Class A?

Hwilliams · September 29th, 2004, 07:48 AM

I know that this may be a dumb question but could someone explain to me what class A is? I saw this while I was reading the specs on an amp. It said that it had 30 Class A watts. What's the difference between 30 watts and 30 class A watts?

Thanks

HW

weelie · September 29th, 2004, 07:53 AM

http://www.pentalaboratories.com/audio_help6.asp
http://www.duncanamps.com/technical/ampclasses.html

zook · September 29th, 2004, 08:11 AM

http://www.aikenamps.com/ClassA.htm

Randall dispells all the myths and BS.

Just because an amp is cathode biased does not mean it's class A. In actuality, a class AB amp is more efficient.

Single ended amps e.g. Fender Champ and others with only one output tube are class A since one tube works all the time. A Class A push pull amp would have both tubes working at the same time as opposed a class AB with one pushing while the other is pulling. etc.

Don't be swayed by hype.

Winnie

Mik · September 29th, 2004, 09:55 AM

Don't be swayed by Class A hype...but don't ignore the amps just cuz of the hype. "Class A" may be misleading, inaccurate, a downright lie-but I've played and owned a few of 'em and I haven't encountered one yet I didn't like. Dr. Z's, the Gibson Goldtones, Vox, even the Pro Jr (Fender to its credit never called the PJ "Class A", I don't think Z calls his amps A either but folks do), I dug em all. I hear "Class A", I just assume it's a "hot" bias, likely cathode bias, EL84 Class AB amp.

I really don't mind a little "Class A" marketing swindle...uh, I mean sizzle.

Mik

Tim Swartz · September 29th, 2004, 11:44 AM

It is unfortunate, but let's face it, who would buy a Class A/B amp when they can have Class A. It sounds like Class A/B is a compromise... and that is what the marketting liars are capitalizing on. As long as the term sounds better who cares about the electronic definition.

dhdfoster · September 29th, 2004, 12:38 PM

I read the whole explanation, and the only conclusion I was able to firmly arrive at was that I am obviously an idiot. I know what "tube" and "power section" are, but I get lost after that.

Will V. · September 29th, 2004, 01:00 PM

Quote:

Originally Posted by Tim Swartz

It is unfortunate, but let's face it, who would buy a Class A/B amp when they can have Class A. It sounds like Class A/B is a compromise... and that is what the marketting liars are capitalizing on. As long as the term sounds better who cares about the electronic definition.

But, with Class A/B, you get two! LOL!

Uh-oh, I just saw the Allen Brown Sugar is class A/B cathode bias, I'm not getting one now.

Seriously, I'm more interested in how the amp sounds than whether it's class A or class Z.

Rick S · September 29th, 2004, 01:45 PM

Quote:

Originally Posted by dhdfoster

I read the whole explanation, and the only conclusion I was able to firmly arrive at was that I am obviously an idiot. I know what "tube" and "power section" are, but I get lost after that.

Most others don't understand it either. Bottom line is, if you aren't a designer or tech, operating class is absolutely of no concern to you.

As a musician, learn to trust your ears and choose amps based on performance goals for your style and disregard operating class claims as hype.

As Tim said above, it was a marketing agenda that started this. The hypemeisters found out early on that operating class was easily confused as some sort of grading system and was taken hook line and sinker by the masses.
Rick S

guitar_ed · September 29th, 2004, 09:35 PM

The whole point about Class A amps has to do with the power settings on the power tubes/transistors. (You can have a Class A solid state amp.) The idea is to put the tube/transistor in a state where it generates less noise. But there is a cost. Class A amps use more electricity and generate more heat than other amps. Simply put, your electric bill will be higher and your room warmer. Also, a true Class A amp is harder to design and build, and thus should be more expensive than the alternatives.

As Will V. says: Listen to different amps until you find the one you like. It may be tube , it may be solid state, or a mix. In the final result, your preference is the only thing that matters.

Guitar Ed
If a little knowledge is dangerous, I have little enough to be be deadly.

Tremo · September 29th, 2004, 11:07 PM

Quote:

Originally Posted by guitar_ed

The idea is to put the tube/transistor in a state where it generates less noise.

Huh? Noise has nothing to do with class of operation. Who gave you that misinformation?

trag-o-caster · September 30th, 2004, 01:17 AM

Quote:

Originally Posted by Will V.

[
Seriously, I'm more interested in how the amp sounds than whether it's class A or class Z.

Eggzackle-lackle-leeeeeee!

Mr. Droopy-Drawers · September 30th, 2004, 07:17 PM

Quote:

Originally Posted by Tremo

Quote:

Originally Posted by guitar_ed

The idea is to put the tube/transistor in a state where it generates less noise.

Huh? Noise has nothing to do with class of operation. Who gave you that misinformation?

I have a hunch guitar_ed condensed a very convoluted train of thought. In some high-end audio circuits, the theory might be that switching transients and noises may be present. Class A would have no such concerns, because the devices are biased in a way that they are always 'on'. This isn't a problem with tube amplifiers anyway, because the OPT has the wonderful 'feature' of common mode rejection.
There's a lot to consider, and a lot to think about. But the scientific theory is waaay beyond me. So I'll just mosey along.

Tremo · September 30th, 2004, 11:00 PM

Quote:

Originally Posted by Mr. Droopy-Drawers

I have a hunch guitar_ed condensed a very convoluted train of thought. In some high-end audio circuits, the theory might be that switching transients and noises may be present. Class A would have no such concerns, because the devices are biased in a way that they are always 'on'. This isn't a problem with tube amplifiers anyway, because the OPT has the wonderful 'feature' of common mode rejection.
There's a lot to consider, and a lot to think about. But the scientific theory is waaay beyond me. So I'll just mosey along.

Interesting guess, but a guess none the less. Regardless, it's technically incorrect. Sorry, maybe guitar_ed should answer for himself.

Rob DiStefano · October 1st, 2004, 05:40 AM

Class A? Class A/B?

Who the heck cares as long as the amp sounds great, is quiet, is reliable.

Amen to all the Class BS.

mark norwine · October 1st, 2004, 09:42 PM

Quote:

Amen to all the Class BS.

your amp runs in class BS? cool! bring it over to the shop...i want to see it on the scope!!

Tremo · October 1st, 2004, 10:18 PM

I thought only Groove Tubes could be biased into class BS!! Damn, learn something new every day.

jjmantele · October 1st, 2004, 11:23 PM

"Class A" in an advertisement means nothing. Kind of like if your amp was "Turbocharged."

The easiest way to understand Class is to think of a lumberjack using one of those giant saws to cut thru a log. Sometimes there's a lumberjack on both ends of a double handled saw. That set-up is "push=pull" for obvious reasons. The key question is, are both lumber jacks pushing and pulling 100% of the time or does each guy take a "rest" during some/all of the pull stroke (for example.)

One guy: Must push and pull all the time >Class A
Two guys: Push and pull 100% of the time >Class A
" : Push but don't pull >Class B
" : Push but pull some of the time >Class AB

Of course it's more "efficient" to have 2 guys since each guy can specialize in just pushing (for example) resulting in more output than compared to having 2 guys pushing and pulling on the same handle. Almost all 2 output tube guitar amps have the 2 tubes in "push pull" Class AB.

Rob DiStefano · October 2nd, 2004, 04:40 AM

Quote:

Originally Posted by mark norwine

Quote:

Amen to all the Class BS.

your amp runs in class BS? cool! bring it over to the shop...i want to see it on the scope!!

Heck, if ya think that's cool you oughta see my amp power cord soldering techniques.

September 29th, 2004, 07:48 AM	#1 (permalink)
Hwilliams Tele-Meister Join Date: Apr 2003 Location: Dry Creek, La Age: 35 Posts: 173	Class A? I know that this may be a dumb question but could someone explain to me what class A is? I saw this while I was reading the specs on an amp. It said that it had 30 Class A watts. What's the difference between 30 watts and 30 class A watts? Thanks HW

September 29th, 2004, 07:53 AM	#2 (permalink)
weelie Tele-Afflicted Join Date: Apr 2003 Location: Helsinki, Finland, Yer-up Age: 34 Posts: 1,931 12 Photos	http://www.pentalaboratories.com/audio_help6.asp http://www.duncanamps.com/technical/ampclasses.html __________________ <- I don't need smileys, I'm smiling already.

September 29th, 2004, 08:11 AM	#3 (permalink)
zook Tele-Holic Join Date: Aug 2003 Location: Northeast Kingdom, Vermont Posts: 772	Mostly it's hype http://www.aikenamps.com/ClassA.htm Randall dispells all the myths and BS. Just because an amp is cathode biased does not mean it's class A. In actuality, a class AB amp is more efficient. Single ended amps e.g. Fender Champ and others with only one output tube are class A since one tube works all the time. A Class A push pull amp would have both tubes working at the same time as opposed a class AB with one pushing while the other is pulling. etc. Don't be swayed by hype. Winnie __________________ I have noticed that happy people are often evaluating themselves and unhappy people are always evaluating others. -William Glasser

September 29th, 2004, 09:55 AM	#4 (permalink)
Mik Tele-Afflicted Join Date: Mar 2003 Posts: 1,416	Don't be swayed by Class A hype...but don't ignore the amps just cuz of the hype. "Class A" may be misleading, inaccurate, a downright lie-but I've played and owned a few of 'em and I haven't encountered one yet I didn't like. Dr. Z's, the Gibson Goldtones, Vox, even the Pro Jr (Fender to its credit never called the PJ "Class A", I don't think Z calls his amps A either but folks do), I dug em all. I hear "Class A", I just assume it's a "hot" bias, likely cathode bias, EL84 Class AB amp. I really don't mind a little "Class A" marketing swindle...uh, I mean sizzle. Mik __________________ a "motor-bike with a touch of blood in it is better than all the riding animals on earth, because of its logical extension of our faculties, and the hint, the provocations, to excess."-T.E. Lawrence

September 29th, 2004, 11:44 AM	#5 (permalink)
Tim Swartz Tele-Afflicted Join Date: Mar 2003 Location: Michigan - Tweenst the Great Lakes Posts: 1,775	Reduced to a mere buzzword... It is unfortunate, but let's face it, who would buy a Class A/B amp when they can have Class A. It sounds like Class A/B is a compromise... and that is what the marketting liars are capitalizing on. As long as the term sounds better who cares about the electronic definition.

September 29th, 2004, 12:38 PM	#6 (permalink)
dhdfoster Tele-Holic Join Date: Apr 2003 Location: San Francisco, CA Age: 40 Posts: 944	I read the whole explanation, and the only conclusion I was able to firmly arrive at was that I am obviously an idiot. I know what "tube" and "power section" are, but I get lost after that.

September 29th, 2004, 09:35 PM	#9 (permalink)
guitar_ed Tele-Holic Join Date: Mar 2003 Location: Bankrupt State of California Age: 47 Posts: 711 16 Photos	A few more words on Class A amps.... The whole point about Class A amps has to do with the power settings on the power tubes/transistors. (You can have a Class A solid state amp.) The idea is to put the tube/transistor in a state where it generates less noise. But there is a cost. Class A amps use more electricity and generate more heat than other amps. Simply put, your electric bill will be higher and your room warmer. Also, a true Class A amp is harder to design and build, and thus should be more expensive than the alternatives. As Will V. says: Listen to different amps until you find the one you like. It may be tube , it may be solid state, or a mix. In the final result, your preference is the only thing that matters. Guitar Ed If a little knowledge is dangerous, I have little enough to be be deadly. __________________ Piss off a politician, register to vote. When you complain about the government, remember that you ARE the government. Voting is the ultimate act of civil dis-obediance. AIM - guitar_edg Skype - guitar_edg (had to change on 5/16/06)

October 1st, 2004, 05:40 AM	#14 (permalink)
Rob DiStefano Friend of Leo's Join Date: Mar 2003 Location: Park Ridge, NJ Age: 62 Posts: 4,577	Class A? Class A/B? Who the heck cares as long as the amp sounds great, is quiet, is reliable. Amen to all the Class BS.

October 1st, 2004, 10:18 PM	#16 (permalink)
Tremo Friend of Leo's Join Date: Mar 2003 Location: Silicon Valley, CA, USA Posts: 3,623	I thought only Groove Tubes could be biased into class BS!! Damn, learn something new every day.

October 1st, 2004, 11:23 PM	#17 (permalink)
jjmantele Tele-Holic Join Date: Aug 2003 Location: New Jersey Posts: 837	Class A "Class A" in an advertisement means nothing. Kind of like if your amp was "Turbocharged." The easiest way to understand Class is to think of a lumberjack using one of those giant saws to cut thru a log. Sometimes there's a lumberjack on both ends of a double handled saw. That set-up is "push=pull" for obvious reasons. The key question is, are both lumber jacks pushing and pulling 100% of the time or does each guy take a "rest" during some/all of the pull stroke (for example.) One guy: Must push and pull all the time >Class A Two guys: Push and pull 100% of the time >Class A " : Push but don't pull >Class B " : Push but pull some of the time >Class AB Of course it's more "efficient" to have 2 guys since each guy can specialize in just pushing (for example) resulting in more output than compared to having 2 guys pushing and pulling on the same handle. Almost all 2 output tube guitar amps have the 2 tubes in "push pull" Class AB. __________________ JJman If it says "Vintage" on it -it isn't.