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Here's my latest LM4780 amp and PSU

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This is a snubberised power supply with 2 x 18v toroid and 3 x 3300uF caps per rail. The power LED is connected from the outgoing side of the the two fuses (one fuse for each rail +25 and -25) via an 82K resistor on each. This way, I know if the LED isn't lit, then one of the fuses may have blown.


LM4780-002.jpg



LM4780-003.jpg


The sides are made of 12.5mm Corian and the front and back are 50x50mm aluminium angle. The Corian was drilled and tapped to attach the 12.5mm aluminium angle to it.


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Inside the amp. On the left is my star grounds for power and signal. In the middle is an AudioSector LM4780 board and on the right is my home made LightSpeed Attenuator. Originally the attenuator was to be attached to the chassis bottom, but I made a slight error, I forgot to leave room for the aluminium bar that presses the LM4780 to the heat sink. The attenuator circuit board is in mid air, being held in place by the LM317 regulator which is attatched to the chassis. The board isn't very heavy, so it should be OK. :)


LM4780-005.jpg


The rear section of the amp. The relay in the middle is part of my DC protection board. The wires run from the back of the amp enclosure to the front via slots in the small pieces of Corrian that are either side of the heat sink.


LM4780-006.jpg



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The interconnecting power lead took a while to make, due to trying to get the plastic woven sheath up and under the rubber cable stresses. But I think it was worth the effort, I am very pleased with it.


LM4780-008.jpg


Both the PSU and Amp together.

Each enclosure measures 165mm wide, 150mm deep and 50mm high

I haven't had time to really test the amp, but at first listen, it sounds better that my other chip amp I made, which sounds great.
 
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Had a chance to really listen to this amp now through my TangBand W3-871SC full range speakers (with notch filter). It is definitely on par with my other chipamp (LM3785) I made. I think the Lightspeed attenuator may be giving it the edge. Very smooth sounding music. I am in the process of building a set of Derwent Frugal full range speaker with CSS EL70 drivers. Can't wait to hear the amp and these speakers :)
 
Single enclosure, both the PSU and Amp together (measures 170mm wide, 250mm deep and 45mm high).

There is one single PCB (star ground connection realised with wires between signal ground and power ground for each amp separately).



A very original case design! I like it. :D :D :D

Do you have photos of the inside?
 

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Hi, this is my amplifier with LM3886. Schematic based on Bob Cordel's Super Gainclone. Enclosure of fabrique BMW 7 series car amplifier by Philips.
Some pictures:

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I'm calling this the ParalleLM3886

Introducing my latest creation . . . a 4-channel amplifier made from 4 pairs of parallel LM3886 chips. This project started when I had the opportunity to get a good deal on 12 LM3886’s, 2 huge torroidal transformers, and a bunch of boards and caps through the diyAUDIO Swap Meet forum. I plan to use it with an active X-over for a pair of speakers & subwoofers in my office/ audio hobby room.
Some features of this amplifier:
· It follows National Semiconductor’s application note AN-1192 (http://www.ti.com/lit/an/snaa021a/snaa021a.pdf) for the PA100 exactly, using boards from ChipAmp.com. It’s really easy to use the ChipAmp.com boards for this circuit. The boards have all the connections necessary except for the input filter, which I soldered directly to the RCA inputs, and the 0.1 ohm output resistors, which are soldered directly to the boards’ “OUT” holes. To parallel the chips, one only needs to build each board, then – all the wires going to or coming from each board – make into a “Y” to put the boards in parallel. It’s that simple!
· A separate power supply for each channel. Power supplies are ChimAmp.com “snubberized” design, so that’s 32 MUR860s for those of you counting. Specified filter caps for Brian’s PS are a pair of 10,000µF, but I got a good deal on a bunch of 6,800µF caps, so I used 4 of those per PS. The extra pairs are soldered to the board’s output holes.
· Each channel has a 2-pole, 2-throw switch on the front panel. The UP position both completes the circuit to the PS LEDs (also located on the front of the chassis) and completes the circuit from the LM3886’s pins 8 to pins 4, which turns off the mute feature.
· The amplifier is supposed to have an Elliott Sounds Products P37 softstart, but I couldn’t get it to work. I’ve built one successfully before. I compared it to my working P37 and I can’t find any difference. So I’m stumped with this one! :scratch:There must be a bad component. I’ve got other projects to move on to, but I WILL get back to this softstart eventually!:mad:
· I really want to take measurements. I have an oscilloscope, but I’ve not been able to find any free signal generator software that works with my 64-bit computer. :confused:A lot of software made for the 32-bit machines won’t work on 64-bit machines. If anyone can help me out here, I’d really appreciate it! I was able to measure +/- 32V rails, and -200mV offset.
· How does it sound? I’ve been playing DVDs, CD’s and windows lossless files through my computer, using the USB out to a Twisted Pear USB D/A converter with a GoldPoint attenuator, running a pair of Vandersteen 3A’s. I’m accustomed to listening to my DX Blame MKIII build, and a chipamp really can’t compare to a 200W class A/B amp.:superman: It’s a little weak in the bass, which may be because the Vandersteens’ impedance drops to 3 ohms between 30Hz-40Hz, which is pushing the limits of this design. The heatsinks get pretty hot. It doesn’t quite have the clarity and snap of the DX Blame either. I think it will be more than adequate for casual listening on pair of bookshelf speakers and a little subwoofer.:drink:
 

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my paralell lm4780

Finally found some time to put together the amp. The basic amp components have been ready for long but putting everything together is what took a lot of time. I went through 2 versions of the amplifier boards before I was happy. The preamp went through 1 revision. There's still some work that needs to be done, but I could put the the amp together without them. A a dc protector cum click/pop suppressor controlled through the micro controller in the preamp is still being worked on.
The power supply board was made after going through nationals audio amp power supply design guide, I have made some changes though. National's design had a bridge rectifier unit however I changed to a discrete diodes, I also added fuses on the power supply board itself.There are 4*10000uF caps on board.
The power transformer is a 0-20,0-20 200VA unit , this gives me +- 28V rails, each amp board contains a 4780 in parallel configuration. The amp runs fairly cool even in ambient temperatures of around 29~30C.

Some pics of the amp board :
 

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my paralell lm4780

It took a long time for me to decide the chassis , I had initially thought of making this the traditional way using aluminum sections and using a machined front panel. I was going through the pages of stereophile and found some very neat looking wood chassis and found some very classy looking wood chassis on the solid state gallery also, then I dropped the aluminum idea and got working on the wooden chassis. Wood is much easier to work with, besides you get professional help i.e. a carpenter quite easily. I got all the pieces cut and machined at a carpenters workshop near my home. The heatsinks were drilled and then tapped using a M4 tap drill, some aluminum angles hold everything together using M4 screws to attach them to the heatsink and self threading wood screws to attach them to the wooden pieces. The holes and cutouts were all done at the carpenters workshop. I designed the frontpanel with a big slot where I could basically press fit a preamplifier module. The preamplifier module is fitted on to a translucent plexiglass sheet. The sheet is completely dark except when the LCD backlgiht in the preamp board is on.

I first trial fit the module onto a tranperent plexiglass sheet to check the fit and hole positioning, using this sheet as a template then drilled onto the translucent plexiglass sheet.I still need to polish the wood and glue a push button onto the front panel. Below are some pics of the front panel and the chassis.
 

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