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Old 14th December 2005, 04:38 PM   #1
sachi is offline sachi  United States
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Default Bridged Lm4780. Up and running!

Hey all,

This being my first amplifier project, i am relieved that i have had hardly any problems in the course of builing it.


Arasuk was kind enough to lend me a coupleof his PCBs. These PCBs were designed by him.
The bridged 4780 is going to be part of my tri amped system, driving the dayton 10 inch classics(8 ohms).
So far, the speakers and crossovers are done and are awaiting the amps to drive them.

Will soon test Peter's 4780 in parallel mode( for the midrange) and Brian's 3886 dual mono for the highs.
also, the OPA541 (seen in the pic) will be incorporated in the amp chassis for the center channel for my home theater.

Am using a 650 VA tranny for the center and bridged boards with secondaries of 24V.
while a 300 VA one for the two paralleed mids and two 3886 chips at 21 volt secondaries.

wow!what a feeling it is to get an amp running.

no cracks, thumps or humm.
thisis a seet sounding amp.
have been running it for the past 5 hours and no hiccups at all.
the heatsink is barely warm.
perhaps 3-4 degrees above room temp.

thanks guys.
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Old 14th December 2005, 04:40 PM   #2
sachi is offline sachi  United States
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using my old aiwa speakers as test subjects.
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Old 14th December 2005, 04:56 PM   #3
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hey,
nice work.specifically,nice pcbs.where did u get them made from?how much cost?
how much did u spend on transformers?huge caps(10,000uf?).small caps,dark blue caps,hixon?
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Old 14th December 2005, 05:17 PM   #4
sachi is offline sachi  United States
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Quote:
Originally posted by sagarverma
hey,
nice work.specifically,nice pcbs.where did u get them made from?how much cost?
how much did u spend on transformers?huge caps(10,000uf?).small caps,dark blue caps,hixon?

Hey sagar,
the PCb undergoing testing is designed and made by Arasu.
It was just a one off and he gave a couple of them as they were just lying around.

The other PCBs are from Peter Daniel and Brian GT. i think i paid around 50$ for the Dual mono 4780 and 3886 boards from Peter.
only the OPA541 i got it done here in Bangalore.
Its the layout given in Elektor( a very old elektor issue).
I haven't used snubber or zobel in any of the PCBs.

I paid around 800rupees(18$) for the 650 VA and 450(10$) for the 350VA(typo in the first post).

The big caps are 27000uf(50V) and the smaller blue ones are 13000uf(50V).
The caps are made by Nippon-Chemicon.
the small caps on the PCBs are samsung caps(2200uf at 50V).
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Old 14th December 2005, 05:23 PM   #5
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Quote:
Originally posted by sachi

I paid around 800rupees(18$) for the 650 VA and 450(10$) for the 350VA(typo in the first post).



so cheap.i got 250va(guru),for Rs1000.but its tough as hell,

how much did it cost u to get pcb made?
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Old 14th December 2005, 05:37 PM   #6
sachi is offline sachi  United States
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originally i had planned to use miracle toroidal transoformers. But they were like 3500INR. so i dropped the idea and went for EI.


My friend got it done for me and refused to accept cash for it.(the OPA 541).
He gets a lot of PCBs made and said that he got this one done for free.
God bless him!

The Dc offset measured in at around 10mV.
but i guess its much less than that. unfortunately, my multimeter ain't that good. won't measure lesser values accurately.
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