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Chip Amps Amplifiers based on integrated circuits

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Old 8th December 2007, 09:39 PM   #541
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enzedone: " ... I can just throw on a music DVD and jump on the net. ..."

Likewise ... the DVD-Videos are all I buy anymore = most have 24bit / 48K sound tracks.

That iMac would make a great center piece ... I am installing an older mini-Mac on my main system (ala eBay or Craig's List, etc.) ... plenty of horsepower for audio and they all come with FireWire ports = ... and you need that for the better 24bit DACs.
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Old 8th December 2007, 10:59 PM   #542
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Question Hmmmm

Fire, DAC's, thats all a bit above me, drop me a line when you have finished it all, I would like to see how it all works.
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I realized that a major part of my job was to figure out how to use technology control to create economic force, or leverage, such that money and business flowed in Microsoft's direction” — Alex St.John, father of DirectX.
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Old 8th December 2007, 11:11 PM   #543
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... OK, yes, it can get confusing ... sorry.

There are some of us who thrive on this geeky kind of thing, and there are those of us who are artists, etc. ...
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Old 10th December 2007, 12:47 AM   #544
okapi is offline okapi  United States
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Default Update on LM4780 Amp

I recently finished the cases for my LM4780 amps.

Here are some pics:
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

The case was made from extruded 2X6 inch 6061 aluminum rectangle. I used a half inch ball end mill to make the top heat vents. I cut the bottom opening on the band saw after squaring off the ends on the mill. They slide over the amp chassis and are friction fit.

Unfortunately, as of right now i am unhappy with the sound of these amps and today i pulled them out of my main system and replaced them with my original LM3875, single power supply amp. I lost some of the left/right channel separation that comes with monoblocks but gained a much richer sound. I think i may just rebuild the amp section with LM3875 chips as i don't see how i can improve the LM4780's.

If anyone has any suggestions as to how i can tweak my lm4780's i would greatly appreciate it.

My preamp is still in a temporary chassis as i am continuing to experiment with different buffers and attenuators.
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Old 10th December 2007, 03:57 AM   #545
Aengus is offline Aengus  Canada
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Okapi, what a lovely piece of industrial design. I particularly like the heat vents; but they are very pleasing overall, with elegant proportions and all aspects of the design working together.

Very nicely done indeed.

Regards.

Aengus
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Old 10th December 2007, 08:59 AM   #546
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They look great okapi!!

why don't you like the sound? what is missing? low end? top end?

how much rectification caps are in those power supplys versus your other amp you like more?
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Old 11th December 2007, 02:01 PM   #547
okapi is offline okapi  United States
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Aengus and tangmonster, thanks for the kind feedback. i had been thinking about the design of the cases on and off for the better part of a year. it was only recently that i came up with the idea for the top vents.

tangmonster. i think you are right about the source of the problem being capacitance. my lm3875 has a little over 1500 micro farads per rail while the lm4780 has only 1000 micro farads. In both cases i have 4.7 micro farads just after the bridge on each rail. the large caps are located near the chip (a typical peter daniel set up).

i actually designed my lm3875 amp so i could easily change rail capacitance so i could experiment. it seems i needed to do it with the lm4780 and not the lm3875.

given that the lm4780 has two chips in it i would expect that it needs at least twice as much capacitance as the lm3875 and certainly not less as i currently have it set up? what do you recommend?
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Old 12th December 2007, 10:58 AM   #548
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Many recommends the low capacitance , but in my opinion it is just not enough.

Indeed I would recommend adding more capacitance at the power supply.
I would ad at least ad 10000uF per voltage rail at each of the power supplies.

This should help your rectification and voltage delivery at higher currents a lot. And mostly help with lower frequency's (that needs all the constant current)
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Old 15th December 2007, 06:31 AM   #549
suzyj is offline suzyj  Australia-Aboriginal
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Here's a couple of photos of my partially assembled QRV07 TPA6120 headphone amp:

Click the image to open in full size.

Click the image to open in full size.

I was originally going to roll my own TPA6120 design, but was impressed by Per-Anders efforts, so I bought a board from him, and have been populating it. I cheated a little mounting the TPA6120, by using solder paste and a vapour-phase reflow machine at work to attach it, but the rest of the assembly is by hand. The PCB still has lots of flux on it - I'll clean it after I mount the transformers and terminal strips.

The case is a Hammond extruded aluminium one, and I'm using an Alps volume pot.

I'm really impressed by Per-Ander's board - it's an extremely clean design, with great attention to detail.

Once it's done, It'll sit between my Nokia N95 phone (which I use for playing MP3s) and my Sennheiser HD595 headphones. The N95 doesn't sound good when driving low-impedence headphones, so the amplifier should make a big improvement.
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Old 16th December 2007, 06:27 AM   #550
bcdzt5 is offline bcdzt5  United States
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Default 3875 Chipamp

Here is my 3875 chipamp. It rocks. (Meaning that it plays music and doesn't catch fire.) Thanks to all that gave help during its design!

It contains:
AnTek 32V 300VA transformer, P. Daniel PCBs, waterjet front/back plates, cheap housing extrusions from eBay, nearly a billion spade connectors, and Mouser stuffs

More info:
Original thread

Now the pics:
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