Question in RDH4

[J M Fahey]

Dear alan0354.
Just out of curiosity, I backtracked on some of yours posts.
You mention downloading RDH4 about August 18.
You mention page 40, chapter 2 , on August 28.
That amounts to absorbing 4 pages in 10 days; a mean of 4 pages a day.
That's fast, but let's call it reasonable.
Then, by August 30 , 2 days later, you become engulfed in a discussion about equations found on Chapter 13, page 549 !!!!
That amounts to 255 pages a day !!!!!!!!!
We are not talking a novel here, (which would still be a feat), but a heavy, dry, formula and graph full Technical Book.
Talk about choking!!!
With due respect, I'd slow down and absorb knowledge.
Otherwise, it will simply slip by.
Not to be outdone, the next day you refer to Page 561 .
I imagine a cup full of earth with a flower inside it.
It will be very happy with, say, a spoonful of water a day. At most.
If you empty a bucket of water over it, ... well .... , you can imagine the results.
Personal opinion, you may disregard it of course, I'd read that book page by page, or , to be more precise, concept by concept and not jump to the next until the earlier one is absorbed.
It's fine to read a chapter in full "as if it were a novel" , to have an idea as to where the explanation is pointing at, but then you'll have to restart at proper speed.
Good luck.

[Alan0354]

I pick and choose, I only read the bias, load line setting and I particular concentrates on conversion where I spent 4 days writing program, inputting the data, double checking, learning how to do the graph. Then I look at cpt 13 on the power amp. Then I concentrate on the measurement of 2nd harmonic distortion in cpt 13.

Then I write up notes to condense down to only the important stuffs. You will notice if you write it out and explain it back to yourself, you really find out whether you understand or not and then see the holes of your understanding. That's usually when I start to see discrepancy.

There are a lot of the stuff that is common like the instability....oscillation, poles and zeros compensation, components layout and grounding that I don't need this book to teach me.

The thing that really slows me down is typos. Then you'll be stuck.

[Enzo]

I'll say this and then stop, I don't want to sidetrack your thread. But I absolutely HATE the overdrive channel in the Hot Rod DeVille, and for that matter most Fender amps. And I have to also say I never heard a Matchless anything that I liked the sound of. It is all in what you want to hear. And no two people want the same thing.

[Steve Conner]

I think this thread got quite sidetracked enough by itself. I agree with Enzo's point, before we can "improve" a guitar amp circuit we need to know what "improve" means. Maybe make it cheaper, more reliable, or what interests me the most, get it to make a noise that customers will like more. That is a matter of psychoacoustics, psychology, social whatever, not engineering. At this point in time, I know how to make an amp that I like, but I don't know how that would translate if I ever tried to sell the things.

I also admire your courage in trying to make your own patent application. I tried this once, it was a learning experience to say the least.

PS: Since you worked for LeCroy can you explain why the bloody things freeze up every few minutes to "recalibrate"? It's incredibly annoying.

[Alan0354]

I think this thread got quite sidetracked enough by itself. I agree with Enzo's point, before we can "improve" a guitar amp circuit we need to know what "improve" means. Maybe make it cheaper, more reliable, or what interests me the most, get it to make a noise that customers will like more. That is a matter of psychoacoustics, psychology, social whatever, not engineering. At this point in time, I know how to make an amp that I like, but I don't know how that would translate if I ever tried to sell the things.

I also admire your courage in trying to make your own patent application. I tried this once, it was a learning experience to say the least.

PS: Since you worked for LeCroy can you explain why the bloody things freeze up every few minutes to "recalibrate"? It's incredibly annoying.

I worked for LeCroy between 1981 and 1984. I am pretty sure I never seen the scope you talking about. Freezing up is more than common, usually is software and the micro controller inside. I mainly design the front end of transient recorders in CAMAC crate for high energy physics. At the time, 200MHz 8 bits digitizer was a big deal. We had to have in house special hybrid sample and hold and 4 bit high precision ADC hybrid and use it in "Subrange" configuration. The controller I designed used the 8085!!!

It is not courage, it is pure cheap on my part. I am born cheap!!! Besides I have other ideas, I can't afford to pay a few thousand dollars a pop. You know music electronics, you can have a good idea and it does not sell, people want the vintage ones. And there is very little money in this as everyone is cheap in guitar field!!! Look at pedals, people are complaining about $80 each pedal. I am doing pedals, just the enclosure, the 125B is $8 without holes and labels in small quantity, 16mm Alpha pots are $1 each, then the cheapest 3PDT foot switch is $5. Then the two jack is $1 each. This is $19 just on the hardware, then the pcb and the rest of the electronics. Then you have to build it. Tell me what kind of money are you earning? Of cause this is prototype quantity. But you get the drift!!!

Yes, writing the first patent was a lot of work. The whole thing is on the claims. I spent so much time writing the first Independent Claim, trying to get the point across but being non specific on the nature of the signal and circuit as much as possible. My design use controlled current source, but I had to twist it and calling it XYZ "signal" so if someone use a voltage signal or any other type of signal I never even thought of will be covered. All the functional block had to be named "Means" to perform a function instead.

Actually writing the claim is more like a computer programming than English. They use specific terms like "Means" "Said","Whereby", "Thereby" "Wherein" etc. like you use "IF", "Then", "Else" in programming. Then you define your name using "A" or "An" the first time. And if the name is already defined before, you have to use "Said" in front of the name. The kicker is to write another Independent Method Claim that describe the same thing in turn of a method of function which use a specific heading like "Adding","Mixing", "Driving", "detecting" etc. The sentence of each step has to begin with a word ending with "ing"!!!! I treat it like writing a program.

The real kicker is you can only have capital letter at the first word of the claim, there will be no period, you can only have commas and semi colon. Only a period at the end of each claim. Then you write the dependent referring back to the parent Independent Claim.

Then come the drawings!!! Straight conformation of the spacing on all 4 sides, alpha numerals numbering of components and the lead lines from alpha numerals to the components.

But it's all worth while. The initial filing is $560 for under 120 pages, 3 Independent claims and less than 20 total claims with only black and white drawings. Then you wait until it is being examined and before granting you the patent, you pay about $1200. Then you go into patent pending. It will be good for 3 years before you have to pay for extension they called "Maintenance". By that time, you should know whether you are selling your patent or not to decide whether you want to pay or abandon the patent.

I encourage everyone to take the time to learn how to write a patent application. It is worthy. The nicest part is you do it all at the comfort of your home, everything is online filing. You don't have to fax, and Notarize one document the first time. But after that, if you file another patent application within half a year, you don't have to do it again.

The book I use is

Amazon.com: Patent It Yourself: Your Step-by-Step Guide to Filing at the U.S. Patent Office (9781413313826): David Pressman Attorney: Books

It is pretty good book, Chapter 8 is the most important. Don't trust the forms it provided. e form can be downloaded from USPTO site together with instruction. And for once, people there are very helpful, you can call them and they spend time with you. One time the person was helping me on the problem of my computer that fail to upload and generate the key and he spent over an hour with me.

[Alan0354]

I'll say this and then stop, I don't want to sidetrack your thread. But I absolutely HATE the overdrive channel in the Hot Rod DeVille, and for that matter most Fender amps. And I have to also say I never heard a Matchless anything that I liked the sound of. It is all in what you want to hear. And no two people want the same thing.

I design what I like and let the chip fall.

[jazbo8]

Well, all I can think of is try substituting Emax=2Eb-Emin, Imax=2Iq-Imin instead. In other words, the signal is symmetrical about the operating point.

Yup, that's it.

[jazbo8]

I have another question:

This is in page 34, pentode in triode mode. It is my understanding transconductance gm= ip/vg when plate voltage Vp is constant ( vp=0). Where ip is the change of plate current and vg is change of grid voltage. These are consider AC parameters.

Same definition screen transconductance is gs= is/vg when plate voltage Vp is constant.

Triode transconductance gt= ( ip+is)/vg = gm + gs(2)

As you can see, these are all AC parameters, not the steady state current.

Based on this, gm/gt= ip/ik Which is AC parameters. But the book gave gm/gt= Ip/Ik which is using DC parameters. Why?

The rest of the equations in this page are all using steady state currents. As you all know the DC current has nothing to do with the change in current (AC). I don't see how this is correct. I took a quick scan in the books I downloaded from Austin, I am sure my definition of transconductance is correct.

While in many books use lower case letters to denote AC condition and upper case letters to denote DC condition, this is not the convention used in RDH4, nor in Radiotron's datasheets. So I guess ib=Ib in this case.



Jaz

[Austin]

While in many books use lower case letters to denote AC condition and upper case letters to denote DC condition, this is not the convention used in RDH4, nor in Radiotron's datasheets. So I guess ib=Ib in this case.

[ATTACH=CONFIG]19948[/ATTACH]

Jaz

I think it is interesting that it says both screen and suppressor tied to plate. Does anybody know why you would want to versus screen tied to plate and suppressor tied to cathode? I thought about trying this with an el34 before. Would it make (downgrade?)it even more like a true triode then or something?

[Merlinb]

I think it is interesting that it says both screen and suppressor tied to plate. Does anybody know why you would want to versus screen tied to plate and suppressor tied to cathode?

You can do either- there's very little difference between them. Screen and suppressor tied to plate will in theory be a little more efficient, but it's neither here nor there.

[Jazz P Bass]

I have always thought of it as a radio thing.
A transmitter would have the screen & supressor tied together.
A modulator would ground the supressor.

[Alan0354]

Yup, that's it.

[ATTACH=CONFIG]19947[/ATTACH]

I'll work on this when I have a chance. My parts for the pcb just arrived and I have been building pcb all day till now.

Thanks

Alan

[Alan0354]

Yup, that's it.

[ATTACH=CONFIG]19947[/ATTACH]

I'll work on this when I have a chance. My parts for the pcb just arrived and I have been building pcb all day till now.

Thanks

Alan

[Austin]

check these curves out: http://www.mif.pg.gda.pl/homepages/f...137/6/6888.pdf

This one will really mess with you guys, it shows a pentode being driven from all three grids.

[Alan0354]

check these curves out: http://www.mif.pg.gda.pl/homepages/f...137/6/6888.pdf

This one will really mess with you guys, it shows a pentode being driven from all three grids.

If round curve is good for blues, I want a pair of this!!!!