More audiophoolery: discrete op-amps better than ICs!

[free_electron]

But any claim of better sound must be validated in a "double blind trial".
If you can't tell the difference, it doesn't exist.

How often do "better sound" claims are said to be validated by a double blind trial? 

a doubleblind listening test proved that coathangers work better than expensive oxygen free interlinks

[Zero999]

to never allow your amplifier to go into clipping

You can never assure yourself of that, unless you know the music before you hear it.

You can do some basic math but assuming a reasonable crest factor, you need tremendous amount of headroom for a solid state amplifier to play the same music than you do with a valve amplifier.

Another way to say the same thing: a comparably rated valve amplifier sounds much better than a solid state amplifier playing the same music.

To be fair. For a comparable size or price you can get a solid state amp with at least an order of magnitude more output power.

Exactly, solid state amplifiers are cheap!

Clipping can also occur in the speakers which sounds nasty, regardless of what amplifier you're using. If clipping occurs, just adjust the volume control.

[VK5RC]

A bit of  silly question, has anyone ever seen any data that looks at the effect of ageing on speaker performance?
I have some nice but old (20+ yrs) "Richard Allen HP12B Super" bass drivers.
I would think that age may be not nice on some of the 'plastics/foam' surrounds etc. The surrounds look intact and do not appear brittle to gentle touch.

[Richard Crowley]

Your fellow countrymen, A. Neville Thiele of the Australian Broadcasting Commission, and Richard H. Small of the University of Sydney devised a method of measuring electro-mechanical parameters of loudspeakers some 40 years ago.  The Thiel/Small Parameters. http://en.wikipedia.org/wiki/Thiele/Small.

If you could get the Thiel/Small parameters for the loudspeaker drivers, you could measure your specimens and compare the numbers to actually characterize the deterioration.

Particularly vulnerable are the foam-rubber molded surrounds which don't fare well in many environments.  I have some JBL drivers (and passive radiators) which have been re-coned more than once because of environmental deterioration.

The cited Wikipedia article also includes a brief overview of: "Lifetime changes in driver behavior".
http://en.wikipedia.org/wiki/Thiele/Small#Lifetime_changes_in_driver_behavior

[SeanB]

Speakers do age and the supports and the foam become stiff and lose elasticity. A lot of high end speakers have an active business in replacing the foam rubber and the cone supports, along with the big car audio units.

[VK5RC]

Thanks Richard and Sean, just what I was looking for, many thanks.

[Circlotron]

If you could get the Thiel/Small parameters for the loudspeaker drivers, you could measure your specimens and compare the numbers to actually characterize the deterioration.

Some time ago I fiddled about a lot with all that stuff. After trying a number of unsatisfactory ones I ended up writing my own spreadsheet to do the calcs. All you need is an amplifier, oscillator, resistor, meter and a lump of blue tac of known mass.
http://www.diyaudio.com/forums/attachments/multi-way/23875d1079781945-best-ever-t-s-parameter-spreadsheet-best-ever-ts-parameter-calc.zip
Make sure you put the back of the speaker against a large mass e.g. lengthwise 100x100x300mm post otherwise the speaker vibrates in anti-phase to the cone and gives inaccurate Q measurements. don't cover any vent holes on the back of the magnet though.

[dannyf]

Clipping can also occur in the speakers which sounds nasty

Much less so.

you could measure your specimens and compare the numbers to actually characterize the deterioration.

That's assuming that the T/S model can capture the effect of aging. Without knowing the mechanism of aging that you are trying to study, that's not a sure thing.

I tend to think that the lack of information on that is fairly indicative of aging's impact, or lack of.

On a broader topic, speakers are one of the most impactful, if not the most impactful, elements on sound quality. Yet, many people would buy speakers without first listening to them, and spend the most on the least impactful elements, like cables, power conditioners, or amplifiers...

[VK5RC]

Thanks Circlotron, I had found diyaudio forum but you have spurred me on to register, the diyaudio site has some data on the T/S parameters of the Richard Allan drivers , so I have some data to compare. Unfortunately I might not get to it for a week or so as my wife is about to go away so I will be busy with the carpet commandos.
I suppose I am lucky they are bass drivers as I suspect compliance issues are probably less critical at lower frequencies.
@dannyf, I fully agree that speakers (drivers,cabinet) are THE most important aspect of a good "HiFi" system, room acoustics probably next.

[oldway]

In my younger years, I was projecting and building hi-fi and guitar tubes amplifiers.
For guitar amplifiers, musicians were seeking for amplifiers with  high distortion for "coloring" the sound of their musical instrument.
I then chosed universal low quality output transformers and I biased tubes (mostly EL34) for low quiescent current (working nearby class B)
For Hi-Fi stereo, I chosed expensive and high end output transformers as the most important components in a tube amplifier are the output transformers. (with push pull EL84 / 9W or EL34 / 25W)
What whe were looking for is just what we obtained later with the transistorized amplifier performance.
But there is a big difference between a tube amplifier and a transistor amplifier : the damping factor. (low for a tube amplifier, high for a transistor amplifier)
On this point, the best is the enemy of the good.
With a tube amplifier, loudspeakers operate more freely in their natural resonant frequency, which gives a more pleasing sound to the ear.
I think that's why music lovers say the sound of a tube amp is more enjoyable than a transistor amplifier. (with the same speakers)

NB: I also fully agree with dannyf about speakers and room acoustics...

[Zero999]

But there is a big difference between a tube amplifier and a transistor amplifier : the damping factor. (low for a tube amplifier, high for a transistor amplifier)
On this point, the best is the enemy of the good.
With a tube amplifier, loudspeakers operate more freely in their natural resonant frequency, which gives a more pleasing sound to the ear.
I think that's why music lovers say the sound of a tube amp is more enjoyable than a transistor amplifier. (with the same speakers)

Not everyone likes that.

The main advantage of a solid state amplifier is lower output impedance and a high damping factor to give a more flat frequency response, rather than the horrible peaks at the resonant frequency of the speaker.

Fortunately, if you like that, it's easy to ruin the damping factor by adding series resistors or more than one speaker in series, without having to resort to expensive valve amplifiers.

[oldway]

My choice: MARANTZ 2285B with KEF speakers.
You see that I am NOT a tube amplifier fan !
They are only very useful in the winter...

[dannyf]

adding series resistors

It would reduce output power significantly.

However, some headphone amps do that deliberately, as power ratings there are of minimum concerns.

[Zero999]

adding series resistors

It would reduce output power significantly.

It's still cheaper to buy a solid state amplifier 10 times more powerful (than the same valve amp) and add series resistors. 

[dannyf]

You don't have the headroom then.