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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: To be continuedPosted by Lx_ on: 12/27/2011
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 Romy the Cat wrote:
PP has the ultimate tool that allows detecting a LOT about its operation. Do you observe the same behavior as you describe when you pull out the power cord and let the unit to run from internal battery?

I made experiments in the past running on battery. Sound was improved very substantially, lifting additional dryness. The result was really pleasing giving very relaxed sound. At the beginning I ran on battery by unplugging the power cord of PP. Later I just used the toggle at the back of the unit. There is some slight difference (ground is connected or not) but that is  very minor compared to the improvement you get from battery operation. I do not get to run on battery often though since batteries are quite old and do not last long (only a few minutes).

 Romy the Cat wrote:
Whatever problem you have is less likely related to ground. If I was you then I would check if the unit has full profile sinusoid at full load. Use 10:1 probe, any type of analog scope (you can pit it used for $30) and analyze the bottom and top of the curve. The type of sonic problem you describe ideally associated with minor clipping of sine wave. This eats dynamics and subdue phrasing. The most important is that clipping injects huge amount of HF “white” noise deluding all sound with some king of external “gray” pressure. The effect is very common when idiots run 3-8W SET and drive with them 87dB sensitive speakers. They all sound the same – “stuffy” and partially because the clipping in the wave bombard the speakers with 7, 9 and 11 harmonics at very high frequency.  I do not know if you have the same effect but from what you describe it would be what I would check first.

I will try to pick a scope and measure as suggested.

 Romy the Cat wrote:
I do not think that you will be able to measure signal’s problem, all that you need to is to assure that your unit output proper sinusoid to full load.   I do not think that it is “noise comes through PP” and it is most likely not comes through ground. If you have the assurance that you have no Voltage clipping at full power then there is 80% of change that you PP2000 operate properly. If it runs fine from buttery then your amplification and your output filters are fine as well and then you have a legitimate case regarding the PP2000 intuit stage.

I know that battery operation is excellent which as you say proves that PP can operate properly. I do not use PP at full load (only 40-45%) but will still see how sine wave looks like. I have already suspected the input stage in the past but not sure how to prove that or improve it. Anyway thanks a lot for your feedback, it is much appreciated.

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