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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.

Post Subject: The new PP2000 mysterious “clipping”.Posted by Romy the Cat on: 12/7/2010

Yesterday I spoke with PurePower folks and they are looking into what might be the problem. They do have a log of all changes were made and I hope we will be able to find which one did the damage.

There was however very interesting development. Last night I was listening Berlin Philharmonic and at the loud stroke of the bass dram the playback clipped. It was very clear and definitive clip – something that absolutely shall not take place. I know my playback and I know what it does – it must not be any clipping at that volume even at 0dB. I flip the switch on PurePower resetting the PP2000 to run from the buttery and played a fragment again. That time it was no clipping at all. In fact it was no clipping even at 12 db louder.

I imidetaly called to PurePower informing about it as I thought it would help them to locale the problem more precisely. Meanwhile I took a scope and decided to see how much PP2000 voltage will drop under the stress of my dram stroke. The reason I did it is because I was not so comfortable with the whole situation. The clipping took place on the playback operating in class A – it means that at the lewdest and the most demanding moments of music it shall not draw more current. If so then where the clipping was coming from?

Running the playback from PP2000 it confirmed my fear – the PP2000 output absolutely stable and not sinking voltage under any dynamic expression of playback. I am sure that if I measure current that playback sucked out of PP2000 then it will be very stable. If so, then where clipping was coming and the most important why the clipping was absolutely eliminated when PP2000 was running from own buttery with AC disconnected.

I was listening the clipping again and again and concluders that it might be not clipping but juts a super shallow, super flat and super compressed bass the sounds like clipping. I swear it does sounds like clipping however…

I truly have no idea what is doing on. My initial sentiment was the PurePower disconnect butteries when the system runs from AC and they run inverter directly from DC-DC converter. That would explain everything but PurePower assure me that they do not do it and that the buttery is engaged when the unit runs from AC. Might be the buttery get disconnected accidently. Might be their Chinese partners desired to make improvement and did not let the PurePower people to know about it. I would not be difficult to take an inductive current miter and to see in which direction the current flows from buttery when the unit runs from AC. I did not open my PP2000 yet and I think the PurePower folk need to define it. Still, regardless what is wrong with PP2000 there is still a mystery what produces that sounding like clipping effect if the voltages and currants are stable and in A1 class and the most important – why the effect doe not manifest itself when PP2000 runs from buttery?

The Cat

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