for higher power like 1500W in 8ohm. I need them to work at about +/-140VDC atleast after sag on the psu
so to scale the amplifier to +/-140 IRS2092 limit is about +/-100V so we need an additional stage to convert to that output voltage swing.
IRS2092S
Nigel, Nigel,
Please 95% is a dream and obtainable only with optimum load and driven with a sine wave.
Now I could be wrong but I believe most people do not sit and listen to sine waves but rather music.
Music is transient in nature and so varies from zero signal to maximum, whatever maximum may be.
An average class D amplifier has terrible efficiency below 12% of absolute output. Above 12% the efficiency shoots up to about 80-85%
So with this fellow's dream of using a +/-100v chip on a +/-140v supply let's assume that he got hold of some magic IRS2092's.
The peak output is about 98 volts with continuous sine wave power of about 1,700w into 4 ohm. (Taking into account losses in the output MOSFETs and droop on the supply).
The best average power is about 20% at 344 watts with peaks up to about 1,700w and avoiding clipping.
With typical music the signal will drop below the 12% power figure very often and efficiency takes a nosedive.
Average efficiency will be in the 60%+ region at best.
Nigel, Nigel,
Please 95% is a dream and obtainable only with optimum load and driven with a sine wave.
Now I could be wrong but I believe most people do not sit and listen to sine waves but rather music.
Music is transient in nature and so varies from zero signal to maximum, whatever maximum may be.
An average class D amplifier has terrible efficiency below 12% of absolute output. Above 12% the efficiency shoots up to about 80-85%
So with this fellow's dream of using a +/-100v chip on a +/-140v supply let's assume that he got hold of some magic IRS2092's.
The peak output is about 98 volts with continuous sine wave power of about 1,700w into 4 ohm. (Taking into account losses in the output MOSFETs and droop on the supply).
The best average power is about 20% at 344 watts with peaks up to about 1,700w and avoiding clipping.
With typical music the signal will drop below the 12% power figure very often and efficiency takes a nosedive.
Average efficiency will be in the 60%+ region at best.
If that is the call on the efficiency of Class D at higher power then there is no difference in Class D and Class H in Pro audio as much of the power is used in there as high power in loads.
In that case why do most class d amps have such small heat sinks compared to class AB ?
Class AB is about 60% efficient.
AB only reaches 60% efficiency close to full power. On average its efficiency is way, way lower.
Yes I agree.
I did a C# program to work out power in heat sink and power in load at different voltage outputs.
IRS2092S
Really small heat sinks!!
NOBODY listens to sine waves....we all listen to music so AVERAGE efficiency is substantially lower.
Class H efficiency is dependent on how many steps there are.
The high powered class D amps I design for my clients require large heat sinks for several reasons.
They are for vehicles and are driven hard into low impedances where the losses in the MOSFETs increase with higher load currents.
I guess for a home amplifier of several hundred watts, smaller heat sinks are in order as the absolute power is lower and the heat dissipation is as well.
Really small heat sinks!!
NOBODY listens to sine waves....we all listen to music so AVERAGE efficiency is substantially lower.
Class H efficiency is dependent on how many steps there are.
The high powered class D amps I design for my clients require large heat sinks for several reasons.
They are for vehicles and are driven hard into low impedances where the losses in the MOSFETs increase with higher load currents.
I guess for a home amplifier of several hundred watts, smaller heat sinks are in order as the absolute power is lower and the heat dissipation is as well.
Just use proper MOSFET drivers between the MOSFETs and the IRS2092 chip.
Make separate power supply for the IRS2092 chip.
Make separate power supply for the IRS2092 chip.
yes that also makes sense but can you recommend good drivers through hole ones will help as Im using all through hole components.
I once did an amp with LME49830 driving the Lateral mosfets directly without a driver as the sound quality wasnt very good but now i feel the drivers eventually seem able to drive the mosfets well.
I have a strong feeling that irrespective of any output mosfet there has to be a driver to stop loading the IRS2092 chip badly. So any good through-hole drivers to drive the single or double IRFB4227 per rail.
Thank you
as per the specs of the above driver
>High Capacitive Load Drive: 10,000pF
well in that case can it drive multiple IRF 247 package mosfets?
I am planning to build the subwoofer amplifiers for driving multiple 18 inch or 21 inch subwoofers with full bridge.
can you recommend any mosfets in TO247 package especially for Class D amplifier application? which can dissipate more heat as well.
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