Stupid question time. What determines "wattage?"

[choosebronze]

Please forgive me. I'm a pretty smart guy, but I am not a science guy. Amp building is an interesting hobby for me because I feel like I'm always fighting my own brain. I have to be really careful, pay close attention, and check everything I do 10 times. I can keep doing this, getting a layout and schematic, and making sure they match in my build, but I'd like to actually be learning along the way, too.

Today I got to thinking about "wattage," which I gather is a measure of power, though I'm not sure what "power" means in the context of a guitar amp aside from the resulting loudness. The amp's wattage seems to be mostly affected by the relationship between power tubes and output transformer if I'm getting it right. My understanding is a, say, 5w EL34 amp isn't made because EL34's wouldn't be efficient at power that low, not because it's not possible. I assume it's also the reason you couldn't stick a 50w output transformer in a Princeton Reverb. The two 6V6's can't handle the power required to _________. To what, power the necessary OT? I don't understand what or why. Rob Robinette just posted a modded JCM800 schematic which can run EL34's at 25w. Does other stuff need to change in the JCM800 circuit to do that? Could someone with a 50w JCM800 just put in a 25w output transformer? If not, why not? Is it a matter of impedance at the OT? If so could a theoretical OT be made to match the needed primary OT impedance to the speaker output? Perhaps most importantly, is anything I'm saying even making any sense? I don't even know enough to know what I'm asking, sorry for unleashing a dozen intertwined questions in there.

I've been trying to read about this but I haven't found anything that explains it clearly, at least not in the context of guitar amps. Are there any recommended books that go less into repair or tonal design, and more into the actual mechanics of  the amp? All of the "how an amp works" type things I've read do a good job of explaining amp stages and components, but not necessarily how they interact with each other, or how their alteration change the whole system.

Thanks for bearing with me. If I'm too far gone to be helped, feel free to just give me the name of a book (or five) and tell me to come back in a few months. 

[jjasilli]

Not a stupid question at all.  I'll respond from left field.


Wattage is a statement or measure of Power. Power is logarithmic, like, e.g., the Richter Scale for the power of earthquakes.  To get 2X the power output, you need 10X the wattage. 


Horsepower is also a measure of power (not to mention joules, ergs, candlepower, lumens, etc).  Horsepower is usually used to state the power of engines.  However, Watts can be converted to horsepower, and vice-versa, by a standard multiplication factor.


The reason I mention this is that Horsepower is typically used to state output power.  Watts are typically stated for power consumed, or "dissipated", in order to produce horsepower. So, an electric motor may consume 1200W and put out 1/2 Horsepower.  If we convert W to H, we can calculate how Efficient the electric motor is.


IMHO, colloquial language re the incandescent light bulb, bastardized the concepts involved.  We often say that an incandescent bulb puts out 20W of light.  This is technically wrong.  But we're all familiar with bulb wattage so we know how much light output to expect.  Properly stated, the bulb consumes or dissipates 20W of electricity, and puts out X candlepower or Y lumens. 


The same is true for an amp.  The amp does not literally put out Watts.  Rather a 20W power amp is rated to dissipate 20W of electricity.  If we cause it to dissipate more watts than it is rated for, it will begin to overheat (at some point it will be damaged).  There is a name for people who willingly do this - rock guitarists.   


However, from experience we know about how loud a 20W or 50W or 100W amp will be.

[shooter]

JJ nailed it!

I'm always fighting my own brain

with you there, spent my whole career fixing really cool hi-end electronic systems, only to get all hung up on a "term"

I love this cheat-sheet when I really just want the answer, without the why 

hang in there, you ALWAYS wind up in the tall weeds, but there's great thing hiding inside the weeds

[jjasilli]

Thanks, shooter.  This may work best collaboratively.  Note that the Ohm's Law Pie Chart also contains slices for the Power Formula.  To make all this more pertinent to amps:


*  For PP amps:  W = (Plate Voltage)² / Primary Impedance of Output Transformer. (This assumes that the OT secondary tap = speaker impedance, just shy of distortion)


*  For SE amps: W = about 40% of Plate Dissipation. Plate Diss in W:  W = Effective Plate Voltage X Amps.  (I.e., convert mA to Amps).  For cathode biased amps, Effective Plate Voltage = Plate Voltage - Cathode Voltage.

Now for the screwy part.  OT's don't actually have a primary or a secondary impedance per se.  They have a primary winding and a secondary winding.  (Maybe these have taps for diversity.)  The relation of these 2 windings is the winding ratio.  The OT's primary impedance is determined by the impedance of the speaker load in Ohms, reflected back through the winding ratio to the OT primary.  The amp designer has engaged in a balancing act to match the power tube(s) to the OT, in terms of impedance, plate voltage, screen voltage, and acceptable frequency response and THD.  This process involved scientific & mathematical modeling, followed by empirical testing (educated guessing, trial & error).


The flow of electricity from the power amp, though the speaker load, and back to the amp, involves the dissipation of Watts.  All the components and wires need to be able to handle their share of that power dissipation.

[shooter]

For SE amps: W = about 40% of Plate Dissipation

for more fun with terms;
in SE the tube is typically "biased" for near 100% dissipation (power) - in Watts, the speaker gets ~ 40% in audio (power) also in watts 

starting to get that Linda Blair head swivel going yet? 

[choosebronze]

starting to get that Linda Blair head swivel going yet?

Heck, that was my starting point! Thanks for all these info guys. I'm going to read your responses a few times and see if I can get it to make sense.

[sluckey]

Walk, Don't Run...

If you really want to understand what determines wattage, start at the beginning with some basic electronics theory. When you understand how power, voltage, current, and resistance relate to each other, and what the terms actually mean, then move on to basic circuit analysis. You don't need to dive deep into the math, but you will need more than a 4 banger calculator.

[shooter]

once you get a neck brace 
what Sluckey said, start small

here's a quicky overview; (lots of examples searching, I just snagged this one);

https://library.automationdirect.com/basic-electrical-theory/

[tubeswell]

In simple electrical terms:


Watts = Volts x Amps *


(*This is often written in electrical shorthand I.e. W = V x A, or, in more mathematical terms: P = E x I, where P = Power, E = volts, and I = current. That’s what that chart is all about that was posted above)


Since Volts and Amps are also part of Ohms Law (Volts = Amps x Ohms), then if you know Volts, Amps or Ohms, you can figure out the Watts.


So rearranging the above equation for Watts (substituting Ohms Law into it):


Watts = Volts x (Volts/Ohms)
Or
Watts = (Amps x Ohms) x Amps

[shooter]

or if you want to know how much heat your tube is emitting, (up north heats important:)

1 W = 3.412142 Btu/h

[Ritchie200]

I am also one who knows that a change in component will result in a certain outcome - because I read it here.  Or the original amp manufacturers used this value on ____, and I know the end result.  HOWEVER, I have no idea why and like you wonder how some of these things interact.  So I lurk a LOT and try to take it all in from the really knowledgeable people that post here every day.  I have a pretty good library of the usual suspects, but purchased this book from Richard last year based on PRR's recommendation.  I like it a LOT!  It has filled in a lot of the blanks and I am re-reading sections when I find myself scratching my head.  It might be one to add to your library as well.  Like PRR said, it is geared to a beginner in this cool hobby, and it just might fill in a few of the blanks you have as well.

Jim

https://el34world.com/Forum/index.php?topic=23611.msg254045#msg254045

[Tony Bones]

Start by reading everything you can find. Even if you don't really understand all of it, you'll likely absorb some of it. Don't stress over every sentence that doesn't make sense, or every equation that you're not equipped to understand.

Look for old text books, etc, from a time when tube electronics was the thing. Explore the technical books section of http://www.tubebooks.org/

For what its worth, I cut my teeth on the Radio Amateur Handbook from around 1959. That was the bible for Ham radio operators back when they built their own transmitters. You can download a copy from tubebooks.org. Actually, I might have started with the first 100 pages or so of the RCA Receiving Tube Manual from around the same period. That was essentially a book of tube datasheets, but the beginning is  a very good introduction to how tubes and tube based circuits work. Not just what's in a guitar amp, but the actual first principles of vacuum tubes in a very easy to swallow form.

If you really want to get down to the physics of it without getting a PhD in physics, find a copy of Radio Physics Course by Alfred A. Ghirardi. This book was written in the 30's, before the current 'standard method' of electronics was developed, so you get a very interesting look from someone that understood electronics without the modern dogma. OK, dogma is too strong of a word, but if you look at most electronic texts written in the past 75 years, they all present more or less the same info from the same point of view. It makes sense; the authors are just regurgitating what they learned from the text books they used in college. Modern introductory electronics texts all present exactly the same material in exactly the same way. But Ghirardi didn't learn electronics from text books, so he wasn't predisposed to present it that way. It's very refreshing, even for someone that already understands the material.

It might be available for download, or get a used copy from https://www.abebooks.com/book-search/title/radio-physics-course/

[PRR]

> start at the beginning with some basic electronics theory.

+1

> you will need more than a 4 banger calculator.

A 5-banger: you need a square-root function. I have seen these as little as $1.

A 1/x key is a real bonus once you learn to think in ratios and why you would invert a fraction. That may be a $5 calculator.

[st]

Power is logarithmic

No it's not.

like, e.g., the Richter Scale for the power of earthquakes. 

the Richter scale is a scale of magnitude and in the formula you can clearly see that that is a function of the logarithm of the amplitude (see https://en.wikipedia.org/wiki/Richter_magnitude_scale).

To get 2X the power output, you need 10X the wattage. 

This statement makes no sense. I paraphrase: 2 x power (in Watts) = 10 x power (in Watts).
There are ways to express the ratio of power quantities on a log scale (in dB), but I think you are confusing things.

[shooter]

No it's not.

into the weeds;
I'm by far a math guy, but if the line curves you need funky math to solve for the area under that line, any point on that line you can have with linear math.

when you express power in Db's pretty sure you gotta get out the log tables.  Pretty sure you need them for dynamic power also, but for close enough guitar amp, you can cheat 

[Ritchie200]

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W) = 10 ⋅ log10( P(W) / 1W) + 30

RMS, PEP, PP, SWL, SPL, potato, potaato

It takes a ten times increase in wattage to "perceive" an amp to be twice as loud (power...ful  )  HOWEVER, the human ear is not linear and diferent freqs take more or less wattage to "perceive" that increase in volume (POWER!  ).  The Major does not play by any of these trivial rules and is just LAS.

Jim

[choosebronze]

Thanks everyone. I've got some reading to do.

Look for old text books, etc, from a time when tube electronics was the thing. Explore the technical books section of http://www.tubebooks.org/

What a great website! So many books to go through. I also stopped by the library and was able to get a book on tube radio repair that goes into theory, and some study aids for electronics students that dive deep into Ohm's Law.

I assume I'll be back soon with questions about things bouncing around inside my head...

[st]

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W) = 10 ⋅ log10( P(W) / 1W) + 30

Just another measure of power level on a logarithmic scale, which let's just say isn't typically used for thermal power and audio amplifier output power, but whatever...

It takes a ten times increase in wattage to "perceive" an amp to be twice as loud

This is somewhat true (under certain conditions).

I guess that there are two approaches to discussing discussing guitar tube amps. The first is nu using the math and physics of it ("power is..."). In that case you have to do it right or else it'll make no sense. The second is by using your gut feeling and natural feel ("this amp sounds..."). Better not to mix the two...

(Edit: quotes)

[shooter]

you have to do it right or else it'll make no sense.

and you fail math class and wind up a musician that wishes they could design amps

[jjasilli]

"you have to do it right or else it'll make no sense."

People tend to make sense of amp wattage in terms of audio volume; light bulb wattage in terms of brightness; horsepower in terms of speed.  Based upon the way the original question was framed, it seemed appropriate to point out that Power is an item in the Laws of Physics which applies universally to all things.  Amplifiers are not a unique, special case.  They are subject to the same Laws of Physics as is everything else. 

You need 10X the watts to get 2X the audio output in volume.  As to "perception", if we use 1000Hz as the test frequency, then our human ears will agree with instruments of measurement, to eliminate that variable. 

Likewise for an automobile, you need 8X the horsepower to get twice the speed.  8X = doubling 3X, or 2³.  IOW, if it takes 10 Horsepower to go 50 mph, then it takes not 20, but 80 Horsepower, to double the speed to 100 mph.  And it takes 640 Horsepower to double that speed to 200 mph.  Hence the huge horsepower of racing cars.   Why 10X for an amp, but 8X for a car;  probably because momentum is working in our favor for cars.  In any event, the underlying concept is the same:  it takes a lot of increase in power to produce a relatively small practical result.

[shooter]

it takes a lot of increase in power to produce a relatively small practical result.

staying with the tall weeds;
If you want a fun exercise in math n physics calculate the amount of energy (in Watts :) it takes to create a solar panel that provides free energy 

[PRR]

> Why 10X for an amp, but 8X for a car;

Air drag Power is V^3, so 8X.

Sound pressure is square-root of sound Power, so the exponent should be 2.

"Loudness" must also include the AGC action inside the ear, which compresses our sensation. If we assumed the ear AGC cuts change to half, we have an exponent near 2.5.

The number "10" (exponent 3.3) is probably wrong for everybody *except* the makers of high-power amplifiers.

[jjasilli]

it takes a lot of increase in power to produce a relatively small practical result.

staying with the tall weeds;
If you want a fun exercise in math n physics calculate the amount of energy (in Watts :) it takes to create a solar panel that provides free energy 

How many solar panels for a free lunch? 

[Ritchie200]

Quote from: jjasilli on June 20, 2019, 02:15:48 pm

Power is logarithmic

No it's not.


Quote

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W) = 10 ⋅ log10( P(W) / 1W) + 30

Just another measure of power level on a logarithmic scale, which let's just say isn't typically used for thermal power and audio amplifier output power, but whatever...

Is this where I get to say "No it's not" or "That makes no sense" or "but whatever..."?  Apparently it was clear to all but you, that JJ and I were talking about dB in our power statements.  I would also argue that the formula applies whether in RF or AF.  Or have you developed the worlds first true linear amplifier and speaker?


Quote

It takes a ten times increase in wattage to "perceive" an amp to be twice as loud

This is somewhat true (under certain conditions).

And those conditions are?  Just so you are not confused we ARE talking about a guitar amp.  I'll let you do a Google search in case you are not familiar with the typical frequencies.  It is your friend. 

So lets recap, shall we?  "No it's not", and then a statement apparently saying it is. And then to save space and my typing fingers, you have disagreed with much of what has been posted by others, yet you provide no useful information whatsoever, much less anything to back up your statements?  There is a term for someone who posts like that.  But whatever...

Jim

[jojokeo]

Power is logarithmic

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W) = 10 ⋅ log10( P(W) / 1W) + which let's just say isn't typically used for thermal power and audio amplifier output power, but whatever...

Is this where I get to say "No it's not" or "That makes no sense" or "but whatever..."? 

It takes a ten times increase in flash powder to "perceive" an amp to be twice as flammable. (Ritchie’s rule of thumb)


We ARE talking about a guitar amp. It is your friend. But whatever...

But it is when using a logarithmic pot! 😜😂


If sluckey wants a doubling of power/volume without all the math all he has to do is turn up his hearing aid 🤔😘


If Ed needs it he just adds another 4x cab 🤗


If SG needs it he just plugs into the 240V socket of his welding machine 🤙😊


Are we talking about “distorted” power? 🙄😈

[st]

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W)
...
It takes a ten times increase in wattage to "perceive" an amp to be twice as loud

I believe the confusion revolves around the presumably well defined (logarithmic) relation between power, spl and loudness. The formula above is for power (in dBm) and it doesn't change the fact that a 2x increase in power is a 2x increase in power. Of course you can use the dBm unit to express the power of guitar/audio amps, but it is never done; we just always use watts. Furthermore, that 2x increase in power may result in a 10x increase in spl (in dB)/loudness, but doesn't have to, because it is dependent on conditions, most likely related to the device you use to turn electrons into sound waves (i.e. your speaker), or the device you use to peceive the loudness of those waves (your ears). You joke about me having developed the first linear amp, but do you have the ideal type speakers and ears? I have, finally, never suggested that the 10x wasn't a good approximation.

The reason i have not contributed much else is because jj and the rest had already said it. 

To conclude, I have not failed to notice that theoretical discussions of this sort are not appreciated here, so I'll leave it at that.

Best, st

[PRR]

> Of course you can use the dBm unit to express the power of guitar/audio amps, but it is never done; we just always use watts.

In the dim past, audio boxes were often rated in dBm. A good studio console should deliver +26dBm. A long-line buffer might be over +30dBm. A Champ near +37dBm; a Twin near +50dBm.

> Furthermore, that 2x increase in power may result in a 10x increase in spl (in dB)/loudness, but....

2X power is 3dB more power, which is 1.414X the pressure. (Sound pressure and air displacement work the same as volts and amps in electrical power.) If I am reading your words correctly, it violates "TANSTAAFL". It promises free energy.

[Ritchie200]

PRR,

dBm is still used in RF applications so I guess I have a dim past...


st,

Now we are having a discussion, not just dismissive comments.  I, for one, welcome these discussions as I try to learn something new every day - and there is much to learn here, at least for me.  If we end up having to agree to disagree, I will usually make a derogatory remark about the guitar or amp that you use and we shake hands.  I think I am painting with a broader brush, but I believe we are saying the same thing.  I am using words like "perceive" and "not linear", and you are talking about specifics like speakers and ears.  I'd say we are in agreement.  Although I am painting with a broader brush, the math does back up the 10 times increase in wattage to achieve twice the dB - even if it is "perceived".    But again there are amplifier and speaker and venue and variances and limitations.  Doing my own Google is my friend search, I found this, which I thought was very interesting:

You are designing a system where the farthest listening position from the loudspeaker is 100 meters, and the desired Sound Pressure Level is 85 dB SPL The loudspeaker chosen for the job has a sensitivity rating of 95 dB. With the minimum recommended amplifier headroom of 3 dB, then you need to choose an amplifier that can supply at least 1,995 watts to the loudspeaker.

Equations used to calculate the data:
dBW = Lreq - Lsens + 20 * Log (D2/Dref) + HR
W = 10 to the power of (dBW / 10)

Where:
Lreq = required SPL at listener
Lsens = loudspeaker sensitivity (1W/1M)
D2 = loudspeaker-to-listener distance
Dref = reference distance
HR = desired amplifier headroom
dBW = ratio of power referenced to 1 watt
W = power required


I always thought that audio dB was just a number on a reference scale like a speedometer.  Well yes, and NO!  You can't measure the absolute quantity of anything in decibels - watts, volts or digital signal levels. A measurement in decibels is always a ratio between one level and another. So you can say that one signal or sound is 10 dB higher in level than another, but you can't say that a signal or sound has a level of 10 dB, or any other number of decibels. What you can do however is give a measurement in decibels compared to a standard reference level. The common standard reference level of 1 picowatt (a millionth of a millionth of a watt) per square meter and call this 0 decibels sound pressure level, or 0 dB SPL.  I'm probably preaching to the choir with you guys, but I just learned something new!  I should have made the terminology transfer from RF to AF, but that woosh you hear was it going over my head....

NOW, back to the formula.... is that wattage in RMS? PEP? PMP? WQRP?  Is that a single speaker?  What if I have a speaker array?  What if I bi-amp?  Or tri-amp?  aaaaaaaaahhhhhh! 

Jim

[Ritchie200]

I've posted this several times here so I hope everyone isn't rolling their eyes...  However, I think it is the coolest article talking about sound reinforcement issues and solutions that we take for granted at shows these days, was cutting edge back in 1974.  It does cover Watts and dB SPL!

Jim

https://www.prosoundweb.com/topics/audio/history_files_tycobrahe_sound_company_and_the_california_jam/

[jojokeo]

... WQRP?

Isn’t that in Cincinatti? 🎩🐢


My god that was a lot of reading😴 I much prefer PRR’s analogies such as how much power is applied in a tractor pull or at harvest time 🌾🌾🚜🌾🌾

[jjasilli]

http://www.sengpielaudio.com/calculator-levelchange.htm

[Ritchie200]

I like the statement “More often it’s not about music, but about noise and noise level.” 


I’ve heard Jojo play, it’s not music....


Jim

[PRR]

> give a measurement in decibels compared to a standard reference level. The common standard reference level of 1 picowatt (a millionth of a millionth of a watt) per square meter and call this 0 decibels sound pressure level, or 0 dB SPL. 

The logical reference level for a Pressure is a Pressure. Not a Power (as we do in wires).

Actually in wires we often measure "pressure", Voltage, not power; then calculate Power from a known/assumed Resistance load. Acoustic Resistance is a thing, but harder to know, and we don't use sound to cook or pump (where Watts is what counts), so acoustics usually sticks to Pressure.

Anyway dB re:1pW would probably be dBp (like dBm).

The reference level for Sound Pressure *could* be Atmospheric Pressure; but we never work with sounds that big. And we often are interested in the effect on humans. And because positive numbers are convenient, they picked "the lowest pressure the average person can hear". Several broad studies gave numbers near 20 μPa (roughly the sound of a mosquito flying 3 m away), so 20 μPa is the SPL reference level unless otherwise specified.

[jojokeo]

I’ve heard Jojo play, it’s not music....


Jim

That’s only what you perceive with what’s left of your hearing from years of kt88 abuse and the ringing of tinitus! 😈🏝🏄‍♂️

[jjasilli]

jojo, you probably just have to play louder.  Make sure to use an amp that goes to 11.  How many watts is that? 

[shooter]

reminds me of HS, all the jocks jostling for "mines biggest, my dad can beat your dad"    I'd just smile, thinkin about their girlfriends hanging out with me as I listened to them bitch n KNOWING if I made a good - backed up argument, my dad would just kill 'em from 100yds n not think twice 

[jojokeo]

jojo, you probably just have to play louder.  Make sure to use an amp that goes to 11.  How many watts is that? 

“Well...it’s one mo’ izent it? It’s one loudah! When most blokes have their geetar on ten, where can you go? No where, exactly. What we do is when we need that extra push ovah the cliif what we do is, we go to eleven. Exactly!” 💥🤙


But I still don’t think it’s any help to Jimbo? 😈

[jojokeo]

  I'd just smile, thinkin about their girlfriends hanging out with me...”

According to Jimbob it wasn’t only ”thinkin” he was a “doin”!!! 🎩🕺 If I only had a nickel for all the supposed hook-ups he made after the goggin was done...?! 🥰🙄

[John]

I thought wattage was determined by the Marketing Dept? 

[jjasilli]

I thought wattage was determined by the Marketing Dept? 

Yes,  !  See, companion thread on Princeton Reverb vs. Deluxe Reverb (15W vs. 22W).

jojo, you probably just have to play louder.  Make sure to use an amp that goes to 11.  How many watts is that? 

“Well...it’s one mo’ izent it? It’s one loudah! When most blokes have their geetar on ten, where can you go? No where, exactly. What we do is when we need that extra push ovah the cliif what we do is, we go to eleven. Exactly!” 💥🤙


But I still don’t think it’s any help to Jimbo? 😈

jojo, don't let Jimbo goad you into playing TOO loud.  It's a trick!  According to the indomitable Laws of Psycho-Acoustics, and the Doors of Perception, if a sound is loud enough, no one can hear it!

[Ed_Chambley]

Power is logarithmic

P(dBm) = 10 ⋅ log10( 1000 ⋅ P(W) / 1W) = 10 ⋅ log10( P(W) / 1W) + which let's just say isn't typically used for thermal power and audio amplifier output power, but whatever...

Is this where I get to say "No it's not" or "That makes no sense" or "but whatever..."? 

It takes a ten times increase in flash powder to "perceive" an amp to be twice as flammable. (Ritchie’s rule of thumb)


We ARE talking about a guitar amp. It is your friend. But whatever...

But it is when using a logarithmic pot! 😜😂


If sluckey wants a doubling of power/volume without all the math all he has to do is turn up his hearing aid 🤔😘


If Ed needs it he just adds another 4x cab 🤗


If SG needs it he just plugs into the 240V socket of his welding machine 🤙😊


Are we talking about “distorted” power? 🙄😈

Don't know what kind of pot log metric is, but I am a willin to learn. My knowledge only extends to perfecting the Volume Pot treble bleed.


Isn't there always just a little distorted power, if not a lot.  I mean to get a good tone from a single coil, you gotta add some boost.  Here again, we are screwing with "perceived loudness" and cannot signal strength mess with us too.


If you are learning, simply start with ohms law.  If tube is you thing, read tube books.  I happen to believe is someone will read the entire RDH4, just read it and keep it for a reference it goes a long way.  Then there is frequency, receiving and transmission, but if you just want to stay in audio amps, that is a good place.


The biggest help to me was starting to use an oscilloscope.  It takes time to learn what you are looking at, but when you see the top flatten.   


Look at schematics and compare tube changes like Octal preamps tubes in the mid 50's Fenders, but also all of the other amps.  The values that were used.  The Fender Schematics seem to be easier to read.  Look at the amount of current needed.  The more current available the more potential power/wattage and therefore more headroom.  Had to say headroom, just couldn't pass it up.


Mainly, have fun and be careful doing it.  And transformers are another topic for another day.

[shooter]

transformers are another topic for another day.

can't wait for that mini-series