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 ?

Any gotchas with this project ?

Thanks

TonyL

"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 ?

Any gotchas with this project ?

Thanks

TonyL

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. If
you're building a single supply to power both amps, then I would go for a 5
amp supply. If the 'speakers you're going to use are closer to 4 ohms than
8, you may like to double the current capacity.

No particular "gotchas" with these as far as I'm aware, they do what they
say they do.

S.
--
http://audiopages.googlepages.com

"Serge Auckland" wrote in message
news

"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 ?

Any gotchas with this project ?

Thanks

TonyL

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. If you're building a single supply to power both
amps, then I would go for a 5 amp supply. If the 'speakers you're
going to use are closer to 4 ohms than 8, you may like to double the
current capacity.

No particular "gotchas" with these as far as I'm aware, they do what
they say they do.

S.
--
http://audiopages.googlepages.com


Agreed. Of their time superb amps. They were later replaced with a power
MOSFET version which had a somewhat higher slew rate, but nontheless the
HY was a very good amp.

Just make sure, as above, that the supply can provide the current. You
should even consider a regulated supply as (and I'm sure someone will
enlighten us) you will get better and cleaner bass. Although the HY60s
have built-on heatsinks it would still be wise to attach them to a
chassis that is capable of dissipating at least some of the heat.

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.


--
Woody

harrogate three at ntlworld dot com

"TonyL"

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 ?

** Class AB amps are typically about 65% efficient at full output - with
78.5% ( pi/4 ) being the theoretical maximum.

So, at 30 watts max sine wave output the DC power consumption is around 46
watts.

With +/- 25 volts rails, a DC current rating of 1 amp per amplifier ( ie 50
watts) will be fine.

Go for a toroidal tranny with twin, 18 volt secondaries wired in series (
for 18-0-18) rated at 3.3 amps (or 120VA) for a stereo amp - the extra AC
current is need in the conversion from AC to DC.

Filter caps need to be around 10,000uF - at 35 volts for safety.

BTW:

Forget the mad answer Serge posted.



...... Phil

"Serge Auckland"


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,

** That is the rms AC current in the load - not the DC supply current.

add a little for the amp's overhead, and so you need a minimum of 2 amps
per amplifier.

** Nonsense.

Each DC supply rail only delivers current to the amp on alternate half
cycles and it is the average value of that half sine wave current that is
the DC supply current.

The average value of a half sine wave is 0.318 ( 1/pi ) times the peak
value.

30 watts at 8 ohms requires 2.74 amp peak.

2.74 times 0.318 = 0.87


...... Phil

"Phil Allison" wrote in message
...

"TonyL"

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 ?

** Class AB amps are typically about 65% efficient at full output -
with 78.5% ( pi/4 ) being the theoretical maximum.

So, at 30 watts max sine wave output the DC power consumption is around
46 watts.

With +/- 25 volts rails, a DC current rating of 1 amp per amplifier ( ie
50 watts) will be fine.

Go for a toroidal tranny with twin, 18 volt secondaries wired in series
( for 18-0-18) rated at 3.3 amps (or 120VA) for a stereo amp - the
extra AC current is need in the conversion from AC to DC.

Filter caps need to be around 10,000uF - at 35 volts for safety.

BTW:

Forget the mad answer Serge posted.



..... Phil

My brainstorm, sorry. However, if 4 ohm loads are to be used, a higher
power supply rating is advisable.

S.

--
http://audiopages.googlepages.com

In article , 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.

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

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

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.

Graham

p.s don't forget to derate the transformer VA rating for the non-sinusoidal
currrent draw. Allow an ~ extra 30% VA over the DC watts.

Graham

Phil Allison wrote:

"TonyL"

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 ?

** Class AB amps are typically about 65% efficient at full output - with
78.5% ( pi/4 ) being the theoretical maximum.

So, at 30 watts max sine wave output the DC power consumption is around 46
watts.

With +/- 25 volts rails, a DC current rating of 1 amp per amplifier ( ie 50
watts) will be fine.

Agreed 100%


Go for a toroidal tranny with twin, 18 volt secondaries wired in series (
for 18-0-18) rated at 3.3 amps (or 120VA) for a stereo amp - the extra AC
current is need in the conversion from AC to DC.

Filter caps need to be around 10,000uF - at 35 volts for safety.

I'd be happy with 4,700uF if it's only driving 8 ohms.


BTW:

Forget the mad answer Serge posted.

Quite so !

Graham