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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Bread-boarded Melquiades FullrangePosted by anthony on: 2/2/2017
Romy,

Using the Fullrange PS I have bread-boarded the Fullrange amplifier...

Lights On.jpg


Turn off the lights and it looks much better.


Lights Off.jpg


To my surprise (this is my very first amplifier build) everything seemed to work pretty much straight away.  The voltages seemed right, nothing blew when I applied power to the Bias string, which was my main concern and once I was sure things seemed relatively stable and well warmed up I plugged in my daughters CD player and played the Frozen Soundtrack.  Nice!

I do have some concerns with the Bias string though, with regards to it seeming to drift, or not stay at 0VDC offset.  I could not find anywhere on the site where you describe the process of tuning the Bias.  I measured the current across R11 and R12 in the range of 8mA - 9mA, which does not seem to be enough, so I paralleled another pair of 5kOhm resistors to halve their resistance and ended up with 15mA-16mA.  But the Bias will still not stay at 0VDC.  Romy, are you able to describe the process to tune the Bias String?  Please treat me like a novice this is my first build and my background is farming, not electronics.

Regards,

Anthony

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