Serge Auckland wrote:

The original 405 didn't provide enough current for anything other than
nominal 8 ohm loads. It struggled a bit even with 4 ohm loads. Given that
a nominal 4 ohm loudspeaker is allowed to go down to 3.2 ohms, and many go
below that, Quad felt they had to provide more current capability, hence the
405/2.

Not to mention a COMPLETE change of the 'technology' of the output devices from
slow to moderately fast.

Graham

Jim Lesurf wrote:

More to the point, the original IV limiting using on the 405 was
particularly severe for reactive loads - rather common for loudspeakers!

I could write an article on the subject. I modified one (actually a family) of
my own designs to take account of complaints we had from owners specifically of
one single make/model of loudspeaker. EV SX500 btw.

When I heard it, I was convinced. There was a nasty rasp in the upperish
midrange. When I modelled it I was STUNNED that ANY loudspeaker manufactuere
let alone EV would let loose a speaker with such wild load phase angles.

Graham

Jim Lesurf wrote:

More to the point, the original IV limiting using on the 405 was
particularly severe for reactive loads - rather common for loudspeakers!

That's a very interesting subject in its own right.

Back then, designers tended to be 'over-protective' of their output devices. No
doubt influenced by the fragility of early parts.

Things have moved on a bit. I tend no to look mainly at average dissipation as
opposed to instanteous V/I limiting now.

Can't say I've seen many failures.

Opps, giving my secrets away here.

Graham

Geoff Mackenzie wrote:

I do like some of their definitions - a good amp being "straight wire plus
gain".

But can it drive pure inductive or capacitive loads ?

Graham

"Eeyore" wrote in message
...


David Looser wrote:

"Glenn Richards" wrote
David Looser wrote:

opinions are divided on this group but it does make a difference.
I love that!, "opinion is divided, but I'm right"

Heh, ok, posting written rather quickly... but you get the idea.

In your opinion of course.

In my experience, yes, speaker cables do make a difference to the
sound.
As do interconnects to some extent.

But can you hear the difference when you don't know which cables you are
listening to?, that's the question.

Can you hear +/- 1dB ? or +/- 0.5dB ?

I can assure you some people have NO trouble doing so.

Graham

Rather depends on frequency, level and whether you're listening to tones,
noise or programme. It will also depend on whether the +-1dB or +-0.5dB
change is across the band, i.e. a level change or, say, at 10kHz, where is
would have the effect of a tone control. +-1dB change on programme is pretty
difficult, but some would manage it, +-0.5dB is tougher still, and most
wouldn't manage it on most programme material.

S.


--
http://audiopages.googlepages.com

"Serge Auckland" wrote in message
...

"Eeyore" wrote in message
...


David Looser wrote:

"Glenn Richards" wrote
David Looser wrote:

opinions are divided on this group but it does make a difference.
I love that!, "opinion is divided, but I'm right"

Heh, ok, posting written rather quickly... but you get the idea.

In your opinion of course.

In my experience, yes, speaker cables do make a difference to the
sound.
As do interconnects to some extent.

But can you hear the difference when you don't know which cables you are
listening to?, that's the question.

Can you hear +/- 1dB ? or +/- 0.5dB ?

I can assure you some people have NO trouble doing so.

Graham

Rather depends on frequency, level and whether you're listening to tones,
noise or programme. It will also depend on whether the +-1dB or +-0.5dB
change is across the band, i.e. a level change or, say, at 10kHz, where is
would have the effect of a tone control. +-1dB change on programme is
pretty difficult, but some would manage it, +-0.5dB is tougher still, and
most wouldn't manage it on most programme material.


Indeed, Graham's original question: "Can you hear +/- 1dB ? or +/- 0.5dB" is
meaningless unless qualified with all sorts of other information.

I would have no trouble hearing the change as a 1dB gain or loss is switched
into a circuit carrying tone or a continuous musical note, but if Graham is
claiming that he can listen to a programme, leave the room for 30 seconds
and when he returns be able to say if the level had been changed by 1dB in
his absence then I would be very sceptical.

Or if we are talking about a frequency response change it will of course
depend a great deal on where in frequency terms that change occurs, how much
of the band is affected, what the spectral content of the programme is etc.
And again if anyone claims that he could detect when re-entering the room
whether this change was made when he was out of the room I would be very
sceptical.

It seems to me that we are in the same area as with those who claim to be
able to hear the difference between expensive and cheap wire. It's easy to
claim that you can hear this or that, but doing so under double blind
conditions is a whole different ball-game.

David.

Adrian C wrote:

Eeyore wrote:

Great to hear a man who knows his onions talk good sense.

Onions with opinions?

Red or white ?

Graham

Serge Auckland wrote:

"Eeyore" wrote
David Looser wrote:
"Glenn Richards" wrote
David Looser wrote:

opinions are divided on this group but it does make a difference.
I love that!, "opinion is divided, but I'm right"

Heh, ok, posting written rather quickly... but you get the idea.

In your opinion of course.

In my experience, yes, speaker cables do make a difference to the
sound. As do interconnects to some extent.

But can you hear the difference when you don't know which cables you are
listening to?, that's the question.

Can you hear +/- 1dB ? or +/- 0.5dB ?

I can assure you some people have NO trouble doing so.

Rather depends on frequency, level and whether you're listening to tones,
noise or programme. It will also depend on whether the +-1dB or +-0.5dB
change is across the band, i.e. a level change or, say, at 10kHz, where is
would have the effect of a tone control. +-1dB change on programme is pretty
difficult, but some would manage it, +-0.5dB is tougher still, and most
wouldn't manage it on most programme material.

I would broadly agree but you ought to try the +/- 1dB test yourself before
becoming too dogmatic.

Explains the 'golden ears' thing though.

I do believe that on extended listening I've heard - 0.3dB @ 20kHz. I was
younger then of course.

Graham

"Eeyore" wrote in message
...


For all the usual reasons like DCR, L and C. Togther with the amp's output
impedance and the loudspeaker, these form a complex filter. I'd not be
surprised to see +/- 1dB variations.


Based on looking up some likely constants for speaker wire I calculate that
the effect of these parameters for 10m of 2.5sqmm figure-of-eight speaker
cable is to produce an upper -3dB point at something like 1MHz. This puts
the -1dB point well above the audio band. "Exotic" cables might, of course,
have a higher capacitance and thus a lower -3dB point, making them
marginally (but probably imperceptibly) worse.

A greater change in frequency response is probably caused by the variation
in speaker impedance with frequency causing changes in the current, and thus
volt-drop in the resistance of the cable. Using the same hypothetical 10m of
2.5sqmm cable this would result in an additional 0.3dB frequency dependant
loss at a frequency where the impedance of a nominal 8 ohm speaker dropped
to 4 ohm. Again not what I'd call particularly significant.


Their preferred cable was IIRC UK T&E 4mm2 mains wiring cable. Back then
heavier 'grades' were very rare.

What use is the earth conductor when the cable is used this way? 4sqmm mains
cable is very stiff and a thorough pain to connect up.

Yup, the more copper, the better.

To a point. It's a law of diminishing returns.

David.

David Looser wrote:

"Serge Auckland" wrote
"Eeyore" wrote
David Looser wrote
"Glenn Richards" wrote
David Looser wrote:

opinions are divided on this group but it does make a difference.
I love that!, "opinion is divided, but I'm right"

Heh, ok, posting written rather quickly... but you get the idea.

In your opinion of course.

In my experience, yes, speaker cables do make a difference to the
sound. As do interconnects to some extent.

But can you hear the difference when you don't know which cables you are
listening to?, that's the question.

Can you hear +/- 1dB ? or +/- 0.5dB ?

I can assure you some people have NO trouble doing so.

Rather depends on frequency, level and whether you're listening to tones,
noise or programme.

Programme. Sorry not to make that clear.


It will also depend on whether the +-1dB or +-0.5dB
change is across the band, i.e. a level change or, say, at 10kHz, where is
would have the effect of a tone control. +-1dB change on programme is
pretty difficult, but some would manage it, +-0.5dB is tougher still, and
most wouldn't manage it on most programme material.

Indeed, Graham's original question: "Can you hear +/- 1dB ? or +/- 0.5dB" is
meaningless unless qualified with all sorts of other information.

Sounds like a get out clause to me. I mean +/- 1 dB over the audio band. As
might be created by a cable / amplifier / loudspeaker interaction.


I would have no trouble hearing the change as a 1dB gain or loss is switched
into a circuit carrying tone or a continuous musical note, but if Graham is
claiming that he can listen to a programme, leave the room for 30 seconds
and when he returns be able to say if the level had been changed by 1dB in
his absence then I would be very sceptical.

I didn't say LEVEL. Although I have matched level on a tape machine 'line-up'
test BLIND to +/- 0.3dB. One track was within 0.1 dB.


Or if we are talking about a frequency response change it will of course
depend a great deal on where in frequency terms that change occurs, how much
of the band is affected, what the spectral content of the programme is etc.
And again if anyone claims that he could detect when re-entering the room
whether this change was made when he was out of the room I would be very
sceptical.

It seems to me that we are in the same area as with those who claim to be
able to hear the difference between expensive and cheap wire. It's easy to
claim that you can hear this or that, but doing so under double blind
conditions is a whole different ball-game.

Pontificate, pontificate, pontificate.

Either you can hear it it or you can't.

My eyesight isn't totally brilliant. I make no special claims for it. How's your
hearing ?

Graham