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Old 26th March 2013, 10:29 PM   #1
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Default Strange crackle in my Rega Mira

Hoping someone can help with this ...

I have an old but much loved Rega Mira clamshell amp, used daily for years.

Yesterday I noticed that the volume seemed a bit weaker than usual, and there was a definite crackling, sometimes almost like a buzz in the right channel that seemed to coincide with peaks of volume.

I established it was not the speaker; then this morning, it appears in both channels. The sound is also slightly distorted as well.

I ran another power amp off the Rega's pre-amp out sockets, and that sounds fine, so the problem is with the Mira's power amps.

Anyone experienced something similar? Any clues as to what is wrong???
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NAD: C730, C541i; 7100, 5000; Rega (clamshell): Mira, Planet, Radio R; Denon: DR-M14HX
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Old 26th March 2013, 10:41 PM   #2
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Location: Not where whatever I am looking for is at.
One or more elco's may be giving up the gost, I would first look at the PS. If the Rega's preamp has a regulated PS, it might not be affected, but the power stage would be.
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Last edited by vacuphile; 26th March 2013 at 10:44 PM.
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Old 27th March 2013, 12:01 AM   #3
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Try cleaning or replacing the volume control.
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Old 27th March 2013, 01:17 AM   #4
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Thanks for the tips folks. Volume control operates smoothly and is before the pre-amp out, so that cannot be the problem; but the pre-amp and driver stages do have separate regulated power supply ... so I'll check power amp power supply first.
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NAD: C730, C541i; 7100, 5000; Rega (clamshell): Mira, Planet, Radio R; Denon: DR-M14HX
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Old 27th March 2013, 01:36 AM   #5
eyoung is offline eyoung  United States
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Hola Y'all...

I'm afraid Mr. Vacuphile may be heading in the right direction more than likely weak electrolytic caps they get noisey when aged get a schematic and lets see whats in that bugger...

Regards, E
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Old 31st March 2013, 11:55 AM   #6
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circuit

Turns out my initial diagnosis was wrong. Only the left channel is a problem; and it is only the power amp.

Not a power supply issue: both power amps share the same power supply.

Have checked various voltages around the circuit to compare left with right; and no differences at all.

Any thoughts?
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NAD: C730, C541i; 7100, 5000; Rega (clamshell): Mira, Planet, Radio R; Denon: DR-M14HX
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Old 10th January 2014, 02:35 PM   #7
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Default Same thing

Hi!

I have a problem with my mira that sounds extremely like the one described by you. I open the mira and touched the shaft of the alps input selector. This way I can reproduce the crackle on one channel. The other channel is ok.

Maybe it is the same for your circuit.
I sended the mira to rega several times for repair, but the didn't fix the problem. So I want to fix it myself. Does anyone know where to get the spareparts?

best regards,
Christoph
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