Goldpoint SA4M-47 passive 'preamp' winging its way to Marco Towers...

[Marco]

How can something passive have balls, drive & punch?
All a passive anything can do is subtract from the signal.

Yes of course.

What I meant was that good ones (well matched to the partnering power amp) lack nothing in those areas in comparison with an active design, i.e. they don't sound 'soft', as indeed can be the case with bad passives and/or ones not well suited to the rest of the kit

Marco.

[lurcher]

Can I just point out that EVERY active preamp contains a passive preamp.

If the system requires the active part, the active preamp will sound better, if it doesnt then a passive preamp will sound better.

Good active preamps are a lot harder to design than most people imagine. Bad active preamps are easy.

Some people like what bad active preamps do because the result sounds better for them.

Few people dislike like what good active preamps can do, but because they are hard to make, most people have never heard one.

Its much easier to make a good passive than a good active.

To make a good active preamp, it needs to contain a good passive preamp

Most bad active preamps have a bad passive preamp in them as using a good passive is lost because of the bad active parts.

[struth]

[The Black Adder]

If the system requires the active part, the active preamp will sound better, if it doesnt then a passive preamp will sound better.

An excellent way of looking at it, Nick

[DSJR]

Gutless sonics from passive pres may also simply be the wrong value passive pot being fitted. My old Croft preamp uses a 500K log pair and I believe this is mainly so the phono stage (the earlier design, not as current) doesn't lose bass. Using the tape output to drive a separate headphone amp arrangement (less than 47k input impedance) caused the bass to disappear. Glenn has a mod to the phono stage for this, so it's not unknown to him.

What's got me with active preamps is actually how invasive they can be, especially the awful US valve ones from a few decades back. The revered ARC two-box preamps were more like sonic processors rather than neutral line stages and later LS designs of theirs weren't much better. hell, their 'Reference' preamp range has so many generations now (at eye-watering prices) it makes one ask if they'll ever get it right.

By the way, you can make a VERY truthful line stage with a couple of properly supplied ic op-amps or even one two-channel one - most CD players have one on the output to give the 2V as specified. It's not rocket science you know, but of course, Top End is all about making things look complex when they don't need to be. Marco, your Croft may well be the dogs danglies, but it's frighteningly complex looking inside now

[lurcher]

The op amp was originally designed for use in analogue computers, and it was used very much for rocket science.

[The Black Adder]

Marco, your Croft may well be the dogs danglies, but it's frighteningly complex looking inside now

Hi Dave.

Not sure, but I take it that your looking at the pic I posted? The pic is actually mine inside and it's not that complex. Maybe the angle of the photo makes it look like that?

Mine is dual regulated which adds another set of regulation valves, it's PSU is also externalised so what you are seeing are those big caps and extra wiring because of it being dual regulated. Everything else in the line and phono is pretty much as it was from stock with the exception of a few caps which are simply replacements of the originals. So nothing has been added apart from on the power side of things. In fact, some things were simplified.

[The Black Adder]

The op amp was originally designed for use in analogue computers, and it was used very much for rocket science.

Now I didn't know that... you learn something every day. Interesting.

[The Black Adder]

Aaanyway, Marco moochacho, hows the Goldpoint sounding after today?

[lurcher]

Now I didn't know that... you learn something every day. Interesting.

yep, just for a moment more off topic, the op part was short for operational, as in arithmetic operation such as addition, subtraction, multiplication, integration and so on. And they were of course originally valve based.