WHAT IS CLASS "A" mean in a mic pre

[nestle]

I know its silly but what does this much bandied class A discreet mean?

[object88]

Frankly, I don't understand "class A" in a mic preamp either. But "discreet" typically means that no ICs were harmed-- er, used, in the circuit. However, it could just means that there are no ICs in the audio path (i.e., still some in the control paths).

Of course, this is also highly dependant on marketing influences.

[Rick Hunter]

what is an IC. sorry.

[object88]

"Integrated Circuit"-- a chip. A whole slew of resistors and transistors jammed into a small package. Often regarded as the death of audio, because budget-minded audio companies would pick the cheapest they could possibly find, which most often sounded bad or had poor performance.

Of course, you can get good ICs which work just as good as individual components, but you'll pay more. (More than the individual components? Depends on how much is jammed in there, etc.)

[xonlocust]

IC - integrated circuit

oops, beat to the punch.

to add to the above, people sometimes trash the TL074 chips for being cheaper, or conversely the burr-brown chips (opa-whatever the # is) are sposed to be better.

for ex, the sytek pre is IC based, but is much better sounding than say a mackie, because the particular ICs are better suited to the design and so on...

[Al]

Well, Marlborro is a class "A" cigarette, is that the same thing then?

Al

[greatmagnet]

I'm glad someone broke the cherry on this one as I've been in the closet about my ignorance on the issue as well.

But I feel it's thus far been only half-answered. I now know what "discreet" means, and I found out what an "IC" is. So, what about the original question: WHAT IS CLASS A???

Same as the above (no microchips) or something else in addition to that?

[brew]

www.google.com

[Josephratf]

http://www.rane.com/par-a.html#amplifier_classes

[Josephratf]

There are many different types of amplifiers class A is just one. The above link will go thru em.

The discreet means no Intergrated Circits

[object88]

Here's the thing that confuses me... does anyone actually bother doing anything aside from class A outside of power amps?

See, I understand "class A" in terms of a power amp, or at least tube-based guitar power amps. It makes a lot of sence, when dealing with such high amounts of current, to use something other than class A. But anywhere else? I don't get it. In particular, in every tube amp circuit I've seen, the preamp (and when present, phase inverter) are class A. It's just the power section that is A or AB.

Does anyone actually use class AB (or other non-A) in a preamp or line-level device?

[Theron D]

A class A amp involves the entire signal being driven through a single amp (transistor or tube) rather than having a push -pull type network where two amps are used (One to drive the positive signal and one for the negative signal). Class A is desired because there is no crossover distortion that occurs for when you are turning on and turning off. Off coarse when a single amp is used, heat becomes an issue since it is one 100% of the time versus only 50% of the time for a push-pull network. For a pre amp this should not be an issue because the currents are very low when compared to a power amp.

Regards
Theron D

[object88]

A class A amp involves the entire signal being driven through a single amp (transistor or tube) rather than having a push -pull type network where two amps are used (One to drive the positive signal and one for the negative signal).

Well, this part isn't true. You can have a push-pull class-A topology. Both tubes / transisters are on 100% of the time, just in opposite directions.

[soundguy]

Does anyone actually use class AB (or other non-A) in a preamp or line-level device?

MOST of the preamps commonly available are run with AB outputs. Many many many more discrete transistor class AB designs that class A designs. Neve 1073/1272 is class A, langevin AM16, 1176 Rev E, others. Many of the class A designs in preamps that are very popular in the vintage fiending circles are pretty saturated sounding IMO. AB amps are a little more mellower sounding to my ear.

dave

[TapeOpLarry]

As fas as preamps, a Class A circuit can be designed with ICs. It can also be done with discrete components. You'll find that people that know their shit and can design great sounding stuff can do so either way...

An unnamed gear sales person at the NAMM show did tell me that a preamp had discrete Burr Brown op amps - a physical impossibility. I didn't say anything...
Larry