The data I provided was for open circuit. What interesting I swapped out the purifi modules and DC voltage decreased to:
R:-10.7mV
L:14.6mV
With connected source it measures:
R:-1.0mV
L:-0.8mV
So definitely it shouldn’t be a problem. My speakers are Tannoys XT8f with 91dB sensitivity.
SMPS1200A400 has built in soft start therefore, in theory, additional delay of “amp enable” line shouldn’t be necessary.
Yes, correct. But now I’m confused if this is 100% for sure.
Test with S1 was done during the day. Test with manual enabling via “amp enable” was performed during late evening where ambience noise levels are usually lower and hearing perception more sensitive. This could influence my verdict although I put my ears really close to speakers in both cases.
Test with additional really in the “amp enable” path revealed similar clicks.
Good point. I did that test and then click is almost inaudible. I said almost because then its level is comparable to the little his audible from the tweeter.
Amp enable and S1 is the same. It pulls down the “amp enable” signal to the ground.
“amp enable” doesn’t really decrease power consumption (it’s decreasing from ~24W to ~20W). In my opinion it should be treated rather as “mute” function not stand by.
Even SMPS in stand by takes ~10W what nowadays is not impressing in terms of power saving
Initially I planned to use a relay with built in delay function but as it didn’t work as expected (quiet click is still audible) I abandoned this idea.
My goal is to use bistable relay with momentary switch on front panel to cut the AC power for SMPS.
Only small 5V AC/DC module taken from usb phone charger will be powered in stand by mode.
Indeed.
What is interesting, when you touch with your fingers the “amp enable” wire, clicks and crack noises are audible from the speakers. Maybe S1 has the advantage over the long wire because the path is short B and not exposed to external interference... Maybe this is why S1 is quieter...?
My NAD C356 has relays before speaker terminals so I’m not used to hear any clicks...
But you’re right. It’s so quiet and rather safe so we shouldn’t take it as a risk.
You’re right. I thought it’s related to the fact that amp section is enabled too early. It turned out it’s not the case
I still think that S1 is a little bit quieter than amp enable but I already get rid of S1 and cannot re-run the test.
I’ll have to live with that click
Especially, that in my opinion this can be forgiven in DIY project more than in commercial implementations for more $$.