star ground for power tubes and ct, or soldered to chassis?

[Alan0354]

I stopped, you asked.

[R.G.]

I respect you Alan, so I'll say this once. EM field theory reduces to the "classical" and simpler laws at low frequencies, just as relativity reduces to Newton's laws of motion at low speeds.

At even higher energy levels, electromagnetics, the strong force and the weak force become unified with electromagnetics under the best explanations of unified physics theories available now. The theoretical physicists are looking for ways to unify gravity with the other forces in a "Theory of Everything".

Going to full electromagnetics theory is a vast over-complication of grounding for audio equipment, just as going to the full N-space description of electromagnetics is an over-complication of what's needed for describing high speed electronics.

[potatofarmer]

I don't even want to guess how expensive a Fender amp would've been if they had to hire theoretical physicists to run the assembly line.

I imagine it went something like this:

"Hey boss! We soldered up a prototype and this ground here introduced a lot of hum."
"How much is a lot?"
"Probably too much."
"Alright, toss it in the scrap bin and next time move that ground to, oh.... here."
"You got it boss."

(time passes)

"Okay, boss; I moved the ground and now the noise is better. There's still some humming though-"
"Whatever, send the new diagram to the line. Hey, we got a deal on these ceramic caps so I'm going to update the BOM. We're saving two cents per amp!"
"But boss, think of the mojo!"
"....You're fired. Your cousin still looking for a job? Great, he's my new layout guy."

[Alan0354]

I respect you Alan, so I'll say this once. EM field theory reduces to the "classical" and simpler laws at low frequencies, just as relativity reduces to Newton's laws of motion at low speeds.

At even higher energy levels, electromagnetics, the strong force and the weak force become unified with electromagnetics under the best explanations of unified physics theories available now. The theoretical physicists are looking for ways to unify gravity with the other forces in a "Theory of Everything".

Going to full electromagnetics theory is a vast over-complication of grounding for audio equipment, just as going to the full N-space description of electromagnetics is an over-complication of what's needed for describing high speed electronics.

As I explained over and over before, I never mean to have to do simulation and/or deep into theory of EM for this kind of design. What I tried to do is to explain why the method of Fender work so great.

Also, you never have to do simulations for new design. Just knowing that ground current is governed by EM field.....that ground currents are localized. Using progressive layout from preamp to power amp, put the filter cap progressively in their respective place(as Fender wire the power and ground from the cap to the right place), you don't have to worry about all the complicated ground scheme. This is meant to be simplify, not complication.

And lastly, I believe people just make it more complicated by reinventing with all the one point ground, star ground and get themselves in trouble. In my experience, you talk to 10 engineers, they all know what they are doing, they think it's so simple. It's only when they get into trouble, you are asked to go and pick up the pieces, then you know how careless they are, that they know but not paying attention. You work in this industry, I am sure you had been asked to fix someone's project that was going nowhere!!!! I sure did a lot of these.

I know all about what you described in the EM theory, I studied for years over and over to write this. This is my passion. Yes, at low frequency, you can see the dD/dt and dB/dt become very small in the Maxwell's eq. and people want to say it's zero. But remember you easily get gain of 1000 or more in high gain amps too. Like I said, if it is so unimportant, why are people keep getting into trouble? Why this subject keep coming up?

[Alan0354]

I don't even want to guess how expensive a Fender amp would've been if they had to hire theoretical physicists to run the assembly line.

I imagine it went something like this:

"Hey boss! We soldered up a prototype and this ground here introduced a lot of hum."
"How much is a lot?"
"Probably too much."
"Alright, toss it in the scrap bin and next time move that ground to, oh.... here."
"You got it boss."

(time passes)

"Okay, boss; I moved the ground and now the noise is better. There's still some humming though-"
"Whatever, send the new diagram to the line. Hey, we got a deal on these ceramic caps so I'm going to update the BOM. We're saving two cents per amp!"
"But boss, think of the mojo!"
"....You're fired. Your cousin still looking for a job? Great, he's my new layout guy."

I don't think Leo Fender even think about theory, I bet he just use his common sense. To a great mind, great methodology is just common sense to them.

[überfuzz]

One of my favourites Fender inventions is the tone stack. How they changed the Williamson stack ever so slightly and ended up with something pure genius.

[Alan0354]

One of my favourites Fender inventions is the tone stack. How they changed the Williamson stack ever so slightly and ended up with something pure genius.

Leo Fender obvious was a very genius person. He created one of the best amp of all time, Everybody copied the tone stack, Marshall outright copied the 59 Bassman preamp with very few changes. He had the first active noise cancellation for single coil strat in 1984. He was the creator.

How about the Strat, the tele? those two make up 60% to 70% of all the guitars in this world used. No only his designs 60 years ago were the best, they survive the test of time. I was watching VH1 and was absolutely surprised the metal bands all used Strat, P-Bass..........

I was so impressed when I saw the documentary how he put a neck on a piece of wood, nail the pickups on a small block of wood and move around under the strings to find the right sound and nail it down!!!

That's what I was talking about, his simple grounding scheme is the best. Simple common sense progressive layout. This scheme survived the modern high gain design with flying color. Only when people start to think they know better, making the star ground, one point ground..........and then they cannot count the ground lines and mess up!!! If only people just follow Leo Fender, we might not even talk about grounding!!! I bet he know nothing about EM, just a good does of common sense......put the more sensitive part on one end, then propagates down!!!! Now we common people has to pull EM theory to justify his ingenious creation. To a genius, these are common sense.

[NateS]

I don't know about genius vs happy accident. The circuits aren't original to Fender. And Leo's idea of what it was all supposed to sound like was basically 1940's country music. Clean amps. Icepick bridge pickups. Actually Leo's idea of what it was all supposed to sound like is probably closer to "Ka-ching!" than any particular brand of music.

[Alan0354]

He hit the jackpot time after time after time. Somewhere along the line, you have to give the man credit of being able to keep doing it right all the time.

Again, to a genius, it's just common sense or even luck. But to common people, it is ingenious.

BTW, I am bringing the EM to justify what Leo Fender did, not to "get a rise from it"!!!! I just want to show there is a solid theoretical explanation why Fender grounding work so good. It is so simple and with so much common sense that people think that is not good enough.

Believe me, I don't call people genius lightly. I spent half my career working in environment with 75% PhDs day in and day out. It's a smaller company of about 50, but you should look at the drawful and drawful full of scientific papers published in the scientific journals in the library.

[Chuck H]

Well, Leo was a good foreman. That's what he did building Fender. He mad decisions in a very practical way and IMHO never placed the quality of the actual product he was offering at the bottom. Which is so common in todays business model. I actually give new Fender credit for delivering an acceptably representative product in todays highly competitive market. Same goes for Peavey. Those would be my top dogs in the production amp game right now. You're not doing bad if you can compete with so many more players in the game than Leo ever did and still imply the legacy with your product. A Deluxe Reverb (or the HR series) capture "the sound", are fairly reliable and remain competitive. That's probably why you see one at every other bar gig you go to!!! I can build you an amp that sounds maybe 10% better for about two and a half times the price. And that "better" adjective is subjective anyway. You could always spend that money with Fenders "Pro Shop" and get a bona fide Fender custom amp instead of a "Chuck H"!?! Kudos to Leo for being smart, practical and focused. And kudos to Fender now for following the example and keeping the flame lit.

[Alan0354]

Some where along the line, you have to give Leo the credit and respect. Life is based on result, not potential. I frankly would pay to listen to Leo Fender in lecture of his life, things that motivated him in the product OVER all the randall smith, Dumble, Soldano etal of the latest amp. To me, they are ONLY the followers, stressing.....FOLLOWERS, just a modification and variation of the original 59 Fender Bassman with the CF and tone stack( can't count how many of them..Soldano, Bogner etal.).........OR the variations of BF with added stages( Mesa or some Dumble). Ding ding ding ding!!!! they are all from Leo Fender. I don't think I would even waste my time going to listen to them. I think I have more respect towards some people here!!!! Anybody with some knowledge of tube amps can play with the value of the resistor and capacitors and some how land onto a good sound. It's the topology, the circuit configuration, the first one that successfully implemented into a complete amp that is the creator and founder.....That deserves all the respect.

Leo Fender's first active noise cancellation system in 1984 for strat predates all the other active and passive noise cancellation designs for single coils for years(humbucker is not single coil).

People keep saying Fender is no big deal............Go invent something, create the trend. It's so easy to sit back and critique. Stand up and lead, then see how easy to be another Leo Fender. You can laugh about the cheapness of Fender, then why people keep copying and following Fender if it's so cheap and lousy?

That's why I did spend the time analyzing the grounding of the old Fender amps. I can't say enough, it is simple, it is ingenious, and most important, it works.

[NateS]

Nobody is saying that Fender didn't create some iconic stuff we all love. I'm just objecting to the fawning over Leo Fender as the reincarnation of Isaac Newton who just decided to apply his genius to musical instrument amps. You need to remember, that during this time, building radios from RCA and other examples was basically a high school science project. It's certainly something the average HAM radio operator was quite capable of.

[loudthud]

I think the reason you don't see kits with a ground layout like an old Fender is that very few people have the big soldering iron needed to solder directly to the chassis, although some kits use the brass plate under the pots. Fender amps seem fine until you add another 40dB of gain or connect the input through an effects until with it's own safety ground. When Leo sold the company, none of the amps had safety grounds and most had ground switches and death caps.

Edit: Ever step up to a microphone and get a shock on the lips? Leo's idea was that you plugged the microphone into the same amp as your guitar.

[Alan0354]

I did a high gain amp exactly the same as Fender grounding. I worked years in low noise designs to post this. This is not debating from theory, this is my real life experience as an electronic engineer for 30 years. Unless people know what they are doing.......I mean really know what they are doing, stay with single ground plane, don't be fancy and think you know better.

I can tell you, I had to remove the input grid stop resistor, I had to use DC filament to lower the noise of my amp. I have not have to do anything about the single chassis ground plane yet.

I use copper tape that has conductive achieve, and have screws drilled through the chassis to get better grounding connections. I have no problem soldering onto the coper tape.

[Alan0354]

Nobody is saying that Fender didn't create some iconic stuff we all love. I'm just objecting to the fawning over Leo Fender as the reincarnation of Isaac Newton who just decided to apply his genius to musical instrument amps. You need to remember, that during this time, building radios from RCA and other examples was basically a high school science project. It's certainly something the average HAM radio operator was quite capable of.

Anyone during that period manage to be this successful? As I said, it's the result that count, not the ability, potential. If it is that easy, why didn't all the rest did not do what he did? Why everybody copy his design? I know for sure the tone stack for record player is totally different equalization as I was in that period of time and I tried to hooked the guitar into the record player using both the crystal or electromagnetic pickup. His tone stack was new at the time and is still being used by almost everybody.

It is so easy for people to sit back and criticize, why don't people do it if it's so simple? People still hang on to his designs 70 years later, still using a variation of his tone stack, circuit configurations, now that is a shame!!!

As I said, I worked in company with 75% PhDs with cabinets of published papers in scientific journals just from that small company. I don't get impressed easily and I don't call people genius or intelligent easily.


I keep going back to another example, Leo Fender patented the FIRST noise cancellation system for single coil pickup years before anyone else. I am not sure whether he came up with the Vintage Noiseless or Dimarzio came up with their Virtual Vintage stacked coil noise cancellation pup first. Someone might know. But I know the first active noise cancellation design was patented by Leo Fender, not assigned to Fender. That's ground breaking.