Ha! Bat amps, schmat amps!

My father had a kenner close-and-play.

Not really, but he did buy a Magnavox monstrosity: console with color TV, AM, FM stereo, record changer. THE WORKS in a beeeeeeeeeee-uuuuuuu-teeeeeeee-ful console cabinet with fake (not faux, even tackier than faux) wood speaker grilles.

This was my introduction to the world of audio. This fine piece os @#%%$ made such an impression in me: I just KNEW that there had to be better than this and I started out to find it. The magnavox's video left an even more negative scar/impresion: one that I am just starting to recover from. Where's my therapist?

Oh, well. Back to the model 200.

Scott's latest response poses at least as much questions as it answeres. I clearly understand amplifiction classes A, AB, B and C. Beyond C, I have not kept up with the various classes because so many producs are mis-labeled as to what digital or analog trickery class-du-jour it is. The marketing department had as much, or more, to say as to what class the product would be alleged to be in as did the engineering department.

In regards to the model 200 and it's class AB mode of operation, at what voltage output level does it leave class A mode? I thought this would be a good point to sneak in a serious question.

I think a white paper on the model 200 is in order: to explain what class G is, at least as far as Outlaw Audio is concerned. If memory serves me correctly, essentially class G involves switching to a higher voltage power supply(s) when the output of the amp becomes big enough to require it. I vaguely recall several Japanese companies doing something along these lines in the late 70s to mid 80s. With modern power semiconductors, I would expect the result to be much better: the 2uSec switching speed seems to indicate this, as long as the magnitude of any switching glitches within the 2uSec time period are held to reasonably low amplitudes.

Class D is a switching amp. I don't know what happened to letters E and F. I'm shure that other letters are used, such as H and T, for other classes of amps. Well, anyways, the model 200 sounds like a very interesting product.

Paul

------------------
the 1derful1


[This message has been edited by Paul J. Stiles (edited December 03, 2002).]

VERY interesting. Now the discussions will start instead of "I wonder". And we'll all learn something. I second Paul with some of his questions. I would think that 80 watts of AB power would produce heat - especially if driven hard so I doubt you'd want to stack them.
Oct. 02 issue of Stereophile has an article by Sam Tellig about similar concepts in the PS Audio HCA-2.While it's not the same, it is good background info on these new generations of amps.
Sounds to me like it's an 80 watt amp with dynamic power up to 300 watts like you would get in an old Proton or an NAD amp today.
But it's getting interesting.

I'm just assuming this thing is still relatively stable into 4ohms, right? I don't remember seeing anything mentioned about it. Will it still put out something like 300W into 4ohms, and more dynamically, or is it pretty much maxed out at 300W, or...?

Jason

Hello Steve,

With all due respect, as one of our valued Saloon Members, you are drifting into areas where you are making judgments based upon speculation. This is precisely why we were somewhat hesitant to discuss our technological approach until the unit would also be available for audition. However, for the record:

1) This unit will put out 200 watts at less than .05% THD all day long if asked. It has the capability of providing 300 watts dynamically.

2) Please do not compare this amp to the PS Audio in that the approaches taken to these amplifiers defer significantly.

3) Some of the Outlaws have extensive experience in NAD and Proton amplifiers. As a matter of fact, one member of the gang is responsible for naming Proton. Working with NAD engineers, this same person developed NAD’s Power Envelope Technology.

That said, there is no relationship between the design philosophy of this amplifier and any NAD or Proton amplifier. We truly believe that instead of trying to second guess (or for that matter guess) what the engineers did, the best judgment you can make would be in experiencing this amplifier for yourself.

Best,

Scott

Hi Scott:

With all due respect, I wasn't making judgements, just guessing and wondering about thigs which goes on all the time in this Saloon.
#2 I stated that "it wasn't the same thing" in regards to the PS Audio. But now we all know.
#3 Proton(Ihave one) and NAD have great reputations - a feather in your cap.

This saloon is all about guessing and second guessing. That's what happens when you give out basic specs and not much more. Sorry if I touched a nerve, but you have given us a lot more info in the last couple of days.
I know anyone can try it and send it back but shipping is not cheap.
I guess(again) I'm the only one interested in this as there doesn't seem to be any other comments out there.
Thanks for the info you have given us.

Steve

Okay, Paul asked about amp classes... I second that request. I know (or think I know) about classes A, B, AB, and D, but I really have no clue about C, G, H, or T, or what other classes there are.

Could someone in the know post (or post a link to) a brief description of these types? It doesn't need to be too long or complex, just a few lines or so on what each type is and what it means to the sound quality.

I'd do some research myself but I don't even know, really, where to begin searching for information on amp types and what I do know is information I've kind of absorbed from others over the years and I'd hesitate to repeat it for fear of polluting someone else's idea of amp types.

------------------
Matthew J. Hill
matt@idsi.net

Matthew I did not take the time to really READ these and could not find anything definitive Like a Home theater primer type article will look more later. I would like to get these down. On a quick search I ran into engineering courses to register for…with out an explanation of the different classes this is the little I found quickly.
http://www.class-d-amplifier.nl/Classes.htm

http://www.eatel.net/~amptech/elecdisc/ampclass.htm

http://www.geocities.com/SiliconValley/2775/clsses01.html

Like SLL, I haven't really read thru this stuff, but the Rane audio dictionary gives a brief rundown of the various amplifier classes here http://www.rane.com/par-a.html#amplifier_classes

Class C is where the output device(s) are conducting less than 180 degress (less than half) of the input waveform. I think class C is mostly used in RF stuff.

Class H is: (longer explanation) Picture a power amp with +/- 50v supplies for the output stage (plus 50v and minus 50v). For a given voltage gain of the amp, the amp can correctly amplify increasingly larger input signals untill the output transistors are fully turned on. The amp. is on the verge of clipping at this point. The output voltage magnitude will be a little less than the +/- 50 volt supplies because the output devices have a minimum resistance and any current passing through this minimum resistance will result in a minimum voltage drop. If the input signal gets too large, the output signal will no longer increase, the output waveform will stay where it is (assuming a well behaved amp with response down to DC and ideal supplies for this discussion) untill the input signal comes down to a value that results in an output signal that is comfortably within the +/- 50v of the output supply. In class G, before the output gets too big, the output voltage is switched from the +/-50v supplies to larger supplies, lets say +/- 100v. Now, when the input signal is big enough to reqire an output of more than what the +/- 50v can supply, the larger supplies take over. If the switchover time is quick and smooth enough, the output waveform is disturbed minimally by the switchover from one set of supplies to the other.

The advantage of this is in the reduced heat produced by the amp compared to one that used the big output supplies all of the time.

The instantaneous heat power dissipated by an output transistor is the current through it multiplied by the voltage across the output transistor at any given instant. If we are using an amp with small output supplies we will produce less heat than an amp with big supplies. Of course, this amp with small supplies will deliver less maximum power to the speaker. If we switch in big supplies only when we need them, we will be producing "big supply heat" only when the output waveform is big enough to demand the big supplies. When we are playing music at a level that does not need the big supplies, we only use the small supplies and only produce "small supply heat".

So, a class G amp, when playing "quietly" produced "small supply heat". When playing loudly, produces a combination of "small supply heat" and "big supply heat" which, at the WORST case (say, producing full output square waves) will be about equal to "big supply heat" but will much more likely be closer to the "small supply heat" example when playing MUSIC.

A variation of the class G is where, instead of switching from small supplies to big supplies and back as needed, the supplies, when needed, vary as needed to allow the amp to put out an unclipped wave form. The output supplies track the input signal (above a certain level). The output transistors have enough voltage to produce an unclipped output but not a lot extra to waste as heat. This variation can result in even less heat but it is more complicated and tricky to execute properly.

Paul

------------------
the 1derful1

Nice Link Ellen, I'll have to spend some time in there.