Technical support
Yes. The 400kHz signal you see at the output of the amplifier is the residue of the switching nature of class D amplifiers. This is completely normal and does no harm. For more information please refer to our EMI application note.
https://www.diyclassd.com/FAQ-Hypex/Technical-support/I-hooked-up-my-UcD-to-an-oscilloscope-and-I-see-some-HF-sine-wave-at-about-400-kHz.-Is-this-normal
You need to drive one of the modules 180 degrees out of phase by simply swapping the negative and positive input signal wires. Tie the loudspeaker between both positive loudspeaker outputs of the amplifiers and connect a 100n/200V capacitor across the loudspeaker terminals at the amplifiers’ side. This set-up is most applicable for 8 Ohm loads since each amplifier ‘sees’ 4 Ohms with an 8 Ohm load attached. A 4 Ohm load might trigger the current protection leaving you with not nearly as much power as you might have expected.
https://www.diyclassd.com/FAQ-Hypex/Technical-support/I-need-double-the-power-in-an-8Ohm-load-than-a-UcD-amplifier-can-produce.-Is-there-some-way-I-can-bridge-two-for-example-UcD400-s
The HPR12/HNR12 are voltage regulators like the 7812/7912 IC’s. The difference is that they have a wider bandwidth, lower noise and lower output impedance. Additionally, they have kelvin-sense inputs so you can make a local regulator that doesn’t have to be physically close to the circuit being powered. Typical op-amp based circuits have a much greater sensitivity to power supply ripple and noise than the data sheet’s DC PSRR values would suggest.
https://www.diyclassd.com/FAQ-Hypex/Technical-support/What-is-the-purpose-of-the-optional-HxR-regulators
Clean supplies are part and parcel of good audio. The noise and rejection specifications of the HxR modules are unparalleled and as such make a great upgrade for any circuit using (or in need of) regulators.
https://www.diyclassd.com/FAQ-Hypex/Technical-support/Does-my-amplifier-really-sound-better-when-upgraded-with-HxR-regulators
Input sensitivity is dependent on the desired output power, the impedance of the speaker and the gain of the amplifier. Naturally the desired output power cannot be higher than the rated maximum of the amplifier. In the example the input sensitivity for a 400W output in 4 Ohm is calculated. The gain and maximum output power is given in the datasheet. The speaker load is dependent on the user application.
