In article , Form@C
wrote:
On Sun, 04 Jan 2004 11:09:48 +0000, Ian Molton wrote:

On Sun, 04 Jan 2004 08:27:50 GMT "Form@C" wrote:

It's no use turning down a 100-200W monster amp because you arn't
running them at their best.

what?

Sorry, it wasn't very clear was it? What I meant to say is that "high"
power amps are usually designed and set up to produce their best results
an appreciable way up to their rated power output.

That isn't my own experience. Nor was it what I intended when designing
200Wpc power amps myself. :-)

The purpose of the high power (and voltage/current) ratings is to ensure
the amp can be used in wider range of circumstances, hence encompassing
higher powers and more awkward/less efficient loads. Thus the idea is that
the amp should sound good over a wider range of levels, from low to high.
If it does not sound right at low power, then something is wrong with it,
irrespective of its power rating.


They won't perform at their best at a very low percentage of that level.
I *know* that many are *supposed* to be class A at low levels, but they
are generally not designed as class A amps, and are not really running
as such (the output stage quiescent current is usually too low to allow
correct class A operation on a class AB amp).

In general, class AB amps are not designed as class A or class B. This
isn't really a matter of the power rating as such. However...

The quiescent current in most of the good high-power amps I have known was
similar to, or higher, than in lower power amps. Hence your statement about
"usually too low" could be argued to probably apply more to low power amps
than to high power ones. High power amps should work nicely at low powers
in terms of the 'class A at low powers' argument. Also, using the devices
with lower levels of collector-emitter (or equivalent) variation in
fractional terms also should help here. I would not personally take this
"class A at low power" argument very far, though, as the reality isn't
really described by this. The problems may be elsewhere.

Thus it is a mistake to judge low-power audio systems by simply turning
down the volume on existing "high" power equipment & changing the
speakers for more sensitive ones.

Depends upon the amp and the speakers. :-)

FWIW I use +200Wpc amps with speakers like ESL63's and before that ESL57's.
Been doing this for around 20 years, now. Generally I only play at quite
low mean power levels. The results sound fine to me even though I never go
anywhere near 200 Wpc. Having an amp that can drive difficult loads means
the amp is finding this task easy, even when I once used parallel pairs of
ESL57's for a while. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Roy
wrote:


No that's nonsense. Most power amps are running at a fraction of their
RMS max (let alone peak max) most of the time. Let me quote you an
example.

I listened to a pair of ATC SCM10s driven by an AVI 250W/ch amp with a
power meter attached. Listenening at realistic (not thunderous) levels
to Sibelius Violin Concerto, the quiet introduction drew barely a watt
per channel with a few moments of maybe 5w. The orchestral tutti (2 very
loud chords) drew an instantaneous 400W per channel.

FWIW my experience is similar. With acoustic/serious music that is well
recorded I'd would have said that peak/mean ratios of 15 - 20 dB is fairly
common.

May be different for heavily compressed/limited 'pop' music, though. But
then in general I don't listen to that.... :-) Ok, Ok, do sometimes. I
admit to listening to 'Sounds of the 60's' on R2. This seems to have a
dynamic range of about 1dB and a peak/mean of about 0dB. ;-

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Roy
wrote:


No that's nonsense. Most power amps are running at a fraction of their
RMS max (let alone peak max) most of the time. Let me quote you an
example.

I listened to a pair of ATC SCM10s driven by an AVI 250W/ch amp with a
power meter attached. Listenening at realistic (not thunderous) levels
to Sibelius Violin Concerto, the quiet introduction drew barely a watt
per channel with a few moments of maybe 5w. The orchestral tutti (2 very
loud chords) drew an instantaneous 400W per channel.

FWIW my experience is similar. With acoustic/serious music that is well
recorded I'd would have said that peak/mean ratios of 15 - 20 dB is fairly
common.

May be different for heavily compressed/limited 'pop' music, though. But
then in general I don't listen to that.... :-) Ok, Ok, do sometimes. I
admit to listening to 'Sounds of the 60's' on R2. This seems to have a
dynamic range of about 1dB and a peak/mean of about 0dB. ;-

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On Sun, 4 Jan 2004 00:01:48 +0000 (UTC), "David"
wrote:

No. Highly efficient speakers are generally less accurate than "lowish"
efficiency speakers. They tend to become unlinear at high outputs.

Actually, the exact opposite is true. It's insensitive speakers that
have problems at high SPLs, for reasons which should be obvious.

I have often found that the easiest way to deal with bass is just not to do
it at all! Small, sealed (infinite baffle) enclosures made with very heavy
damped panels and a simple crossover using very high quality drive units
often sound fantastic (BBC monitor LS1 fans may now smile smugly) BUT they
need vast amounts of amplifier power to produce any response below 100Hz
(and no - a subwoofer is not the answer)

Oh yes, it is! And BTW, those speakers can't *handle* vast amounts of
power, so you are stuck with no bass.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sun, 4 Jan 2004 00:01:48 +0000 (UTC), "David"
wrote:

No. Highly efficient speakers are generally less accurate than "lowish"
efficiency speakers. They tend to become unlinear at high outputs.

Actually, the exact opposite is true. It's insensitive speakers that
have problems at high SPLs, for reasons which should be obvious.

I have often found that the easiest way to deal with bass is just not to do
it at all! Small, sealed (infinite baffle) enclosures made with very heavy
damped panels and a simple crossover using very high quality drive units
often sound fantastic (BBC monitor LS1 fans may now smile smugly) BUT they
need vast amounts of amplifier power to produce any response below 100Hz
(and no - a subwoofer is not the answer)

Oh yes, it is! And BTW, those speakers can't *handle* vast amounts of
power, so you are stuck with no bass.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sun, 04 Jan 2004 08:27:50 GMT, "Form@C" wrote:

On Sat, 03 Jan 2004 22:11:11 +0000, Roy wrote:

"Form@C" wrote in message
news
On Sat, 03 Jan 2004 15:47:40 +0000, Fish wrote:

I'm moving to a smaller house soon and alas my present audio stuff
will need changing for a smaller, more neighbour-friendly set-up.

At present I have a Bryston pre/power combo (250-watter) and a pair of
large Dynaudio floorstanders. Nothing-special CD-player as imho cd-players
are nothing special.

Why the hell do you want to change anything? Just crank the volume
down a notch or two!

Sheesh - 250W is enough to cook on.... :-)

No, barely adequate.

Depends on the system, but often true.

Have a look at any mid-price, fairly sensitive, half-decent speakers &
couple them with a little pure class A amp. Valves are nice...

No, they aren't - if you want *accurate* reproduction.

(you
could even build your own! I've just built a MOSFET headphone amp that
would scale up quite easily.

And what have MOSFETs to do with valves?

I bet it only cost me £30 or so if you
include the bits from the "scrap box".) You may be surprised at how
little power you really need; most people can get away with about 3W to
5W per channel under real-life surroundings.

During the "average" situation maybe. Lets say a symphony orchestra
burbling away steadily. Then comes the climax. One or two huge peak
demands. Maybe several hundred watts. It is the 5W valve amp's inability
to cope with peak requirements without distortion which is it's weakness.

But in this case the OP wants a more neighbour-friendly system... :-) We
arn't allowed to aim at full concert-hall volume here! In any case, how
close would you be sitting to the orchestra to reach the dB level for
"several hundred watts" *at your seat*?

That's typically 100-105dB, so it depends on your room and your
speakers.

Remember to take the sqrt of the
power each time you double the distance back. You tend to sit far closer
to speakers than you do to the orchestra in a concert hall.

And the square law no longer applies once you are half way down the
room..................

Try it. Use a
*good* low power amp and sensitive speakers. It's no use turning down a
100-200W monster amp because you arn't running them at their best. They
will be set up, probably anyway, to sound best at about 25-50% of full
output.

Absolute garbage!

Remember that to double the volume you have
to square the power,

No, you need ten times the power.

so 250W is about twice the volume of a 25W amp,
which in turn is about twice the volume of a 5W amp! The more sensitive
your speakers are, the better.

Yes, but you still need good amplifier power to ensure adequate
headroom for peaks.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sun, 04 Jan 2004 08:27:50 GMT, "Form@C" wrote:

On Sat, 03 Jan 2004 22:11:11 +0000, Roy wrote:

"Form@C" wrote in message
news
On Sat, 03 Jan 2004 15:47:40 +0000, Fish wrote:

I'm moving to a smaller house soon and alas my present audio stuff
will need changing for a smaller, more neighbour-friendly set-up.

At present I have a Bryston pre/power combo (250-watter) and a pair of
large Dynaudio floorstanders. Nothing-special CD-player as imho cd-players
are nothing special.

Why the hell do you want to change anything? Just crank the volume
down a notch or two!

Sheesh - 250W is enough to cook on.... :-)

No, barely adequate.

Depends on the system, but often true.

Have a look at any mid-price, fairly sensitive, half-decent speakers &
couple them with a little pure class A amp. Valves are nice...

No, they aren't - if you want *accurate* reproduction.

(you
could even build your own! I've just built a MOSFET headphone amp that
would scale up quite easily.

And what have MOSFETs to do with valves?

I bet it only cost me £30 or so if you
include the bits from the "scrap box".) You may be surprised at how
little power you really need; most people can get away with about 3W to
5W per channel under real-life surroundings.

During the "average" situation maybe. Lets say a symphony orchestra
burbling away steadily. Then comes the climax. One or two huge peak
demands. Maybe several hundred watts. It is the 5W valve amp's inability
to cope with peak requirements without distortion which is it's weakness.

But in this case the OP wants a more neighbour-friendly system... :-) We
arn't allowed to aim at full concert-hall volume here! In any case, how
close would you be sitting to the orchestra to reach the dB level for
"several hundred watts" *at your seat*?

That's typically 100-105dB, so it depends on your room and your
speakers.

Remember to take the sqrt of the
power each time you double the distance back. You tend to sit far closer
to speakers than you do to the orchestra in a concert hall.

And the square law no longer applies once you are half way down the
room..................

Try it. Use a
*good* low power amp and sensitive speakers. It's no use turning down a
100-200W monster amp because you arn't running them at their best. They
will be set up, probably anyway, to sound best at about 25-50% of full
output.

Absolute garbage!

Remember that to double the volume you have
to square the power,

No, you need ten times the power.

so 250W is about twice the volume of a 25W amp,
which in turn is about twice the volume of a 5W amp! The more sensitive
your speakers are, the better.

Yes, but you still need good amplifier power to ensure adequate
headroom for peaks.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:
On Sun, 04 Jan 2004 08:27:50 GMT, "Form@C" wrote:

[snip]

Hmmn, looks like I might inadvertently have started a slight disturbance
in the noodle shop here. The Linux groups have nothing on the audio
ones, I see.

Well, I will be changing my setup. Largely because the present speakers
are darn large and require a lot of air around them. There simply won't
be the space for them in a smaller room.

Besides, small is the new big and minimalist is the new maximalist, as
I'm sure you'll all know from reading the wise and almost shatteringly
profound advice on lifestyle choices in this weekend's Sunday
supplements. Strangely, they don't mention hifi, or Linux.



Fish

Stewart Pinkerton wrote:
On Sun, 04 Jan 2004 08:27:50 GMT, "Form@C" wrote:

[snip]

Hmmn, looks like I might inadvertently have started a slight disturbance
in the noodle shop here. The Linux groups have nothing on the audio
ones, I see.

Well, I will be changing my setup. Largely because the present speakers
are darn large and require a lot of air around them. There simply won't
be the space for them in a smaller room.

Besides, small is the new big and minimalist is the new maximalist, as
I'm sure you'll all know from reading the wise and almost shatteringly
profound advice on lifestyle choices in this weekend's Sunday
supplements. Strangely, they don't mention hifi, or Linux.



Fish

On Sun, 04 Jan 2004 12:31:32 GMT, "Form@C" wrote:

On Sun, 04 Jan 2004 11:09:48 +0000, Ian Molton wrote:

On Sun, 04 Jan 2004 08:27:50 GMT
"Form@C" wrote:

It's no use turning down a
100-200W monster amp because you arn't running them at their best.

what?

Sorry, it wasn't very clear was it? What I meant to say is that "high"
power amps are usually designed and set up to produce their best results
an appreciable way up to their rated power output.

No, they aren't.

They won't perform at
their best at a very low percentage of that level.

Absolute garbage!

I *know* that many are
*supposed* to be class A at low levels, but they are generally not
designed as class A amps, and are not really running as such (the output
stage quiescent current is usually too low to allow correct class A
operation on a class AB amp).

Excuse me? A class AB amp *always* runs in class A up to some
predetermined level, which may be less than 1 watt or as many as 50
watts. I use an amplifier which runs in true class A up to 50 watts
into 8 ohms, and in class AB above that level, up to its rated maximum
of 400 watts into 1 ohm. It sounds just fine at very low levels.

Thus it is a mistake to judge low-power
audio systems by simply turning down the volume on existing "high" power
equipment & changing the speakers for more sensitive ones.

Depends on the amp......................
--

Stewart Pinkerton | Music is Art - Audio is Engineering