Any one recognize this WOPL 400

stetter

stetter

Journeyman
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Dec 1, 2018
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Tower, MN
Bought this to use while I do a full WOPL on my own PL400. Any one recognize their work by chance. Just wondering about age of rebuild and any other info on it. The owner lives in Las Cruses NM. He had it about a year now. He is trying to get more info on who did the work. Any Ideas any body
 

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I will need advice on proper adjustment of those as well for my original one did not have them. Now wondering more about information on this amp
 
Volume controls are pretty standard....turn to the right to increase power. Doesn't look like one of my rebuilds...
 
I remember a post a while back, FredR was putting gain controls on his 400’s it looked a lot like this one.

I would bet a $2 bill this is a FredR WOPL
 
It looks very clean. Photos don't show enough of the control board to tell the vintage on it. Guessing a RevD but need more of a full photo to tell. Revision is silkscreened on the lower right face of the control board.
 
What about the faceplate? Hand made? Short run? Kind of a Unicorn. I did not see it if it was on Ebay.
 
It was only up a few hours, It was priced at $600, I have already put together my cost sheet for my own amp so I knew this was a good price for a stand in amp for my own while I WO it, and when mine is done this one will power a set of Magneplanars in the shop out in the garage. Parts alone cost more than the price on this one. It is still in transit to my house. Suppose to come Friday, I will send more pictures when it gets here. Are the controls volume or gain setting? I know turning up gain increases volume ( not always the right thing to do with gain in the signal chain more so for signal matching) and when reading the info on a PL700 it sounds more like you use gain to match input level of the incoming signal from the pre amp or source like I use on my mixing board and other musical gear. So any help here in understanding the use on the PL400 would help.
 
Those are actually input attenuators. Those plots, if set up like the 700's , add resistance to the input impedance, lowering the signal level...all the way to the right shouldbe no attenuation......
 
so on my old PL400 my pre volume controlled the over all volume so if I understand right I should set the dials all the way CW to run it and use the pre volume to control output volume.
 
laatsch55 said:
Those are actually input attenuators. Those plots, if set up like the 700's , add resistance to the input impedance, lowering the signal level...all the way to the right shouldbe no attenuation......
Click to expand...

Correct. They do not affect the amp gain stage, simply attenuate the input signal
 
Thank you for the quick reply's, only if Fedex was faster...... , The amp came like this with the control knobs? Looking forward to hearing a WOPL. Geegz you won your bet, FredR is in fact the builder.
 
Typically, the use of volume pots (approx. 100K ohms) will affect the signal-to-noise ratio by a few dB and most significantly the phase shift at 20kHz (worst case scenario is) when the pot is at the 12 o'clock position. More to follow.
 
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We know that a PL400 is like a Ford truck is to a Chevy truck fan or vise versa, to the WOPL700 sniffer
 
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