The OP asked for opinions on upping the PSU filter caps on a Pioneer SA-9100 and a SX-838. Some of us have given opinions and experience based on many decades of restorations and repairs of said equipment.
That doesn't mean you're all doing it in the best possible fashion.
You conspicuously do not address the ringing issue. If I correctly understand your position: (a) you are largely or totally unaware of the ringing issue and (b) you do not believe it is a problem, and that is specifically does not affect amplifier performance in any meaningful way.
But you have not addressed the effects of conduction angle, current load on the capacitors and the concomitant effect on lifespan. If I'm wrong here, you ought to pony up a reason.
Having benched hundreds of pieces of gear before and after PSU filter cap upgrades and not simply 'drinking the capacitor koolaid' that many others seem to enjoy consuming, I'm happy to state that your ongoing diatribe (or simply a thread-crap) is quite simply a non-issue in these two cases.
Wait, what? I am a member of a capacitor cult? Moi? Wow! Which cult? Are there meetings? Because I haven't been going to them. Do I get a t-shirt and a cap?
You haven't addressed any of the clearly explained electrical engineering concerning the ringing issue.
I have reviewed many of your postings and conclude that hammering a point home, over and over, is more important to you than helping a fellow member of AK enjoy, improve, and restore their gear in a way that makes them ultimately happy. I could be wrong, but I'm pretty sure that is what this place is about.
And the
ad hominem comes out, right on schedule.
The issue here is electrical engineering vs. hobbyists endlessly repeating internet lore. I've explained the issues involved in doubling capacitance in a capacitor-input power supply from an engineering standpoint. You don't care, don't read it. But you can't just stamp your foot and dogmatically say it's all wrong without explaining
why it is wrong.
Electrical engineering has advanced since those power supplies were designed and built. We now:
(a) have better design methodologies, better test equipment that is commonly available, and possibly know a lot more than the engineers building those devices
(b) have the means to implement, sometimes with technology not available to the original designers, better solutions at an affordable price.
I have explained issues of which I think most hobbyists are unaware. The OP certainly was.
Education.
The OP would likely prefer a working amplifier which doesn't stress or damage the rectifiers or transformer through over-current spikes, have ringing or oscillation issues from modulation, and delivers lower distortion. Throwing capacitors at a problem does not always solve it. Many times the amplifier has enough capacitance, but what it really needs is elimination of noise and ringing. Adding snubbers is an inexpensive way to dramatically clean up the supply. The ringing is clearly visible if one looks for it.
Again, why not explain where the electrical engineers who explained those issues (see the links and quotes I provided) were wrong. Explain how the power supply does not modulate a carrier wave with mains harmonics. Explain this. Because I would like to know why the engineering and physics are wrong.
This is the problem. It always degenerates to a dogmatic opinion vs. engineering analysis.
If the engineering is wrong I'll happily concede because I will have
learned something. Facts. Formulas. Physics. But an explanation of the purported mistake is required.
Why is Mark Johnson wrong? He's one of the smartest, most competent, and most skilled engineers working in this area. If he's wrong, I want to know
why. I find it inconceivable that he is wrong, when the noise is visible on an oscilloscope. It shows up in simulations, too. Am I hallucinating? Is everyone else hallucinating?
The same goes for the engineers at CDE who write application notes about snubbers. That's one of the biggest component manufacturers in the world. I want to know why those engineers are wrong, too.
And the hobbyists who wrote those papers, too. Tell me why they are also wrong.
This is how engineering works. It isn't about "we've always done it this way and nothing bad happened."
I'm generally excited to learn something new about electrical engineering and audio. Knowledge expands the ability to understand what is happening in a circuit and generalize it to other circuits. I remember when I first learned how I could stop hidden oscillation (which was not creating instability) in a tube amplifier by adding a resistor to ruin the Q of the tank circuit and simultaneously reduce the risk of arcing. Amazing! Why doesn't everyone do this? Cost savings. Ignorance. Stubbornness. Learned that, too.
At this point I'm done with this as it is pointless. It always turns into an opinion that the laws of physics and properties of electrical engineering are some sort of local phenomenon varying by lot and block, and even by equipment on that lot.
As the kids say,
whatever.
