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Old 14th Oct 2023, 5:42 pm   #3321
Jez1234
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Default Re: The Audiophoolery Thread.

Rumble wise an idler wheel on a motor shaft in direct contact with the platter is always at a disadvantage compared to isolating the drive with a complaint rubber belt or using a brushless direct drive motor at final speed and with little added noise over that due to its own bearings. Pre DD, idler drive was often used on broadcast decks simply for fast start up of a pre cued record. Thorens TD124 managed to combine belt and idler drive with a "suicide clutch" to get the best compromise at the time.

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Old 14th Oct 2023, 8:18 pm   #3322
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Come to think of it, I struggle to think of anyone but myself, Doug Self, and no doubt one or two that escape me right now, who are currently actually involved in the industry who actively fights back and calls charlatans and snake oil merchants out for what they are.
The books from Self are priceless, all of them - I really enjoy the way he approaches these sensitive topics in very ironic and direct ways. Nevertheless, I believe this kind of thing happens in whatever market. As long as people are susceptible to bad actors with cheap sales talk that make sense to someone that doesn't understand the underlying principles of operation of something, there will always be people buying low-cost products for an absurd amount of money.

On the other hand... if people buying these products are happy, and their level of happiness increased because they spent such amount of money, who cares if they ended up with a low quality product? If their perception is that it provides better experience to them, I'd say: let it be.

Alex
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Old 15th Oct 2023, 10:54 am   #3323
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Still waiting to hear everyone else's opinions on the change in sound quality with a PSU added....
In the days when I owned Naim equipment I found that adding and upgrading PSUs did change the sound quality.

Ironically, I reckon that as you went up through the upgrade path, you often got further away from the 'exciting', 'raw' sound that first attracted you to Naim.

I don't have any Naim equipment these days, but I do think that some of these seemingly 'impossible' improvements do actually make a difference. If you were really interested I expect you could develop measurements that showed this.

At the end of the day it's whatever you find that enables you to get the maximum enjoyment from the music that counts, and only you can determine whether the cost is VFM or not. There are very few 'absolutes'.
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Old 15th Oct 2023, 11:06 am   #3324
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Default Re: The Audiophoolery Thread.

I don't know if this is the case, but if Naim's uprated power supplies sagged less, then the amps would clip that little bit later and provide a cleaner signal.
From what I can tell, a large part of Naim's 'exciting' sound reputation was built on the amps being driven into clipping. (The rest was bullshit!)
Interesting that Martin Colloms's amplifier comparison tests carried out in the 1970s under blind and properly controlled conditions failed to show any audible difference between Quad and Naim amps (and one other, I think M&A)when all amps were kept out of clipping.

Amazing what marketing will do!

S.
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Old 15th Oct 2023, 12:18 pm   #3325
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under blind and properly controlled conditions
I think these tests are often pretty flawed as they don't accurately replicate how people actually listen to music at home.

You put people under pressure in unfamiliar environments with unfamiliar partnering equipment and so you tend to end up with a lot of 'no-result' outcomes.

And I don't really think that listening testing amplifiers independently of speakers makes much sense since the amplifier's primary job is to drive the transducer properly.
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Old 15th Oct 2023, 12:19 pm   #3326
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Default Re: The Audiophoolery Thread.

The original NAIM amps back in the day did not include a series L and RC across the output. They were very twitchy indeed, and required that you used NAIM's own low capacitance cable to stop the thing from blowing up.

It is something that NVA still do. They say on their site

"IMPORTANT - there is no protection circuitry or filtering on the output of our amplifiers (that's one of the reasons why they sound so good!), so care must be taken in use. Do not short circuit the output; doing so will fatally damage the amplifier boards. Do not use high capacitance speaker cables as these could damage the amplifier by creating a virtual short-circuit at high frequencies. Do not use bi-wiring with non-NVA cables. Do not use Litz, Goertz or woven cables. Do not twist cables together. Avoid cables with a capacitance of greater than 200pf per metre (failure to do so will invalidate our warranty) and do not use non-NVA cables over 10 metres in length. The best sounding speaker cable for NVA and the perfect electrical match, is our LS series of low capacitance cables. Proof of purchase of NVA speaker cable, or another suitable low capacitance speaker cable, may be required when submitting any NVA amplifier for warranty repair"

They also use acrylic for all their enclosures (other than heatsinks). Even their moving coil phono stage uses an acrylic box.

All very very quirky. And has been since it was founded by the late Richard Dunn.

The good thing is that none of their prices are at a ridiculous level, they are British through and through, now based not near Peterborough but near Durham.

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Old 15th Oct 2023, 12:44 pm   #3327
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Default Re: The Audiophoolery Thread.

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under blind and properly controlled conditions
I think these tests are often pretty flawed as they don't accurately replicate how people actually listen to music at home.

You put people under pressure in unfamiliar environments with unfamiliar partnering equipment and so you tend to end up with a lot of 'no-result' outcomes.

And I don't really think that listening testing amplifiers independently of speakers makes much sense since the amplifier's primary job is to drive the transducer properly.
Whish it will do if the load is within the manufacturer's design parameters.

As to putting people under pressure...

S.
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Old 15th Oct 2023, 12:47 pm   #3328
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Default Re: The Audiophoolery Thread.

Clipping has a part to play in the subjective experience.

Guitarists like valve amps, and ones with valve rectifiers. They drive them hard and not only is overdrive distortion part of their performance, they also get a hard attack followed by the power supply sagging as the light-load charged reservoirs fall to their heavy load voltage.

Similar effects, though not quite so extreme happen in home audio amplifiers.

With transistors, amplifier design has to be different. The nature of the devices gives a lot of distortion unless large amounts of feedback or local degeneration is employed. Once such an amplifier is driven into clipping, the effects can be dramatic as all feedback is abruptly lost. The onset of distortion is dramatic and also extends to higher order products than simplistic low-feedback valve circuits give.

Also on the not-good side for the transistors are various circuit techniques which tend to lock-up for a while if clipped, holding a clipping event far longer than the causal transient in the programme material. So the degradations of clipping are extended in time and made much worse sounding.

There are two ways out of this problem...

Firstly, to just build a monster amp where clipping becomes progressively less common at listenable levels.

Secondly, to look at circuit design, recognise that transients happen in recordings of music, and design an amplifier that can be clipped cleanly and come out of clipping cleanly without any hang-up timeconstants delaying recovery.

Once these things are done, you wind up with an amplifier which although it doesn't make things any worse than what is included in the programme material, is found by some people to be less engaging., flat, lacking in character, disappointing.

Also we have had the shift from analogue recordings to digital equivalents. In radio, FM deviation has to be managed carefully in order to not splatter into the channels next door. People reckon that FM broadcasts are less dynamic than vinyl records. On records, groove pitch can be managed to allow periods of high modulation of the groove and exceptions to the top end of dynamic range can be planned - to the limit where the reproducing stylus.cartridge can no longer track.

The CD has a defined number of bits and so there is a limitation on the maximum number which can be expressed. You have to have some form of limiter at the to end because otherwise you have a simple and crude brick wall to run into. Some people find CDs less engaging, less dramatic and there are reasons. Yes, the CD could be scaled quieter, sailing closer to the small signal limitations of their dynamic range and getting some breathing space at the top end, but the loudness wars have militated against this, and even if done, the compressive effects that people got with vinyl records and valve amps aren't there. Both the digital data structures and the transistors impose hard and abrupt limits that have to be kept clear of.

A guy called Bob Carver did some amplifiers with unusually high supply voltages that could drive large power surges to speakers, but though higher voltage, the power supplies were a bit wimpy and their output voltage would fall back should the surge go on too long. In a way this was a throwback, but was an attempt to fit the capabilities of an amplifier design around the time/power demands of music.

An alternative is just to make a huge transistor amplifier, capable of running those surge powers until the cows come home and accept that the hardware isn't really needed most of the time.

So we come back to the fact that some people really like dynamic changes to the music and they find the result better.

I see two possibilities:

If these effects are wanted to make the music attractive, maybe they should have been applied back at the studio?

If the studio/artist wants to sell clean recordings, but some listeners want them, then maybe an effects box in the home could add them at the low level stages of the setup. Doing things like this at low level is easier than trying to get them in large signal stages. There are more freedoms and one of them would be for the consumer to choose between different processors offering different effects and choosing the ones he likes. It's easier than having to throw away entire and exensive power amps.

There are boxes intended to recreate the sounds of classic guitar amps but they haven't been accepted as being as good as the real thing. Maybe they haven't been done well enough? Maybe the following power amp isn't big enough and clean enough to not add effects of its own into the process? I suspect corners have been cut and babies dumped with the bathwater.

It's an interesting field. There's a good bit more psycho than there is acoustics or engineering.

One thing cuts through it though. If you're making claims of accuracy and faithfulness to the recording, then effects have no place. They invalidate the claim.

The clue to the missing thing being overload-related is that the tests where various alternatives were found to be indistinguishable ALL involved amplifiers carefully kept out of clipping.

The clue to there being psychological things like expectations and justifications on the go is that subjectivist reviews seem to find lots of huge differences offering stunning revelations, and very few small differences and absolutely no "Sorry, I can't hear any difference" results. I suspect egos are involved and people unable to admit to there being limits to their perception. In the real world, small things normally outnumber large things. There are statistical theories about such things. Hifi reviews run significantly counter to these expectations. There is something else at work, not just the equipment.

The result is a fertile field for charlatans, scammers and just marketing departments hyping things.

David
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Old 15th Oct 2023, 12:49 pm   #3329
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Default Re: The Audiophoolery Thread.

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Originally Posted by Craig Sawyers View Post
The original NAIM amps back in the day did not include a series L and RC across the output. They were very twitchy indeed, and required that you used NAIM's own low capacitance cable to stop the thing from blowing up.

It is something that NVA still do. They say on their site

"IMPORTANT - there is no protection circuitry or filtering on the output of our amplifiers (that's one of the reasons why they sound so good!), so care must be taken in use. Do not short circuit the output; doing so will fatally damage the amplifier boards. Do not use high capacitance speaker cables as these could damage the amplifier by creating a virtual short-circuit at high frequencies. Do not use bi-wiring with non-NVA cables. Do not use Litz, Goertz or woven cables. Do not twist cables together. Avoid cables with a capacitance of greater than 200pf per metre (failure to do so will invalidate our warranty) and do not use non-NVA cables over 10 metres in length. The best sounding speaker cable for NVA and the perfect electrical match, is our LS series of low capacitance cables. Proof of purchase of NVA speaker cable, or another suitable low capacitance speaker cable, may be required when submitting any NVA amplifier for warranty repair"

They also use acrylic for all their enclosures (other than heatsinks). Even their moving coil phono stage uses an acrylic box.

All very very quirky. And has been since it was founded by the late Richard Dunn.

The good thing is that none of their prices are at a ridiculous level, they are British through and through, now based not near Peterborough but near Durham.

Craig
How to make a virtue out of a flawed and inadequate design...

I wouldn't give houseroom to any amplifier that wasn't fully protected and unconditionally stable. Other manufacturers manage that and maintain sound quality, so NVA and at one time NAIM's unwillingness to do so is perverse in the extreme.

One test I have applied to every SS amplifier I've used is to stick an old screwdriver across the loudspeaker outputs at full power. If it fails, it goes back.

S.
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Old 15th Oct 2023, 12:51 pm   #3330
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Default Re: The Audiophoolery Thread.

Performing a listening test on an amplifier without any speakers does seem rather difficult....

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Old 15th Oct 2023, 12:58 pm   #3331
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Performing a listening test on an amplifier without any speakers does seem rather difficult....
Just use a screwdriver. ;-)
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Old 15th Oct 2023, 5:07 pm   #3332
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My experience of Naim...

About 30 years ago I got to see inside their then top-end CD player. In all respects but one it looked like a reasonable player priced at 10 times what it should have been. For example the CD transport was the Philips CDM4 -- the plastic deck one. The decoder and DAC chips were the normal Philips ones.

The one respect it differed from a reasonable design? In the datasheets for the chips Philips stated that some decoupling capacitors had to be SMD types on the underside of the PCB soldered directly between the pin on the IC's DIL package and a ground plane (to minimise the series inductance of course). Naim used through-hole components a good 1cm from the IC. Maybe they knew what they were doing, but I am not too sure.
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Old 16th Oct 2023, 10:23 am   #3333
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One test I have applied to every SS amplifier I've used is to stick an old screwdriver across the loudspeaker outputs at full power. If it fails, it goes back.

S.
Why?
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Old 16th Oct 2023, 11:14 am   #3334
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My experience of Naim...

Maybe they knew what they were doing, but I am not too sure.
Personally I don't like Naim. However of course they do sell, so kudos to them: but whether it's on the perceived "sonic" excellence in the mind of the consumers or just that they have good shill gurus convincing the flock, is a matter for personal deduction. (It's not a hard process!)

Every one markets their wares, its just a bit tacky when you find they don't live up to the hype in some way.

Caveat Emptor always applies, and the buyer should always engage their bullshit detection sensors when reading marketing copywriters prose or so called impartial reviews, then run a mile if they start to activate, pools and their money and all that

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Originally Posted by Craig Sawyers
(NVA.)The good thing is that none of their prices are at a ridiculous level, they are British through and through.
No comments on the technology, (or lack thereof) I have heard their products in action and was a pleasant enough experience. And also true they're not as expensive as some, but I still think £460 quid for 6 metres of (effectively) twin tri-rated is still a bit steep! But locking the customer into buying their products is a survival tactic which is understandable I suppose.
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Old 17th Oct 2023, 8:38 am   #3335
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One test I have applied to every SS amplifier I've used is to stick an old screwdriver across the loudspeaker outputs at full power. If it fails, it goes back.

S.
Why?
To make sure any claim of short circuit protection is true. I only have amps that claim full protection and that's a simple way to test it.

S
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Old 17th Oct 2023, 8:43 am   #3336
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The one respect it differed from a reasonable design? In the datasheets for the chips Philips stated that some decoupling capacitors had to be SMD types on the underside of the PCB soldered directly between the pin on the IC's DIL package and a ground plane (to minimise the series inductance of course). Naim used through-hole components a good 1cm from the IC. Maybe they knew what they were doing, but I am not too sure.
That's the standard improvement that most designers made to the standard TDA1541 (etc) DAC circuit for the better class of players. Seeing this in anything shows that they were at least trying and is generally the sign of a decent machine. The SMT ceramic capacitors are inevitably microphonic to some extent so the improvement is to replace them with less sensitive film types. As well as Naim you will find this technique in the Philips CD960 (= Marantz CD-94), the B&O Beogram CD5500 and derrived types, various TDA1541x based Sony players, that Creek one with the Double Crown chip in it and many others. I'd imagine Naim were following the heard on this one.

Those capacitors are used in the Dynamic Element Matching part of the circuit and so contribute to the overall linearity of the DAC. Wheter this modification makes a difference is open to discussion but there is at least some technical reasoning behind it. I've not seen it applied to the earlier 14x4 chipset (dual TDA1540s etc) but the same components are there so it could be done. However, the CD100 / CD104 (...) sound fine to me as they are, so I've left mine alone.
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Old 17th Oct 2023, 9:51 am   #3337
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Default Re: The Audiophoolery Thread.

The interesting thing is that lossy SMT capacitors - such as X7R - are better for decoupling than C0G/NP0. Reason is that tracks feeding them have some inductance, and X7R losses act as damping, where as C0G etc can give rise to ringing,

All part of EMC compliance

But using discrete capacitors on digital stuff is just asking for trouble, and not of an EMC kind. You only need to look at the self resonant frequency of a discrete cap, plus track inductance, to see that the rails will ring and give rise to jitter.

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Old 17th Oct 2023, 10:20 am   #3338
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More CD player design oddities here. In this case its a Krell which was on my bench yesterday - I don't normally touch Yank tanks but this one slipped through.

In the middle there's a perfectly ordinary TEAC VRDS transport, servo and decoder unit. On the the right there's a power supply which seems far too large for the job at hand. On the left is the DAC chip (front) and then 4 lines of transistors, perhaps 50 in each, stretching off to the (balanced) outputs at the back. They are all small but together they get pretty hot - perhaps that's what the monster power unit is for?

There is a familiar technique for low noise amplification where the noise of a number of transistors is averaged out by paralleling them up, but I remember reading that the practical limit for the usefulness of this layout is about 9 devices - after that other effects take over and the performance declines.

Either way I'm at a loss to see what must be 200-odd transistors do in this machine. It sounds OK, but I've heard much simpler ones that do a better job.

See the attached picture - not the same one but I can't face taking all those silly little screws out again!
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Old 17th Oct 2023, 10:57 am   #3339
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But using discrete capacitors on digital stuff is just asking for trouble, and not of an EMC kind. You only need to look at the self resonant frequency of a discrete cap, plus track inductance, to see that the rails will ring and give rise to jitter.
And yet through hole was all we had when designing broadcast TV equipment back in the 80s. Clock and data speeds much higher than digital audio but we still managed somehow.
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Old 17th Oct 2023, 11:00 am   #3340
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I only have amps that claim full protection and that's a simple way to test it.
I guess if you are a bit careless it's quite an important aspect. Don't go messing with any mains plugs though, you could really get yourself into trouble.
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