The Audiophoolery Thread.

[ajgriff]

Although I do like learning more about some of the finer technical aspects of these things sometimes I think we should just get back to enjoying the music. Aren't we in danger of becoming audiophools if we don't?

Alan

[HamishBoxer]

Indeed Alan,you get my vote.

[mark_in_manc]

Originally Posted by Craig Sawyers

As applied to loudspeakers, it is much more meaningful. In particular bass reflex and ABR speakers can indeed sound bloated and muddy at the bottom end.

I think the joke we were making had to do with the time ('fast') and frequency ('bass') domains being conjoined in the form of Fourier transform pairs (in a causal universe - which in the context of this thread could add another layer to the joke!) - the window length necessary for observing anything like 'bass' being anything but fast. But as usual explaining a joke makes it less funny, and there's not much less funny than an engineering joke even when you don't explain it

Actually, all that stuff about 'what do you hear when you hear the Q - the freq domain band-limited gain, or the modal decay time which goes along with it' once bothered me greatly, and I even have a JAES paper or two on it. But I'm blowing my own trumpet, which is embarrassing on an electronics forum where everyone knows more than I do!

However, even there it is subject to analysis, as Richard Small and Neville Thiele showed in their seminal papers on low frequency speakers in the early 70's.

(More trumpet blowing - I once met them both at a conference, and seizing my courage in both hands went to sit with them at a formal dinner. Alas, my leg hit the table trestle, a big (lit) candlestick tottered, and for a moment it seemed I might achieve notoriety as the man who set light to either Thiele's beard or Small's wife).

[OldTechFan96]

What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

[Radio Wrangler]

It's just the level of synesthesia that is average in the human population... For example red is associated with warm and blue with cold. Yet anything radiating blue black body radiation is an awful lot hotter than anything radiating red!

Alternatively you can interpret it as meaning that the amplifier has such a non-uniform behaviour at different frequencies that it is immediately obvious. High infidelity!

David

[Craig Sawyers]

And thus, the native hue of resolution is sicklied o'er with the pale cast of thought

[bikerhifinut]

Originally Posted by OldTechFan96

What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

It means it isn't working properly.

A.

[Ted Kendall]

Originally Posted by OldTechFan96

What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

I think it's a perception first voiced in the hi fi press during the 1970s "musicality" craze, when some writers got hold of ageing Quad IIs and the like and interpreted response errors in the pre-amps and differences in the onset of distortion compared to modern mass market amplifiers as evidence of some magical "valve" quality which they dubbed "warmth". Those who acquired Quads and Radfords, as I did under their influence, were agreeably surprised by their performance (and why not?) and only later did the realisation dawn that this was down to excellence of design and construction rather than any inherent characteristic of valves.

Conversely, in a 1966 review of the Dynaco 120, one of the first transistor amplifiers with pretensions to top-quality performance, Len Hulley spent much time between blow-ups trying, and failing with the test procedures available to him, to pin down the difference he heard between this and two high quality valve amplifiers, which he described as a subtle improvement of low level detail. This, in fact, was crossover distortion - the 120, notoriously, was pure Class B and Dynaco made a virtue of the fact that it passed no quiescent current in the output stage.

As one contributor here pithily put it - if your valve amplifier sounds warm, there's something wrong with it.

[Craig Sawyers]

From the 4th Edition of the Radiotron Designer's Handbook, 1952, page 603:

"The purpose of high fidelity reproduction is to satisfy a particular listener, who is primarily interested in the emotions arising of what he hears. The complete process involves sensations and emotions which cannot be treated objectively and must bring in personal preferences and differences of opinion"

On pages 604-5 there is a section on "Imagery for describing reproduced sound"

So subjectivism and musicality it is not a phenomenon of the 1970's, it rather pre-dates Fritz Langford-Smith's RCA tome of 1952.

Craig

[Ted Kendall]

Originally Posted by Craig Sawyers

...So subjectivism and musicality it is not a phenomenon of the 1970's, it rather pre-dates Fritz Langford-Smith's RCA tome of 1952.

In general terms, of course, this is so, otherwise the hi-fi market might not have taken off at all, but the specific trend of regarding hi fi valve amplifiers as inherently "warm" dates from around the mid-seventies, at least in the UK, and was in part a reaction to the heavy promotion of ever-lower THD figures in transistor amplifiers as a "must have" parameter. Some of this may also have spilled over from rock music, where the warmth, for which read distortion, of over-driven valve instrument amplifiers is cultivated as part of the required sound.

[Craig Sawyers]

Indeed - in many solid state guitar amps, there is also a valve stage which can be deliberate overdriven using a front panel control for that purpose.

But adding distortion to guitars using fuzz boxes, wha-wha pedals etc has been going on pretty much since Les Paul invented the solid bodied guitar in 1940 - and he became one of the key figures in special effects. Some of the recordings of him with his wife Mary Ford have really stood the test of time. https://en.wikipedia.org/wiki/Mary_Ford

Craig

[Radio Wrangler]

Originally Posted by Craig Sawyers

From the 4th Edition of the Radiotron Designer's Handbook, 1952, page 603:

"The purpose of high fidelity reproduction is to satisfy a particular listener, who is primarily interested in the emotions arising of what he hears. The complete process involves sensations and emotions which cannot be treated objectively and must bring in personal preferences and differences of opinion"

All fine and dandy with me.

But while they're doing this, they also make loud claims of rightess and accurate reproduction of the original sound which is somewhat amusing. But it's when pseudoscience gets wheeled out as justification for claimed perceptions that it gets silly.

People don't realise that in matters of personal taste, no justification or explanation is necessary. "I just like it" is factual and unassailable. The attempts at justification seem like signs of insecurity.

I built myself a silly amplifier many years ago. It's performance is far over the top in some respects. I built it this way for fun. It required no further justification. I enjoyed designing it. It still works and sits in the corner of my living room. It works sufficiently well that it vanishes. It is totally unimpressive. It wouldn't have made a good commercial product. It's hard to sell something imperceptible.

The Emperor didn't buy his new clothes because he liked the look of them, he bought into the lifestyle advertising

David

[knobtwiddler]

Originally Posted by OldTechFan96

What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

The concept of 'warmth' (sic) has been exploited by marketers, culminating in its ultimate conclusion, the 'marketing valve'. These have been seen in items ranging from mass-produced budget mic preamps, to car stereo head units. In order to install your marketing valve, you don't want necessary acutruments such as HT supplies or transformers getting in the way, so you might run the anode from a DC to DC converter, so you only need a couple of rails for the whole design (most of the work done with low-grade IC opamps). A dual triode, I.e. ubiquitous 12AX7, preferably from China, is also handy as you only need one for stereo. You then cut a small window in the front panel to make sure your valve can be seen. Voila! You have a 'starved plate' valve, running on 60 volts. It will sound 'warm' on account of the resultant 2nd harmonic that comes from using a valve well below its optimum B+

I can think of some items of audio that have gone onto acquire cult status with their starved plates on 60v. There's subjectivity for you!

Personally, having used valve gear designed by the likes of T de Paravincini, I reckon few would be able to discern it from well-designed transistor circuitry in an ABX comparison. Mr P's designs get criticised in hifi circles for being too clean! He does his job too well.

[Sinewave]

Originally Posted by OldTechFan96

What does 'warm' mean when used to describe the sound produced by a valve amplifier?

I've heard it so many times. Is it just one of those things people say without really thinking?

Certainly with guitar amplifiers, a valve amp has a fuller warmer tone. Solid state amplifiers tend to have a thinner sound, can often sound compressed. It makes a big difference.

I refer to it as warmth and depth.

[stevehertz]

Out of interest, the use of the word 'warm' to describe the sound of a valve amp, tuner, whatever, is also frequently used to describe the sound of any vintage hifi be it SS or valve. It's also a popular 'big up' often used to aid a sales pitch. My own explanation of how the term came about is more to do with what the hifi component isn't, rather than what it is. And by that I mean 'less treble'. Not that I think it's use in that context is justified, but nonetheless it's used that way.

[M0FYA Andy]

Here's a new one on me, concerning valve rectifiers in a guitar amplifier affecting the guitar's strings -
"As more power is consumed (you turning the amp up!) an increased voltage drop occurs, resulting in the time-honored tube-rectified feel. The overall response is ‘spongier’ and causes the strings of your guitar to feel more elastic and often easier and ‘more juicy’ to play".

Andy

[fetteler]

Are you a guitarist Andy?
It doesn't affect the strings per se, rather I guess they mean it affects the feel of how you play, we are all used to hitting the strings with a certain force for a desired sound and the amp, being in 'series' with this chain of sound will thus affect the feel of the guitar. pretty obvious to me.
Steve.

[Ted Kendall]

Agreed. Anything which changes the apparent response to manual control inputs (onset of overload in this case) will affect the "feel" of the whole, rather like a stiff accelerator pedal in a car.

[Craig Sawyers]

Another odd positive side effect of valve rectifiers is the lack of reverse recovery. They therefore do not excite the leakage inductance/interwinding capacitance resonance of the mains transformer.

Regular solid state rectifiers generate reverse recovery transients like a champ, so every time each rectifier diode turns off, a burst of oscillation occurs via the above effect usually in the range 200kHz to 1MHz with a Q of 5-10.

Of course you can use more sophisticated soft recovery diodes, and/or use a C-RC snubber across the secondary winding of the transformer, which kills the oscillatory transient dead if you get the RC in particular correct.

There is a small circuit on DIY audio that enables these values to be determined by direct measurement https://www.diyaudio.com/forums/power-supplies/243100-simple...ubber-using-quasimodo-test-jig.html

Craig

[avocollector]

I've always thought of 'warm' as bassy ie sound has a lot of bass content and not very high trebles, I understand that valves emphasise the even harmonics and trannys the odd which may also have something to do with the sound - after all the early tranny radios and amps were often said to be 'tinny' = emphasising the trebles.

But there again this may all be due to what our ears get used to as a child - I was one back in the 50-early 60's so valve amps were the norm back then, I don't notice it so much nowadays but a) speakers have got a lot better b) my hearing is probably starting to go a little at the top end as a result of being 67.