Why so deathly quiet here??

Some people (like me!) think pretty much all electronics sound the same, unless deliberately engineered not to. In that case, they're not HiFi, but effects boxes. The effects might be nice, and might sound 'better' to some people, but they're not transparent, which is what HiFi means to me.

I think very few people use HiFi equipment correctly, insofar as they buy an amplifier and a pair of loudspeakers that sound 'good' together, but with no measurements to back up that view. As so few amplifiers have fast metering, and most don't even have a clipping indicator, how is an untechnical user to know whether their amp is actually right for the load?

All properly conducted listening tests that I've had knowledge of indicate that amplifiers when used within their design parameters, not allowed to clip and listened to blind and level matched sound identical. I can't think of any better way of proving that amplifier sound is in the head of the listener, not something that's real. Yes, amplifiers can sound different if allowed to go into clipping, or the evaluation isn't blind, or level-matched. Perhaps that's how people actually use the equipment, but it's not the way it should be used, and to me, a totally invalid way of assessing sound.

Good luck with the hybrid amplifier. What's it a hybrid of? I would be interested in seeing some numbers.

S.

 

I see there are a few new posts in DIY today (one a for sale post) but I'm afraid I have no interest in and little knowledge of digital stuff. I am a proud Luddite and continue my efforts in refining purely analogue techniques.

 

I believe the modern day fascination with valve is ludicrous. I can well understand they are expensive, because to get them to perform well, so much peripheral circuitry has to be employed. Valve amplifiers are like Alfa Romeos - once out of the showroom they decay faster than a well rotted carcase. True, for high power broadcast and communications, there are no substitutes. But they are different animals altogether and are incredibly expensive - so expensive some are designed to be torn apart and rebuilt, with laser - cut control grids and high tech doping of cathodes. Nothing like the antique bottles that people rave about today.

Criticism of transistors has passed into folklore and to be fair, it took several years to progress from Germanium to Silicon, to FET, to Mosfet. However, there is very little goes wrong with a well designed Solid State Trannie Amp. Even Class A Amps are so much better due to improved solid state devices. Not so valves - the same problems bedog them today as they did in the fifties when I first started working with valve communications equipment. Huge stocks of valves had to be held because of their failure rates, which were horrendous.

They weren't seen to be pretty in those days as their warm Glow which so hypnotizes Valve Enthusiasts, was hidden from view. I believe it to be a big con - which I don't have a problem with as if people have the money to spend, then at least they are putting cash back into circulation and helping keep unemployment down. But it really is a question of "Who will tell the King he has no clothes"?

If it can't be measured - it doesn't exist. 0.005% is as good as zero as one can get. Of course, many will say they can hear the difference, whilst claiming they can also see "Dark Matter", no doubt. I do believe a lot of issues surrounding early tranny amps were down to inadequate power supplies. That generally has not been a problem associated with Class A as the demand for good supplies has been known since before the advent of the transistor.

 

I'm afraid you are virtually on your own in that view Serge! A few like minded folk probably hang out on ASR or whatever it's called but that's about it. To me it beggars belief that anyone could claim the massive audible differences between electronics don't exist. These differences can sometimes be more important than differences between speakers IME as minor FR variations between speakers are soon assimilated and ignored (if not too severe) whereas the differences between say power amps, whilst seemingly slight at first listen, seem to become more and more aggravating with familiarity.

Whilst the new amp will likely have a production run of 1.... the prototype I end up using in my own system (if it sounds good enough), I do design with an eye to possibly building and selling hence I can't share too much of a technical nature.

It is a hybrid of triode valves, mosfets and bipolar transistors. It is class A (as are most of my designs these days) and around 18WPC. The "USP" is that almost all the gain (and hence feedback correction) is from a single triode valve, hence avoiding "memory effects" of silicon, modulation of varicap like SS junctions and other potential negative aspects of SS. The SS "housekeeping" electronics around the triode allow it to give measured performance not possible with traditional valve circuit techniques.

It is capacitor coupled to the speakers but in such a way as to lose nothing in comparison with direct coupling whilst guaranteeing protection from "going DC".

Measurements are very good but as I've said before I don't believe there is any point striving for 0.00001% THD when there are bigger fish to fry elsewhere (which probably can't be measured but are critical to subjective sound quality).

With only 27dB of feedback it delivers <0.005% THD and the low feedback combined with wide open loop bandwidth means this is virtually the same at 10KHz. Bandwidth is a few Hz to a few hundred KHz but I'll probably add a LPF to set HF roll off around 50KHz. Damping factor is very high and the (I believe unique...) OPS topology is such that the OPS alone has >50 damping factor and THD< 0.005%.

Good measured performance is important to me as I want my amps to be "blameless" but if I thought it mattered to have 0.00001% THD rather than 0.005% then I would have done things rather differently!

 

Looks like Serge has found an ally!

Seems I occupy a no mans land on hi fi as in almost all hi fi forums I'm called a "deaf idiot" etc etc for not believing total bollox about fuses and wires making a difference BUT on a few sites I was on which were frequented mainly by fellow engineers I was virtually drummed out for insisting that electronics do sound different in spite of measurements. So.... I'm the only one who's right then!

 

Frankly even 0.1% is as good as zero provided that's at all levels, frequencies and permitted loads.

As to Class A, I really don't see the point as it just consumes power for no benefit that can't be achieved with Class AB or these days, Class D.

S.

 

My point being the demand for good power supplies that could sustain the output, were known - inherent in the nature of Class A.

When Class AB came along, many early designs could not sustain full output, because although greater efficiency was possible, it translated; in the minds of some, that power supplies would be cheaper to manufacture and thus saving production costs.

I am referring to the very early days when the view/arguments about which was better and the "Characteristic Valve Sound" was being implanted in the minds of some who to this day condemn solid state.

 

Indeed. One of the ironies of Class A amongst audiophiles is that they have stiff power supplies. A Class A amplifier draws a constant current from the supply, regardless of the audio power being put out. The energy either goes in heat, or goes to the loudspeaker (which then largely puts out the heat). Oddly, a pure Class A amplifier will run cooler when at maximum output than at idle, as the heat is being diverted to the load.

Class B needs far stiffer supplies than Class A, which I think is the point you were making above.

Fortunately, Class D amps also generally come with a SMPS, which will be pretty stiff. Again an irony is those audiophiles that grudgingly accept Class D provided it has a linear supply!

To me it's a great pity that HiFi manufacturers have been dominated by marketing, I suppose because the technical limitations were fixed decades ago, and marketing a new box as 'just another transparent amplifier' won't cut it.

S.

 

"even 0.1% is as good as zero provided that's at all levels, frequencies and permitted loads". IF those criteria are met then I largely agree. However, if the 0.1% includes high order distortion products from crossover and switching artefacts then it is way too high!

Linsley-Hood had a letter published in WW in which he claimed that under very specific conditions he (and others he asked to listen) could reliably detect 0.002% of high order (9th, 11th etc) distortion of a single tone. Somewhat bizarrely to me no one seems interested in this as I gave a full wright up of his claims on a few hi fi forums and my posts were completely ignored! I was surprised that no one even considered this worth discussion but there ya go...

On class D well the jury is out still but it seems it can give very good results nowadays. I don't "do" class D because it seems that to achieve exemplary results very advanced signal processing, involving often digital as well as analogue techniques, are required and this is done by proprietary LSI IC's. For reasons which I will not deny are founded on "not invented here" syndrome and wanting to involve my efforts only in areas where one guy working alone can still make a difference, I leave it to others to plough this field
I have "for a laugh" designed a class D in simulation but I'm well aware that anything I could design around discrete circuitry and op amps etc would very likely fall well short of the current SOTA using 350 pin BGA SMD class D controller IC's.... I don't try to design and build smart phones for the same reasons

Class A I regard as still the true SOTA when size, heat, price and green-ness are secondary concerns. Class A measures vastly better than class A/B in pretty much every way, sometimes by an order of magnitude before the "sticking plaster" of feedback is applied. Lack of crossover distortion is just the tip of the iceberg when it comes to the advantages of class A (life's too short to spend the next hour iterating them all. Do your own research folks!)

...and yes Serge I know that as class A/B amps can readily be built to have <0.01% THD you will regard this as irrelevant. How you get the THD down to this level is more important to sound quality though IMHO.

 

If electronics sound different, that's because of measurements, not in spite.

S.

 

As you know I completely disagree when an amplifier is "blameless".

I'm surprised you like SMPS! I'm strongly against them on grounds of reliability and their being such a nightmare to repair that a failed SMPS will often result in the unit having to be scrapped. The difficulty in making them sufficiently low noise also weighs against them... though it can be done.

In spite of this I have designed and built a few (with varying results...) with an eye on saving on the cost of traditional transformers and mainly for use with valves (HT and LT from SMPS). If wanting to make a profit on something like a small valved pre amp a good start is to avoid paying around £100 for a small mains transformer similar to that once fitted to a small 4 valve table radio!

 

Unfortunately it's much worse than that! We've reached the point where the vast majority of sales blurb from manufacturers is a pack of lies!

To the average non technical punter electronics is "here be dragons" and the hi fi industry is well aware of this so often doesn't even try, these days, to explain any technical feature in sensible and honest fashion.... most punters simply wouldn't understand it... SO... they make up a load of crap about "anti resonance" IEC mains sockets with "linear crystal" metal used and the virtues of bamboo dielectric capacitors (I wish I was making up the bamboo capacitors but I'm not!) and no doubt that they are only built on a full moon etc.

 

I too am no fan of SMPS - I can see an advantage when used as chargers - particularly for high load systems, with battery back-up. But even then they have caused problems with "Hunting" - multiple SMPS competing to supply the output. However, that was a few years ago and probably no longer applies. Noise is an issue though.

It conflicts too, that any manufacturer would go to extreme lengths to get distortion and noise down in an amplifier, then include in a design any device which didn't better its noise figures by a considerable margin. Equally bizarre, amplifiers having 70db or better channel separation, being used with cartridges with no better than 25 - 30db. separation.

 

"Unfortunately it's much worse than that! We've reached the point where the vast majority of sales blurb from manufacturers is a pack of lies!"

So what! If Punters are well heeled enough and stupid enough to spend vast sums of money, without researching the subject properly, that's their problem. I am beyond saving the world from itself. Ploughing money back into circulation keeps people employed, regardless - let them learn from their mistakes. There are a lot people who are being equally dishonest in the way they earn their salaries - so to a degree, it's pay-back!

 

Oh what a cynic you are!

S.

 

Thank you, you are too kind. I have studied Socrates, Seneca, Hadrian, Epicurus - we have much to learn. But, although working very hard toward the exalted status of being regarded as a True Cynic I have a way to go yet. I must purge myself of Sarcasm, Irony and Satire.

 

I strongly disagree and in fact take exception with that opinion. WHY?? Because it denigrates and demeans the historic and present day efforts of EE's and techs etc who brought us to the current SOTA and propagates the moronic views on audio that dominate today's world of hi fi... By this I mean the way that a large proportion of audiophools think the fore mentioned bamboo capacitors, anti resonant mains fuses and similar foo bollox are A THING and important BUT when actual technical stuff that is real is brought up they don't want to know... "la la fingers in ears I'm not interested 'cos I don't understand it", and worse still have been brainwashed into pretty much believing all people with electronics knowledge are the enemy. It's rather like the way religious nuts think anyone who tries to explain that there are not really invisible, all seeing, all knowing, sky wizards above us must be from the devil and sent to try their faith! It's got so bad that the phools who have been taken for £250 for a "directional purify power bees wax filled fuse" will bend over backwards to defend the snake oil merchants who swizzled them... and then slag off engineers who try to explain WHY it's all a con.

Mark Twain — "It's easier to fool people than to convince them that they have been fooled". This is oh so true and in fact I can't recall a single person who has been conned into believing in and paying for such as a £250 magic fuse being persuaded that they were taken in. Not a single one... not even when they are a plasterer and three electronic engineers and a professor of physics are all telling them they've been conned and that a mains fuse cannot have any effect (yes that scenario is for real!).

It's very clever marketing really but predated by Reggie Perrin's "Grot" empire!

 

I have to agree with Jez on this. As someone who studied electronics and practiced firstly as a design engineer, later in Broadcast technical sales, I am offended by the snake-oil so prevalent in the audio industry. Grounding boxes filled with kitty-litter, and in a similar vein, the latest I've seen is a loudspeaker 'improver' containing magic crystals with only one wire that attaches to one of the loudspeaker terminals.
Add fuses, mains cables cable risers and other total nonsense, and there's more con going on here than at a homeopathic convention.

I was fortunate than when I started work, I had the HiFi shit knocked out of me by older, wiser and kinder engineers.

Caveat Emptor is all well and good, but the dividing line between being economical with the truth and outright cheating and lying has been completely rubbed out by these charlatans, and they need to be called out and ridiculed at every opportunity.

S

 

Bloody Hell Ark - hope you don't make Pope! It's just a game nothing is for ever and every new generation has to make its own mistakes - you can't teach experience.

I was doing some training years ago, with a bunch of Libyan Techs. We Stopped for a coffee break while the test equipment was warming up. When we came back, I took the interlocks off the 10kw transmitter I was using for training, which was fired up on carrier only. They all got back promptly, except for one laggard. He swans in with a cup of thick Turkish coffee, took a sip and realising the bulk was sediment, threw the coffee grains into the transmitter.

There was an effing great bang as all the trips operated. Wrecked the transmitter. I glared at this little s---t, but before I could bollock him he declared, "Maa'lesh Inglese, soon it will be dust in the desert."

While on the same project, having given the guys their tasks for the week, I was pretty much up to speed with everything. So, I asked the senior sparks on site, if there he wanted any help. Crafty sod said, "You could always wire up the incoming mains to the Main Distribution Panel. That was a large armoured cable and made an entry via the basement. Jeez, that was hard work, but I stuck at it and everything was going well.

Said sparks turns up, squats with his back against the wall, watched for while, sipping his coffee. Then this little Glaswegian git says, "Aye, no bad - are you ganna leave it like that?". Gets up and walks away chucking to himself. Bloody sense of humour of the man - could do nothing but laugh myself.

 

Amen to that Serge Though I rather doubt there were many foo mains cable believers around when you started in hi fi!

To continue on the theme, one of the most pernicious aspects of all this is that fake news becomes accepted wisdom if repeated often enough. We have reached a ridiculous point where "anyone who has any real knowledge of hi fi knows for a fact that mains cables and interconnects have a big effect on sound quality"... to the degree where if you oppose this view you will likely have people thinking "who is this idiot that is so lacking in hi fi knowledge as to not even know that mains cables can boost bass!?". You couldn't make it up.... (IME non audiophiles laugh their heads off at the idea that there are people so gullible as to pay £500 for a mains lead... hence my saying on various occasions that no one knows less about audio than the average modern audiophool... no knowledge of a subject is probably better than a head full of false information on that subject!)

Many companies that (should) know better are pretty much forced to propitiate customers by using "linear crystal silver plated wiring" and magic fuses etc if they want to be taken seriously by potential customers