Chip Amp Photo Gallery

I'm new here

Hello, I'm new to this forum.
I'm Cristian Ortega del Rio from Argentina, but mi friends call me Pato, which means "duck" in english.
I've been doing some amps since a long time ago. I had to stop doing it, and now I'm back after a few years (more like 6).

I have to say that all of YOU ARE GREAT! OMG you're excellent designers! what a beautiful designs you have!

I saw all of them, I'm planning to build my own amp also (just i'm trying to learn all the glosary you have here, like gainclone and mores :) )

Anyway, I hope to show you my design pretty soon. It will be based on chip LM1875, I'm planning to use a Regulated PSU +20/-20 x 3A which I'm intended to make it a kind of universal PSU, so I won't have to rebuild another one for a different design (more Volts or Amps).

Okay then, this is my very first post here, hopefully first of many mores. Thank you guys for sharing those designs, and inspire me (and the rest of us) with them.

Regards!
**Hope my level of english will be understandable** :)
 
hy. it`s been a long time since i`we done something...two weeks im building a cmoy and gainclone amp...the best two weeks of my life :D

some pics of cmoy, it`s done, works, perfect...i had samo hum but the 0.1uF cap on chip power supply pins fix that.

http://img.w3dizajn.net/images/P1000633cvsn.jpg
http://img.w3dizajn.net/images/P10006288k8n.jpg
http://img.w3dizajn.net/images/P1000710fwnx.jpg
http://img.w3dizajn.net/images/P1000712a4r.jpg
http://img.w3dizajn.net/images/P1000656qu2t.jpg
http://img.w3dizajn.net/images/P1000733g82h.jpg
http://img.w3dizajn.net/images/P1000737fv7.jpg


it`s not perfect but it`s my...sound it`s great, i love it.

gc pics, when it`s done :D
 
This is my first post to a very inspiring forum!

I built this LM4780 amplifier during the last week and, being the first, mainly as an experiment, opted for a cheap Maplin aluminium case. The transformer is a 160VA 25-0-25V from Farnell and results in a (measured) 2 x 37V supply. PSU smoothing uses 2 x 4700uF /50V (Panasonic) per rail. There is also 220uF per rail on the amplifier board.

The amplifier circuit is built on plain board, drilled as necessary and then point-to-point wired for simplicity. Earlier attempts to drill the chip’s holes in 0.1” pitch matrix board failed miserably as there was a distinct lack of space between the required rows.

Two polypropylene 2.2uF input capacitors can be seen placed on either side of the Alps volume control. The star point connects to the case and mains safety earth via a large 39 ohm resistor in parallel with 0.33uF X2-rated capacitor.

From the photos, it should just about be apparent the two rows of holes in the base of the box aligned with the spaces between the heatsink fins. The intention was to create a degree of convected air flow out of the upper side holes. In practice, this proves fairly effective, although the case still becomes quite warm at high listening levels.

Initial tests revealed output offsets of around 58-60mV, which seemed safe enough to eventually connect to my Monitor Audio 14s. The sound quality is quite remarkable for such a simple circuit and, after playing a few CDs, I have to say the sound is incredibly detailed and with a cleaner, “nicer” bass when compared to my existing Denon PMA520 amplifier. There is no discernable hiss or hum at zero distance from the speakers. Very satisfied indeed!

At some point, I’ll need to build a preamplifier as there isn’t quite enough output from my tuner. This amplifier has a gain of 26 (28.3dB).

Steve
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I built my chip amp with a wood frame and a piece of aluminum as a top plate. The wood I stained with some oil and then sealed with a wax. Looks great and no drying out at all. In fact at times the chip amp has been getting heat from the amp and then some sun on the outside as well. During different times of the year the sun can actually hit the thing but I don't mind if it fades it or colors it a bit. I like wood that's been distressed some.

So for me, no problems with the wood drying out or cracking. BTW I think the wood I used is poplar. My fear had been that the frame would warp and not sit level after a few years but no problem there either. Still square as a bear!
 
Affordable Enclosure and Non-Stick Too

I'm writing this post about my “Power Pot” chip-amp project. Although most of it is based on the BrianGT LM3886 chip-amp kit, I made some different choices in electronics and had fun with the enclosures. In this case, I have separate amp modules for each speaker and the power supply in a 3 quart sauce pan. I kept looking at the nice round transformer and thinking, this thing is the biggest and heaviest part of the whole amp. Shouldn't the power supply be the same shape?

The individual amp modules are based on theory, but unsupported by any measurable advantage. I like the idea of having the amplifier very closely coupled to the speakers so that the damping of the amp can better control the speakers. It also doesn't hurt that the AC and switching noise of the diodes are some distance away from the amp module and the interconnect cables. The idea in this case is to have each amp module sit behind the speaker and the power supply on the floor between the speakers.

As you can see, the pot makes a good enclosure for the power supply. If you try it, I recommend that you select an aluminum pot because the stainless steel variety is very hard to drill or cut. In my case, the power supply board is mounted inside the pot on the old bottom (now top) of the pot with the power LED peeking through some cooling holes. The transformer is mounted to a triangular piece of plywood that attaches to the pot by angle brackets. Computer power cords are used for both the AC power from the wall and for the DC voltage to each amp module.

Electronics

This project is a house warming gift for my friend Bob. He has nice equipment, but his old Dynaco kit amp is from the 70's and could use replacing, both for quality and age. As a result, I wanted to match the gain of his old amp and dropped the gain of the chip-amp to 14. Based on the National Semiconductor Application Notes, a lower gain may be advantageous for noise.

Each amp module has an additional 2200 uF reservoir capacitor on each leg of the DC supply voltage. This is to make sure that the DC cables from the power supply didn't pick up any noise along the way.

The biggest change I made was to add a coupling capacitor (1 uF) in series with the input signal. It combines with the input impedance resistor (bumped to 47k) to form a 3 Hz high pass filter to filter out any DC. Since the capacitor is in the signal path, I chose a nice quality, Solen polypropylene capacitor to avoid any coloring of the signal by the cap. I prefer this approach to the optional feedback capacitor in the kit because it does a better job of filtering DC. Also, as my father pointed out, if you use the feedback capacitor, the amp doesn't have a ground reference at DC because the impedance of the capacitor goes to infinity. At the very least, the feedback capacitor should be paralleled by a 10 Meg resistor to keep a ground reference at low frequencies.
 

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Very original design. The pot seems ideally suited for the PSU.

Just two tips.

Don't use the same connectors for mains and the DC circuits. The risk of sticking the mains cable into the wrong place is too high. Big Bang will follow. :hot:
If Bob has children, you should under all circumstances still replace those DC connectors with others. :att'n:
If he doesn't, replace them anyhow. :D

And it is also useful to have the male connectors at the sink (amp) and female connectors at the source (power supply). That way you avoid two things. One is touching live connector pins (even low voltage DC can be dangerous). :dead: And two is producing shorts, when those pins touch other conductors, e. g. when they fall on the amp case while connected to the PSU. :hot: In your design that could easily happen at the amp side of your DC connection cords. Especially with the type of connector you chose, where the pins are sticking out with no protection at all.
There is a reason, why cables usually are designed the other way round. ;)
 
Power cord best practice

Pacificblue

First of all, Bob will be fine since there are no kids and I've given him strict instructions on hooking it up. I admit to being a bit lazy and using what I had for DC cords rather than doing the right thing. I did set it up the way I did to minimize the chance that anyone would plug the amp modules directly into mains voltage. In fact, that is why I had the cord turned around. I figured that very few male/male cord exist and that it was better to fail the power supply by putting mains power on the output side than to fail the amp.

You are correct, however, that the DC power could be on without being plugged into the amp and be dangerous. Thanks.
 
Sticking mains into the power supply units DC outlets will cause some capacitors to explode. Connecting electrolytic capacitors to mains was a sport during my formation days. If you are lucky that pot is heavy enough to not get hurled around by that explosion and to not hurt anybody. However the stink afterwards is impressive and stays in the room for quite long, even with all doors and windows wide open. And then there are those countless little pieces of charged paper or foil from inside the capacitors floating around everywhere and sticking to absolutely everything. Might become a truly unforgettable present. :D