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NAD 310 No Turn on Delay Circuit?

 

New member
Username: Kpeters

Post Number: 6
Registered: Jul-11
Hi guys I was wondering if any of you know if the 310 has a "Soft Start / Delay" circuit to avoid the "thump" of the speakers when you turn it on.

I got it paired with some Boston CS260 II and when I power the unit on, the woofers travel A LOT... like from start to finish but not violently but kind of slow. It's hard to explain the just go back and forth when I press the button and sounds like a deep thump.

Odd enough the speakers won't pop when I turn off the volume.

This amp is great and I know it's a budget NAD so I was just wondering if it lacks that circuit and if so what can I do to avoid it? is there something I can place on the lines?

Thanks!

Konrad.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16870
Registered: May-04
.

Short of placing an external speaker switch between the amp and the speakers there's nothing that can disconnect the signal path. How old is the amp and when was it last serviced for power supply capacitors?


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New member
Username: Kpeters

Post Number: 7
Registered: Jul-11
The amp is a 1997 bought it used and has done this since I bought it only difference is that it had smaller Bose speakers before. Haven't done any service on it.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16875
Registered: May-04
.

Then it might be time. If there's no problem with the amp, there should be no charge. You could always call NAD and ask about the amp.
 

New member
Username: Kpeters

Post Number: 8
Registered: Jul-11
Well I placed a support ticket with NAD meanwhile check this out this is the video of what I'm having: http://www.youtube.com/watch?v=DZzWr3PMY-A

Let me know if you consider that normal! I don't care as long as it doesn't screw up my new fresh from the oven speakers.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16876
Registered: May-04
.

Have you tried setting the volume control at its minimum before you power up the amplifier?
 

New member
Username: Mashley_nad

Post Number: 4
Registered: Jun-09
The NAD 310 does not have speaker delay/protection relays; plus it has a massive 4,700 mf output coupling capacitor - hence the huge switch-in thump. It's quite an odd design - now almost all solid state amp circuits avoid an output coupling capacitor competely.

How to fix this? You can can find speaker delay/protection relay kits online; or you could put a resistor across the speaker terminals, say 1,000 (1k) ohm; then put a switch in one of the speaker leads for each channel. Switch on, wait for 30 seconds, then switch the speakers in ...
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17567
Registered: May-04
.

If you're breaking the circuit with a switch, no signal can get through the open switch. Why bother with anything else inline?
 

New member
Username: Mashley_nad

Post Number: 5
Registered: Jun-09
Jan Vigne: The switch-on thump is caused by the 4,700 mf capacitor charging through the speaker. So to avoid the thump you need to (1) temporarily take the speaker out of the circuit and (2) provide an alternative way for the capacitor to charge - hence the resistor.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17568
Registered: May-04
.

The purpose of this capacitor is what? I can't remember when I've last seen a capacitor hung on the output of a solid state amp. Maybe a '70's Pioneer receiver. No zobel network? This can't be good for sound quality. Bass extension and quality must suffer. Is the NAD in danger of passing DC to the speaker?





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New member
Username: Mashley_nad

Post Number: 6
Registered: Jun-09
To prevent DC flowing through the speaker! The DC voltage at the cap was half the power supply voltage. It was standard practice in early solid state power amp circuits before they used balanced power supplies which made the mid-point voltage near zero allowing them to eliminate the cap. If you are interested pm me and I'll send you the NAD 310 circuit diagram or just Google it.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17569
Registered: May-04
.

No, thanks, I'm not a NAD fan so I'm not that interested. This does sound like a throwback to a "vintage" circuit design that should have been left behind in the simply "old and in the way" file. Half the power supply voltage?! Even the old Pioneers weren't that poorly designed. So, what's the rollout frequency for this amp's outputs? About 60Hz?



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