HY60
 

"Rob" wrote in message
...
Jim Lesurf wrote:
In article , Rob
wrote:

Do you think most off the shelf amplifiers are designed to be driven
hard continuously, and if not, how is the sound affected?

I still don't understand this 'all modern amplifiers sound the same'
thing - hence the question!

The problem with such vague and sweeping assertions or questions is
that
any 'answers' can only either also be vague and sweeping, or be based
on a
set of a assumptions that may not always apply. I would suspect that
different amplifiers will be designed on the basis of
a range of various assumptions about what the amp is to cope with.

Ignoring the "modern" I can make a clear distinction.

When Ted Rule designed the Armstrong 600 series amps he made them to
work
up to about 40wpc continuous. But with small heatsinks, so you could
only
get high levels for a modest time. Reason being that at the time most
audio
fans listened to music with a high peak/mean ratio and with a wide
dynamic
range. Generally with speakers that were not a difficult load.


As it happens, I got one of those (1974, a receiver) on ebay recently,
works perfectly. I just use it for radio with some Dynaudio speakers.

But when I designed the 700 I made them work up to much higher
sustained
levels, into lower loads, and gave them far bigger heatsinks. Reason
being
that by c1980 people wanted to play louder music on less efficient
speakers
with more awkwards impedances.

Not sure I understand - are you saying the 700 series could play music
at high levels for sustained periods, whereas the 600 series could
play music to similar levels, but only for short periods, beyond which
they broke?

And ever more of the music audio fans were
choosing had started down the hill to having boooger-all dynamic
range and
peak/mean ratio.


Don't understand that.

Some amps will clip or current limit in situations where another will
not.
Some will have their output modified by variations in load in a
different
way to others. etc. You may or not notice any difference, depending
on the
use circumstances.


I've been using a NAD 3020 perfectly happily for the past couple of
months. At low levels I would not claim to be able to differentiate
between the NAD and any of the SS amps I have (or had, I suspect). But
at higher levels I'm pretty sure something's going on - things that I
identify as difference. Won't bore anyone with adjectives but it's to
do with bass in the main.

I agree that "all modern amplifiers sound the same" is as daft an
assertion
as "all amplifiers sound different to the other". The reality,
though, may
be that many 'modern' amplifiers used in many situations produce
results
which the users would be unable to distinguish simply on the basis of
the
sound.


I'd agree with that on the whole. I'm pretty sure that the speakers I
use (Dynaudio) contribute to my 'amplifiers can vary'
experience/thesis.

Rob



Have you got the 'soft limiting' switched on? If so turn it off and try
again.


--
Woody

harrogate three at ntlworld dot com

HY60
 

Eeyore wrote:
Don't be silly. Even Metallica isn't square waves with no dynamic range.


or twice that using 4 ohm speakers.

Who mentioned 4 ohm speakers. Other than you ?

Serge and Woody mentioned them.

Haven't you heard, or heard about, the new Metallica CD?
It was in the news recently that it was so compressed that even heavy metal
fans were complaining, so pretty close to square waves with no dynamic
range.

Have some smilies for my next few posts, as you don't seem to recognize
humour. :-) :-) :-)

--
Eiron.

HY60
 

Eeyore wrote:
TonyL wrote:

I'll probably go for a
regulated supply simply because I have a nice transformer with a
27-0-27 volt secondary and a boxfull of 2n3055s and MJ2955s.

Do you also have a boxfull of heatsinks for them ?


Not since I raided my heatsink store for a previous project...a 13.8V 30A
transceiver supply. For this little project the metal enclosure will make an
adequate heatsink.

TonyL

HY60
 

Eiron wrote:

Eeyore wrote:

Don't be silly. Even Metallica isn't square waves with no dynamic range.

or twice that using 4 ohm speakers.

Who mentioned 4 ohm speakers. Other than you ?

Serge and Woody mentioned them.

But not the OP. Whom I hope is aware of the issue.


Haven't you heard, or heard about, the new Metallica CD?
It was in the news recently that it was so compressed that even heavy metal
fans were complaining, so pretty close to square waves with no dynamic
range.

I heard about the poor dynamic range.

It won't be square waves though, so no worse than full-power sinewave. And no
matter how hard you compress it'll probably still have 3 dB of dynamic range. I
speak as someone who has run such tests.

Graham

HY60
 

TonyL wrote:

Eeyore wrote:
TonyL wrote:

I'll probably go for a
regulated supply simply because I have a nice transformer with a
27-0-27 volt secondary and a boxfull of 2n3055s and MJ2955s.

Do you also have a boxfull of heatsinks for them ?

Not since I raided my heatsink store for a previous project...a 13.8V 30A
transceiver supply. For this little project the metal enclosure will make an
adequate heatsink.

How do you KNOW that ? I'm a heatsink expert too btw.

Graham

HY60
 

"TonyL"
Eeyore wrote:
TonyL wrote:

I'll probably go for a
regulated supply simply because I have a nice transformer with a
27-0-27 volt secondary and a boxfull of 2n3055s and MJ2955s.

Do you also have a boxfull of heatsinks for them ?


Not since I raided my heatsink store for a previous project...a 13.8V 30A
transceiver supply. For this little project the metal enclosure will make
an adequate heatsink.


** Don't let Eeysore spook you with his BS.

Your regulator pass transistors do not have to dissipate much heat - maybe
up to 15 watts each, worst case. Long as the case is 1.5 mm aluminium, it
will be fine.

Use at least a 2,200 uF cap on the regulated DC output rails, so the output
impedance is low and the pass devices only see the average DC current.


...... Phil

HY60
 

"Phil Allison" wrote in message
...

"TonyL"
Eeyore wrote:
TonyL wrote:

I'll probably go for a
regulated supply simply because I have a nice transformer with a
27-0-27 volt secondary and a boxfull of 2n3055s and MJ2955s.

Do you also have a boxfull of heatsinks for them ?


Not since I raided my heatsink store for a previous project...a 13.8V
30A transceiver supply. For this little project the metal enclosure
will make an adequate heatsink.


** Don't let Eeysore spook you with his BS.

Your regulator pass transistors do not have to dissipate much heat -
maybe up to 15 watts each, worst case. Long as the case is 1.5 mm
aluminium, it will be fine.

Use at least a 2,200 uF cap on the regulated DC output rails, so the
output impedance is low and the pass devices only see the average DC
current.


..... Phil





Point of interest: the larger the value of a capacitor the more
inductance it has, so it is a good idea to put some small value caps in
parallel to reduce any high-frequency content on the supply lines.
Something like a 0.1uF polyester will do, and if you live in an area if
high RF (i.e. near a transmitter site of any sort) you might even
consider another 10nF ceramic as well. Best location for these caps (if
they are not already present) is where the power leads connect to the
amp PCB.

I may get flamed, but in this high-noise environment in which we live
these days, such little bits of additional help, whilst probably not
making any audio difference may help prevent the clicks and bangs.


--
Woody

harrogate three at ntlworld dot com

HY60
 

In article ,
Woody wrote:
Point of interest: the larger the value of a capacitor the more
inductance it has, so it is a good idea to put some small value caps in
parallel to reduce any high-frequency content on the supply lines.
Something like a 0.1uF polyester will do, and if you live in an area if
high RF (i.e. near a transmitter site of any sort) you might even
consider another 10nF ceramic as well. Best location for these caps (if
they are not already present) is where the power leads connect to the
amp PCB.

I may get flamed, but in this high-noise environment in which we live
these days, such little bits of additional help, whilst probably not
making any audio difference may help prevent the clicks and bangs.

These sort of small value caps are also fitted to prevent RFI emission
*from* the device.

--
*A woman drove me to drink and I didn't have the decency to thank her

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

HY60
 

In article ,
Dave Plowman (News) wrote:
In article ,
Woody wrote:
Point of interest: the larger the value of a capacitor the more
inductance it has, so it is a good idea to put some small value caps in
parallel to reduce any high-frequency content on the supply lines.
Something like a 0.1uF polyester will do, and if you live in an area if
high RF (i.e. near a transmitter site of any sort) you might even
consider another 10nF ceramic as well. Best location for these caps (if
they are not already present) is where the power leads connect to the
amp PCB.

I may get flamed, but in this high-noise environment in which we live
these days, such little bits of additional help, whilst probably not
making any audio difference may help prevent the clicks and bangs.

These sort of small value caps are also fitted to prevent RFI emission
*from* the device.

Can also help suppress snap noise from the bridge diodes if you haven't
already shunted the diodes with suitable RF caps.

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

HY60
 

Woody wrote:

"Phil Allison" wrote
"TonyL"
Eeyore wrote:
TonyL wrote:

I'll probably go for a
regulated supply simply because I have a nice transformer with a
27-0-27 volt secondary and a boxfull of 2n3055s and MJ2955s.

Do you also have a boxfull of heatsinks for them ?


Not since I raided my heatsink store for a previous project...a 13.8V
30A transceiver supply. For this little project the metal enclosure
will make an adequate heatsink.


** Don't let Eeysore spook you with his BS.

Your regulator pass transistors do not have to dissipate much heat -
maybe up to 15 watts each, worst case. Long as the case is 1.5 mm
aluminium, it will be fine.

Use at least a 2,200 uF cap on the regulated DC output rails, so the
output impedance is low and the pass devices only see the average DC
current.

Nonsense. The output Z of the regulated outputs is so low that there won't
be enough ripple for those caps to do any useful job.


Point of interest: the larger the value of a capacitor the more
inductance it has, so it is a good idea to put some small value caps in
parallel to reduce any high-frequency content on the supply lines.
Something like a 0.1uF polyester will do

Which then creates a high impedance resonant circuit at some high frequency
depending on the ESL.

This is classic *BAD ADVICE*. If you NEED low ESL use a low ESL cap such as
for switching supplies..

Graham