Hi all,
Recently picked up a Cambridge Audio A5 amp from ebay to replace my A1 Mk3 se as I am having trouble finding replacement TDA1514A for that.
Anyway, the A5 seems to be a nice unit, however ive noticed that after 3/4s switching off the amplifier i get a kind of "squelch" noise.
I have traced it to the NE5532 Opamp in the Preamp stage (U105), i have desoldered the decoupling caps on that board and checked them (all ok) but did replace them with new good caps for the sake of it, but still get the noise.
Happens with or without a source connected and is attenuated by the volume control (so i know it is from U105). I have the attached scope capture from Pin 7 of the 5532, it is the same on pin 1 also.
Admittedly i can just make sure it is turned to zero before switching off, but wondered if this is a normal characteristic for the amp?
Edit: No idea why but my scope photo is upside down. will try to edit that.
Recently picked up a Cambridge Audio A5 amp from ebay to replace my A1 Mk3 se as I am having trouble finding replacement TDA1514A for that.
Anyway, the A5 seems to be a nice unit, however ive noticed that after 3/4s switching off the amplifier i get a kind of "squelch" noise.
I have traced it to the NE5532 Opamp in the Preamp stage (U105), i have desoldered the decoupling caps on that board and checked them (all ok) but did replace them with new good caps for the sake of it, but still get the noise.
Happens with or without a source connected and is attenuated by the volume control (so i know it is from U105). I have the attached scope capture from Pin 7 of the 5532, it is the same on pin 1 also.
Admittedly i can just make sure it is turned to zero before switching off, but wondered if this is a normal characteristic for the amp?
Edit: No idea why but my scope photo is upside down. will try to edit that.
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The noise your hearing is the discharging of the 8 x 2200uf power supply smoothing capacitors.
The A5 has no speaker protection relay hence the speakers are directly connected to the output stage(s).
The A5 has no speaker protection relay hence the speakers are directly connected to the output stage(s).
Yes so similar in a way to my Quad 405 Power amp.
However this has the oscillation noise, which you could say sounds like a coat zip or a squelch, where the oscillation frequency varies as the power rail discharges.
But i wanted to see if other A5 users/owners had heard the same.
However this has the oscillation noise, which you could say sounds like a coat zip or a squelch, where the oscillation frequency varies as the power rail discharges.
But i wanted to see if other A5 users/owners had heard the same.