#1
this may sound completely stupid but is it possible to get a class A amp tone in a 80-100+ watt head without digital amp modeling? (i.e. line 6 spider or pod)
#3
like the i'm really digging the clean tone from the epiphone amps but are a little quiet. i was wondering if getting that in higher watts would mess with that sound at all
#4
Well when you say class A that just refers to how much of the amplifier is actually being processed by the tube (if i remember correctly). But honestly what it means is class A amps are just a type of amplifier. The amp class really does not have that much to do with your overall tone. It has more to do with tube beakup/headroom and overall tube sag.

I know there are large wattage class a amps because bogner 101bs used to have the option for that, and they are 120 watts.

SO basically, go for tone not class.
Originally Posted by StewieSwan
schtick_bomb is actually a Tare. An evil race of aliens from the planet Nibiru who have come to fight the power of Jesus Christ.


#5
You can get amps that sound amazing clean that are very loud if that's what you wanna know.
"In modern music, a lot of people are really stuck on the example, asif it were the idea. It takes millions of examples to articulate an idea, so don't get stuck on the f*cking example." - Joshua Homme, 2008.
#6
Quote by schtick_bomb
The amp class really does not have that much to do with your overall tone. It has more to do with tube beakup/headroom and overall tube sag.


I know what you are getting at, but I disagree. I think those things have a lot to do with tone.

TS: you could always reamp it?
#7
there's going to be a big difference in tone between class a and class b. That being said...most class a amps are going to be fairly low in watts. They aren't good for high headroom amps. The tubes run hotter, the circuit runs hotter and all that.

in order to have 100 class a watts you'd need something like 10 el34s.

Most Class A amps cap out at about 15-20 watts. That being said why do you need 100 watts of clean class A power. that's doing it wrong.

Also, what digital modeling amps have class a tone?

so much fail.

The bogner has an a/ab switch but switching to class a cuts the amps power by 2/3s. In half power mode, with triode/old mode, and class A the amp is only putting out 7 watts.

Which, hilariously might make it the best bedroom amp ever made.
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Last edited by AcousticMirror at Jun 23, 2010,
#8
Quote by 311ZOSOVHJH
TS: you could always reamp it?

You mean slave?

EDIT: And, following on from what Min said, there are a few other amps that you can switch classes on. My Mark IV can be run in both AB and A (Simulclass) or just A, but to run in Class A it drops the power quite a bit. Class A is really too inefficient to run at such high wattages.
Slightly off topic, but heres a good explanation of Class A (Warning, Long read)
http://www.mesaboogie.com/US/Smith/ClassA-WebVersion.htm
Last edited by littlephil at Jun 23, 2010,
#9
Quote by AcousticMirror
there's going to be a big difference in tone between class a and class b. That being said...most class a amps are going to be fairly low in watts. They aren't good for high headroom amps. The tubes run hotter, the circuit runs hotter and all that.


how about the inefficiency of the circuit as well, and the tubes don't run 'hotter' so much as they run almost twice the amount of time of a class A amplifier.


Quote by AcousticMirror
Most Class A amps cap out at about 15-20 watts. That being said why do you need 100 watts of clean class A power. that's doing it wrong.


i think this trend of low wattage class A amps is sorta a throwback. most class A amps were around 30 watts. like a vox ac30 or my THD bivalve for example, rated for 30 watts, class A.

Quote by AcousticMirror
Also, what digital modeling amps have class a tone?


you mean emulators of class A amps like a vox ac30? i don't know of any digital modelers that attempt to tackle a vox ac30

Quote by AcousticMirror
The bogner has an a/ab switch but switching to class a cuts the amps power by 2/3s.


and the custom shop oranges have switches that switch the power section between A and A/B. (2) EL34's are rated for 50 watts in A/B and 30 watts in A. same with my buddy's old VHT 50/50.

yeah, you totally owned him there

but why own on him so much. he is obviously a but confused as no one has really pointed out what class A is and the other classes of operation aren't even referred to.

http://en.wikipedia.org/wiki/Electronic_amplifier#Power_amplifier_classes

as with any circuit, sound depends on the components that comprise the circuit. basically what i mean is different tubes will have quite different characteristics from one another. bigger tubes like 6550's and KT88's have loads of headroom and you can get a pretty clean class A amp rated a bit over 30 watts. mind you 30 watts in my THD is louder than all hell
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#10
I didn't do any owning. I just laid the facts out. straight truth fo real real. it's like if you did a google search and like read the wikipedia in an ominous face.

true class a depends on biasing doesn't it/plate voltage doesn't it? I read somewhere that a lot of push/pull class a amps were actually running a/b when pushed.

I think I was thinking only of single-ended class a amps.
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#11
Quote by AcousticMirror
I didn't do any owning. I just laid the facts out. straight truth fo real real. it's like if you did a google search and like read the wikipedia in an ominous face.

true class a depends on biasing doesn't it/plate voltage doesn't it? I read somewhere that a lot of push/pull class a amps were actually running a/b when pushed.

I think I was thinking only of single-ended class a amps.


no, i am not so evil as to actually do research at that point. but back before i bought the THD i did a bunch of research, at the time i had a TT and thought it was the bestest of the bestest and decided i wanted another class A amp.

so i got knowledgeable and found out a bunch of things. for example, i found that (2) EL84's in a single ended, class A config only makes like 5 or 7 watts. i asked roc why they don't make A/B amps with el84s much and I also asked how my TT makes 15 watts class A with (2) el84s; he informed me that the TT was not a true single ended class A, which would explain many things.

there seems to be much hocus pocus going on with labeling an amp's operation, so try not to get too hung up on the labels and play toward things you know. imo, buying an amp based on it's labeled class of operation is "heading in the wrong direction" as it tends to be more of a marketing gimmick than reality. with another example if you mind, almost without exception every tube guitar amplifier out there is class A to an extent because the preamp runs in class A almost every time... so what are they really labeling and how true is it to it's label?
punk isn't dead, it's always smelled that way.

"A perfection of means, and confusion of aims, seems to be our main problem."
-ae
#12
There are lots of class a/b el84 amps. I own several. One single ended el84 is used in many 5w amps. So I would think there is no point using 2 to make 5watts.

I doubt that the tone from one class a amp is going to translate into the same tone in another. Amps just have too many other tone defining characteristics. The big way to decide on an amp is to listen to it.

so what are they really labeling and how true is it to it's label?
They are labeling the power amp and it's universally understood that it's the power amp.
#13
Quote by fly135
There are lots of class a/b el84 amps. I own several. One single ended el84 is used in many 5w amps. So I would think there is no point using 2 to make 5watts.

I doubt that the tone from one class a amp is going to translate into the same tone in another. Amps just have too many other tone defining characteristics. The big way to decide on an amp is to listen to it.

They are labeling the power amp and it's universally understood that it's the power amp.


are their amps with a single el84? thanks for putting me on the map there. but there is a point in using (2) el84's for a 5 watt rating if you want class A operation. i seriously doubt how universally understood it is when most people couldn't tell you what a 'power section' of an amp is. you may be an EE and know, but many companies that sell amps aren't quite honest in their dealings and much misleading advertising is running around.

i think i also implied that there are many class A/B designs using el84's, but i'd like to see a few advertised as such...

i was not trying to address the issues you brought up, i was trying to show TS that truthfully you can get class A operation out of a preamp pedal if class A is all he wants. i was trying to show him there is much misleading info out there for the suggestable buyer. but thx for the chime in.
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"A perfection of means, and confusion of aims, seems to be our main problem."
-ae
Last edited by gumbilicious at Jun 26, 2010,
#15
^yes but many people believe it is. from my limited understanding a true class a amp running 4 EL84's would be about 10 to 15 watts.
punk isn't dead, it's always smelled that way.

"A perfection of means, and confusion of aims, seems to be our main problem."
-ae
#16
if anything it goes a to a/b when it gets turned up.
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#17
it is really class AB1. i didn't feel like getting into the 'what class operation a ac30 really is' debate, so i used an amp i knew was perceived as class A above even though i knew it wasn't true class A. mainly cuz most people go "I want a class A sound like a vox ac30".

i got called and it's the truth.

but it also backs up what i said earlier, in that there is much misdirection over true class operation of amplifiers. and it is not as clean cut as looking for a PI tube to figure it out. EL84's don't need PI tubes due to their high gain output.
punk isn't dead, it's always smelled that way.

"A perfection of means, and confusion of aims, seems to be our main problem."
-ae
#18
Quote by gumbilicious
but it also backs up what i said earlier, in that there is much misdirection over true class operation of amplifiers. and it is not as clean cut as looking for a PI tube to figure it out. EL84's don't need PI tubes due to their high gain output.
Not true. EL84's do use a PI for class a/b operation. A PI is used to invert the phase to one of the EL84's. That's how class a/b works. One EL84 works on the inverted signal and one on the non-inverted.

Whether class a vs a/b means anything wrt tone I couldn't say. Maybe amp manufacturers have found it useful to imply that's something special. I was just looking at a low end Cisco switch where the advertising make a big deal of how it controlled data flow between the ports. The thing is that every since switches came out they've been doing that and to find a switch (known as a hub) that doesn't is next to impossible.

but there is a point in using (2) el84's for a 5 watt rating if you want class A operation.
If you are using 2 EL84's in class A mode you should get 10 to 15 watts.

i seriously doubt how universally understood it is when most people couldn't tell you what a 'power section' of an amp is.
I meant anyone who had a clue as to what A vs A/B meant would understand it's referring to the power amp.
#19
Quote by schtick_bomb
Well when you say class A that just refers to how much of the amplifier is actually being processed by the tube (if i remember correctly). But honestly what it means is class A amps are just a type of amplifier. The amp class really does not have that much to do with your overall tone. It has more to do with tube beakup/headroom and overall tube sag.

I know there are large wattage class a amps because bogner 101bs used to have the option for that, and they are 120 watts.

SO basically, go for tone not class.



class a =/= class ab in terms of tone.

class a is less efficient though.

class a amps don't sag btw
#20
no way 2 el84s in class a gets you 15 watts. that's pushing the limits of the spec in pushpull.
true class a will get you about 7-8. ab1 gets you 15.
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#22
most lower wattage amps ARE class A single ended.

vox AC30 is MOSTLY class A. it's biased hot enough it could be classified class A until it's turned up so high. so it's technically a push-pull class A amp.

phase inverter is needed for push-pull operation. an amp could be push-pull class A.
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#23
Quote by ECistheBest
most lower wattage amps ARE class A single ended.

vox AC30 is MOSTLY class A. it's biased hot enough it could be classified class A until it's turned up so high. so it's technically a push-pull class A amp.

phase inverter is needed for push-pull operation. an amp could be push-pull class A.


Yeah true, most people instantly go "if it has a PI then it's class ab"

now class c and d, those are other things. as far as i know the classes go all the way to z
#24
class A means all the signal is amplified by each (or just one) power tube.

class B means HALF the signal is amplified by each (two, four, etc) power tube.

class AB means SOME of the signal is amplified by the tubes. there ARE overlaps between the power tubes. when the tubes start amplifying most of the signal, it becomes more class A.
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#25
Quote by AcousticMirror
no way 2 el84s in class a gets you 15 watts. that's pushing the limits of the spec in pushpull.
true class a will get you about 7-8. ab1 gets you 15.
Well if 1 EL84 in class a mode gets you 7-8, what do you think 2 will give you?
#26
where amp are you playing that gets 7-8 with one el84?
an el84 will give you 5 and that's pushing it.
it really puts out closer to 3.5-4

a single ended el34 will give you 7 watts maximum.
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#27
single ended EL84 output section would get 6w with 50% max anode dissipation. it's pretty tough though...

if it was biased at 12w (max plate dissipation), and say we had a 300v HT, 300v screen voltage, 7.5k primary OT. make the bias 10.5v or so, at 40mA. screen current would be something around 8mA, so add that to the equation, cathode resistor would be around 218R. so just use 220R, a standard value.

that's got the HT 300v, plate current 40mA, giving the plate dissipation of exactly 12w. this isn't the output though.

looking at the loadline, the input sensitivity would be around 15v p-p? that's the maximum output before clipping. the maximum anode voltage is about 500v, which is 176vRMS, and maximum anode current of 80mA, which is 28mA RMS.

so 176 x .028 = 4.928wRMS that's the output of this output section. see? not even 5w.


imanerd.


btw min, my amp has a calculated 9.6w at full output before clipping. it probably gets around 13~14w at full blast. not so sure
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#28
Quote by ECistheBest
single ended EL84 output section would get 6w with 50% max anode dissipation. it's pretty tough though...

if it was biased at 12w (max plate dissipation), and say we had a 300v HT, 300v screen voltage, 7.5k primary OT. make the bias 10.5v or so, at 40mA. screen current would be something around 8mA, so add that to the equation, cathode resistor would be around 218R. so just use 220R, a standard value.

that's got the HT 300v, plate current 40mA, giving the plate dissipation of exactly 12w. this isn't the output though.

looking at the loadline, the input sensitivity would be around 15v p-p? that's the maximum output before clipping. the maximum anode voltage is about 500v, which is 176vRMS, and maximum anode current of 80mA, which is 28mA RMS.

so 176 x .028 = 4.928wRMS that's the output of this output section. see? not even 5w.


imanerd.


btw min, my amp has a calculated 9.6w at full output before clipping. it probably gets around 13~14w at full blast. not so sure


your amp is gonna shoot off into your eye.
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