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In the Forum: Audio Discussions
In the Thread: The ultimate buffer – light in the end of a tunnel
Post Subject: The Placette oscillations – pass the test.Posted by Romy the Cat on: 2/17/2008
Latterly is have been some controversy with new Placette output impedance, it does not look like it is 3R but rather 37R according to my measurement. I need to clear it with Guy.
I also desided to address (since the Active Placette is a discrete op-amp) the fear of oscillations and I made a few measurements to see how stable this thing is. Here is a feed from my “better” generator at 0dB digital outputting the whole 5.95V RMS into Placette. The voltage is much-much more then usually music plays (normal listening level is at 0.2V-.5V with 1-1.5V in peaks), with 5V and connected speakers I would burn the drivers. So the setting was following. The Placette is driver by 5.95V RMS 1000Hz sinusoid. The Placette output loaded into Milq and paralleled into the HF 50R input of 150mHz scope. In the scope input mounted 3mHz first order filter to keep all sound and to get only oscillations. I will not comment on the result- you can see it. The first image is the setting as described and the second is the same setting only the Placette is loaded to 0.1uF capacitor.
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