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Old 14th February 2006, 02:12 PM   #801
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That is USB with SPDIF signal.... uh if I am not mistaken a lot of external devices use raw data so then jitter means nothing. Also SB's use ethernet for raw data, so no Jitter involved. The only jitter should be between the SB's input and DAC. That is all I can think of....
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Old 14th February 2006, 07:46 PM   #802
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Quote:
Originally posted by Destroyer OS.
That is USB with SPDIF signal.... uh if I am not mistaken a lot of external devices use raw data so then jitter means nothing. Also SB's use ethernet for raw data, so no Jitter involved. The only jitter should be between the SB's input and DAC. That is all I can think of....
I disagree, but I wont say any more about this in the AudioSector thread. Keep your eye on that link - there are more measurements coming.
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Old 16th February 2006, 07:20 AM   #803
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i like SPDIF as it is. welcome to my bulky mp3 server. not finished

i never was a big fan of usb being a tech for 10 years. usb can be a pain in the butt

but when it does work im sure it sounds good
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Old 16th February 2006, 02:11 PM   #804
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Try .FLAC

I plan to probably integrate a green board from Peter into my desktop before the summer which has yet to happen is over.
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Old 18th February 2006, 04:27 PM   #805
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Peter, a friend of mine who purchased your LM4780 board has asked me to kindly post this question.

On the first time he completed the board, his brother turned it on when he was not around and one channel of the amp blew together with 4 pcs of the MUR860. He doesn't know what actually happened, as he did not have first hand information but he suspected it could be a faulty chip. He has now replaced the chip and the MUR860 and powered it up and it seems fine. No smoke or smell. He measured the output for DC and found it had negative voltage on both channels, -125 mv on one and - 18.7mv on the other. Is this acceptable and or normal? he is worried and have not attached speakers to it. Maybe tomorrow, after your response. BTW, the LM3875 boards arrived and are as beautiful as the LM4780 boards. You sure put out high quality stuff.

Thanks.
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Old 18th February 2006, 04:37 PM   #806
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So far nobody reported a faulty chip yet. It could be short connection on the board (from assembly) that destroyed the diodes.

What configuration is used for LM4780 (parallel, stereo)?

-125 mv on one and - 18.7mv on the other is still acceptable in a way that it should not damage the speakers. The offset should be measured with source connected.

While 18.7mV is perfectly fine, -125mV is a bit high, that's why I was asking about configuration and if the source was connected.
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Old 18th February 2006, 05:05 PM   #807
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Peter, the chip was not from you. You are most probably right about the assembly part.

On the negative dc voltage on the output, the amp is in parallel config and no source was connected. BTW, which are the coupling caps for this amp? I am about 80% completion of my LM4780 from your board too. Actually the amp and PSU boards are completed but not wired together yet. I'll have eveything come togther in my case as soon as it's completed. In my parallel config, I have remove the zobel (cap and resistor) as you have suggested. Dying to hear how it sounds.

Thanks for the reply. Looking forward to more guidance or test procedures.
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Old 18th February 2006, 05:13 PM   #808
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The parallel configuration has usually higher offset than a single chip. Also, LM4780 has usually more offset than LM3875.

There is no coupling cap specified in the kit, but you can use any value between 2uF- 100uF at the amp input.
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Old 18th February 2006, 05:22 PM   #809
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Peter, he just hooked up some satellite speakers and the amp is playing well. DC at output on both sides is 35mv. I guess everything's fine.

Hell, no. I am not going to put any coupling caps into the LM4780. After listening to my previous LM3886 GC without the coupling caps, I don't think I ever want them in my amps.

Thanks Peter. I'll try to post up some pics of my friend's implementation as he used a car audio amplfier enclosure for this and it looks good. Great stuff.
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Old 18th February 2006, 05:32 PM   #810
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Peter, can I buy the 22k and 220R caddock Reistors and the 680R Rikens from you? Since I have heard so many good things about LM3875 amp, I thought I wanna go all th way for this that I am going to build after I complete my LM4780. You can send me a mail, if you prefer on the pricing and sending to Malaysia.

Thanks again for the great support and Good night. It's late over here now.
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