how good are class D amplifiers?
 

"Jim Lesurf" wrote in message


e.g. Despite Sony being a regarded name I recently tried
a DVD recorder from them. It had a cooling fan that was
so loud that it was distracting when listening to
dialogue on items recorded. This is absurd and needless,
yet when I asked a local Sony center their reaction was
'they all do it'. They seemed not to think it was a
problem, and clearly had no idea that quiet fans can be
bought. Perhaps they think everyone is too busy looking
at the pictures to notice the sound of a helicopter
accompanying it. ;-

I find no logic to the noise levels of DVD recorders. I have a
Philips/Magnavox at home that is as quiet as a mouse (no fan) and a Philips
at church I bought a few months later that has a fan and is noisy. I just
bought a RCA with a hard drive in addition to the DVD burner, and it is
smaller, cooler, and has no fan.

how good are class D amplifiers?
 

"Arny Krueger" wrote in message
...
"Keith G" wrote in message


"Arny Krueger" wrote

(in the context of amplifiers)


Tough titty - I opened the topic up - it happens, it'll be about pickled
onions soon...



There's nothing wrong with wondering whether or not a
full set of conventional measurements are a reliable
guide to sound quality in normal listening. It is a
question that has been answered again and again,
affirming the idea that a full set of conventional
measurements are a reliable guide to sound quality.

So simple, isn't it?

Not at all. It is almost impossible to find a set of manufacturer's
specs for a consumer amplifier, that includes anything like a full
set of conventional measurements.


Wake up. Anyone who is staring hard at figures to 'get an idea' will
probably be looking in the trade press at people like Martin Colloms or
Noel Keywood...



When you are selecting kit, you just
buy a heap of stuff where the figures (or, at least, the
figures 'as claimed') tell you it'll work and Bob's your
uncle!

Typical of your stupid straw-men, Keith. The topic is amplfiiers,


Was - see above....


and now
you're ranting and raving like a loon about "kit" which as I
understand your vernacular, means any kind of audio gear.


Define 'ranting and raving'....??



Yet the (hifi) world is full of people who have
done just that and who are not happy with the result -
time and time again, some of 'em!

That's because they made the same stupid assumptions that you have
embodied here, Keith.


Could explain what those 'assumptions' might be?



You'd think it would be impossible to get it wrong,
wouldn't you??

Keith, with loons like you misreading everything that's posted, I'm
not the least bit surprised.


I think you should move on to *decaff*, Arny...

how good are class D amplifiers?
 

"Jim Lesurf" wrote

e.g. Despite Sony being a regarded name I recently tried a DVD
recorder
from them. It had a cooling fan that was so loud that it was
distracting
when listening to dialogue on items recorded. This is absurd and
needless,
yet when I asked a local Sony center their reaction was 'they all do
it'.
They seemed not to think it was a problem, and clearly had no idea
that
quiet fans can be bought. Perhaps they think everyone is too busy
looking
at the pictures to notice the sound of a helicopter accompanying it.
;-


A further thought - if you are not averse, one thing you could try is to
have the lid off and line the tin with sticky 'acousting damping'
panels* (or floor tiles), if there's enough room?? It couldn't do any
harm - and ensure a good airflow over the machine, of course...


*Can't remember the name offhand but all the speaker parts people do
them.

how good are class D amplifiers?
 

"Arny Krueger" wrote in message
. ..
"Serge Auckland" wrote in
message

I think that with electronics, it is pretty much
impossible to get it wrong if you buy on the figures,
*provided* that you understand what the figures are
telling you *and* that the published figures are
reliable.

Right - that's the same think we've been trying to explain to Keith
and his fellow loons for a dog's age.


Loon?

I get *cloned* - you get what?


I bought my last 4 sets of speakers either unheard, or heard and
thought they sounded pretty poor in the demo room.


Add them to the 600 power amps for DBT-ing you mentioned the other day
and no-one could accuse you of being feint-hearted about it, could
they??

how good are class D amplifiers?
 

"Keith G" wrote in message
...

"Jim Lesurf" wrote

e.g. Despite Sony being a regarded name I recently tried a DVD
recorder
from them. It had a cooling fan that was so loud that it was
distracting
when listening to dialogue on items recorded. This is absurd and
needless,
yet when I asked a local Sony center their reaction was 'they all do
it'.
They seemed not to think it was a problem, and clearly had no idea
that
quiet fans can be bought. Perhaps they think everyone is too busy
looking
at the pictures to notice the sound of a helicopter accompanying it.
;-


A further thought - if you are not averse, one thing you could try is
to have the lid off and line the tin with sticky 'acousting damping'
panels* (or floor tiles), if there's enough room?? It couldn't do any
harm - and ensure a good airflow over the machine, of course...


*Can't remember the name offhand but all the speaker parts people do
them.


I remember now - it's called 'Dedsheet'!

(How TF could I not remember a sparkly little name like that? :-)

how good are class D amplifiers?
 

"Arny Krueger" wrote


I find no logic to the noise levels of DVD recorders. I have a
Philips/Magnavox at home that is as quiet as a mouse (no fan) and a
Philips at church I bought a few months later that has a fan and is
noisy. I just bought a RCA with a hard drive in addition to the DVD
burner, and it is smaller, cooler, and has no fan.



Steady on, old bean - you'll have that transatlatic twerp raving about
this being an *amplifier* thread in a moment....

:-)

Fan noise (was: how good are class D amplifiers?)
 

"Keith G" wrote in message
...

A further thought - if you are not averse, one thing you could try is to
have the lid off and line the tin with sticky 'acousting damping' panels*
(or floor tiles), if there's enough room?? It couldn't do any harm - and
ensure a good airflow over the machine, of course...


*Can't remember the name offhand but all the speaker parts people do
them.


I remember now - it's called 'Dedsheet'!

You will have to find out if the main problem is the noise of the air
turbulence from the fan or whether the fan is making the case vibrate.
Dedsheet and similar damping sheets (there are a lot out there) will only
work on the case vibration and my guess is it is probably the other. Test
by pressing soft things on the outside of the case to reduce the vibration -
if that reduces the noise then damping sheet will help. You can reduce
noise from the air movement by making the air pass through a tunnel lined
with sound absorbing material, of course wide enough not to reduce the air
flow. If you have to bend the tunnel to fit it in, so much the better.

--
Tony W
My e-mail address has no hyphen
- but please don't use it, reply to the group.

how good are class D amplifiers?
 

In article ,
Keith G wrote:
So simple, isn't it? When you are selecting kit, you just buy a heap of
stuff where the figures (or, at least, the figures 'as claimed') tell
you it'll work and Bob's your uncle! Yet the (hifi) world is full of
people who have done just that and who are not happy with the result -
time and time again, some of 'em!

You'd think it would be impossible to get it wrong, wouldn't you??

Well, you apparently buy on only what your ears tell you and are never
satisfied for more than a few minutes. Hence all your posts about your
latest toy - home made or whatever. If each of these 'improvements' is so
dramatic as you claim, you must have started from a very poor base.
Thing is you seem to be going in the opposite direction. Many older ones
here will have started out with SET amps and single driver speakers - even
horn loaded. But moved on as better became available. That's not to say we
didn't gain a deal of pleasure in starting out down this long route - but
revisiting those techniques of yore is always a disappointment.

--
*Sleep with a photographer and watch things develop

Dave Plowman London SW
To e-mail, change noise into sound.

how good are class D amplifiers?
 

"Keith G" wrote in message

"Arny Krueger" wrote in message
. ..
"Serge Auckland" wrote in
message

I think that with electronics, it is pretty much
impossible to get it wrong if you buy on the figures,
*provided* that you understand what the figures are
telling you *and* that the published figures are
reliable.

Right - that's the same think we've been trying to
explain to Keith and his fellow loons for a dog's age.


Loon?

I get *cloned* - you get what?

I get sick of your habitual lying, Keith.

I bought my last 4 sets of speakers either unheard, or
heard and thought they sounded pretty poor in the demo
room.

Add them to the 600 power amps for DBT-ing you mentioned
the other day ...

In what alternative universe was that, Keith?

Fan noise (was: how good are class D amplifiers?)
 

"Tony" wrote in message
. uk

You will have to find out if the main problem is the
noise of the air turbulence from the fan or whether the
fan is making the case vibrate.

Easy enough to do, as the related noises sound vastly different.

Dedsheet and similar
damping sheets (there are a lot out there) will only work
on the case vibration and my guess is it is probably the
other.

IME the most profitable route is to look at the fan itself.

Vibration is usally caused by a fan that is out-of-balance or spinning too
fast or both.

Air turbulence noise is caused by a fan that has badly-designed blades, or
is spinning too fast or both.

It's easy enough to find fans that turn slow and have well-designed and
well-balanced rotating parts.


Test by pressing soft things on the outside of
the case to reduce the vibration - if that reduces the
noise then damping sheet will help.

After you get a good fan, any remaining vibration is usually best first
addressed by compliant mounting of the fan.

You can reduce noise
from the air movement by making the air pass through a
tunnel lined with sound absorbing material,

Good work if you have space for it.

of course
wide enough not to reduce the air flow. If you have to
bend the tunnel to fit it in, so much the better.

There's a lot to be said for simply parking the computer as far away as
possible and investing in longer cables for the display, keyboard and mouse.
USB-connected drives can address the problem of mounting removable media if
you do that a lot.