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Old 24th September 2007, 02:42 PM   #51
DanDini is offline DanDini  United Kingdom
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Yes, it is still audible, more so on the more sensitive speakers I have in the living room (90db as opposed to 88). It's something like 30mv peak to peak. It would be a major cosmetic mod to rotate the mains transformer as it is not square and would not fit within the cover anymore. It must be induced mains as the basic sine is at 50Hz and supply ripple/ac heater noise or similar would be at 100Hz, no?

Dan
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Old 24th September 2007, 04:01 PM   #52
Salas is offline Salas  Greece
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Supply ripple sure is 100Hz, but as I recall your heaters are AC fed, so still 50Hz for them. If we assume that your GND loops are all gone by now, it can be an electromagnetically induced residual that you pick up, or at least the best part of it.
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Old 25th September 2007, 03:41 PM   #53
DanDini is offline DanDini  United Kingdom
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I set this up last night in my daughter's room. It's quiet in there (when she's not around). I was surprised that actually the noise was mostly inaudible. I need to try it with other speakers, but overall the sound was enjoyable. It's actually got quite an involving feel and Eva Cassidy came over well at first listen. I'm not expert at describing sound quality, but I will arrange a listen with a friend of mine who is, so expect more to come.
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Old 25th September 2007, 03:43 PM   #54
Salas is offline Salas  Greece
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If you replace those gray coupling caps with something better you will have a lot more to listen to.
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Old 27th September 2007, 08:10 PM   #55
DanDini is offline DanDini  United Kingdom
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One thing I didn't consider in lifting the ground between mains earth and the input is that other devices which are earthed reintroduce the loop. My original testing was with a battery powered cd player - no earth. It also works fine with my marantz cd player - again no earth as it is 2 pin only to mains.

How best do you think I can earth the input so that connecting other devices with three pin plugs don't cause a massive hum?

Thanks,

Dan
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Old 27th September 2007, 08:26 PM   #56
Salas is offline Salas  Greece
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By braking with a 10R.
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Old 27th September 2007, 09:24 PM   #57
jnb is offline jnb  Australia
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Connecting to safety earth is OK. Connecting at multiple points is the problem.
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Old 1st October 2007, 09:10 AM   #58
zapp is offline zapp  Singapore
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Just got this amp from ebay. It runs hot like crazy - any chance of how to do the resistor thingy for someone who has ZERO electrical/electronics experience...?
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Old 1st October 2007, 09:32 AM   #59
Salas is offline Salas  Greece
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I would advise you to print out page 1 of this thread with my instructions for lessening the heater voltage and dropping the bias, and off you go to your nearest TV repair guy or some other technically adept fellow. Its very easy for someone who has put a couple of circuits together before. You STAY away! Lethal voltages inside, even when not plugged to the mains.
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Old 1st October 2007, 11:54 AM   #60
zapp is offline zapp  Singapore
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hi salas - tks for the reply. yes i will take your advice and leave the physical handling to the pros lol.
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