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Old 4th Oct 2020, 12:05 am   #1941
Craig Sawyers
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Default Re: The Audiophoolery Thread.

Apologies - the large bass horn is intended for mounting next to a wall, which increases the effective mouth area by a factor of four, to give an LF cutoff of 40Hz.

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Old 4th Oct 2020, 12:19 am   #1942
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Default Re: The Audiophoolery Thread.

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Also Dinsdale's articles and designs in WW March, May and June 1974 are worth reading. His design for a horn that goes down to 40Hz measures 1.6m wide, 1.3m high and 1m deep. The mouth is 1.4 m^2 . That goes down to 70Hz, but as a result of floor reflections it goes to 40Hz.

But even so it is a beast. And constructed from either ply, or sand filled panels.

I toyed with the idea of building that at one stage, but it was beyond my woodworking skills at that time, and beyond the size of room by some margin!

Craig
I read Dinsdale's WW articles at the time and was absolutely enthralled by his ideas. To be fair to myself I do not think the designs were beyond my woodworking skills, but, they were massively beyond my means to afford.

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Old 4th Oct 2020, 5:53 am   #1943
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Default Re: The Audiophoolery Thread.

There were also articles kicking around at the time about people who had had massive brickwork horns built under their houses as the houses were built. Such things had previously been the preserve of cinemas.

What happened next was the advent of large amounts of affordable power as transistor amplifiers made the grade, and took the pressure off of loudspeaker efficiency.

One branch of the audio hobby (let's not forget that it's a hobby) has taken the view that everything that happened in the mainstream was to make sound worse and has gone backwards, to wind up with 1930s period single ended triodes, and horns.

Quad thought that moving from the valved II to transistors in the 303 and 405 was a perfectly sound thing to do. They thought it was progress. Was their hearing that bad?

Thorens thought that moving from idler wheel drive to belt drive as the TD125 replaced the TD124 was also an improvement. Couldn't they hear the differences some people claim?

Back in the day these firms did do listening tests, they took care that the results form panels were not triggered by other clues, they did good statistical work to be sure that results were not made erratic by small sample sizes. Human hearing hasn't improved since then. Because of greater sound level exposure and an ageing population, it's probably got worse on average and there is not likely to be any change in outliers in the good direction. Were people back in the day stupid? Or might they just have been right?

Was what was then seen as progress not actually progress?

Perhaps not in all cases. There was certainly a gee-whiz factor of look! we're using the latest doodads! but there was also an underlying trend from serious people taking care over what they did, using good scientific method and taking care that their results were impartial.

We have technologies they never had in the good ol' days. What we do not have is better brains or better ears. People back then were not stupid.

Early transistor amplifiers had problems but they steam-rollered their way through to manstream on cost, convenience and an increase in power. People not off-their-heids on gee-whizz factor waited until the failings got recognised, analysed, and fixed.

Maybe the population, on average, is more stupid now that they were then? Back then going to a university and studying a science or engineering subject was considered respectable. Nowadays we have lots of noise from people who oppose vaccination claiming it to all be a plot by 'the government' but I think it's a matter of appearance. Modern technologies have allowed people to make a lot more noise and maybe the proportion offolk having a bee in their bonnet has not risen, but they've got better intercommunication and they are now all egging each other on more efficiently.

I remember when hifi magazines had a degree of weight to them and took care to see that what they found and described could be backed up by independent analysis/research. At the same time there were subjectivist publications circulating like underground comics as A4 photocopied works. I remember seeing a few of these, particularly remembering one with a cartooned imaginary fist-fight between Alan Sugar and Ivor Tiefenbrun. Considering the bias of the publication, you can guess the imagined outcome. All I thought was that their markets had so little overlap I couldn't see the point. The world had room for both.

If I'd come across some of the unexpected differences, at the strengths they are described, with my own ears, I would be moving heaven and earth to find and understand the cause. I've played around with things and found that I can trick my own ears with simple things like slight changes in level and slight changes of frequency response causing small changes in the 'character' of what I think I perceive. I suspect I'm not unusual in this. I believe and I accept that I'm fallible, so I need to take care to assess things in ways that take these failings out of the equation. What I see are some people strongly averse to such protections. This worries me.

My attitude to the whole audiophool thing is that I'm disappointed there seems to be no curiosity about double-checking their findings and devising ways to ensure impartiality. Here, I think criticism is deserved. I get very critical when they wheel out pseudoscience to try to justify their beliefs, the harder they try, the funnier it gets, the more insecure they seem to be.

What I do not criticise are simple statements like "I've done it this way simply because I like it" or that they did it for the fun of it, or they like its style.

I'd be a hypocrite if I said anything against those positions. There is a very silly amplifier sitting in my lounge where it's been for the last forty years, and I ride a horse for heaven's sake! which is definitely as old-tech as anything gets, despite a perfectly satisfactory car in the drive. I need no other justification than "I like it" and "it's fun". Sticking someone in a saddle on the sort of beastie I enjoy riding would create terror in most people. lots of people would find my silly amplifier unnecessary. Fine. I don't feel it necessary for everyone to agree with my tastes.

But when I say something like "This detector design has a non-linearity of +/-0.012dB over a 20dB dynamic range" I've measured a number of them, with equipment having 0.001dB resolution and I have a good idea of the measurement uncertainty. To the point where I would reasonably expect other people to measure the same design using different test gear, possibly with different approaches but similar performance, to come out with a closely similar result because I've gone looking for trouble and designed some side experiments to check that I really was measuring characteristics of the detector and not so much my test gear. Good science involves having self-doubt and then deciding what to do about it. To be a good engineer, you first have to become a good scientist.

David
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Old 4th Oct 2020, 8:12 am   #1944
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Default Re: The Audiophoolery Thread.

5:53am David?

Regardless, and excellent and thoughtful post.

Craig
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Old 4th Oct 2020, 8:17 am   #1945
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Default Re: The Audiophoolery Thread.

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I read Dinsdale's WW articles at the time and was absolutely enthralled by his ideas. To be fair to myself I do not think the designs were beyond my woodworking skills, but, they were massively beyond my means to afford.

Steve.
What I did build was a pair of irregular pentagon cross section cabinets (I don't recall which magazine the design was in). I put in about a hundred nails into the inside to anchor the concrete lining (which was my own bonkers idea). I must have been 16 or 17 at the time.

And forgot they had to go up the stairs to get them into the house - which was an impossible task.

So they sat in the shed, sad and unused.

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Old 4th Oct 2020, 8:35 am   #1946
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Default Re: The Audiophoolery Thread.

Well said David, could not agree more.

Peter
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Old 4th Oct 2020, 8:42 am   #1947
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Default Re: The Audiophoolery Thread.

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There is a whole lot of fundamental horn stuff in Keith Holland's early work, including his doctoral thesis, on horns:
He was our external for a bit. Nice fella.
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Old 4th Oct 2020, 10:05 am   #1948
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Default Re: The Audiophoolery Thread.

Keith did some consultancy work when I was involved in the Mercury project. We needed to test the assembly at the sort of acoustic fields when a launcher fires up. Until it clears the tower, it gets up to >160dB for a few seconds, which can damage the payload instruments, so you need to test them at that level.

That was done in ISVR's echoic chamber. Non-parallel walls hard walls. Inner chamber hydraulically isolated inside an outer chamber, and two sealed and interlocked doors. And in the measurement lab it was still 100dB. Part of the cost of the work was in calibrating the transducer, and then rebuilding it afterwards. It generates so much SPL that it damages itself.

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Old 4th Oct 2020, 11:37 pm   #1949
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Default Re: The Audiophoolery Thread.

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Quote:
Originally Posted by fetteler View Post

I read Dinsdale's WW articles at the time and was absolutely enthralled by his ideas. To be fair to myself I do not think the designs were beyond my woodworking skills, but, they were massively beyond my means to afford.

Steve.
What I did build was a pair of irregular pentagon cross section cabinets (I don't recall which magazine the design was in). I put in about a hundred nails into the inside to anchor the concrete lining (which was my own bonkers idea). I must have been 16 or 17 at the time.

And forgot they had to go up the stairs to get them into the house - which was an impossible task.

So they sat in the shed, sad and unused.

Craig
Hey Ho! The folly of youth eh? I have to say that I identify very strongly with the sort of character you are describing
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Old 8th Oct 2020, 8:04 pm   #1950
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Default Re: The Audiophoolery Thread.

Hi.
I've had some single ended valve amps to look at recently. They use 300B's as outputs a 5U4G with 1N4007's strapped across the valve, that is effectively redundant, the blurb though says "it gives a mellow valve sound but the silicon diodes reduces sag on loud passages". Oh dear what a load of twaddle.
The design is very iffy with EF86's running way over their design limits, no HT surge limiting, they only have one fuse, a 3.15a mains fuse.
The audio quality is poor with distortion on high frequencies. Cost around £2500. another one I looked at was double the price and weighed a ton. The back of the power switch is exposed and had no wire dressing on the tags, HT via a 5U4G was nearly 600v and the valve had collapsed, again no surge limiting and the reservoir cap is 100uf (4x 100uf 500v in series parallel).
Built in unreliability at its worst. Although they are around 15 watts, my Mullard 3-3 with only 3 watts per channel knocks spots of them for quality and lack of distortion, plus plenty loud enough.
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Old 8th Oct 2020, 9:22 pm   #1951
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Default Re: The Audiophoolery Thread.

Mullard had someone sit down with full valve data, including production spread data, and a slide rule. He did a proper engineering design and was honest in his calculations. Results were measured honestly. What came out at the end was an honest amplifier, producing the expected results. Capable of being manufactured or being built at home and still produce the expected performance.

In the boutique amplifier world, the direction a design goes in is jerked around by fashion, and the fashionistas haven't got a clue about anything quantitative. In fact they consider such things to be bad. So boutique designs seem to be randomly created.

By comparison, engineered designs are almost like cheating, they have so many advantages over random hacking.

It's ironic that there seems to be more money in being fashionable than in being good.

There is an emperors new clothes aspect to saying 'Actually, this is rubbish' all the fashionistas will attack you, even ones who aren't sure.

All that distortion and non-flatness is 'Character' and they want lots of character. Through blind randomness, they get it.

But if older, cruder technologies are more acceptable to the boutique crowd, what's stopping them going back to mechanical gramophones?

David.
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Old 8th Oct 2020, 9:45 pm   #1952
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Default Re: The Audiophoolery Thread.

Very good point David.
I'll stick with good design and engineering.
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Old 8th Oct 2020, 11:42 pm   #1953
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Default Re: The Audiophoolery Thread.

I can't help thinking that with silicon diodes strapped in parallel with the 5U4G's diodes that the latter will be doing virtually nothing, apart from wasting heater power and having its life frittered away for visual appeal when it could at least be employed in providing some sort of contentment in a guitar amp. Even if we assume that an unwisely large amount of reservoir capacitance is employed to mitigate against hum in the single-ended output stage (resulting in high peak currents), the voltage across the 1N4007s is unlikely to be above 1.5V or so, barely rousing the space charge in the 5U4G to bother strolling across to the anodes to any significant extent.

In the case of the other amp with a directly-heated 5U4G feeding 100uF to produce nearly 600V- well, that's just foolish, wanton cruelty and waste towards even the most mundane and inexpensive of the breed, and risks wrecking a no-doubt expensive mains transformer as collateral.
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Old 9th Oct 2020, 12:03 am   #1954
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Default Re: The Audiophoolery Thread.

Ah, but it's knowing that the 5U4G is there that signals to certain people that they should be hearing certain attributes. Take it away, and provided they know it's been taken away then they will cease to hear those attributes.

How do these people know what attributes they should be hearing? The attributes are created in the head of an acknowledged pundit and are then promulgated through hifi magazines and the internet. The readers then know what to hear once they know what they're listening to. Simple!

I've tested this theory. I have a hifi system of no overt make, no badges, but very definitely something serious. Now, when someone of the audiophile persuasion comes across it, They don't know what it is, so they don't know what they're supposed to say to describe what they hear. So they go silent for fear of saying the wrong things.

Guitarists wanting a soft power supply could indeed use those valves. They can exploit it in their playing. The softness could be made in many ways but valve rectifiers are one way.

David
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Old 9th Oct 2020, 8:31 am   #1955
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Default Re: The Audiophoolery Thread.

My son plays guitar, including bass guitar. I bought a Trace Elliot AH1000 for him donkey's years ago. This fan-cooled beast has multiple power amps that can be flexibly configured (bridged etc), and an electronic crossover. It was originally intended to drive their BFC (Big F'ing Cabinet) with a separate amp for each driver.

Anyway, the AH1000 is a very serious piece of pro audio kit. But because musicians want a bit of soft distortion there is a valve stage in the otherwise solid state amp that can be switched in or out, and a knob to set the drive level - from linear through to soft clipping.

Craig
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Old 9th Oct 2020, 9:15 am   #1956
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Default Re: The Audiophoolery Thread.

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But if older, cruder technologies are more acceptable to the boutique crowd, what's stopping them going back to mechanical gramophones?

David.
I think David is onto something here. You can already buy audio grade shelves (so that's the wooden enclosure sorted), audio grade isolation feet, fancy 'directional' hinges and some seriously exotic oils for lube, plus the ability to listen to the music without the influences of cabling, gain-stages or power, be it AC mains or batteries! Brilliant ...

I too have had a listen to 'high-end' audio, back when they were held in hotels, which of course is ideal, what with all that IT/WiFi infrastructure and Air-Con running in the background. My first request was usually to turn the music down, I want to hear it, not feel it! Needless to say, my audio equipment is a real mix of good & home-made, using original datasheets as a starting point.

How does it sound? Not too shabby and as suggested, those who are 'that way inclined' cannot comment. How 'should' it sound?

Mark
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Old 9th Oct 2020, 9:37 am   #1957
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Default Re: The Audiophoolery Thread.

On one occasion I was helping at at a stand for an old friend and musician who was ill advisedly was in the loudspeakers business. This show was for UK manufacturers only.

Unusually I had persuaded my wife to come along. We walked into one room in which a CD of Marc Cohn was being played, which was a piece we knew extremely well.

It sounded to dire ("as if someone was scratching the back of my eyeballs") that my wife started to laugh out loud. I ushered her out, and explained that company had worked very hard indeed to make something that sounded so awful.

Craig
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Old 9th Oct 2020, 11:46 am   #1958
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Default Re: The Audiophoolery Thread.

Hi Craig.
So you know your post made me laugh so much the tears were running down my face........ Brilliant.
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Old 9th Oct 2020, 6:04 pm   #1959
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Back to reality (in this thread?) I bought a "sound bar" for my wife's telly* as I found the TV's sound awful. The thing is only 2"x3"x18" and it makes a very good show of itself, not quite hifi, bloomin' close though. How on earth is that done in such a small box? 10 out of 10 to the designers.

*married bliss... I live in the kitchen with radio and like cooking, 'er in the lounge with telly and likes my food.
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Old 9th Oct 2020, 7:52 pm   #1960
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Hi Craig.
So you know your post made me laugh so much the tears were running down my face........ Brilliant.
Great! My friend is actually a concert grade pianist, played internationally and was winning piano competitions since the age of four. He went to the Julliard school of music in NY. Not a business bone in his body, and although he is knowledgeable about acoustics, that does not mean he can design loudspeakers and make a go of it.

We met up in London at one stage - at a little restaurant at St Pancras. He insisted on paying, but needed to take out the cash. We went to a hole in the wall, and he shoved in a card. Tried three times to remember the code, at which point it eat his card. He shoved another one in, but this time he fished a piece of paper from his pocket, peered quizzically at it and tried the number - same end result.

I said that I'd treat him to lunch. Over lunch he was saying that he had bought his ticket on one of the cards, so why could he suddenly not know the number.

He said that he could play for forty hours straight from memory, not counting the operas he played at during rehearsals (including 15 hours of the Ring alone) - so why could he not remember a four digit number. Prodigious musical talent. We went to one of his concerts, one piece was one of the Beethoven sonatas. He launched into it, and after maybe ten seconds stopped, apologized and said "er-wrong sonata", and started again playing the right one.

So I told him to remember the credit card numbers as a chord sequence. He looked at me - and said that I was a genius, and how on earth did I think of it. He then proceeded to mutter "diminished 7th, augmented 4th..." actually moving his hands as if playing them on a virtual piano, and announced with a beaming smile that he never would forget the numbers again.

Craig
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