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The Ten Biggest Lies in Audio

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I don't have as implied, but I'm more than happy to compare the relative merits of ours and other products like Boeing and Airbus do for example.

Geoffrey Horn is in his late eighties now and quite frail, he hasn't reviewed since Gramophone was acquired by Haymarket some years ago.

Believe it or not Geoffrey designed Quad's original AM and FM tuners and was a lifelong friend of Peter Walker, both were lovely people and full of fun.

Ash
 
Ashley James said:
Geoffrey Horn is in his late eighties now and quite frail, he hasn't reviewed since Gramophone was acquired by Haymarket some years ago.

Believe it or not Geoffrey designed Quad's original AM and FM tuners and was a lifelong friend of Peter Walker, both were lovely people and full of fun.

Ash
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I can remember reading Geoffrey Horn's reviews in Gramophone, I believe the original tuners were fine pieces of equipment. I use a lovely pair of "Walker's Wonders" in my system, amazing speakers that I will never part with.
Errol.
 
Ashley James said:
Tone Tone Tone!

It's all to do with the duty cycle in music and the very simple load presented by a 5 ohm driver, and of course an electronics engineer and genius mathematician to make sure that the inevitable increase in temperature doesn't exceed electrical safety regulations.

We're fanatical about controlling cost because our customers appreciate not having to pay for what they don't need.

What you actually get is a full 650 Watt peaks, but they are over so quickly that the average power consumption is pretty low.

AV processors are the same and dimwit reviewers still haven't cottoned on, so see it as a negative. It's why most still don't use Class D.

Ash
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Fabulous hyperbole!

Surely a speaker's duty cycle is 100% whilst music is playing?

But I like the admission that the amplifier's power rating is peak (which can be 10x more than the nominal RMS figure that other makers use).

Here's an interesting article on Wiki about audio power.
 
Ashley James said:
Geoffrey Horn is in his late eighties now and quite frail, he hasn't reviewed since Gramophone was acquired by Haymarket some years ago.

Ash
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Geoffrey Horn died on June 1, 2009. How do I know? My father was a regular customer at his shop in Oxford and attended his funeral.
 
I'm terribly sorry to hear that, he was a dear friend, but he was old, frail and very deaf, so he had a good innings and I guess his quality of life was poor. He'd also lost his wife some years earlier.

He was an RAF wireless technician in Singapore during WW2, so was in Japanese captivity for a time.

Horns of Oxford were the biggest Quad dealer in the world in that they sold the most ESLs, which was probably helped by having a proper IEC dem room, so things sounded as they should.

Geoff had sold the shop before I met him.

Ash
 
prowla said:
Fabulous hyperbole!

Surely a speaker's duty cycle is 100% whilst music is playing?

But I like the admission that the amplifier's power rating is peak (which can be 10x more than the nominal RMS figure that other makers use).

Here's an interesting article on Wiki about audio power.
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Here are some waveforms that you can both see and hear and are 'peaky' http://www.comparisonics.com/ColorWaveformDemo.mov

Peak amplifier output is 1.414 * RMS. There doesn't appear to be a 'standard' that manufacturers follow. This may be RMS, Peak or Peak-to-Peak or any other figment of some ones imagination. So a 10w amp may also be 14w or 28w! Also peak power output can be significantly higher than continuous output. Its a factor of the power supply and the current rating of the output devices. I have huge amps that can deliver 1600w continuously into 4 Ohms but a peak of 150A into 1 Ohm thats a max peak of 22500w!!! Basically these amps have 20 pairs of 7.5A rated output devices......

I can't comment on AVI kit as I don't know anything about it.

Cheers,

DV

PS Here are some measured spl of musical instruments:-

Violin 84-103 dBA Cello 84-92 dBA
Bass 75-83 dBA Piccolo 95-112 dBA
Flute 85-111 dBA Clarinet 92-103 dBA
French Horn 90-106 dBA Oboe 80-94 dBA
Trombone 85-114 dBA Xylophone 90-92 dBA

Note the difference in spl between the quietest 75dB to the loudest 114dB is 39dB thats circa 8000 times!!!
 
Ashley James said:
The facts are that the bass amps are 250 Watts RMS, which means peaks double that and 500 peak power.

Music comprises of a continuous average level of a fraction of a Watt with regular peaks running into hundreds. Volts would be a better way to express music's requirement of an amp because Watts are an energy time thing.

Therefore and either way, you can never extract the total RMS from an amplifier because when the peaks are clipping, you're still not consuming many Watts, but the voltage peaks will be very high.

Ash
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It's unfortunate that we've become conditioned to thinking of amplifiers as providing Watts. A much better way would be for amplifiers to be rated in volts, both continuous and for 20mS into a range of loads, for, say, 1% distortion. For example:

Output continuous, 28.3 volts into any load above 2 ohms and within the frequency range 20Hz -20kHz and for <1% distortion. 30v as above, for 20mS.

S.
 
No point anyway DV because ADMs have established themselves as doing as claimed.

The best way to see what is needed to play music is a cheap scope, Maplins do one for £80 odd.

Switch the scale to read in volts the peak an amp can produce and play a wide variety of program material. Obviously a lot of music is heavily compressed to play on low powered stuff, but movies have massive swings as does some music. On quite a bit of material and if you're amp has the headroom, you'll see a continuous of a volt or less, but peaks of 40-65 Volts!

Current isn't an issue with active speakers because, if they use an 8 Ohm driver, 5.4 ohms is the hardest load the amp will see.

Stand alone amp designers must allow for lower impedances to be safe.

Ash
 
Out of interest Ashley, how many volts RMS will the larger ADM9 amplifier deliver into an 8 ohm load before clipping? Simple enough question I'd have thought, easy to measure.
 
So to be able to maintain 50V RMS continuously across 8 ohms you must be running at least +/- 70V rails. Is that right? What are the caps rated at? 100V?

ADM9amp.jpg


And this transformer also provides power for a smaller HF amp aswell? It appears to be about 7cm diameter. It must be exceptionally efficient to run 325W worth of power amplifiers. Most 300VA transformers are more like 12cm diameter at least.

I'm just trying to clarify what the spec is in terms that other manufacturers use.
 
Patrick Dixon said:
So RMS is half Peak then is it Ashley?

Jesus there's a lot of crap being talked here!
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You are just baiting Ash. OK he deserves it!

I think this is what he may mean 250w RMS continuous thats 350w 'peak' continuous. Then we have the short term 'instantaneous?' 500w.

But that tranny and associated kit doesn't look to have the muscle in the photo above.

Cheers,

DV
 
Surely 50V RMS is about 70V p-p which is +/-35V?

But that transformer looks more like 80VA to me.

(When Ash talks about 'genius' mathematicians, I think he's talking more in the 'Apple' sense than in the 'Wayne Rooney' sense.)
 
Oh dear, misleading specs once more.

Doesn't take a rocket scientist to see that is good for no more than 75 watts.
 
pure sound said:
. Most 300VA transformers are more like 12cm diameter at least.
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Its is about 12cm diameter looking at the picture, shirley if it were 7cm it'd be tiny?

Darth Vader said:
I think this is what he may mean 250w RMS continuous thats 350w 'peak' continuous. Then we have the short term 'instantaneous?' 500w.
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Didn't Ash say that they were 250w into a 5ohm load, and the 500w peak was for the new speakers (which have different amps!).
 
pure sound said:
So to be able to maintain 50V RMS continuously across 8 ohms you must be running at least +/- 70V rails. Is that right? What are the caps rated at? 100V?

ADM9amp.jpg


And this transformer also provides power for a smaller HF amp aswell? It appears to be about 7cm diameter. It must be exceptionally efficient to run 325W worth of power amplifiers. Most 300VA transformers are more like 12cm diameter at least.

I'm just trying to clarify what the spec is in terms that other manufacturers use.
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To give some idea, we run a >250VA transformer giving +/- 36v rails to deliver 120w RMS - and a large heatsink hanging off the back of the speaker.
 
Patrick Dixon said:
Surely 50V RMS is about 70V p-p which is +/-35V?

But that transformer looks more like 80VA to me.

(When Ash talks about 'genius' mathematicians, I think he's talking more in the 'Apple' sense than in the 'Wayne Rooney' sense.)
Click to expand...

I don't think so. 50v RMS ~ 70v peak and ~140v peak-peak. So two rails +/- 70v but this would be off or lightly loaded. Under load this voltage would tend to approach the RMS value of 50v depending how much umph the xformer, rectifiers and storage/smoothig capacitors can deliver.

I wish I knew how to imbed a graph here.

Cheers,

DV
 
Ashley James said:
I

Geoffrey Horn is in his late eighties now and quite frail, he hasn't reviewed since Gramophone was acquired by Haymarket some years ago.

Believe it or not Geoffrey designed Quad's original AM and FM tuners and was a lifelong friend of Peter Walker, both were lovely people and full of fun.

Ash
Click to expand...

Ash,

Sadly, GH passed away in 2009.

Always enjoyed reading his reviews - definitely a no nonsense audio journalist.
 
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