What's the purpose of a preamp?

[Macca]

Indeed, Anthony, which brings us to what Martin wrote yesterday:



The bit in bold of course refers to the point just made. Once it's gone, it's GONE.

No speakers can make up for any signal degradation/information loss further up the chain. All they can do is alter the tonal presentation, and perhaps add some 'zing', but it won't genuinely address any loss of leading edge definition, upstream. That's the unfortunate reality.

In terms of the first sentence, Martin. that's quite a step change from your position when this subject was last discussed, only weeks ago, and where you were adamant no such 'softness' existed...

Marco.

We're not talking about signal degradation as such, more a tonal balance, so I'd argue that it can be compensated for. Assuming it is an issue to begin with. As I said above, with a quality passive it is fractional at best.

[Marco]

We're not talking about signal degradation as such...

Well actually, we are. If a passive preamp sounds 'soft', directly as a result of compromising leading-edge definition, which otherwise is present in the signal path, then factually, that represents a form of signal degradation.

Alternatively, at the very best, what's happening is that the passive preamp in question is smoothing out the sound in some other way, and in turn making it 'soft', which thus acts as a form of coloration, neither of which is desired or can fundamentally be fixed by one's choice of speakers.

In any case, so are you now accepting that said 'softness' can exist with some passives, in certain systems, compared with the very best active designs?

Marco.

[Macca]

I never didn't accept that. I've also not heard every passive in existence so I cannot make a blanket statement.

I'm not convinced that the passive is 'losing' the leading edge in any case. We are using the word 'softening' as a convenient shorthand but it would be a mistake to think that is exactly what is happening. The effect is far more subtle than the use of the word 'softening' might indicate and IME it is dependant on the other components of the system also.

Secondary to that you are also assuming that the alternative is more accurate when there are no grounds for that. Most active pre-amps are far less transparent than a decent passive and are not a benchmark to judge anything by.

[Marco]

Well, at the end of the day, all that matters about what is 'accurate', is what you hear that's considered as better... We've been here many times before!

However, it was you yourself who wrote earlier:

I'm inclined to agree with Alan that a passive does maybe sound slightly soft, loses a bit of the leading edge.

*You* chose that language, when making your statement, so I guess it's up to you how you define "sound slightly soft" and "loses a bit of the leading edge", and in comparison with what...

Marco.

[Simon_LDT]

Are you sure ??
The Khozmo website appears to be very much open for business and selling Khozmo branded attenuators:

https://khozmo.com/index.html

I could go through the entire ordering process right up to PayPal payment without a glitch.

Hattor is also based in Warsaw but doesn't appear to be linked to Khozmo (although selling similar products but with a very different aesthetic).

EDITED TO ADD - weird - just checked again and they have indeed got exactly the same business address

They are made by the same guy/company. The Hattor are the premium line of passives, hence the higher prices and more bling cases.

[montesquieu]

The only problem with active pre-amps is that most of them are poor and the good ones cost a bomb even second-hand.

Tom: I've listened to many passive pre-amps of all types and one thing I have never heard is one sounding harsh so I'm interested in which one that was and in what set-up.


I'm inclined to agree with Alan that a passive does maybe sound slightly soft, loses a bit of the leading edge. With a good one it is fractional and you can compensate for that to an extent with the speakers. I think that softness also accounts for the 'lack of drive' some perceive. But that perception will vary from system to system because there are the source, power amp and speakers to consider which will all have their own balance vis a vis 'leading edges'. Speakers especially.

Yes to be fair, 'harsh' is probably the wrong word. 'Unattractive' is probably more like it. Or perhaps 'stark'. It's hard to get warmed up to the sound in the way a nice tube preamp does the business. I've tried lots of them too including expensive ones such as a (then) top of the line MFA TVC Mark 2, which retailed at £5k. What I did notice particularly was that this effect was less with some sources and really obvious with others so I dare say it's possible to mitigate this to some extent.

Ultimately though, my belief is that if a passive preamp was the best solution for most applications then that's what we would see almost everywhere, and a powered preamp would be an oddball choice. It stands to reason that if the cheapest option was best for most purposes then that's what would be near-universally adopted. In fact it's the other way round, and believe this is overwhelmingly for sonic reasons.

The appeal of passives seems to be 1) they are cheap ... though not always of course, or 2) people believe that 'simple' = unadulterated/pure and therefore better.

It's my view that the latter point is a fallacy based on incomplete knowledge of how electronics works and in particular what can happen to a signal routed through passive components vs one routed through an active circuit. Either can damage or otherwise have negative effects on the output of the source component vs what arrives at the output - the idea that a passive is necessarily more pure or less damaging to the signal is, frankly, wrong.

[Marco]

Hi Simon,

Did you read post #43 and the link contained therein?

Marco.

[Marco]

Ultimately though, my belief is that if a passive preamp was the best solution for most applications then that's what we would see almost everywhere, and a powered preamp would be an oddball choice. It stands to reason that if the cheapest option was best for most purposes then that's what would be near-universally adopted. In fact it's the other way round, and believe this is overwhelmingly for sonic reasons.

Whilst I agree with the thrust of your argument, Tom, I don't think that's the main reason, which is likelier that passive preamps are not normally mainstream/commercial items, and thus somewhat more niche, in the sense that they're generally only available from 'specialist' manufacturers.

Sonic considerations aside, that is most likely why 'powered preamps' are the norm

The appeal of passives seems to be 1) they are cheap ... though not always of course, or 2) people believe that 'simple' = unadulterated/pure and therefore better.

It's my view that the latter point is a fallacy based on incomplete knowledge of how electronics works and in particular what can happen to a signal routed through passive components vs one routed through an active circuit. Either can damage or otherwise have negative effects on the output of the source component vs what arrives at the output - the idea that a passive is necessarily more pure or less damaging to the signal is, frankly, wrong.

I completely agree, or basically when they're coupled to partnering equipment and/or cables that in some way inhibit their efficacy.

That's the danger of assembling a system, or choosing equipment, based on specs or measurements (and thus what is perceived as being more 'accurate'), as they mostly always only tell part of the story!

Marco.

[Yomanze]

The Khozmo stepped attenuators look to be extremely well-engineered, but I would advise anyone considering one to choose carefully. They do three different types of attenuators which they call shunt, ladder and series.

In my opinion the series type is the best. The ladder type is really just the same as the series type but switches resistors unnecessarily which introduces an additional switch contact. The rationale for this type of attenuator is (presumably) that there are fewer resistors in the circuit at any one time, and fewer resistors must be better. No, more resistors is the better option in my opinion because there's less voltage dropped across any one resistor therefore less distortion, and thermal noise is reduced slightly by using more resistors.
The least desirable is the so-called shunt type. This type of attenuator has no merit in my opinion because the input impedance varies wildly with the volume setting and the output impedance is always higher than it needs to be. The rationale for this type of attenuator is that "there's only one resistor in the signal path". Well, no there isn't. It betrays a basic misunderstanding of electronics to believe there is.
Anyone who has tried a "shunt" attenuator passive pre-amp and found it wanting should try again with a series attenuator.

Take a look at this: https://www.audialonline.com/topics/...olume-control/

Of course it means you need a very low source impedance...

[mikmas]

All becoming a bit moot either way as the old 'pre+power' paradigm joins other Dodos (like disk-based media) on the scrap heap of technological history and fully integrated solutions of all kinds become the norm.

As to tubes, never been a big fan so whether passives work well or badly with them never really bothered me. Always found them a bit too syrupy sweet for my liking.

As I said earlier, I have found a simple 'pot in a box' attenuator coupled to either of my Quad power amps to work every bit as effectively as either of my Quad pres when using high output sources. Never notice any 'softening', 'harshness' or other form of distortion to speak of. Although I'm sure there are bound to be some who'll spring in to note that Quad pres are crap anyway

As always - YMMV