

[Dr Bunsen Honeydew]

Anyway back to subject which is not Marco and AoS idiosyncrasies.

There is also a basic misunderstanding that I contribute to, and that is calling it a passive pre-amplifier, but I have to as no one would understand what it is otherwise. In reality it is not an amplifier, pre or otherwise, it has no voltage or current gain so it can't be, it is a passive attenuator box with input switching, to give it its real name.

[slinger]

Just to be pedantic, I'd say that passive pre-amplifier is a totally correct description. Pre comes from the latin 'prae' which simply means 'before' so it's before the amplifier. I'm on your territory here Doc, and I'm sure you'll correct me if I'm wrong, but as far as I remember a passive component is one that in it's simplest definition is a component incapable of power gain. So, Passive pre-amplifier makes perfect sense to me.

[Dr Bunsen Honeydew]

OK Dokay, but in technical terms it isn't and it can't be, but accepted terminology has made it so.

EDIT - from Wiki

An amplifier, or (informally) amp is an electronic device that increases the power of a signal. It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. In this sense, an amplifier modulates the output of the power supply.