Do we have to worry about reactive load as in RDH4?

[Steve Conner]

I've actually seen that done by some guy on Youtube. Sounded pretty distorted though, I think a MOT is about 30lb of iron short of the optimal design.

That transformer was actually a 2.2kV, 1A plate transformer from some piece of industrial equipment. I had to scrap it because of a shorted turn.

[Austin]

I've actually seen that done by some guy on Youtube. Sounded pretty distorted though, I think a MOT is about 30lb of iron short of the optimal design.

That transformer was actually a 2.2kV, 1A plate transformer from some piece of industrial equipment. I had to scrap it because of a shorted turn.

He stole my idea! j/k but I did post that on 4hv forum a long time ago.. I might have tried to re wind that colossal transformer. Don't you think a de-shunted mot would be good for a couple hundred watts? Sposed to be 1 kva I thought.. I have like 6 of them now

[Alan0354]

I think you are too focused. Tube electronics is completely obsolete as you pointed out, that means that it is mainly used to mess around with for fun.

No tube amp designer (that I've heard of) ever worried about the reactive loads. Reactive loads cause excessive peak power dissipation, but tubes are very forgiving of that, because the big heavy plate averages it out even at the lowest audio frequency.

With the benefit of 50 years of hindsight, the main issue in guitar power amp design was surviving a too-high magnitude of impedance (such as a woofer at resonance) without burning out the screen grids. If you drove the amp into clipping with a highly reactive load, you could also generate big flyback pulses that would endanger the OT and tube sockets. Nowadays we can protect against that by putting flyback diodes across the tubes, but that wasn't economically viable in the 60s.

That's music to my ears. I read and understand how to draw the ellipse and how to series and parallel with the resistive load. The point is it is very tedious to draw and you have to calculate many points and plot it out. Then after that, what can you do with it? It's not as if you have a way to match the full locus of the load ellipse. You pretty much draw a line through the ellipse to get the average value...........which is right back to the resistive load line!!!

I have to be focus, I just barely studied over half of cpt 2, looks like I need to study cpt 12 and 13.

[Steve Conner]

Douglas Self showed that if you plot out all the possible ellipses, you get a load line that terminates at the current you would expect from Ohm's law and the resistive part of the load, at one end. But the other end is I=0, V=2x the supply voltage. This is considering peak currents, though, as it is used in solid-state design.

[R.G.]

... This is not easy to draw and tedious to calculate all the point of a reactive load...xactly resistive...Bottom line, is this important to learn... I skipped the section ...
Bottom line, I don't want to study anything that is not pertaining to audio amplifiers. This is not as if it's a useful technology that it worth the time anymore. Just trying to study the minimal to design amps.

Don't bother. You're too tightly scheduled to go learn just the important parts of designing tube amps. Even with a technical background, there is a lot to cover to do more than a minimally adequate job.

I have a fundamental difference with you. I too budget my learning. I just do it the opposite way. The rest of life - sleeping, eating, all the business of the rest of life - is subtracted from the desired 100% of time spent learning new technologies. Allocating a set time for learning "all the good parts" is an approach which practically guarantees you will not understand any of it fully or in a satisfying manner.

I collect technologies inside my head. I recently gave myself a pretty decent start at metalworking and machining. I can knap (and have done) flint arrowheads, and know how to cut a tree to use the growth pattern of the tree layers to make a better bow from it. I know how the newer pearlescent paints got started and how to smelt iron. I know which way to hold out your hand to a horse you don't know, how to track a wounded deer and entice perch to bite a visible hook. I know why Damascus swords were Damascus swords and (probably) why they stopped being made and the technology was lost. I know where to cut tree limbs to cause the least damage to the remaining tree, and how to set tile, as well as pour concrete.

And a few others.

To me, scheduling when one has learned just enough is like when to stop enjoying life. The proper amount to learn is 100% of everything. No, we can never get there, but like golfing by hitting only holes-in-one, we ought to do as much as we can.

But that's just me.

[Alan0354]

This is just your opinion. I've studied about 40 pages of the cpt 2 of RDH4 so far, you know that this is not exactly a theory book. It is a very detail cook book. For example, the value conversion part in p36 is a cook book approach that it gives you the conversion factor and the power factor and you should just follow it. It is by no means explain why it is like this or anything. No mathematical derivation of any sort. You don't really understand understand per say.

As a engineer, it is very often you need to design circuit that you are not familiar with, you have the basic electronics knowledge of EM, network theorem, amplifier, feedback stability etc. Then you look at the new topics and relate to what you know from before and get a good feel and design the project. Use common sense to determine which part is important and need to spend more time and which part to skip. That's how you get the project done in reasonable time. Talk to any engineer here in this forum and they will have the same experience.

For me, I worked with all different transistors for years, there are a lot of similarity between this and solid state designs. Granted it's not as easy to transition from BJT to FET, but it is at least 80%+ similar. I think I know enough to have a feel what is important and what's not. In this particular topic of reactive load line, it is quite clear there's not much people can do about it. It's just matter of how much leeway you need to give. So according to Steve Conner, you really don't have to worry too much. That's good enough to know. Else, just lower the power slightly if needed. You don't plot out the graph!!!

At the other extreme, I am studying the value conversion part, this what I need . I would spend a few days if needed to be because it's important. I am even planning to do a conversion on one of the tube using the data sheet.

[R.G.]

This is just your opinion. I've studied about 40 pages of the cpt 2 of RDH4 so far, you know that this is not exactly a theory book. It is a very detail cook book. For example, the value conversion part in p36 is a cook book approach that it gives you the conversion factor and the power factor and you should just follow it. It is by no means explain why it is like this or anything. No mathematical derivation of any sort. You don't really understand understand per say.

In my opinion, the cook-book nature of RDH makes a deeper understanding of the subjects even more necessary. Again, this is just my opinion. In my opinion, "design" implies having a deeper understanding of the issues involved with a design than is expressed in the design.

As a engineer, it is very often you need to design circuit that you are not familiar with, you have the basic electronics knowledge of EM, network theorem, amplifier, feedback stability etc. Then you look at the new topics and relate to what you know from before and get a good feel and design the project. Use common sense to determine which part is important and need to spend more time and which part to skip. That's how you get the project done in reasonable time. Talk to any engineer here in this forum and they will have the same experience.

Actually, I'm a formally trained and experienced project manager as well. So yes, I do understand the need to allocate the triple constraints of time, money, and performance against specifications in both an intuitive and an objective way. If nothing else, that background has deepened my feeling that the more diverse your learning, the more capable you are of doing any one task.

Please take this as advice, not criticism. I wish you success with your efforts. But don't artificially limit your learning by thinking that at some point, you already know enough or don't need to know more than some particular limit.

[Old Tele man]

The SCIENTIST translates theory into reality.

The ENGINEER extrapolates beyond known knowledge to develop new devices/technologies.

The TECHNICIAN interpolates within bounded knowledge to apply, service, modify existing devices.