Question about NAD C320 2-Channel Amplifier

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Nad c320 The amp crackels and cuts in and out when low frequencies are played through it. It's getting progressivly worse. This only happens when the speakers are connected. If you're listening with headphones it's ok.

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  • handlestash Feb 14, 2008


    They're Tannoy speakers. I can't remember the model but I've had them connectede to this amp for 10 years or so with no issues.

    It's a new problem and is getting so bad I can't turn the amp up past '1' because it goes into safety mode (is this the speaker protection you ask about?) when the bass cones in. I don't have the bass EQ turned up or anything, never have.

  • handlestash Feb 14, 2008

    Hi Robotek,

    The speakers you say. Hmmmm. I don't keep the covers on and the woofers look ok.

    How does one check their integrity?

  • handlestash Feb 15, 2008

    Hi again,

    I checked the surrounds last night. The rubber looks fine. No dryness or cracking. The action feels good when pressing them lightly (I could be talking about anything here)

    I tried panning the amp hard left and right and the sound drops out on each speaker at about the same level. I can get reasonable level from my cd player through the amp but I have my pc sound card connected to the amp too and I can only turn it up a tiny bit if I'm playing back bass frequencies (kick drum or bass guitar) before it starts to cut out.

    I don't know a thing about electronics I'm afraid.


  • Graeme Ross
    Graeme Ross May 11, 2010

    If you could indulge me with a little more information from you...

    1. what make and model of speakers are you using

    2. has the problem just begun, or an ongoing thing.

    3. is the speaker protection oerating when it cuts out?






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It does sound like the speaker protection operating. First, try this.
Unclip the covers off your Tannoys, and check the integrity of the woofer cone surrounds... check that the surrounds have not failed that may be causing the voice coil to pole.

If they are ok, the amp may need some attention by way of resoldering of dry/cracked solder joints about the output stages. This occurs from the heating and cooling of the unit in normal operation. Check the speakers first, and we go from there.. :)

Posted on Feb 14, 2008

  • Graeme Ross
    Graeme Ross Feb 15, 2008

    Hi again, the reason I asked you to check the speaker surrounds for was to see if they have perished, and or disintegrated. When this occurs, cone misalignment will often force the voice coil to pole in turn presenting an unreasonable load on the amp. The poling effect often occurs when bass energy is being delivered by the amp. This follows your problem fairly closely, so worth a check to see..

    And with Rhodtech's indulgance, the headphone output IS connected directly (sometimes via speaker switching) to the speaker outputs in all HiFi amps... not as Rhodtech has suggested, from the preamp. The headphones do offer a much smaller load on the output stages, hence the problem not there when headphones are being used.

    The problem is inside the amp, from here is gets more involved. Do you have any experience with electronics, at least enough to check over the pcb for dry solder joints? Let me know. :)




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If your amp is under warranty, bring it to the nearest service center to have it fixed. But if not, and you know a little electronics, check for the bloated capacitor and/or a burnt resistor on the audio module and replace it. still not working, change the audio I.C. of the amp. If you don't know electronics, bring it to the electronics shop. Audio coming out of the headphone is different form the audio of the speakers. Sounds on your headphone is coming from the preamp circuit. That explains why the headphone audio is ok.

A Simple Thanks is Good Enough

Posted on Feb 14, 2008


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