My 6 Channel LM4780 Wiring Diagram - diyAudio
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Old 3rd June 2011, 02:33 PM   #1
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Default My 6 Channel LM4780 Wiring Diagram

Well gentlemen, here we have a professional artistic impression of my new 6 channel Audiosector LM4780 amplifier.

Hopefully you can see what I have tried to draw, but if there is any questions please ask.

In terms of real world presence I have built the chassis, the Antek Toroidal's are in and I have all the connectors, cable, etc etc. I expect about a days work to finish the build.

The AS-4222 has dual 115v Primaries, so I will use them in series for 250V. There is only dual secondaries which will be split with a terminal block but I got lazy and drew it as is. There is also an anti-static cable coming from the toroidal which I haven't drawn because I have no idea what to do with it.

I look forward to any constructive feedback and advice.
Cheers
Dean
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File Type: jpg 6 Channel LM Amp Schematic v3.jpg (128.7 KB, 418 views)
File Type: jpg LM4780 Chassis 1.jpg (151.5 KB, 377 views)
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Old 3rd June 2011, 05:14 PM   #2
frank1 is offline frank1  United Kingdom
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Quote:
Originally Posted by thunk303 View Post
There is also an anti-static cable coming from the toroidal which I haven't drawn because I have no idea what to do with it.

I look forward to any constructive feedback and advice.
Cheers
Dean
Earth it!
You could have economised on the toroids but its too late now.
Incidentally, I used one common transformer in my similar (5 channel) amp with two sets of rectifier/smoothing.
Frank
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Old 4th June 2011, 12:44 AM   #3
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Cheers Frank.

Any comments on the mains wiring or am I good to go ??

Dean
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Old 4th June 2011, 01:52 AM   #4
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I will have to assume at this point that my wiring diagram is correct and just build it ......
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Old 4th June 2011, 02:04 AM   #5
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Hi Dean, how are you going to mount the toroids? Cable ties through the bottom of the chassis? Not sure if it will be an issue but toroids radiate the most energy out the hole, so three in line like that, may lead to some interference (with each other), It doesn't look from the picture that they could be mounted horizontally in the space. Note that I'm purely speculating here!

The other issue here may be that some of your input jacks may be right in line with the maximum radiated emf from the toroids (it wasn't a problem with my amp which has a vertically mounted toroid and very compact though. I made sure that the inputs weren't "on axis" with the toroid hole ).

Tony.
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Old 4th June 2011, 02:19 AM   #6
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Hey Tony.

I had planed to mount the three as is with a 35mm wooden dowel through the guts and a mounting plate at each end. I would then use thin sheet rubber to wrap the dowel for a snug fit and between the units to keep them separated with support from underneath also. This would all be bolted together so there was no movement. I am going to be installing partitions running the length of the chassis separating the PS stage from the audio stages. I was also thinking about installing a 5mm alloy partition between each toroidal.

Peter Daniel recommended a single 300Va unit for each pair of amps but after franks comment I suddenly started thinking perhaps I could just mount 2 toroidal's flat and run 3 x LM4780's per 400VA transformer.

What do you think.

The only problem I have then is a back panel with 3 switches/fuses installed.

Dean
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Old 4th June 2011, 02:23 AM   #7
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A quick note..

No, all three transformers will not fit unless standing up.

The chassis will be separated into almost equal thirds. The center being the PS section and each outer third containing the audio stages. They will be separated by a 5mm alloy barrier running the length and height of the chassis.

The back panel is arranged in the same manner so no audio connectors will share the same internal space as the PS section.

Dean

Last edited by thunk303; 4th June 2011 at 02:33 AM.
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Old 4th June 2011, 02:41 AM   #8
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The more I look at it the easier it would be to install only 2 of the AS4222 and remake the back panel. This would make the toroidal mounting very easy and I could make a new back panel in an hour or two.

Does anybody know If 1 x AS4222 could power 3 AudioSector parallel LM4780 modules???


Dean
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Old 4th June 2011, 02:52 AM   #9
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I'd keep the 3 X 300VA's I think 300VA is a good size for two channels. It's what I'm using, and I do still get some PS sag doing low frequency power tests. Having the partitions and only having input connectors on the amp partition allays any concerns I had

As long as the dowel is wooden I think everything should be ok

Are the LM4780's running bridged? I'm using one 300VA for 2 X LM3886's Overkill? maybe, certainly real world music it at normal listening volumes it draws no where near that!! Scarily low in fact. I'll hook up the power meter and check and report back .

edit again: My daughter just asked to go to the park, so will have to be a bit later

Tony.
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Last edited by wintermute; 4th June 2011 at 03:02 AM.
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Old 4th June 2011, 03:04 AM   #10
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Thanks again Tony.

The AS4222 is 400Va and I am running the LM4780 in parallel, so 2 x 3886 in parallel, and thats for each of the 6 channels.

I look forward to your results.

Dean
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