What makes Dumble style amp sound better?

[Zippy]

I am interested in reading your dissertation. Can you please post it? Thanks.

No, I cannot post it. The copyright is owned by the University of California.

If you're serious and not just trolling, PM me, and I'll provide you the titles of journal articles that I've published, that were based on my Ph.D. dissertation.

[Smitty]

Thanks for the links. There is good information there. I read the paper regarding cyclic strain and the corresponding change in magnetoelasticity. I noticed that the minimum stress applied to any sample was 115MPa or 17000 psi. I believe that is a stress which is orders of magnitude beyond anything induced in a transformer lamination through magnetic flux. ...

About the nail analogy: the fatigue limit of iron is about 100,000 psi. The stresses induced on a transformer in an amplifier are significantly below the fatigue limit. This is obvious in that the fatigue limit has never been approached or exceeded during normal operation of any transformer that I am aware of. I am wondering how this analogy applies to the discussion.

You are correct. I will attempt to answer your question. Essentially my argument is that one can trade MPa for cycles (unproven and likely not a linear relationship).

Every experiment that I've read about does deal in larger amounts of plastic deformation than exist during normal operation in a guitar amplifier transformer. My hypothesis is that the relationship between plastic deformation and stress relaxation, while very insignificant (and hence uninteresting to laboratories that serve the steel industry), is still present in guitar amplifier transformer laminations. And that while the resultant stress relaxation is orders of magnitude smaller on a per-event basis, does accumulate over time with each cycle to relieve the stresses induced during the manufacture of the lam.

I break in at 5,000 Hz. That's 7,200,000 cycles per day. I have found that I really need to run every circuit in the amp at full power to notice a change in the capacitor dielectric (shoes) and transformer laminations (nails).

I wish I had all the equipment to run tests like the one in the file I attached. My sense is that the result would settle the discussion, but more importantly provide the community with a solid recommendation for a reasonable break in procedure for transformers. Perhaps Zippy has the resources to assist...

My intuition is that the procedure would likely happen before installation. Something like a variac connected to the primaries and a resistive load on the secondaries. Juice that baby up for a month and see what happens. Likely not commercially viable due to excessive energy costs.

[Smitty]

I am interested in reading your dissertation. Can you please post it? Thanks.

No, I cannot post it. The copyright is owned by the University of California.

If you're serious and not just trolling, PM me, and I'll provide you the titles of journal articles that I've published, that were based on my Ph.D. dissertation.

Thanks. PM sent.

I'm very interested to learn about the relationship between plastic deformation and stress relaxation in steel at very low energy levels. And if it can accumulate over millions of events.

I believe that the opposing argument is that below a certain energy level, no stress relaxation can occur (however small the amount). Please correct me if I am characterizing your argument improperly.

[Max]

I don't think theres a right or wrong answer here. A-lot of belief, which isn't a bad thing.

One more opinion:

"It is clear, then, that the idea of a fixed method, or of a fixed theory or rationality, rests on too naive a view of man and his social surroundings. To those who look at the rich material provided by history, and who are not intent on impoverishing it in order to please their lower instincts, their craving for intellectual security in the form of clarity, precision, "objectivity", "truth", it will become clear that there is only one principle that can be defended under all circumstances and in all stages of human development. It is the principle: anything goes."

Source: Paul Karl Feyerabend "Against Method" (1975)

"I want to defend society and its inhabitants from all ideologies, science included. All ideologies must be seen in perspective. One must not take them too seriously. One must read them like fairy-tales which have lots of interesting things to say but which also contain wicked lies, or like ethical prescriptions which may be useful rules of thumb but which are deadly when followed to the letter.

...

Scientific "facts" are taught at a very early age and in the very same manner in which religious "facts" were taught only a century ago. There is no attempt to waken the critical abilities of the pupil so that he may be able to see things in perspective. At the universities the situation is even worse, for indoctrination is here carried out in a much more systematic manner. Criticism is not entirely absent. Society, for example, and its institutions, are criticised most severely and often most unfairly... But science is excepted from the criticism. In society at large the judgment of the scientist is received with the same reverence as the judgement of bishops and cardinals was accepted not too long ago. The move towards "demythologization," for example, is largely motivated by the wish to avoid any clash between Christianity and scientific ideas. If such a clash occurs, then science is certainly right and Christianity wrong. Pursue this investigation further and you will see that science has now become as oppressive as the ideologies it had once to fight. Do not be misled by the fact that today hardly anyone gets killed for joining a scientific heresy. This has nothing to do with science. It has something to do with the general quality of our civilization. Heretics in science are still made to suffer from the most severe sanctions this relatively tolerant civilization has to offer."

Source: Paul Karl Feyerabend "How To Defend Society Against Science" (1975)

Cheers,

Max

[Tubetastic]

As long as your happy...

[talbany]

Here is a pretty good example of how time might actually improve performance (in the form of rust)..Notice core temp, amps and power loss. Not all that scientific but a point well proven and a transformer company actually saying rust can improve efficiency of a power /output transformer over time..What could they possibly gain from this?

http://www.mercurymagnetics.com/pages/n ... mernik.pdf

Tony

[Tubetastic]

The bit where he says "IF theres any shift at all". Thats an IF. A big if. Thats an opinion. Otherwise he'd make a statement of it IS.

Why don't they make a rusty stock model if its better?


I've an open mind but it needs more persuading than an IF. And as he has previously said a new transformer will sound like an old one -in so many words- after a certain amount of hours then I see no need for seasoned.

BTW - I've the greatest respect for you Tony - and Max, my quoting your original post was about the Fog and Rain. The rest of what I posted wasn't directly/indirectly related to your post. Words on the net, eh?

[talbany]

The bit where he says "IF theres any shift at all". Thats an IF. A big if. Thats an opinion. Otherwise he'd make a statement of it IS.

Why don't they make a rusty stock model if its better?


I've an open mind but it needs more persuading than an IF. And as he has previously said a new transformer will sound like an old one -in so many words- after a certain amount of hours then I see no need for seasoned.

BTW - I've the greatest respect for you Tony - and Max, my quoting your original post was about the Fog and Rain. The rest of what I posted wasn't directly/indirectly related to your post. Words on the net, eh?

Yeah I saw the 'IF" word to..But you really have to use that word in this context (as it relates to sound) Since a shift that small in performance someone like Eric Johnson might notice it before someone who is not so sensitive might not! so you have to use (in this case) "IF" to cover those that might not be able to tell the difference..Rust is just 1 part of the aging process..

BTW - I've the greatest respect for you Tony - and Max, my quoting your original post was about the Fog and Rain. The rest of what I posted wasn't directly/indirectly related to your post. Words on the net, eh?

[/quote]
With much respect back!!

Tony

[Tubetastic]

"someone like Eric Johnson"

I'll see your Eric Johnson and raise you a Jerry Donahue - I've a George Lynch in the background, too.

Ok, bat like hearing is a bonus.

[talbany]

"someone like Eric Johnson"

I'll see your Eric Johnson and raise you a Jerry Donahue - I've a George Lynch in the background, too.

Ok, bat like hearing is a bonus.

...Hey quit typing so loudly..It's driving me NUTS!!!..
Off to get my Wolf bite checked!

Tony

[talbany]

BTW>> While we brought up EJ...I would just like to add one more thing to this disscussion as it relates to our perception of sound!!..Then I will try to bow out of this discussion gracefully!!!

I don't know if I have a good set of ears (compared to others that might)..I just know what I hear!!..
I remember when EJ mentioned how the back trem cover affected the tone of his Strats.. I thought the same thing, he has some very sensative hearing,until I actually expiermented with removing the covers..The change is subtle (more noticable at high volumes) but the key was knowing what to listen for.. The same goes for the type of battery's used in Fuzz Faces,again if you know what to listen for it can be quite noticeable..Personally I don't think Eric has Bat ears (he has had tinitus for god sakes) he was just the fist one to identify it (perhaps someone told him about it)and speak about it publicly..
My point here is when we are dealing with such subtle changes, most can go un-noticed unless you know what to listen for..
I remember bringing 2 identical amps to friend and wonderful player once and had him pick between the two amps..He choose 1 amp over the other..I asked him why this amp and he said this one responds a bit faster..This was something I never noticed until he mentioned and pointed it out...After I played both amps it was a very subtle change but yet he was right and I noticed it...This was a great learning experience for me,and one of the big reasons why I hang out here as you never know when someone might just point out something you have never noticed before,but you have to go on and and test and identify with the change yourself to see if it's something you like or dislike..I think seasoned iron falls into this category

I'l Shut up now!!

Tony

[vibratoking]

Tony, I was right there with ya regarding the subtle changes and knowing what to listen for. Then you brought it back around to seasoned iron. So much for graceful. Lol

[Smitty]

Interesting read. Talks about Magnetostriction in transformer laminations and cores, harmonics and vibration velocity versus pressure as a valid measure.

[Smitty]

OK. Did some more home work. I'm still convinced that stress relief is in play with what were are calling 'seasoned' transformers. There are several ways to relieve residual stress in ferromagnetic alloys:

1) Curing. Just let the metal sit for a long time and the stresses will relieve themselves.

2) Thermal stress relief (TSR) where heat is used to relieve the stress.

3) Vibratory stress relief (VSR) where vibration is used to relieve the stress.

http://en.wikipedia.org/wiki/Vibratory_stress_relief

Does not require the pressure or heat referenced in Zippy and Vibratoking's refutation of my assertion.

Have read a little about VSR I think it may be what Vibratoking was referring to as 'quantitative theory regarding the frequency dependence of permeability and how it changes after break-in' and is the missing support for my earlier assertions. Still wrapping my head around how resonance is factored in...

It may, however, provide a technological path around the levels of plastic deformation that Zippy is requiring for stress relief.

I remain convinced that lamination vibration is a factor in output transformer break in. However, having learned a little more, I now suffer from having a lot more questions than answers.

BTW, curing provides the technological underpinning for the old transformer argument. Older = less residual stress = different permeability.

[martin manning]

Maybe this paper would have some relevant information: http://ieeexplore.ieee.org/xpl/articleD ... 3A22829%29

"A high rate of manufacturing rejects occur from time to time in production lots of instrument current transformers. This has initiated a systematic search for the causes. One cause is the aging of grain-oriented electrical steel strips. Presented are the effects of aging on magnetic ac permeability, over a wide range of inductions from 0.005 T to 1.4 T on laminated and wound cores exposed to temperatures of 150°C and 60°C for up to 10 000 hours. These cores were made from M5 grain-oriented electrical steel strips 0.30 mm thick from various manufacturers. It has been found that the steel manufacturers have generally solved the aging problem of the grain-oriented electrical steel strips, since strips of most manufacturers do not age in the as-supplied condition. However, certain quantities of the grain-oriented electrical steel strips of some steel manufacturers show a considerable tendency to aging. The instrument current transformer manufacturers, therefore, should by proper quality control limit the steel suppliers to those who manufacture a consistent product. Another cause of aging could also be an improper stress relief annealing performed by the instrument current transformer manufacturers."