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Old 10th Oct 2023, 6:27 pm   #3281
Craig Sawyers
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Default Re: The Audiophoolery Thread.

I think most people see "wall wart" and think "switched mode". Not that there is any problem with a switched mode supply if done right (usually expensive).

As an example the Halcro power amps https://www.bluemoonhouse-sophos.com...38-stereo-amp/ which use a power factor corrected switched mode supply (at the bottom), Then DC-DC switchers to derive the power rails, and then a monster power amp at the top. Mortals cannot afford these.

But a mains transformer in a wall wart - what is the matter with that?

But yes - make a monster power supply with shunt regulators and charge a grand or two for it. That is what NAIM do; the Naim XPS DR Power Supply is £4.5k.

I attach a picture from the webify to show what you get for your four and a half grand. Mains transformer. Four bog standard bridge rectifiers, a board with some electrolytics, and what look like three discrete regulators.

Craig

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Old 10th Oct 2023, 7:21 pm   #3282
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Default Re: The Audiophoolery Thread.

They can only make a difference when and where there is a good reason for it. If an amplifier with an external PSU has no internal smoothing, decoupling and regulation then indeed the difference between a pretty crude unregulated PSU with small smoothing caps and one with large smoothing caps, LC or RC filtering and good voltage regulation giving a very low source impedance can be huge yes. But in the case of my phono stage it uses a voltage tripler for a start. This is a rather crude and dirty way of doing things and has intrinsically rather poor regulation, hence it would make no difference at all whether the mains transformer were a tiny thing or a dirty great massive thing (so long as the raw AC voltage is in the correct range). An analogy could be that if you are lifting something of 3kg mass using a thin semi elasticated string with a breaking strain of 4kg then it would make no difference whether the thing supplying the lifting force were a 12 year old kid or a massive traction engine... the stretchy breakable string is so much weaker than either as to make any other factor academic.

After this voltage tripler, which also derives a floating ground so there can be + & - rails from the 12V AC input, there are RC filters of 82R and 1000uF on each rail. These filter out all the crap on the rails to give a nice smooth DC voltage. This means all garbage on the rails is equally well filtered out no matter what the size of the AC transformer is (never mind the tripler betwixt transformer and RC filter!) and also means there is an 82 Ohm resistance between the input supply and what comes after... remember that weak stretchy string? Oh and of course the tripler means the incoming voltage is stored, only at mains peaks, in capacitors which then pass it on, adding to whats already there, at each mains peak only. The amount passed on at each stage is dependent on the size of these caps which are 330uF and 1000uF as that's adequate to do the job at the small current draw of a phono stage.

Now having clean and filtered DC at around +/- 25V at the outputs of the RC filters there are 3 pin voltage regulators (with 60dB+ of PSRR) which regulate this at +/- 18V to feed the actual circuitry.... which they do via further RC filters with large 2200uF caps (all these caps are bypassed with multilayer ceramic 0.1uF's at RF BTW) for each stage. I hope you can see from this the complete impossibility of different transformers, within the correct voltage rating etc limits, making any difference whatsoever. Never mind that it could be vastly improved by removing the ferrite core on the input 12V AC lead! I would expect such good isolation between the power coming in from the wall wart and the actual circuitry that you could arrange for the input power to be randomly switched on and off at frequencies between say 20 and 1000Hz without it having any effect on the sound or measurements of the amp itself.

In the case of your TT the only possible explanation is that the cheap version of the PSU is deliberately inadequate and is allowing distorted mains harmonics and rectification related rubbish into the motor which is then showing up in rumble figures.

(PS is this site really slow today or is it my PC? It's taking maybe 15 seconds or more from hitting "submit reply" or "preview post" before anything happens for me!)
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Old 10th Oct 2023, 8:21 pm   #3283
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Default Re: The Audiophoolery Thread.

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Originally Posted by Craig Sawyers View Post
I think most people see "wall wart" and think "switched mode". Not that there is any problem with a switched mode supply if done right (usually expensive).

As an example the Halcro power amps https://www.bluemoonhouse-sophos.com...38-stereo-amp/ which use a power factor corrected switched mode supply (at the bottom), Then DC-DC switchers to derive the power rails, and then a monster power amp at the top. Mortals cannot afford these.

But a mains transformer in a wall wart - what is the matter with that?

But yes - make a monster power supply with shunt regulators and charge a grand or two for it. That is what NAIM do; the Naim XPS DR Power Supply is £4.5k.

I attach a picture from the webify to show what you get for your four and a half grand. Mains transformer. Four bog standard bridge rectifiers, a board with some electrolytics, and what look like three discrete regulators.

Craig

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I think they were "only" about £2.5K when you got a mains transformer, rectifier and smoothing caps plus a few LM317's for the money... obviously the new discrete regulators are worth every penny of an extra £2K
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Old 10th Oct 2023, 10:11 pm   #3284
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Default Re: The Audiophoolery Thread.

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(PS is this site really slow today or is it my PC? It's taking maybe 15 seconds or more from hitting "submit reply" or "preview post" before anything happens for me!)
Maybe your PC needs a better PSU…
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Old 10th Oct 2023, 11:00 pm   #3285
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Default Re: The Audiophoolery Thread.

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Quote:
Originally Posted by Jez1234 View Post
(PS is this site really slow today or is it my PC? It's taking maybe 15 seconds or more from hitting "submit reply" or "preview post" before anything happens for me!)
Maybe your PC needs a better PSU…
Back to normal now... the cat had knocked the Shakti Stone of the router
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Old 10th Oct 2023, 11:09 pm   #3286
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Default Re: The Audiophoolery Thread.

Mine licked the morphic green cream. Gave him quite a Belt...

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Old 10th Oct 2023, 11:29 pm   #3287
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Default Re: The Audiophoolery Thread.

Could morphic green cream have been named in honour of Morph, the animated blob character?

With the retailer of such stuff living in Leeds, the Aire would have been an abundant and economical source of several shades of green guck. Your cat needs careful observation in case there are after effects. Not all of the stuff came out of Tetleys.

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Old 10th Oct 2023, 11:41 pm   #3288
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Default Re: The Audiophoolery Thread.

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Could morphic green cream have been named in honour of Morph, the animated blob character?

With the retailer of such stuff living in Leeds, the Aire would have been an abundant and economical source of several shades of green guck. Your cat needs careful observation in case there are after effects. Not all of the stuff came out of Tetleys.

David
Who could guess what the late and rather strange Peter Belt meant by morphic. or the rainbow in rainbow film. Or even filing notches in the edges of mains plugs - I recall that there was some rule for the number of notches.

I rather miss his weirdness. It was a typically British weirdness.

Craig
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Old 11th Oct 2023, 1:41 pm   #3289
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Default Re: The Audiophoolery Thread.

I did a bit of a Peter Belt tribute at the UK Hi-Fi Show a couple of weeks ago. The CD player had 'CD100 > OK' written on a piece of paper stuck under it and one speaker had 'MFB > OK' on the back. I didn't have the correct PB red pen but one of my son's felt tips seemed to give similar results.

It must have worked, nothing went wrong all weekend and those silences - inky black mate.
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Old 11th Oct 2023, 3:44 pm   #3290
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Default Re: The Audiophoolery Thread.

PWB actually made some very good speakers and headphones, electrostatic and hybrid, in the early 80's. I guess snake oil was easier and more profitable.
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Old 11th Oct 2023, 9:20 pm   #3291
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Default Re: The Audiophoolery Thread.

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PWB actually made some very good speakers and headphones, electrostatic and hybrid, in the early 80's. I guess snake oil was easier and more profitable.
I never connected the PWB of loudspeakers and electrostatic headphones, with Peter Belt the well known looney. I must have led a sheltered life.

S
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Old 12th Oct 2023, 7:27 pm   #3292
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Default Re: The Audiophoolery Thread.

l've just read the "quantum clip" advert. You couldn't make it up....wait a minute, he did.

l wonder how many they sold? Apparently you could "treat" a whole building with it by holding the clip against a part (of the building) and squeezing the nut with the tweezers.

lt's absolutely crazy. But the description is deadly serious. l wonder if he actually believed it.
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Old 12th Oct 2023, 7:57 pm   #3293
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Default Re: The Audiophoolery Thread.

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l wonder if he actually believed it.
That's the great mystery underlying the whole audiophool universe.

Back in the early 90's there was an aAmerican active on the usenet audio chat groups who claimed to have invented the green pen round the edge of your CDs thing. He was putting an awful lot of effort into telling people that it was all done as a joke.

Some folk believed him, some thought he was having them on, and a smaller number went "Joke or not, it works!" Now did they believe this, or were they having him on.

There are layers and layers and no trustworthy paths to the truth.

There is so much misinformation, flim-flam and scams, you just have to make your own mind up each time. Scientific method is the only thing to hide behind as protection from the gibbering idiots and the merely deluded.

David
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Old 12th Oct 2023, 10:44 pm   #3294
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Default Re: The Audiophoolery Thread.

IME, and as the quote/maxim says, once someone has been conned into believing this sort of rubbish they will never change their mind about it. Not even if they are bombarded with scientific proof that they are wrong!
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Old 13th Oct 2023, 6:13 am   #3295
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Default Re: The Audiophoolery Thread.

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Quote:
Originally Posted by Jez1234 View Post
PWB actually made some very good speakers and headphones, electrostatic and hybrid, in the early 80's. I guess snake oil was easier and more profitable.
I never connected the PWB of loudspeakers and electrostatic headphones, with Peter Belt the well known looney. I must have led a sheltered life.

S
Better yet, he drew Peter Turner, a prolific and sane contributor to Hi Fi News and Tape Recorder in the 1960s, into his web of phoolery by the 1980s, which he advocated in his Hi Fi World column. How and why, Heaven knows.
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Old 13th Oct 2023, 7:36 am   #3296
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Default Re: The Audiophoolery Thread.

I think Jimmy Hughes was a follower too, I remember reading in some of his articles in New Hi-Fi Sound that it was a good idea to take all the stuffing out of your speakers, then put it in a bin bag in the corner of the listening room. I think the bags had to be sealed with PWB rainbow foils, I'll see if I can find the original article.
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Old 13th Oct 2023, 7:58 am   #3297
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Default Re: The Audiophoolery Thread.

There was a little booklet that was a giveaway in one of the hifi mags full of Belt-inspired nonsense. I have it somewhere - if I find it I'll try to find it on the web for everyone's enjoyment.

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Old 13th Oct 2023, 8:01 am   #3298
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Default Re: The Audiophoolery Thread.

Something weird is going on with the forum this morning. It takes forever for a post to go through, so you think something is wrong. So you try again and end up with a double post.

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Old 13th Oct 2023, 10:47 am   #3299
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Default Re: The Audiophoolery Thread.

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But yes - make a monster power supply with shunt regulators and charge a grand or two for it. That is what NAIM do; the Naim XPS DR Power Supply is £4.5k.

I attach a picture from the webify to show what you get for your four and a half grand. Mains transformer. Four bog standard bridge rectifiers, a board with some electrolytics, and what look like three discrete regulators.


Craig
So, for your £4.5K you get the following:

i) Single Layer PCB. Multi-layer may not be needed for a PSU as you don’t have to isolate and shield signals from each other, but at £4.5K this does give it the appearance of something that might have been cooked up in a garden shed with a UV box

ii) Bridge Rectifiers. Again, nowt wrong with them and they can be plenty robust. However, at £4.5K, I would expect to see discrete soft recovery types for audiophool kudos. In an external box they probably wouldn’t make a measurable difference, but they would make for better eye candy than a bank of bridges out of a 1980s PA amp (maybe they are special audiophool bridges?)

iii) Single Transformer. Again, you can get x-talk between channels below -100dB with a single TF, despite inter-winding capacitance. However, you’ll need to ensure that the amp itself has good PSRR (considering Naim pioneered the concept of multiple PSU options for the same amp, I always took it that their PSRR left something to be desired…are they now saying it’s actually ok? If so, why would you buy anything above the base level PSU?). There were sub-£500 Japanese amps from the likes of of Kenwood and Hitachi that gave you separate TFs for L/R.
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Old 13th Oct 2023, 12:19 pm   #3300
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Default Re: The Audiophoolery Thread.

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So, for your £4.5K you get the following:
A smug feeling that you've paid far more than anyone else for a very basic power supply, and thereby demonstrated how rich you are.

This only works provided all the people you wish to impress are sufficiently poor in thinking skills to not realise that it might also demonstrate how dim/gullible you are.

Single diodes are usually easier to find exact replacements for than bridge units. I also remember looking in the failure rate analysis database we had and found that bridge units had failure rates a few times greater than the total for a set of discrete diodes. You also get more choice in discretes. You can avoid RFI monsters and those soft recovery diodes do have a use. The mains is a dirty place with all sorts of transients and no defined max spike voltage. So having rectifiers which can handle it helps reliability. Class-X capacitors across the mains get flashed over and are designed to melt their plates back from the wound, preventing a permanent short. In this way they have limited lifes as they get blasted progressively away. OK Rifas with moisture in them are spectacular, but even the good ones are being eroded away. This is a good motivation for either unplugging gear not in use, or switching off at the socket. There is no point in letting the life expectancy of things be consumed during down-time.

I really loved the recommendation that a certain brand of amplifier should not just be left plugged-in, 24/7 but also left running. There are real reasons why you wouldn't want to do that.

Yup, you can do quite well with a single transformer and there really isn't a need for having twins. After all with one mains connection and a single mains lead.... Oops better not give them ideas. But occasionally there are other reasons. For mechanical mounting and soace reasons, two medium sized transformers may be easier to arrange than one monster.

All the crap about individual transformers, magic mains cables etc can be dumped on the altar of inadequate PSRR and hum loop management.

The made in the home kitchen sink PCB might be because if it was laid out on a computer there would be a risk of the amplifier being infected with digital sound. Also the hand-crafted cottage industry hey-nonny-noe aspect would be missing. People would say that it sounded like keg, not real craft ale in real wooden barrels.

Somewhere, inaudible to the golden eared few, there is a little voice pointing out that in PCB manufacture, the raw board has relatively thin copper and that in proper boards intended for serious currents, the copper thickness is built up by selective electroplating at the same time the plated-through holes are done. Most simple boards I've met just used the basic thin foil. The basic foil is thin to make etching easier, and yet still be good for low current connections. It's become hard to find single sided board with heavier copper.

David
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