Check out Steve H.'s new WAVAC amps!

Thank you one and all!

I understand now much more than I did when I woke up this morning about this subject.

This is why this forum is great.

Steve, I loved your history lesson!

Thanks again!

 

J.,

Your explanation, to use your own word, is off. The strength or the direction of the magnetic field caused by moving electric charges (current) has nothing to do with dv/dt (the rate of changes in voltage).

I don't want to get into various theories and equations in electromagnetics here. Let's leave the quantitative stuff to the physicists. Just think about the magnetic field caused by a DC current first. If it passes through a straight wire, its direction can be determined by the "right hand rule" and its strength is in proportion to the current. If a AC current say, a sine wave, passes through a straight wire, the same right hand rule can be used to determine the direction of the magnetic field, depending the the direction of the AC current, and the strength of the magnetic field varies with the current - its average is zero. Now you superimpose the AC current onto the DC, and the result is a sine wave with a DC bias - the net effect over time is the same as the DC component. You can then extend the straight wire scenario to a coil or a solenoid.

Jim,

I have next to nothing technical knowledge of the WAVAC designs and I sure like to learn about them if allowed. I did not mean to say "all SET amps can permanently magnetize the coils in the output transformer" but that was my observation in a general sense. Clever circuitry could possibly remedy such issue.

I can't comment on the "improving" sound of output transformers as they "break in". Maybe a permanently magnetized output transformer in an SET amp sounds better.

P.S. I apologize for misspelling magnetize/magnetization and have corrected them in my previous posts.

P.P.S. I am attaching this link Current as source of magnetic field for those who are interested.

 

Paul,
I appreciate your thoughts and comments on possible "all SET amps can permanently magnetize the coils in the output transformer". This forum is not really the place for a technical dissertation as you suggested. Certainly, the Japanese designers would have discovered this before now and addressed the problem - if there was a problem.

btw, there is a premium on "old" iron in Japan.

I would encourage you to read articles on modern SET amplifiers to get a better in depth understanding on this issue. No doubt WJ of ARC is very good at PP designs as you referenced him on this topic - he certainly designed some incredible, classic PP amplifiers, no question about that! But keep in mind modern SET designers are just as talented and more focused/more knowledgeable on SET designs, too. As they say, the proof is in the pudding, uhhh, the listening.

If you would like any Wavac catlogs to read, click on the tmh audio link on Steve's homepage and email me your mailing address and I'll put one in the mail to you.

 

Great thread, guys!
Yo, Epstein- you build these things? I am privy to some amazing
handmade tube gear built by some serious electronics freaks in Colorado. Just at the right place at the right time for once.
One of the gurus has ventured into this circuit topology recently.
He has always used the transmitting tubes. I have a pair of WE type monos based on the 812. Really, you don't have to pay the huge expense if you know the right people. However, the parts and labor still run it up there quickly! Upgrades and the law of diminishing returns. But still, lots of fun. Wish I was a builder.
Should've paid better attention in that nerdy electronics class!
Evidently, you did!

 

Tristan,

You are that old? When I went to school, nothing about the vacuum tube was taught in the "nerdy electronics classes". When the professor in a graduate level circuits class asked who knew the origin of the term "triode region" of a FET (field effect transistor), I was the only person who got it right because I was the only audio freak amongst the nerds. One guy thought it came from the three-terminal bipolar transistor.

 

So, did they then think of you as the dweeb or geek in the nerd class? I've had some discriminating looks from stuffy e-guys when I mention tubes. They think they're antiques! Antiquated,
obsolete. And no, I'm not THAT old, although rapidly approaching the middle ages, but I was always the long-haired lead guitarist rebel sitting in the back in the 70's thinking about my old Fender tube amp and how great it sounded in comparison to the SS stuff, and later, the IC crap. Never took to electronics, but wish I had. What kind of gear do you build?

 

This tube loving dweeb also collects records.

The lower the more of them think of us the better. Heck, the new old stock tubes are getting more and more expensive and difficult to find so who needs more competition. And I don't mind being laughed at for being a vinyl addict, either. The Salvation Army, Goodwill and the like need to replenish their supplies.

The gear I built? Man you hit a sore spot, Tristan. My soldering skill couldn't be worse for a guy who doesn't wear eyeglasses. Ray Charles could probably do better. Wanna try the transistor walkie-talkie I made in junior high?

 

Paul: your explanation makes sense but it doesn't jibe with my experience and my partially remembered info. Therefore, I intend to ask someone with more expertise than me and get back to you with either the source of my confusion or yours, if any.

Hopefully we will both learn something, which is my goal here, not to try and make anybody look bad or have the last word. Hope that is OK?

Anyway, for Tristan, take a look at my web site for a little bit of a window into my madness & method.

http://home.earthlink.net/~ellenoler/

Is the Colorado guy you are familiar with named Corey something? I have friends in the Denver area and they speak of him in hushed tones, and they keep their hands in their pockets when they are near his gear!

-j

 

Hey Jeremy,
Thanks for sharing your site. I really like your approach!
Yeah, Corey has that mystique thing going; I've spoken to him several times, once to build a tube headphone amp for me but it never fell through. He is elusive! I know his buddy, Grant and bought my Loesch-type phonostage and SET amp from him.
Another name in Denver is Dale Kronquist. They say Dale has forgotton more about cirucitry than most people have ever known.
Their styles are very different, Grant being more the purist.
We'll have to talk, I have your email now. Perhaps I should get this thread back on track....Steve's WAVAC.

What distinguishes this amp from other SET amps? Where does all the extra power come from? Are these triodes in parallel?
100W of Single-ended power must be amazing, perhaps the missing link between SE and PP. Does it still possess that breathy midrange that the best SET amps have?

Without any copyright infringements or "stealing" can similar circuits be constructed?

 

The high power comes from the gigundo transmitting tube it uses.

To use this tube effectively requires a very high supply voltage and a very low impedance driver circuit: two design obstacles that tend to deter many builders. WAVAC and Nobu Shishido have tackled the challenges head-on.

I haven't heard them myself - Steve seems to like 'em pretty well though!

-j

 

So, keep it away from the kids!
Dims the lights???
"Danger High Voltage" signs nearby?

 

In case anyone cares still:

I checked with a friend who is knowledgeable about transformers.

To summarize our discussion,

- it IS true that this permanent magnetization can happen

- it hasn't been my (or his) experience that this results in a problem. Perhaps this is due to the nature of the operating conditions of the transformer with respect to the residual field, perhaps it is due to the materials used.

He mentioned that you can take a symmetrically wound transformer, and when new it will not sound as good as it does after break-in. Then if you reverse its connection, it will again sound bad, until it is broken-in in the other direction.

The conclusion I drew from this: it is therefore possible that a core with residual permanent magnetization actually sounds better than a completely unmagnetized core.

Hope this helps!

-j