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47 Labs Treasure 0347 : trials and tribulations

Posted 20th January 2012 at 12:48 PM by rjm

And not even sure what a tribulation is, but I'm sure I've had at least one building this amp.

Like the 0247 it's not so much difficult as it is painstaking hard work. The output transistors have to be mounted "just so" so the boards screw to the case properly, the wiring of the thermal protection transistors and gluing them to the output devices is tricky and easy to mess up.

I triple-checked and was rewarded by, it seems, error free boards. I messed up and wired the mute switch incorrectly though (the photos show it wrong, in case you come across this blog post looking for help) and I think the switch has a fault somehow as L and R channels appear to me mixed together. Taming the offsets gave me considerable grief but I think its all OK now.

Tomorrow I'll hook it up to the speakers and see what happens.
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Total Comments 1

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  1. Old Comment
    rjm's Avatar
    The update:

    The next day I went to measure the offsets and both were under 20 mV. It was no sweat to get them under 10 mV, where they stayed.

    No hum, no noise, the amp plays music just fine! Go figure.

    More on the sound and a comparison to my Gainclone in a follow up post.
    permalink
    Posted 22nd January 2012 at 11:18 AM by rjm rjm is offline
 

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