Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: lego4040 on November 04, 2013, 01:13:58 pm
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Good afternoon folks, I'm hoping to start a New amp build(Princeton Reverb). I'm going to get a Mojotone kit and use the Hoffman board instead. It just looks so much nicer and neater with most of the mods and tweaks done aside from one or two. I want to do the individual caps instead of the single can and would like to know if there is a actual advantage to this :dontknow: For my general knowledge and curiosity. Another question is from looking at pictures of inside Hoffmans amps(ex..AB763 single channel)here I see not only center tap star grounded but also grounded to the 100ohm resistors. Most diagrams say you dont need to but my gut says this is done because the more that's grounded is better for the amp noise reduction, am I correct.
I love this forum but way too much to chew on at once, I'm a pedal builder guy with only one tube build under my wing
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From what I understand, the individual electrolytics are cheaper than going with the can. Someone here may say otherwise, though. Getting the can back out for service is tough unless you have a really hot soldering iron too. I've actually seen threads where people switched to the individual caps but left the can in place because of the hassle of removing it. I'm probably going to switch out the cap can on my Vibro Champ to individuals myself, though part of my reasoning is freeing up additional space on the chassis for a larger output transformer.
I'm also planning to build a Princeton Reverb head from a kit at some point. Good luck with your build. :occasion14:
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The cap can is for convenience only, no technical difference between it and individual caps.
The 100 ohm resistors to ground are only needed if your power transformer does not have a filament center tap.
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Thanks for the cap can info. As for the grounding 100ohm and center tap, thats what I thought but here is the picture to Hoffmans Super Vibrolux build with what Im talking about (http://i77.photobucket.com/albums/j72/legomaniac4040/IMG_0633_zps241df763.jpg) (http://s77.photobucket.com/user/legomaniac4040/media/IMG_0633_zps241df763.jpg.html)
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here I see not only center tap star grounded but also grounded to the 100ohm resistors.
I see only a B+ CT, red/yellow. I don't see a green/yellow CT.
Brad :icon_biggrin:
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:worthy1:Thank you Brad, now I see that. It's been a while since I hands inside a amp and I'm going to make sure I all refreshed before I start my next build. I've been building pedals since I finished my Allen amp build and it's time to walk away from that and play with some tubes