"Phil Allison" wrote in message
...
"Arny Krueger" = Compewter Geek Know All


People like Crown and QSC have been building 5+ KW audio power amps
with SMPS for years.

** But they are not regulated PSUs - but simple square wave inverter
supplies that have no voltage regulation and output 50/60 Hz ripple.

Not necessarily true. I have before me the QSC service manual for their
Powerlight series of power amps with SMPS. Referring to the power supply
schematic on page 80:

(1) The IRGPC50U IGBT power amplifiers in the amp's power supply that
convert line voltage to 100 KHz square waves derive their power from
filtered DC from a 40 amp full wave bridge rectifier.


** Square wave inverters have no voltage regulation.

The output varies with the incoming DC so any supply ripple is there to.


(2) The IRGPC50U IGBT power amplifiers in the amp's power supply are
controlled by a SG2535 PWM that provides voltage regulation, etc.

** The SG2535 provides a soft start feature and perfect 50 / 50 duty cyle
for the square wave drive.

Read the data sheet. It has a differential amplifier and provides its own
reference voltage. It is a PWM with an analog differential input, not just a
static source of just 50/50 duty cycle square waves.

Yes it has a soft start facility, but for that to work, the device has to be
able to provide a signal with a variable duty cycle.

"Arny Krueger" = Compewter Geek Know All


People like Crown and QSC have been building 5+ KW audio power amps
with SMPS for years.

** But they are not regulated PSUs - but simple square wave inverter
supplies that have no voltage regulation and output 50/60 Hz ripple.

Not necessarily true. I have before me the QSC service manual for their
Powerlight series of power amps with SMPS. Referring to the power supply
schematic on page 80:

(1) The IRGPC50U IGBT power amplifiers in the amp's power supply that
convert line voltage to 100 KHz square waves derive their power from
filtered DC from a 40 amp full wave bridge rectifier.


** Square wave inverters have no voltage regulation.

The output varies with the incoming DC so any supply ripple is there to.


(2) The IRGPC50U IGBT power amplifiers in the amp's power supply are
controlled by a SG2535 PWM that provides voltage regulation, etc.

** The SG2535 provides a soft start feature and perfect 50 / 50 duty
cycle for the square wave drive.

Read the data sheet.


** Read my post.

The same IC is used in a host of other amplifiers that ALL have no voltage
regulation.

That the chip is capable of it is irrelevant.

The internal DC rails are as stable as the incoming AC supply peak voltage
is - but DO have 100Hz /120 Hz ripple and some modulation when the audio
frequency is below 100Hz.

Stop arguing from a position of ignorance, Arny.

Its only makes you look a fool.


..... Phil

"Phil Allison" wrote in message
...
"Arny Krueger" = Compewter Geek Know All


People like Crown and QSC have been building 5+ KW audio power amps
with SMPS for years.

** But they are not regulated PSUs - but simple square wave
inverter supplies that have no voltage regulation and output 50/60 Hz
ripple.

Not necessarily true. I have before me the QSC service manual for their
Powerlight series of power amps with SMPS. Referring to the power
supply schematic on page 80:

(1) The IRGPC50U IGBT power amplifiers in the amp's power supply that
convert line voltage to 100 KHz square waves derive their power from
filtered DC from a 40 amp full wave bridge rectifier.


** Square wave inverters have no voltage regulation.

The output varies with the incoming DC so any supply ripple is there
to.


(2) The IRGPC50U IGBT power amplifiers in the amp's power supply are
controlled by a SG2535 PWM that provides voltage regulation, etc.

** The SG2535 provides a soft start feature and perfect 50 / 50 duty
cycle for the square wave drive.

Read the data sheet.

** Read my post.

I did so with great interest, Phil. I was wondering if you are man enough to
admit a pretty obvious error.

The same IC is used in a host of other amplifiers that ALL have no
voltage regulation.

So what? You made a global statement that is easy to prove wrong.

That the chip is capable of it is irrelevant.

That's nuts! You made a global statement that it could not be used that
way.

The internal DC rails are as stable as the incoming AC supply peak voltage
is - but DO have 100Hz /120 Hz ripple and some modulation when the audio
frequency is below 100Hz.

True of every power supply that runs off the power line to some degree, if
only microscopic.

Stop arguing from a position of ignorance, Arny.

Actually Phil, its pretty obvious that you did exactly that, and are
unwilling extricate yourself from a careless error that would be easy to
excuse if you would admit it.

Its only makes you look a fool.

Phil, you are caught in a false claim, which you are now multiplying. The
evidence is clear on two critical points:

(1) Phil made a careless error.

(2) Phil will resort to bad logic and out-and-out badgering to avoid
admitting his mistake.