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Old 26th March 2007, 01:18 AM   #1621
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Hi Peter,

I've finaly put your LM3875 Premium Kit in is final enclosure. But I'm having some problems: I can hear a radio station in my speakers. Any solution for this problem?

Thanks,

Paulo
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Old 26th March 2007, 02:17 AM   #1622
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That may be caused by some grounding issues. I posted my preferred grounding method here: http://www.diyaudio.com/forums/showt...773#post787773

Also, you may try to install 300pF capacitor between positive and negative chip input, more info can be found here: LM3886 very prone to mains noise

You may also see if installing Zobel components (Rz=2.7R, Cz=0.1uF) changes anything.
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Old 26th March 2007, 10:47 AM   #1623
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Thanks Peter, I'll try that 300pF capacitor. Just one question, by positive and negative chip input you mean in the rca's ou directly in the board? And the Zobel components won't have an impact in the sound?

Paulo
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Old 26th March 2007, 02:29 PM   #1624
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The 300pF cap mounts directly to chip pins 7 and 8, there is no separate footprint for it on the board.

More than likely, Zobel won't help here, but it won't hurt to try. And yes, it will affect the sound: you may like it or not
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Old 26th March 2007, 02:39 PM   #1625
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OK, just one more question: what kind of cap (ceramic, electro, any kind)? Sorry for the newbie questions...

And with monoblocs how do I apply your grounding, because I can't connect the OG's.


Thanks for all the help

Paulo
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Old 26th March 2007, 03:22 PM   #1626
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I'm using polystyrene caps here.

That grounding method was specifically for stereo amp. Monoblocks are much more forgiving to grounding errors and if you wire them in conventional method (4 wires from rect board to amp board) it should work fine too. You may experience problem though, if Earth ground is connected to chassis, in that case connect output ground to chassis instead (from negative speaker post) and Earth ground not connected (to chassis).
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Old 27th March 2007, 05:45 PM   #1627
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Default Audiosector NOS dac completed!

Hi guys,

Finished the dac . Currently breaking in. I added a HagUSB board as well (modified with Lundahl pulse transformer, BG caps, Caddock resistors).

Enclosure is Michael Woods' 0908 enclosure from DIY enclosures

Check it out. Thanks for all your help

Comments, questions, advice...welcome! Other pics here on audiocircle:

Poseidons Voice NOS USB dac

Anand
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Old 28th March 2007, 06:53 PM   #1628
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Facing the competition from various group buy offers, I decided to introduce new version of LM4780 board. Since my cost is also lower now, I'm passing the savings to potential buyers. The board as you see in a picture is $20.
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Old 28th March 2007, 06:58 PM   #1629
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In other words you are getting two separate LM4780 PCBs at $10ea, as pictured below. Untill I do changes to my website, those prices will also include worldwide shipping. If you order larger quantities, further discount will apply. Just contact me directly through PM.
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Old 28th March 2007, 06:59 PM   #1630
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That offer also applies to LM3875 board, which is available in the same format.
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