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

[Ali Tait]

Yes that's the drawing from the WD forum.

[Marco]

I'm shocked that just ONE series resistor in each channel can make such a sonic difference (I think I really am going deaf now, as resistor tolerance would count more to me than type or maker in this case)...

Well, what I reported is true. I didn't make it up, and it wasn't just me who heard it, but Duncan - and he's a sceptical engineering type, not easily swayed by 'foo'!

The design of the resistor and what materials are used is significant, especially in the case of the AN non-magnetic Tantalums (the 'winner' of the test), as their non-magnetic construction is said to sonically influence their performance, which is why many consider them better than the standard type, and also the old Shinkohs.

I can't say that was why we preferred them, but they were certainly streets ahead sonically of the other resistors we'd listened to up until that point. No question whatsoever.

Maker or cost I couldn't give the slightest shit about. I'm not influenced by such things, and was quite prepared to use the Caddocks (as I really liked what they did), with Duncan in agreement, until the AudioNotes went in. In the final analysis, Dave, I'll always trust my ears over anything else!

Marco.

[Gazjam]

Well there's a thing - a valve power amp that's quieter than a SS pre..

Gary, will bring the Slagle passive over. Free on Friday if you are?

yup, free Friday mate.
lemme know what time n stuff when you know.

[Marco]

Yes, you can clearly hear the differences in the shunted resistor in this sort of setup. All this was tried ten years ago on the WAD forum with just the same results. Its worth pointing out that you can (and I often do) use a shunt with a conventional pot to remove much of the sound of the pot. I do have to point out that I sugested that this was the best solution some pages ago and was told it "just didnt feel right" or some such. But hey ho.

Lol... Indeed, but I was basing it on my experience of a shunted Glasshouse Takman stepped attenuator I fitted to the Croft a few years back, which because of the reduction in gain caused by shunting (chucking away some voltage), sounded soft and lacklustre. When a (non-shunted) DACT unit was fitted instead, it was like someone had lifted a pair of drapes from over the speakers!!

Therefore, at that point, until I tried it with the Goldpoint, shunted, for me = bad. However, the way that Duncan's wired things this time, in this application, has produced a rather different result, and sounds superb

If experience tells you that the shunt resistors equally influence the sound, then that's good enough for me, but I will still try it for myself, as I prefer learning through my own experiences.

You may have thought that places like HiFi collective sell their wide range of components just to pander to fools, no, these things do matter, the reason manufactures don’t normally use them is simple, cost and the effect on their profit margin.

Spot on! HFC don't sell 'foo', but tried and tested products and components that, if implemented correctly, should effect genuine sonic improvements. Nick (at HFC) wouldn't stock them otherwise.

Marco.

[Marco]

An engineer can certainly explain the circuit, but won't necessarily understand the sonic implications. In fact, an engineering background may well bias against hearing any difference. Not in all cases, obviously, or there would be very few advances in sonics.

Indeed, and we see it all the time on forums, from engineers who display rather too much cynicism/rigid thinking, together with a painfully closed mind. If it's not in 'Johnny's book of scientific facts', it's automatically dismissed as imagined!

Thankfully, Nick's not like that, and neither are others here from an electronics engineering background, whose technical abilities and ears I rate. Because of what you've outlined, I also don't buy the 'designer always knows best' mantra, as quite simply, they don't - not *always*!

Marco.

[Marco]

Hiss not terrible, and you certainly dont hear it when musics playing even at low volumes.
Now VERY interested in a good quality passive pre and what it can do for overall system sound.

Marco,
hope you can bring your over to mine when up this way.

No worries, matey. I'll certainly have the Goldpoint with me when I come up, It should be almost finished by then. I know exactly what you mean about hiss or hum, as I get a similar thing (hum, although it is very low-level) when the Croft is connected to the Copper amp.

The problem is, as Nick will know from experience, you can design equipment to be silent in use, measurably, and also in your test system, but when a customer uses it in a different context, with another preamp and different equipment in the equation, then unpredictable things can happen!

My issue with the Croft I suspect is down to an earth loop somewhere, but tracing what's responsible is a ball-ache... However, when the Goldpoint is used with the Copper amp, I get total silence! And that's one of the reasons (amongst other things) why I'm keen to get the Goldpoint to replace the Croft, for line-level duties, and then use the latter simply as a high-quality phono stage.

By the time I'm finished optimising the Goldpoint (and there is plenty to do yet), I'm almost certain that goal will be achieved

Marco.

[NRG]

Yes that's it - that picture looks like the one that was used on the WAD forum. Several people used that mod at the time - often because the WAD PRE II and WD PRE 3 valve pre amplifiers had too much gain. The shunt mod moved the useable section on the volume control.

Well that maybe one reason but it depended on the value of the series resistor, certainly the main motivation for doing it was the improvement in sound quality. What shocked everybody at the time was the quite marked differences between resistors and not everybody agreed on what was the best!

[DSJR]

My issue with the Croft I suspect is down to an earth loop somewhere, but tracing what's responsible is a ball-ache... However, when the Goldpoint is used with the Copper amp, I get total silence! And that's one of the reasons (amongst other things) why I'm keen to get the Goldpoint to replace the Croft, for line-level duties, and then use the latter simply as a high-quality phono stage.

Marco.

Is it something stupid like an earth loop (both Croft and Copper amp earthed)? If they both are, just disconnect the earth from the Croft (I'm suggesting leaving the earth on the Cooper amp unless Anthony says otherwise).

If it's not an earth loop, but noise transmitted from the preamp, an unpopular (I suspect) but definite reduction would be if the levels from pre to power were reduced slightly (by reducing preamp line-stage gain somehow). The volume control would need to be set higher for the same sound output, but background hum and hiss would go down.

Just a thought or two before the Croft is condemned to phono stage only duties...

[Marco]

Good suggestion, and I may look into that, if it's noise transmitted from the preamp. I've tried the earth-lifting thing, and that doesn't really make any difference.

Thing is, based on what I'm hearing with the Goldpoint, even now in its non-fully optimised state, I can tell that it has the potential to usurp the Croft, on line-level. Therefore, noise or not, I think that's they way things are likely to go.

The other point to bear in mind is that no matter how much I end up spending on the Goldpoint, if it does eventually outperform the Croft, that amount will pale into insignificance when compared with what the Croft has cost, all in, with all the mods that have been carried out to it, most of which incidentally also influence the performance of the phono stage

Therefore, even if the Goldpoint ends up costing me a grand, doing what I need to do to it, the end result will be worth it, as I'm confident it would compete favourably with many, much more costly commercial designs on the market - and that's the whole point of this project, as was the whole point of anything else I've modified: to end up with something that delivers the highest SPPV, and it's not necessarily about doing it cheaply, simply as effectively as possible.

Also, I'm enjoying learning new things as I go along (something I wouldn't otherwise have been able to do if I'd simply gotten someone to build me a passive preamp from scratch), as I've never professed to be an 'expert' of any kind; merely someone with discerning ears, who knows what a good sound is, and wants to hear his music at its absolute best. It's FUN, and in my world, that's what life is about!

Besides, what else should I waste my disposable income on?

Marco.

[struth]

Good suggestion, and I may look into that, if it's noise transmitted from the preamp. I've tried the earth-lifting thing, and that doesn't really make any difference.

Thing is, based on what I'm hearing with the Goldpoint, even now in its non-fully optimised state, I can tell that it has the potential to usurp the Croft, on line-level. Therefore, noise or not, I think that's they way things are likely to go.

The other point to bear in mind is that no matter how much I end up spending on the Goldpoint, if it does eventually outperform the Croft, that amount will pale into insignificance when compared with what the Croft has cost, all in, with all the mods that have been carried out to it, most of which incidentally also influence the performance of the phono stage

Therefore, even if the Goldpoint ends up costing me a grand, doing what I need to do to it, the end result will be worth it, as I'm confident it would compete favourably with many more costly commercial designs on the market - and that's the whole point of this project, as was the whole point of anything else I've modified: to end up with something that delivers the highest SPPV, and it's not necessarily about doing it cheaply, simply as effectively as possible.

Also, I'm enjoying learning new things as I go along (something I wouldn't otherwise have been able to do if I simply got someone to build me a passive preamp from scratch), as I've never professed to be an 'expert' of any kind; merely someone with discerning ears, who knows what a good sound is, and wants to hear his music at its absolute best. It's FUN, and in my world, that's what life is about.

Besides, what else should I waste my disposable income on?

Marco.

Me!