Chipamps (a.k.a. Gainclones)
In the hi-fi world, there is a class of amplifiers known as "chipamps" (or "Gainclones", from the 47Labs Gaincard, one of the first to bring attention to hifi IC amplification). These amplifiers use precision-manufactured, high-quality integrated circuits from National Semiconductor and others for amplification, and are usually chacacterized by a very clean and clear sound.
Personally, I think the Gaincard is somewhat unattractive (what's with the cylindrical barrel for the power supply?), and that is why it is great that we can easily replicate much of what it has to offer, for much less money at that.
The reason behind the great sound of chipamps is the chips themselves. Good construction practices work to bring out the chips' potential. Most of the cheap chip-based stereo systems are not built in a way that really takes advantage of the chips. (They also usually come with crappy speakers that ruin the experience as well.)
Some advantages that I see with integrated circuits versus discrete transistors:
- Minimal wiring to pick up noise and parasitic reactance.
- Thermal overload and short-circuit protection is an integral feature of the chips.
- The mass production of integrated circuits ensures consistency between channels.
- Construction/mods are a piece of cake once you know the concepts of opamp circuitry.
- The chips are cheap - a few bucks a piece.
- Troubleshooting and tinkering is easy and not incredibly risky.
Typical properties of a chipamp:
- Minimal external components.
- Minimal power supply filtration (e.g. smaller-than-usual capacitors on the rectifier for the currents involved). The chips apparently are able to reject AC ripple on the power rails quite well.
- Short wiring paths.
- Some people also like to build the power supply unit separate from the amplifier and supply DC through an umbilical cable.
- Low building costs (allowing people to splurge on fancy cases, etc.)
I am not an audiophile, so I can't really give a whole lot of description of the sound in relation to valves or discrete transistors and I am pretty sure nearly all of the audio I have ever seriously listened to has come from some type of chipamp. The "boom boxes" and all-in-one stereos that can be purchased at Wal-Mart and similar stores are usually amplified by integrated circuits, but they don't generally contain the high-quality ICs that are used in most do-it-yourself chipamps. Computer speakers (including the crappy ones that come with the computer) also use ICs, mainly due to the economics factor.
My Chipamps
- LM1875 - National Semiconductor LM1875 chip. This is a "low-end" chipamp as far as power capabilities are concerned.
- TDA2005 - Not really a "hifi" amplifier, but nonetheless a chipamp. The circuit is currently (5/19/2008) being incorporated into an audio mixer board for use as a low-power PA/DJ system. Web page in progress.
Chipamp Information
Buy Chipamp Parts/Kits
Note: I don't endorse any of the online retailers. I have used only ChipAmp.com and received good service. You may want to check them out, however, as they look to be pretty good.
- Chipamp.com - LM3886 Kits and boards
- Ebay - Buy chipamps made both commercially and by individuals.
- Moyer Electronics in Northeast/Central PA, has most of the parts or can get you most of the parts needed to build these things. Their prices are also very reasonable, if you happen to live in the area.
Last Modified: October 11, 2009. 20:17:08 pm