Amplifier power
 

wrote:

I should also mention that I was thinking of using a Benchmark DAC1 as
a pre-amp (hence my post elsewhere on this group). So I'm thinking
about a power amp. Is the Quad 909 needlessly powerful for example?
I want a well built amp of sufficient power for my modestly sized room
and quite sensitive speakers.

Get a *professional* amp not bloody 'hi-fi' if you're serious. You can pick them
up used and still in excellent condition on ebay for pennies in the pound. They
may have some 'rack rash' from touring but they'll utterly blow away audiophool
****.

For example I recently bought one of my own designs, a Studiomaster 700D (which is
only 200+200W into 8 ohms but that's fine for just drining SR tweeters) for a mere
£62. It was 10 1/2 years old yet looked (apart from the scratches on the outside)
about 2 years old inside.

s/n ratio ? 100dB UNWEIGHTED - about 113dB A-weighted.
THD ? 0.008% @ 1 kHz into 8 ohms at rated power.
Full power bandwidth ? 45 kHz !
Freq response ? +0, -0.2 dB @ 20 Hz and 20kHz. (or +/- 0.1dB if you prefer it that
way).

Hi-Fi ? Doesn't even come close. Not even within spitting distance.

Graham

Amplifier power
 

Rob wrote:

Eeyore wrote:

Once only wrote:

wrote in message

If all (properly designed) amps sound the same, how do I decide which
amp to buy?

Is it just a case of choosing one with sufficient power output and how
do I determine this?

No, thats not true - the myth of long wire with gain.
Amplifiers can have very similar specs but have different
sonic characters and abilities.
Bandwidth and an amps ability to pump out the amperes
when fronted with an awkward load etc etc etc.
If I were you the first thing is to not pay too much attention
to the big girls blouses of this group.
Do yourself a favour, don't heed mag reviewers advice either.
Try the pre-owned market, plenty of stereo bargains to be had.
This is just one example, the Pioneer A400 was a huge success
because of it ultra wide stable bandwidth (5 - 100) and it's
impressive ability to drive any loudspeaker and remain stable -
thats the ability to churn out amperes!
It sold by the truck load and often crops up in the for sale ads,
and it is proven to be a rugged longstander, can be picked up
for less than £100. But then there are others, Nad, and even Sony
from the late 80's and early 90's.
First port of call believe it or not would be Cash Converters,
then the specialist pre-owned dealers, then the small ads.
Once you've found a model, look it up!
Don't bother with Naim or Arcam, over-priced and nothing
special.

But don't buy antiques. No matter how well they were supposed to sound. All
the electrolytic caps will need replacing and standards weren't as high then.
Modern amplifiers are much better on the whole.

cross-posted intentionally to rec.audio tech

I have a 20 year old (at least) NAD 3020 - works perfectly but sounds
distinctly soft/mellow compared to a newish SS amp, and indeed an even
older Pioneer receiver. Is this a symptom of old caps, and/or poor design?
Rob

I believe I already answered this but the OP's multi-posting may have effed things
up.

It certainly wasn't poorly designed. In fact I have a great deal of respect for the
designer, a Norwegian whose name eludes me now. He used to work for Dolby Labs btw
at one time btw IIRC. I've have many hours of satisfactory listening through one at
some friends' house through some Mission speakers too (when they still used decent
SEAS units).

Graham

Amplifier power
 

Eeyore wrote:
LAB wrote:

Graham,
don't waste time reading quoting and bad words from Eeyore...

At least the thread is in both groups now.

The OP was in breach of netiquette.

Now punishable by 6 months to 2 years....


geoff

Amplifier power
 

geoff wrote:

Eeyore wrote:
LAB wrote:

Graham,
don't waste time reading quoting and bad words from Eeyore...

At least the thread is in both groups now.

The OP was in breach of netiquette.

Now punishable by 6 months to 2 years....

Or garrotting.

Graham

Amplifier power
 

On 2008-10-13, Eeyore wrote:


wrote:

Jim Lesurf wrote:

It would depend on various factors: What kind of music you like. How large
your listening room is. What speakers you will be using. etc.

Classical music - not excessively loudly but of course orchestral
climaxes can be loud.
Digital sources - not vinyl.
Room 11' x 13' x 8' high (rather small probably for the speakers Focal
JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB)

An orchestra even in the auditorium can peak at over 120dB.

Do you have a reference for this? I have been looking for credible
sources for peak orchestral SPLs in the auditorium for a long while.

I have quite a few health & safety measurements of very good credibility
inside the orchestra and a few at the conductor's rostrum. However I
have only semi-credible figures for places in the auditorium and they
only go up to 109 dB SPL.

--
John Phillips

Amplifier power
 

John Phillips wrote:

Eeyore wrote:
wrote:
Jim Lesurf wrote:

It would depend on various factors: What kind of music you like. How large
your listening room is. What speakers you will be using. etc.

Classical music - not excessively loudly but of course orchestral
climaxes can be loud.
Digital sources - not vinyl.
Room 11' x 13' x 8' high (rather small probably for the speakers Focal
JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB)

An orchestra even in the auditorium can peak at over 120dB.

Do you have a reference for this? I have been looking for credible
sources for peak orchestral SPLs in the auditorium for a long while.

It's a 'well known fact' amongst audio professionals. Google it.


I have quite a few health & safety measurements of very good credibility
inside the orchestra and a few at the conductor's rostrum.

In other words completely useless because they haven't the tiniest clue what
they're measuring. Thankfully or even orchestras would have to be banned from
playing for HSE reasons.


However I have only semi-credible figures for places in the auditorium and they
only go up to 109 dB SPL.

A or C weighted on fast or slow response ? The average dB meter is about as useful
as a wet blanket when measuring either impulses or frankly most music. There is no
correlation between industrial hearing damage levels as measured by a typical dB
meter and music because the waveforms and wavefronts are WILDLY different.

Graham

p.s. I know what I'm talking about. Precious few do. But then I'm an audio
professional.

Amplifier power
 

Eeyore wrote...

Or garrotting.

Isn't that having your Decca London retipped?

--
Ken

http://www.members.lycos.co.uk/buddyduck/

Amplifier power
 

On 14 Oct, 00:40, Eeyore
wrote:
John Phillips wrote:
Eeyore *wrote:
wrote:
Jim Lesurf wrote:

It would depend on various factors: What kind of music you like. How large
your listening room is. What speakers you will be using. etc.

Classical music - not excessively loudly but of course orchestral
climaxes can be loud.
Digital sources - not vinyl.
Room 11' x 13' x 8' high (rather small probably for the speakers Focal
JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB)

An orchestra even in the auditorium can peak at over 120dB.

Do you have a reference for this? *I have been looking for credible
sources for peak orchestral SPLs in the auditorium for a long while.

It's a 'well known fact' amongst audio professionals. Google it.

I have quite a few health & safety measurements of very good credibility
inside the orchestra and a few at the conductor's rostrum.

In other words completely useless because they haven't the tiniest clue what
they're measuring. Thankfully or even orchestras would have to be banned from
playing for HSE reasons.

However I have only semi-credible figures for places in the auditorium and they
only go up to 109 dB SPL.

A or C weighted on fast or slow response ? The average dB meter is about as useful
as a wet blanket when measuring either impulses or frankly most music. There is no
correlation between industrial hearing damage levels as measured by a typical dB
meter and music because the waveforms and wavefronts are WILDLY different..

Graham

p.s. I know what I'm talking about. Precious few do. But then I'm an audio
professional.- Hide quoted text -

- Show quoted text -

Clearly then, you'll know that having two speakers increases the
nominal sensitivity by 3dB for a central sound, and having them in an
average living room gives you another 3dB or so of reverberant sound,
so you can hit a 120dB peak from 91 db/watt speakers with about 23dB
of amp power, which is 200 watts. Not trivial, but readily obtainable
from many modern amps.

Amplifier power
 

wrote:

Eeyore wrote:
John Phillips wrote:
Eeyore wrote:
wrote:
Jim Lesurf wrote:

It would depend on various factors: What kind of music you like. How large
your listening room is. What speakers you will be using. etc.

Classical music - not excessively loudly but of course orchestral
climaxes can be loud.
Digital sources - not vinyl.
Room 11' x 13' x 8' high (rather small probably for the speakers Focal
JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB)

An orchestra even in the auditorium can peak at over 120dB.

Do you have a reference for this? I have been looking for credible
sources for peak orchestral SPLs in the auditorium for a long while.

It's a 'well known fact' amongst audio professionals. Google it.

I have quite a few health & safety measurements of very good credibility
inside the orchestra and a few at the conductor's rostrum.

In other words completely useless because they haven't the tiniest clue what
they're measuring. Thankfully or even orchestras would have to be banned from
playing for HSE reasons.

However I have only semi-credible figures for places in the auditorium and they
only go up to 109 dB SPL.

A or C weighted on fast or slow response ? The average dB meter is about as useful
as a wet blanket when measuring either impulses or frankly most music. There is no
correlation between industrial hearing damage levels as measured by a typical dB
meter and music because the waveforms and wavefronts are WILDLY different.

Graham

p.s. I know what I'm talking about. Precious few do. But then I'm an audio
professional.- Hide quoted text -

Clearly then, you'll know that having two speakers increases the
nominal sensitivity by 3dB for a central sound, and having them in an
average living room gives you another 3dB or so of reverberant sound,
so you can hit a 120dB peak from 91 db/watt speakers with about 23dB
of amp power, which is 200 watts.

Where in the room ? Sensitivity is measured at 1 m.


Not trivial, but readily obtainable from many modern amps.

Also depends on the size of the room, furnishings, surface reflectivities etc.

My numbers related only to the nearfield SPL. Total generalisations are impossible.

Graham

Amplifier power
 

In article
,
wrote:
On 14 Oct, 00:40, Eeyore wrote:
John Phillips wrote:
Eeyore wrote:
wrote:

An orchestra even in the auditorium can peak at over 120dB.

Do you have a reference for this? I have been looking for credible
sources for peak orchestral SPLs in the auditorium for a long while.

It's a 'well known fact' amongst audio professionals. Google it.

For some reason I have come to be wary of claims thrown around on the basis
of being a "well known fact". That sometimes seems to mean, "Loads of
people have been saying it to one another on the basis that someone else
told them. They've been doing this for so long that no-one can recall who
made it up in the first place." :-)


In other words completely useless because they haven't the tiniest
clue what they're measuring. Thankfully or even orchestras would have
to be banned from playing for HSE reasons.

However I have only semi-credible figures for places in the
auditorium and they only go up to 109 dB SPL.

IIRC I read an old article by John Crabbe a while ago that reported
measurements. I can't recall details, but if I do I'll report them.


Clearly then, you'll know that having two speakers increases the nominal
sensitivity by 3dB for a central sound, and having them in an average
living room gives you another 3dB or so of reverberant sound, so you can
hit a 120dB peak from 91 db/watt speakers with about 23dB of amp power,
which is 200 watts. Not trivial, but readily obtainable from many modern
amps.

FWIW The effect of room reverb in UK domestic rooms might be somewhat
higher than a 3dB gain. I did some analysis of this a while ago (see Hi Fi
News August 2008). Hard to give a figure as it will probably vary from room
to room, but 3dB may be on the low side as an estimate of what is typical.
IIRC some texts also give details that indicate well above 3dB for this.

That said (again as discussed in the HFN article) there is a distinction
between the actual instantaneous peak measured power, and the peak level
perceived, due to the way human hearing tends to 'integrate' the effect of
short term delayed reflections into one percieved peak.

Slainte,

Jim

--
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