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Old 27th December 2012, 04:33 PM   #1
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Join Date: Feb 2012
Default Lepai 2020A+

Hi. I am using one of these little amps while my main hifi amp (Vintage Toshiba sc-330) is out of action and awaiting repair.

I am concerned that when I switch this thing on and off the cones on my speakers pop and the bass drivers move slowly back and forth by a considerable amount.

The speakers in question are Wharfdale E50, lovely old things, not something I want to damage (naturally!).

Is this sort of speaker come movement and popping anything to be concerned about?

I know there are some modifications that can improve the performance of these Lepai amp's and I'm aware of the modification thread. However its a massive thread and mentions all sorts of modifications. I don't know if any of the mods would help with the problem Im experiencing or now?

Any help much appreciated.

Thank you .
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Old 27th December 2012, 07:58 PM   #2
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LP-2020A+ mod thread

Bypassing the op-amps for volume and tone (especially volume, since tone can be defeated) drastically reduces turn on thump.
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Old 28th December 2012, 04:39 PM   #3
Bare is offline Bare  Canada
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Location: vancouver
Tone defeat doesn't actually remove the Tone junk...it just pretends to.
Do you seriously expect sophistication in a $15 amp ?
There is was no (pre mods) turn on thump with any of My red pcb Lepais' .
Good chance yours is pre-broken?
READ the WIKI at least
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Old 28th December 2012, 10:11 PM   #4
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Join Date: Apr 2008
Location: Carlisle, England
I don't know about your model but the 2092 based class d amps have a reset capacitor.
However if you start to use very large decoupling then clicks, pops and siren type sounds can occur.
I found the only way around it was to add a small microcontroller that detected when power supply volts were low and held the 2092 in reset.
Murton-Pike Systems PCBCAD51 pcb design software. http://www.murtonpikesystems.co.uk
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Old 29th December 2012, 05:28 AM   #5
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My red one had turn on thump, it still does, but it's way reduced after removing the volume opamp.
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Old 29th December 2012, 04:27 PM   #6
Fynn is offline Fynn  Germany
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Join Date: Nov 2012
My red PCB 2020a+ had a power off thump and a very silent power on thump.

After bypassing the opamps, there were no more pop noises for me anymore.
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Old 30th December 2012, 05:33 PM   #7
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It obviously depends somewhat on the speakers too.
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