Tube amps and math, say it ain't so...

[Structo]

I think Ohm's Law is a very good thing to learn, as it shows the relationship between voltage and current.

For examle, E/R=I

The letters are not real logical since it is based on century old nomanclature.

E= Voltage in volts (electromotive force)

R= Resistance in ohms (that's easy)

I= Current in Amperes (Not sure how I became current)

P= Power in watts.

So you can see by that formula that if you increase R, the resulting current will be less.

Back in the day they would use a water analogy.

Where voltage is the water pressure, Resistance is the size of the water pipe and current is the volume of water through the pipe.

Here is a simple pie chart for Ohm's Law.

[img:500:331]http://www.arad.org.tr/yazilar/ta3bq/ohms_law/pasta.jpg[/img]


I printed the one below and have it on my wall so I can glance at it for reference.

[crbowman]

Especially after getting a couple of shocks :

Yep. 400 volts + accidental contact = pain!

Seriously though, the math side of tube circuits can be a tremendous tool in your tool kit.
Just remember to listen with your ears and not your calculator.
We've all seen the threads where someone claims to hear some particular quality that someone else says doesn't exist because it doesn't appear to make theoretical sense.

[Leo_Gnardo]

pie chart for Ohm's Law. I printed the one below and have it on my wall so I can glance at it for reference.

Good one & thanks Tom! BUT those colors make my eyes go out of focus. I'll have to alter the palette then print that out. I know all that stuff like ABC but sometimes the ol' brain gets lazy.

[dorrisant]

http://digitalmedia.risd.edu/pbadger/Ph ... es.OhmsLaw

Tony

[Reeltarded]

Love that

[Aurora]

I taught electronics, radio and telemetry systems at high school / trade school level for appx 7 years. You certainly don't need college level maths to dabble in electronics, but at college level, using math is a more accurate method of describing the processes involved. OTOH- you certainly do need to extend the theory to practical work in order to enhance and solidify the understanding, so to speak.... which BTW seems to be a universal problem in electronics education these days.
I've seen MSc's more or less totally panicing, realising that they had to leave the computer to do a practical job...

Building by numbers, - building either kits or by tried and true layouts and schematics, can be done with a fair minimum of knowledge of the list below.

Here's a list of what I would concider basic and necesseary knowledge.

Safety aspects of fiddling with mains supplied curcuits and high voltage amlifiers that actually might kill you.
The old advice of handling active circuits with your left hand in your back pocekt is actually not a joke.

Ohms Law, - voltage, current, resistance AND power, and it's application and differences applied to DC and AC.

A reasonably good understanding of impedance and reactive components, and calculating capaciive and inductive reaktance vs frequency.

Transformers - and for tube amps - the difference between voltage and impedance ( and power ) transformation.

Good knowledge of passive components, - how they work. Later the pros and cons of different types of resitors, capacitors, and coils - chokes in this context.

Then, when the above have sunk in somewhat - operation of simple active stages - tubes AND semiconductors. Start with the basic circuits, and then move on the more subtle paarts. Don't even try to start with a schematic of a complete amplifier - even a simple one.

When this level is passed - it is time to start with simple experiements, - or build by numbers with a much better understanding of what's going on.

The start of this may seem tedious, but believe me, - it is necesseary.

AND - don't believe verything you read on teh internet! HiFI and guitar amps are crammed with hype and urban myths. Luckily there's little of it here at TAG. ( Except for teh chase of teh Tone Mojo.. )

[jjman]

I can remember ohms law only in one format. I have to then use algebra to convert it to the format I need, or to solve for the variable I'm looking for. Same for wattage.

Resistance = Volts / amps
Wattage = Volts x amps

"Yes, you will need algebra in life."

[Structo]

pie chart for Ohm's Law. I printed the one below and have it on my wall so I can glance at it for reference.

Good one & thanks Tom! BUT those colors make my eyes go out of focus. I'll have to alter the palette then print that out. I know all that stuff like ABC but sometimes the ol' brain gets lazy.

Just Google for Ohm's Law pie charts.

There is a million of them.

That black and white one I like because it is clear and offers all the forumals I would ever use.

I saw that one with the guys on the water pipe, brilliant!

[talbany]

Greetings all,
I received Bruce Rozenblit's latest book: Tubes & Circuit for Father's Day.
After trying (for the zillionth time) to get my head around the trigonometry and associated formulas he says are absolutely imperative if I ever hope to understand circuit design, I got to wondering if Leo Fender, Mark Sampson and other makers of great amps understood and used math at this level.
I know there are engineers here on the TAG site that know and understand electronics from a math perspective but I suspect (hope) there are others that have found ways to explore electronics and tube amp design in a less math-intensive way. So, what's the deal?, are all you guys great at math?

Rozenblit says I must have a scientific calculator.... I had one once, it's amazing how many pieces one of those turn into when launched from a 6th fl apartment window onto a parking lot.

IMO Guitar amps are designed to be tone generators and not necessarily designed for greater efficiency or in some cases extending operation life..TONE being the main objective so in this case math becomes a tool for understanding how a component or circuit functions to obtain a certain sound/Timbre as well as safe operating parameters..The understanding of how a circuit functions to achieve that sound is no doubt a useful tool in amp design and functionality as well as troubleshooting..Other factors that contribute to the sound of an amp, for instance, materials used or construction methodology of certain components are elements that cannot be calculated and yet have a great impact on sound..Then there is the actual construction techniques such as layout and lead dress,chassis material, orientation on and on, that also effects tone,these can only be determined through trial and error (now enters the art form)..IMO a good amp designer must also have a good ear and be a good guitar player to help guide his designs to a sonic goal.This to me is just as important (if not more so) of a tool as understanding the math..

All The Best!!

Tony