My_Ref Fremen Edition - Build thread and tutorial

Stream

Stream

Member
Joined 2008
s3am.livejournal.com
Hello
1. Can we use R3 = 0.22 or 0.25 ohm with Evo RevA Mod or it's too low value? I found some sources for this values. Unfortunately values like 0.3-0.47 are hard to buy for me.
2. Is it safe for Fremen edition amp to power speakers through long speaker wires (~10-12m each) without output RL-filter as in original lm3886 datasheet?
 
M

madisonears

Member
Joined 2007
I would greatly appreciate some technical advice. There was a power surge here (created by my electric water heater!) which flashed my lights and silenced one channel of my preamplifier. It, or the preamp failing, also damaged one of my monoblocks. Now all I hear with no input is a very loud buzz through the speaker. The LED lights, relay clicks, and I measure only 7MV dc at the outputs, but there is no music, only a loud noise which almost sounds like there is no ground. I do not detect any physical damage. Can anyone suggest where to begin testing the circuit?

Peace,
Tom E
 
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Mark Tillotson

Member
Joined 2018
seven megavolts! No wonder something blew!

Since its one channel out only you can start comparing the two channels. However something like a signal injector and or tracer can be invaluable for figuring out where the signal gets lost. Or a 'scope of course.
 
J

Joseph K

Member
Joined 2004
Tom,
It is intriguing, so to say.. The relay clicking, and Your measurement of the 7mV output offset would indicate that the composite feedback loop works (for sure in DC). It means all the active elements need to be OK..
On the other hand, there is no ground reference to the input signal (buzz)
All this would signal an R11 gone.. but in that case, typically, a strong DC offset is the result.. Maybe it's not totally gone, just got an elevated value (like from 1ohm to some dozen kohm..) .??
though.. this still would not exclude some of the input signal filtering through..🤔
 
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