What's the difference between a 'chip' based amp and a 'discrete' amp?

In a nutshell, amplification is taking a low voltage signal (like 2 V from a CD player or a 1 V signal from an iPod) and increasing the voltage high enough to make sound in speakers or headphones.

 

"Chips," as you called them, are operational amplifiers.  There are cheap and found in many devices.

http://en.wikipedia.org/wiki/Operational_amplifier

 

"Discrete," as you called it, can mean several things.  Usually, it means that each audio channel (2, 5, or 7) is amplified separately. 

 

The difference here is that operational amps usually amplify both audio channels at once on the same device, whereas discrete amps will amplify both channels separately on different components.  The latter is usually the preferred method, but op amps can be pretty decent.

Edited by hodgjy - 1/4/12 at 11:41am

^ Not really.

 

Chip amps are as describe: using IC opamps as the amplification device. These would include amps capable of driving speakers, such as those termed as gainclones, Opamps exist in single, dual, and sometimes quad packages. A chip amp can have each channel amplified by separate chips, and even each channel having its own power supply (mono).

 

Discrete amplifiers employ individual devices such as transistors (bipolar or FET) along with the associated resistors, capacitors, diodes, etc. that are necessary to bias and support the active transistors. Sometimes, the discrete amp stages resemble opamps in terms of architecture,

 

A key difference can be feedback. Opamps by definition require large amounts of negative feedback in order to operate. Discrete designs do not necessarily; in fact discrete designs can be done using no global feedback.

Discrete amps are considered superior (it also depends on the design) they usually use higher grade components. 

Many discrete designs will include very hi quality parts like Dale Vishay  .1% resistors, panasonic caps etc, here's a quote off Ray Samuels site referring to some of the parts he uses in his builds  http://www.raysamuelsaudio.com/products/predator. The hi quality parts will help keep you amp sounding good for years to come and offers a more robust build quality, the built in amp in iPods is an IC, and it offers only basic sound, much akin to the quality of mp3's, ok for a clock radio, but very lacking if you enjoy good music. IC's are small and cheap, so they get used by companies looking to save money, not really caring if the output sound is of any quality, but rather that it makes sound and that's good enough for some, but not us, as it shows you are looking to educate yourself and improve your listening experience. Shop for amps that lean towards discrete designs and the use of hi quality parts. The fact that many discrete amps include an IC or two isnt a bad thing, its amps that rely completely on IC's you should avoid.

Did you hear Ray made a $3k chip amp?

Apache is a 3k 2 piece unit, Ray in a genius IMHO, not sure if that's the one you are referring to, I think most if not all of Ray's Amps have a chip of some type, but also use heaps of discrete parts.  Cheers

discrete transistor designs only have technological advantages in a few situations relevant to head-fi - can handle higher V, and current than many op amps, special audio power "chip amps" do cover higher V, I ranges to a degree - but we still have to go with discrete for ES headphone kV needs

 

for many dynamic headphones properly selected, applied monolithic op amps can handle enough V, I - there are hundreds of models, some part #, designs dating back 30 yrs - not all were ever "good for audio"

 

the last (little more than) decade has seen a huge investment, competition to meet the demand for improved monolithic op amps for medical imaging, Telcom A/DSL - there has been a step change in the performance available in today's best monolithic op amps

 

much of the "discrete is inherently superior" claims date from long ago, have been obsoleted by especially the last decade's new op amp's advances in internal designs, semiconductor processing

 

a monolithic op amp design can still use extreme quality passive components for inputs, filtering, feedback, power supplies

 

 

Linn long ago made $3k + stereo audio power amps with power "chip amp" internals

 

 

my diy composite op amp headphone amp (my avatar) uses more, and more expensive chips than that Linn amp

Edited by jcx - 1/5/12 at 8:55pm

IC is a common acronym for Integrated Circuit, aka a "chip", or more specifically, a "microchip", which is like a miniaturized circuit board. Microprocessors (more commonly referred to as CPUs, the thing that runs your computer) are also ICs. "IC op-amp" is a technical term for digital op-amps, as opposed to analog op-amps.

 

Op-amp is short for "operational amplifier", which you can Google for more info - there's a Wikipedia article on them.

 

MOSFETs are a type of transistor - the acronym is short for Metal-Oxide Semiconductor Field-Effect Transistor.

 

http://en.wikipedia.org/wiki/Op_amp

http://en.wikipedia.org/wiki/MOSFET

 

You might want to learn about basic electronics if you don't know what a transistor is.

 

As far as the headphone audio applications of op-amp vs discrete, the Dynalo is an example of a discrete amp. Here's a pic of a HeadAmp GS-1 module, which is based on the Dynalo: http://www.headamp.com/home_amps/gs1/images/gs1_module_med.jpg

 

AMB's M3 is an op-amp based amp, and there are tons of pictures of various builds here: http://www.amb.org/audio/mmm/gallery.html

Edited by Asr - 1/6/12 at 12:43pm

Isn't the Dynalo based on the TI opamp? OPA227... something?

Nope, it's discrete.

I read somewhere else that discrete used to be better, now they have made the chips better its a tie, sometimes with chips being better.

 

I wouldnt worry about it, its all about how they have designed it, no hard & fast rules, also when people say chips are cheap, remember that the transistors used in discrete amps cost pennies, some chips are quite expensive.

Edited by pinkfloydfan - 1/11/12 at 3:18am

discrete push-pull designs are better at handling multiple voltage and current spikes and dips, from drop and spikes of resistance from the speaker. also better at handling larger currents and voltages for stuff like speakers. discrete basically means all separate components like mentioned. power amps are always and usually discrete. pre-amps and lot of receivers nowadays use op-amps to save space and money cause they use lot of digital processing and inputs to be crammed in there. lot of pre-amps are op-amp/IC's but some are completely discrete as well. i don't know bout headphones but for speakers Discrete is always better. Mosfet is just type of transistor. Mosfet are used lot in computer equipment and in some audio amps as well. mosfet is like same concept of tubes in it's sonic characteristics but superior in design over tubes cause mosfets have 0ohm resistance and when it heats up it softs clip but with less distortion than tubes. mosfets are just not idea when coming to high-powered amplifiers that require massive amounts of voltages and current demands from low-impedance load speakers. they have greatly improved but are usually very expensive.