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10th December 2010, 04:06 PM
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#1 |
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diyAudio Member
Join Date: Jun 2008
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SPiKe™ protection
Hi guys
Does anyone know if the lm3886 SPiKe™ protection causes a buzzing/fuzzing sound when engaged. I'm getting this aswell as increased heat from the chip but i'm not sure if its spike protection of a current/grounding issue. any opinions 
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10th December 2010, 05:51 PM
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#2 |
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diyAudio Member
Join Date: Aug 2008
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Is this happening without signal? If so, it sounds more like oscillations.
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Tyler |
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10th December 2010, 07:05 PM
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#3 |
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diyAudio Member
Join Date: Mar 2008
Location: Atlanta Ga. USA
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I think with SPIKE it just shuts down. But I have seen many of those chips blown up. Is it getting hot? Yeah, I'd scope out your supply rails and look for oscillation. If you don't have a scope, I'd just add some more capacitors on the rails. Also layout of the circuit will make it oscillate if your output is too close to the input. And, lastly, do you have any DC on the output?
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10th December 2010, 08:03 PM
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#4 |
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diyAudio Member
Join Date: Aug 2008
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If you take a look in the documentation, SPIKE actually changes the waveform to reduce the power output, and does cause a lot of nasty noise from what I've read.
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Tyler |
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10th December 2010, 08:05 PM
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#5 | |
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diyAudio Member
Join Date: May 2008
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Quote:
A zobel network will protect the chip against this kind of problem, and in my opinion has no audible impact on the sound of the amp. I use values of 10R and 0.1uF in parallel with the load (speaker) in my LM3875 Gainclone. Regards, Chris. |
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11th December 2010, 10:49 AM
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#6 |
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diyAudio Member
Join Date: Jun 2008
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Thanks for the replies guys.
I'm not running zobel networks (on my future mod list  ) but i can change out the speaker cables as a quick check.Also i am able to manipulate the buzz with the volumn control (lightspeed attenuator) |
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12th December 2010, 04:06 PM
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#7 | |
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diyAudio Member
Join Date: May 2008
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Quote:
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If you've always done it like that, then it's probably wrong. (Henry Ford) |
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