A/V Receiver Impedance Selector Switch

[paveldeg]

Nothing has changed is latest gen amp sections of D&M AVRs in terms oh how the impedance switch works. I also have direct access to the head of engineering Denon Japan and he has confirmed my findings. Be careful what you read on forums from end users that don't have the knowledge on amplifier design.

OK, thanks. I'm just shocked that "head of engineering Denon Japan" basically confirmed that they screwed up their design, instead of keeping power same across all impedances they reduced output power for 4 ohm loads. So much for Japan engineering I guess, hope they proud of it.

 

[gene]

OK, thanks. I'm just shocked that "head of engineering Denon Japan" basically confirmed that they screwed up their design, instead of keeping power same across all impedances they reduced output power for 4 ohm loads. So much for Japan engineering I guess, hope they proud of it.

The switch is there for one reason only, UL certification for 4 ohms with all channels driven. All Japanese AV receivers function similarly. One Yamaha i measured in the past did deliver same power in 4 ohms in low setting as 8 ohms in high setting but again it's limiting your power. Yamaha already has a lot of nannies built in to ensure the amp doesn't fail without having to step down the voltage via the switch.

 

[everettT]

So, any actual technical explanation from you including schematics, besides insulting everybody who is so "mistaken" from your point of view?
I do trust Gene's measurement, but they are mostly for Yamahas, and speaking from common sense perspective - cutting output power for 4 ohm loads does not make much technical sense, the power should be same as for 8 ohms to avoid overheating, so voltage can be limited, but since amperage is higher for 4 ohms loads output power should stay same.
If it's not the case with Yamahas it's just means poor design, nothing else, it's unlikely to be same for all other AVRs.

This horse has been beaten so much I'm shocked manufacturers still offer it. If you wanna limit your amplifier section, go for it, most just purchase an appropriate product.

 

[Trebdp83]