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Old 5th January 2017, 03:19 AM
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Greg. Greg. is offline
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Join Date: Dec 2005
Location: Bristol, UK
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Default Re: Upgrade ideas for 300B PP

Originally Posted by Lyndon Johnson View Post
Greg - that does look like a beautifully built amp. I am intrigued by your battery bias upgrade - presumably the batteries live outboard of the amp for charging purposes? You mentioned this first - is this because you rated it as the most significant upgrade?
No, I mentioned it first because it relates to components at the beginning of the component list. As I said, you will not be able to aquire now NiCad batteries, but you can experiment with others if you wish. Battery bias tends to bring the music more forward in presentation. The batteries are mounted inside the chassis, attached out of sight in my photo, to the inside of the front plate. You can just see a loop of red connecting wire I used. They are generally fit and forget because they receive a charge when the amp is running. I did change mine after over five years use, however the ones I removed were still holding charge and working fine. You could also try resistor only bias. You will loose some gain but the sound will be slightly different.

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