I want to add a single rail (class D) power amp to an existing split / double rail power amp module.
The existing amp is a subwoofer module with a 2x24V AC transformer mounted in a subwoofer cabinet. I want to power the 2 satellite speakers from the same cabinet by adding a class D amp powered by the same supply. I am assuming the power supply has sufficient spare capacity.
Typically class D amps use a single voltage rail. How do I feed this amp from the existing transformer?
I can imagine the ground of the split rail and the single rail get mixed up?
The existing amp is a subwoofer module with a 2x24V AC transformer mounted in a subwoofer cabinet. I want to power the 2 satellite speakers from the same cabinet by adding a class D amp powered by the same supply. I am assuming the power supply has sufficient spare capacity.
Typically class D amps use a single voltage rail. How do I feed this amp from the existing transformer?
I can imagine the ground of the split rail and the single rail get mixed up?
Attachments
you can swap a single polarity amplifier for the dual polarity amplifier.
But you risk adding a short circuit by adding a single polarity as well as a dual polarity.
The dual uses the centre tap as PSU Zero Volts and that voltage is referenced around the amplifier.
The single uses the more -ve side as the zero volts reference.
You have two amps with completely different zero volts references. That is an accident waiting to happen.
But you risk adding a short circuit by adding a single polarity as well as a dual polarity.
The dual uses the centre tap as PSU Zero Volts and that voltage is referenced around the amplifier.
The single uses the more -ve side as the zero volts reference.
You have two amps with completely different zero volts references. That is an accident waiting to happen.
Andrew, thanks. That's what I was afraid of indeed. So I assume the easiest thing to do is to look for a dual voltage class D amp which could share the same +/- and zero voltages.
I've seen them for higher ratings, but the smaller one's, say 2x25W tend to be single rail.
A/B amp boards (e.g Gainclone) tend to be dual voltage, but they put twice the load on the power supply.
I've seen them for higher ratings, but the smaller one's, say 2x25W tend to be single rail.
A/B amp boards (e.g Gainclone) tend to be dual voltage, but they put twice the load on the power supply.
Did you ever find a solution to this problem?
I have a VX-11 subwoofer and that needs a new class-D power amp. the old one seems to feed off a split-rail power supply, similar to your diagram above.
I'm trying to find the right class-D amp as a drop in replacement. I don't need crazy power, but note the measured VDC of 25.8-0-25.8.
I have a VX-11 subwoofer and that needs a new class-D power amp. the old one seems to feed off a split-rail power supply, similar to your diagram above.
I'm trying to find the right class-D amp as a drop in replacement. I don't need crazy power, but note the measured VDC of 25.8-0-25.8.
Something with a TDA8920 matches those supplies quite well - https://www.aliexpress.com/item/2251832626799928.html This one's stereo though, more channels than you'll need.