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In the Forum: Melquiades Amplifier
In the Thread: Valve Preamplifier for Macondo/DSET
Post Subject: Polarity?Posted by anthony on: 8/13/2020
 anthony wrote:

I have brought the Placette Active Linestage back into the room.



This comparison is proving more difficult than anticipated.  Inconsistent results between subject tracks have given me some doubt on just what I have been hearing so I have had to go back to first principles in an attempt to explain it.

Often, the 10y sounds flat out better than the Placette:  more resolution, better transients, more energy.  However, with some other tracks the difference is not so noticeable and there is really very little separating the two preamps.  It has not happened yet where the Placette is clearly preferred, but the two are occasionally quite difficult to differentiate.  

Thinking about why this may be happening this morning led me to think about absolute polarity.  As far as I am aware the 10y inverts phase and the Placette is non-inverting (not 100% sure).  Could the preference for the 10y be coming down to using more recordings where absolute polarity should be reversed?  I don't know and never before has absolute polarity been a concern of mine...but perhaps it should be.  

The buffer that I previously tested was also very good and although it is able to be set to inverting or non-inverting output it had been set to non-inverting.  To get more volume in-room I had also been experimenting with using this buffer to add 12dB of gain before the Placette.  So at lunch I set the buffer to invert the output so it is the same polarity as the 10y preamp and have gone back to some of the recordings where the 10y was ahead.

This is a fairer fight now!  Regardless of how it turns out, there will be some way to set the buffer up to be able to switch absolute polarity on the fly possibly even using the remote.
    

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