New amp and speakers
 

David Looser wrote:

"Eeyore" wrote

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.

They didn't use it (the earth)

It was simply the cheapest large CSA cable there was.

Graham

New amp and speakers
 

In article , Eeyore
wrote:


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.

You mean something like the SCAMP (Society for Cruelty to AMPlifiers)
article in the Hi Fi News section of audiomisc.co.uk ? :-)


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.

Alas, SCAMP seems alive and well. :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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New amp and speakers
 

In article , Eeyore
wrote:


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.

A few decades ago the power devices were rather prone to secondary
breakdown, and had quite modest IV handling.

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.

Not sure what 'secrets' remain. Even by about 1980 I had no problem
designing a 200+ Wpc amp that used no IV SOA limiting for protection. Just
needed power line fuses. Just a matter of designing for the task. I'd
always thought that IV limiters were a dubious idea. The original 405 just
confirmed that for me. Given how much device technology has moved on, I'd
expect it to be a trivial to make a safe amp with no explicit SOA
protection these days if the designer knows what to do.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

New amp and speakers
 

In article , Eeyore
wrote:


Jim Lesurf wrote:


BTW I'm currently working on comparing loudspeaker cables.
Investigating out one or two aspects I can't recall being dealt with
before in any detail. All being well, results will appear first in HFN
in coming months.
:-)

Oh they CAN and DO.

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.

Studio Sound did this of course about 25 years ago under controlled
(i.e. non 'hi-fi') conditions and found exactly the same.

Yes, it is fairly well known that CLRG variations can cause changes in the
frequency/phase response when combined with the source and load
impedances. That wasn't really what I was referring to. I am presently
investigating other possible factors that some people have said can affect
performance. No conclusions as yet, but some interesting measured
results... :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

New amp and speakers
 

In article , Eeyore
wrote:


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 ?

Unless you qualify that by giving values, frequencies, etc, then no
amplifier could be said to return an unconditional 'yes'. But if you set
plausible values for domestic audio, then various amplifiers would return
'yes'. So your question is rather too vague and sweeping to be useful.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

New amp and speakers
 

In article , Serge Auckland
wrote:

"Jim Lesurf" wrote in message
...


Perhaps also worth recalling that around this time HFN organised a
detailed set of listening comparisons. The results of which showed
that the listeners couldn't tell one amp from another when all were
used with the same system gain and none were being taken outwith their
limits. The amps tested included the 405 IIRC.

Yes, but the operative bit here is "none taken outside their limits".
The original 405 could be so taken fairly readily due to the limited
current capability, and, as you pointed out, the severe IV limiting on
reactive loads. I don't know which test you are referring to, so don't
know what the load was. I recall a similar test being done using Yamaha
NS1000 monitors, you may remember we corresponded about that one a year
or two back.

A number of similar tests were done during the late 1970s and early 1980s
with broadly similar conclusions. The one I had in mind was published in
the June 1978 issue of HFN. I've not had a chance to carefully re-read it
this morning, but from a quick scan, they used a Quad II, 303, and 405. On
page 75 the article says, "Yamaha NS 1000 loudspeakers were used (although
this would not have been Acoustical's preference)" They used a scope to
check there was no clipping or limiting that might show up.

Maybe some subjective reviewers came to fancy the NS1000 because it tended
to be what they'd call "revealing". i.e. causing current limiting in some
amplifiers so they could hear a difference when they wound the wick up.
:-) Afraid I've forgotten what we said previously about the NS1000, though.

The Nov 1978 issue re-visited this kind of test, and later comparisons were
expanded to use different amps and speakers. Martin Colloms also in the Nov
1978 issue produced some measured results showing the changes in frequency
response for some examples of amp-cable-speaker combinations due to cable
impedance interactions with source and load.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

New amp and speakers
 

"Eeyore" wrote in message
...


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

In a way I do, almost every time I use my Hi-Fi. My Meridian-based system
has the volume control as part of the loudspeakers, and the steps are 1dB at
the levels I listen at. (I think but haven't measured that they get further
apart as volume goes down, and closer together at very high volumes, but at
the volume I listen at, they are ~1dB apart as measured on my Sound Level
Meter)

Adjusting the volume by 1 step isn't readily perceptible. I think I can hear
a difference, but as I've just made the change, that's not surprising. I
certainly couldn't step out of the room and return and tell a 1dB difference
on programme. Two steps seems to be the minimum I can tell readily, although
even here, I don't think I could step out of the room and return and say the
volume has changed. 3dB seems the minimum to tell readily there's been a
change.

Similarly, with tone changes, the Meridians have treble and bass shelving in
1dB steps, and a 1dB change is imperceptible, 2dB in the treble and 3dB in
the bass becomes noticeable, boost more readily noticeable than cut.

It is possible, however, that I am rather less sensitive to level change
than others, so I would not be dogmatic that because I can't hear it, others
can't either. On the other hand, I'm extremely sensitive to stereo
positioning, a 1dB difference in loudness between L and R moves the image
enough to be irritating.

S.



--
http://audiopages.googlepages.com

New amp and speakers
 

On 2 Jul, 20:05, Eeyore
wrote:
David Looser wrote:
"Glenn Richards" wrote

opinions are divided on this group but it does make a difference.

I love that!, "opinion is divided, *but I'm right"

In your opinion of course.

Oi ! *I'M right ! OK ?

Graham

Glenn has always had lots of opinions, but never the guts actually to
put them to the test. I am still offering £1,000 to *anyone* who can
hear differences among cables under standard double-blind and level-
matched conditions. That offer has been on the table now for more than
seven years, with not one single contender from all these loudmouths.

New amp and speakers
 

New amp and speakers
 

Eiron wrote:
wrote:
On 2 Jul, 20:05, Eeyore
wrote:
David Looser wrote:
"Glenn Richards" wrote
opinions are divided on this group but it does make a difference.
I love that!, "opinion is divided, but I'm right"
In your opinion of course.
Oi ! I'M right ! OK ?

Graham

Glenn has always had lots of opinions, but never the guts actually to
put them to the test. I am still offering £1,000 to *anyone* who can
hear differences among cables under standard double-blind and level-
matched conditions. That offer has been on the table now for more than
seven years, with not one single contender from all these loudmouths.

Welcome back. The lunatics have taken over the asylum since you left!


Well, not entirely. Didn't actually see Stewart's post, just your reply.

d