Eeyore wrote:

Serge Auckland wrote:

"TonyL" wrote in message

I've found a couple of HY60 amplifier modules in my junk box. I have a
data sheet which indicates a +/- 25v power supply voltage rails
requirement but no indication of current. Power into 8 ohms is 30W. If I
put a power supply together what sort of current should I be expecting to
supply to each module ? Presumably, a simple dual rail
transformer/rectifier/electrolytic type of supply would be OK ?
Nice little amps!

Assuming that you're not going to be using these amps to drive some extreme
loads, then 30 watts into 8 ohms is a current of 1.94 amps, add a little for
the amp's overhead, and so you need a minimum of 2 amps per amplifier.

2 amps at +/- 25V ? That's 100W of DC per amplifier. Even run continous sinewave
it won't need that ! You're forgetting the current is shared between the + and -
rails.

1 Amp at + and - 25V per amp would do very adequately even for continuous
sinewave duty.

What if you want to listen to the latest Metallica album? That's 1.4A
per HY60 per rail, or twice that using 4 ohm speakers.
Best to get 4 car batteries, just to make sure.

--
Eiron.

Eeyore wrote:

TonyL wrote:

I've found a couple of HY60 amplifier modules in my junk box. I have a data
sheet which indicates a +/- 25v power supply voltage rails requirement but
no indication of current. Power into 8 ohms is 30W. If I put a power supply
together what sort of current should I be expecting to supply to each
module ? Presumably, a simple dual rail transformer/rectifier/electrolytic
type of supply would be OK ?

Yes.

You can work out the current for yourself of course, but then it varies
depending on whether you plan to drive it hard continuously or just play light
orchestral.

Graham


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!

Thanks, Rob

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.

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. 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.

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 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.

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

Eiron wrote:

What if you want to listen to the latest Metallica album? That's 1.4A
per HY60 per rail, or twice that using 4 ohm speakers.
Best to get 4 car batteries, just to make sure.


He he ! You mean that horribly limited/compressed offering ??

My music tastes are fairly eclectic....Bach to techno. Hey, Bach was that
guy who did all that synth stuff....right ?

I've already got an audio setup and this HY60 project is by way of interest.
It is also going to be a junk box project and 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. So, in practice, power
supply rating has turned into a moot point for me. There will be oodles of
amps.

Thanks for the advice everyone.

TonyL

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

In article , Rob
wrote:
Jim Lesurf wrote:
In article , Rob
wrote:



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.

I use one also for a radio in the room where I have the computer I've
typing on now. Use it with a Freeview DTTV box as a tuner. Gives nice
results with a pair of Spendor LS3/5A's. :-)

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?

No. Sorry if what I wrote wasn't clear. The distinctions were

1) One amp would only go to a level characteristed by about 40wpc for
sustained medium term use. Whereas the other goes to 200wpc.

2) One can only sustain this for a relatively short time before it
overheats, whereas the other can run at the higher power for much longer.

3) The spec values were just for 8 Ohm loads. For 'difficult' loads the
difference is more marked - unless you play the music at levels low enough
to escape the relative limits of *both* amplifiers. Thus the 700 will run
happily for long periods playing music at levels into loads where the 600
would either cease playing, or sound unhappy due to clipping or saturation.

If you drove an early 600 to its limits like this, then it might fail. More
likely blow a fuse. Later versions include a thermal cutout. The 700 had a
cutout on all models.

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.

Have a look at the articles on clipping and dynamics on my website (and in
many other places on the web). These show how a lot of modern commercial
recordings and broadcasts have their level dynamics compressed into a tiny
'always loud' range. This wasn't the case for most of the music audio fans
played before c1980. It means modern source material tends to require to
amplifier to play relentlessly at high power, whereas older (more naturally
recorded) material tends to be at a lower level more of the time with
occasional peaks to the highest powers. This makes a big difference to the
power dissipations and levels of waste heat the amp has to get rid of.

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.

Some NAD models 'soft clip' although I have no idea if that is relevant in
your circumstances. Two amps may sound indistinguishable at low power
levels as neither is struggling to drive the load. At a higher power one
may start to clip or limit whilst the other doesn't - and that can make an
audible difference.

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.

That can happen if you over-drive some of the amps, or if some of the amps
being used have a relatively high output impedance. Either can cause a
difference which is measurable and/or audible.

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

Rob wrote:

Eeyore wrote:
TonyL wrote:

I've found a couple of HY60 amplifier modules in my junk box. I have a data
sheet which indicates a +/- 25v power supply voltage rails requirement but
no indication of current. Power into 8 ohms is 30W. If I put a power supply
together what sort of current should I be expecting to supply to each
module ? Presumably, a simple dual rail transformer/rectifier/electrolytic
type of supply would be OK ?

Yes.

You can work out the current for yourself of course, but then it varies
depending on whether you plan to drive it hard continuously or just play light
orchestral.

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

Professional ones like I design are.

The sound is affected in the worst case by its absence followed by a burning smell.


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

Well they don't. For a host of reasons, the simplest being that not all have as flat
a frequency response as others. Most valve amps' freq resp varies significantly with
load impedance dips and peaks (like speakers) due to relatively high output
impedance (it forms a filter) and would you expect an amp with 2% THD like some
audiophool SE tubed/valve ones to sound like an amp with 0.003% THD ?

Graham

Eiron wrote:

Eeyore wrote:
Serge Auckland wrote:
"TonyL" wrote in message

I've found a couple of HY60 amplifier modules in my junk box. I have a
data sheet which indicates a +/- 25v power supply voltage rails
requirement but no indication of current. Power into 8 ohms is 30W. If I
put a power supply together what sort of current should I be expecting to
supply to each module ? Presumably, a simple dual rail
transformer/rectifier/electrolytic type of supply would be OK ?
Nice little amps!

Assuming that you're not going to be using these amps to drive some extreme
loads, then 30 watts into 8 ohms is a current of 1.94 amps, add a little for
the amp's overhead, and so you need a minimum of 2 amps per amplifier.

2 amps at +/- 25V ? That's 100W of DC per amplifier. Even run continous sinewave
it won't need that ! You're forgetting the current is shared between the + and -
rails.

1 Amp at + and - 25V per amp would do very adequately even for continuous
sinewave duty.

What if you want to listen to the latest Metallica album? That's 1.4A
per HY60 per rail,

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 ?

Graham

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 ?

Graham

Jim Lesurf wrote:

Woody wrote:

I built a dual mono MOSFET power amp based on the Ambit boards
containing a Hitachi design. It was good and provided 110wpc without
difficulty. I then built the regulated supply designed by the late great
John Lindsey-Hood and fitted that - and the aural difference was
dramatic, and not least that it did 110W into 8R and 220W into 4R. The
PSU design also provides d.c. offset protection for the speakers. I
think I have a copy of the circuit of anyone wants it.

That isn't really a matter of changing to an actively regulated PSU. Just
one of ensuring the PSU has a low output impedance and ripple even when the
current demand is high. if the "aural difference was dramatic" then I'd
suspect something was wrong with the unregulated PSU you'd used.
Unregulated supplies can give the advantage of providing higher peak
transient powers. Given that music tends to have higher crest factors than
test sinewaves that can be quite useful. However the amp has to be built to
cope.

Even pro amps with SMPSs don't make any serious attempt to regulate the rails.

Graham