AudioNervosa
Systemic Development => Amplification and Preamplification => Tubes => Topic started by: Maxamillion on January 05, 2012, 06:01:54 AM
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For my wife to use in the office. It started life as a 1962-vintage Grundig Majestic console that was being tossed away (so it was free!), and now it's a docking station with 8.5W per channel output, 2 aux inputs, a remote control, and even charges the i-Pod while it plays. Telefunken 12AX7 and Lorenz ELL80 tubes in push-pull (the original tubes). Check out the before and after:
(http://i609.photobucket.com/albums/tt177/Stupidoctor/GrundigAmpClosed.jpg)
(http://i609.photobucket.com/albums/tt177/Stupidoctor/GrundigipodTopRight.jpg)
Came out so nice that now my son wants one for his college dorm next year. That'll be a scratch build unless I get lucky and find an old console again!
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Wow! Way cool! :thumb:
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Great stuff! Nice project and use for something unwanted. Ugly duckling into beautiful swan...
Bryan
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I just love it when old technology meets new technology. Your son is going to have fun answering the question "nice docking station, but what are those things sticking out of the top?"
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Thanks, guys. The top plate is .062" copper finished with an 800 grit wet sand to a brush finish with no coating - the idea is to let it develop a natural patina over time to match the antique copper paint on the docking cradle and screws; hard to see in the picture, but it's already starting to develop some funky patterns.
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Very cool Max!! Love the copper top, and the wood will make the iPod pop. Big output iron in there, huh?
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Nicely done :thumb:
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Very cool Max!! Love the copper top, and the wood will make the iPod pop. Big output iron in there, huh?
Here's a pic with the i-Pod in place and also shows the remote.
(http://i609.photobucket.com/albums/tt177/Stupidoctor/GrundigipodFront.jpg)
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Big output iron in there, huh?
Actually, the output iron is a little undersized, giving a -3dB point of 30Hz, but that's fine for this application as my wife will be using speakers that don't get down below 50Hz anyway. The power tranny is big because it was meant to also power the tuner and preamp sections of the console. I used the extra heater winding for the preamp and tuner tubes to supply +5VDC for the i-pod charger and +2VDC for the +/- data pins of the USB connector to fool the i-Pod into thinking it was connected to an Apple USB charger - Apple likes to put those little tricks in to keep 3rd parties from selling accessories that work with the i-Pods. Took a while to figure that one out, but I was determined not to have an Apple wall charger plugged in with this unit.
I built a little board to rectify the 6.3V AC to the required DC voltages:
(http://i609.photobucket.com/albums/tt177/Stupidoctor/GrundigAmpipodchargerdetail.jpg)
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Very nice! Interesting iPod charger hack.
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Very Cool Max! :thumb:
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A wonderfull talent to have. Looks great.
charles
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Interesting concept. Especially the charger mod. So what speakers re being used with it?
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Sorry for the late reply, just saw this post.
She's using an old pair of Koss M-65 Dynamite speakers. I got them for $3 at a church flea market, refoamed and recapped them, and they sound pretty darn good for the size. I'm trying to talk her into a bigger set, like the Altec Capris I just re-did.
It sounded excellent on the Rectilinear XIs I have on my workbench, but they're just too big for appropriate WAF.