Nad 3020a

[leesonic]

@leesonic thanks for an answer. You see I'm from Europe myself. Now it's all disconnected, because waiting for snubber to arrive.
But, white red wires is disconnected because, as I said there would be sound delay as I turn on. There would be no sound for like 10 seconds. So that's why I disconnected the wires. With wires disconnected, the sound appears as soon as I turn on amp.
I tried to trace the circuit from red/white wires. There is resistors, diodes, and transistors. Every of these elements seems to work. Doesn't know where to look for a problem... No cold solder joints as well.

Yes, there is a delay, that's the whole point of the muting circuit. It is designed to reduce the thump through the speakers generated by the preamp. If the timing is off, it's because there are bad caps in there or the wrong values. It could also be the resistors or the diodes. The cost of the whole circuit is less than a couple of Euros, so rather than chase it, just replace everything in that circuit. IMHO, NAD should have saved the money on the preamp muting circuit, and the soft clipping, and put in a speaker relay. Most people using a preamp/power amp know to turn the preamp on first before the power amp, that way there is no thump through the speakers.

 

[GytisBal]

Yes, there is a delay, that's the whole point of the muting circuit. It is designed to reduce the thump through the speakers generated by the preamp. If the timing is off, it's because there are bad caps in there or the wrong values. It could also be the resistors or the diodes. The cost of the whole circuit is less than a couple of Euros, so rather than chase it, just replace everything in that circuit. IMHO, NAD should have saved the money on the preamp muting circuit, and the soft clipping, and put in a speaker relay. Most people using a preamp/power amp know to turn the preamp on first before the power amp, that way there is no thump through the speakers.

So, you want to say, that turn on delay is okey. (if its safe for amp itself, I don't mind turo delay at all) but if i get pop on speakers, because of mutting part of scheme, i should fix it. Maybe you got muting scheme?
And if you say so. I need to find scheme for diy speaker overload relay

 

[GytisBal]

@leesonic also, if I install speaker protection with turn on delay.
Maybe I don't need original mutting circuit. And i can leave it unplugged (white/red wires).

 

[GytisBal]

P.s. does speaker protection circuit affects sound quality?
What controls the circuit. I think amp output, no? Something has to pick up high ac/dc rush to output, am i right?

 

[MonkeyRelish]

@leesonic thanks for an answer. You see I'm from Europe myself. Now it's all disconnected, because waiting for snubber to arrive.
But, white red wires is disconnected because, as I said there would be sound delay as I turn on. There would be no sound for like 10 seconds. So that's why I disconnected the wires. With wires disconnected, the sound appears as soon as I turn on amp.
I tried to trace the circuit from red/white wires. There is resistors, diodes, and transistors. Every of these elements seems to work. Doesn't know where to look for a problem... No cold solder joints as well.

That’s how it’s meant to work.

Mr Relish

 

[gmandyontv]

Hello,

I have accured few problems with my NAD.
Firstly, when I turn the amplifier on, there is a Pop sound on speakers, or headphones (not loud, not terrible but still its exist).
Secondly, when i turn the amplifier on, there will be no sound for ~10 seconds. After that, sound would increase slowly, first on one side, when after 1-2 seconds on other side. After another additional 5-10 seconds sound will reach selected desired level of sound.

Thanks, for replies my friends

I similar to you with my speakers, when I power the amp I get i get a short deep hum for maybe 1 second, volume of the hum dependent on the volume setting. Done it from new (1982 i think) on both my originally purchased KEF Coda 3s then my replacement 10 yr ago, Monitor Audio Silvers. even hum on both channels L/R