Options to replace odd cap value

[bepone]

In PP amp you dont need too much filtering at all to avoid hum at the output. It is enough resistor 300-500ohm between Ub+ and Ug2 node.

Noisewyse I agree, but then the amp will become very sensitive to the volume you play at. I've done some tests and (also depending on the loadline you have chosen) the resistor can be set to be good at low volumes (higher value, lower screen current) or high volumes (the opposite), but the sweet spot is always controversial. A choke simplifies it alot.

470ohm resistor is not so high.. and also choke has similar resistance, 100-500 ohms depending of the wire used, but always is some thin..
to make good amp sound, is IMO always at the medium volume, so 50-65% , also on the breakup clean/crunch...at low volume there is everything missing in the tone..i think no any resistor in g2 can help with that

[pdf64]

… We have something similar in Italy and EU as well, but I don’t recall the name.

I think it will fall under the electromagnetic compatibility EMC directive.

[R.G.]

… We have something similar in Italy and EU as well, but I don’t recall the name.

I think it will fall under the electromagnetic compatibility EMC directive.

All members of the EU have laws saying essentially "follow the CE rules", which include EMC and safety. CE marking on a product means meeting all of that.

One of my pet peeves is that the standards organizations in Europe do the same trick that UL does - you have to follow their rules, but the protect the rules by copyright and only sell copies, at a cost of several hundred US dollars per copy. The rules also change from time to time.

Another pet peeve is that in the EU, any person or company can self-certify compliance and put the "CE" mark on their product. But any licensed testing lab can then test any product they like, and if they find a failure to meet the standards, issue an advisory to the country's ?? legal something or other?? that stops all sales until the product is tested and certified by one of the license labs. If I understand correctly, this setup was intended to allow customers to ask a lab to test a product that they think causes problems. This has resulted in many private labs have gone to testing things on whims, trying to find products to fail, on the hope that they will get the certification fees.

[R.G.]

Random power supply tech comments:
How "stiff" a regulated power supply performs can be easily adjusted. A voltage source can be modeled as a perfect voltage source with zero source impedance, followed by a resistance modelling the internal source impedance of a real world power supply.
A super-tightly regulated power supply can be "softened" by adding ... a resistor after its output. You can introduce any amount of sag you like. This can also be done at a lower power dissipation by tinkering with the feedback and gain setup inside the regulator circuitry itself for some types of regulators.
I think it would be interesting to run an amp listening test with a tightly regulated power supply and varying amounts of sag resistance. This is what I was alluding to in one of my earlier comments.

[bepone]

Another pet peeve is that in the EU, any person or company can self-certify compliance and put the "CE" mark on their product.

you can, but you need to satisfy at least LVD and EMC. othervise is forbidden. you can risk a lot of penalties. there is million stupid people around putting CE , also "CE" on devices in some strange format font so this people even doesnt know what is CE adn how to construct it
i never understood how is possible to put in the market in US any electronic device , like guitar amplifier, without any cerificate?
Dumble didnt have anything.

also i saw many amplifiers DIY or not DIY , mostly not certified and tested in US market. also in Hi-Fi world, the same. how is possible this in the US?

[R.G.]

Another pet peeve is that in the EU, any person or company can self-certify compliance and put the "CE" mark on their product.

you can, but you need to satisfy at least LVD and EMC. othervise is forbidden. you can risk a lot of penalties.

I was not clear: the law in the USA, EU, and nearly all countries requires the manufacturer's products to meet the standard, on penalty of law. In the USA, you must get specially authorized by the FCC to be able to self-certify as to RFI and EMC. That is, you are assumed to NOT be capable of self certifying unless you have what amounts to a license to certify. In the EU, you are presumed to be capable to self certify, until proved different. Of course, the remainder of that post was about "rogue" testing labs trying to find products that don't fully meet standards, to get more business for themselves. And yes, there are legal penalties in both places.

there is million stupid people around putting CE , also "CE" on devices in some strange format font so this people even doesnt know what is CE adn how to construct it

Some factories world wide will print >>anything<< on any product they manufacture for you.

i never understood how is possible to put in the market in US any electronic device , like guitar amplifier, without any cerificate?
Dumble didnt have anything.

also i saw many amplifiers DIY or not DIY , mostly not certified and tested in US market. also in Hi-Fi world, the same. how is possible this in the US?

In the USA, there is no law that all products must be certified, for safety or for RFI/EMC. It's voluntary. Of course, you can get sued for safety problems, and get fines and possibly jail time if your product causes real world problems - including if you are certified or not. The "certified" thing helps reduce court awards and fines if your product is violating.

[imjonwain]

Following up on what RG said. Big companies that have entire compliance departments tend to pay for all the testing they can across the board just to cover themselves. Smaller places may role the dice or not even understand. It may not be an issue until or unless you're caught for violating the rules.

EHX/New sensor got bit about 10 years ago and so did Behringer I believe. The main thing in guitar pedals or amps is radiated emissions 9kHz and over.

[R.G.]

Correct~ the pertinent part of the FCC rules applies RFI and EMC rules to anything using "switching frequencies" greater than 9kHz. So if your circuit is all analog, no switching (hah! only guitar amp makers would try that these days) so it's just possible that an old school amp, only tubes, might not need to do RFI/EMC testing by definition. They would still have to follow the safety rules, and the high voltages in tubes makes this harder.

Well, and tubes make it harder too. You remember how hot rectifier tubes and output tubes get? They can have surfaces at 200C. It's a violation of the safety rules to have those exposed so that they can be touched by the "standard finger". This is about 8 inches long with multiple knuckles and tapers to a minor point. Hot surfaces have to be un-touchable with this thing even when pressed by some force. One of my designs had perforated metal shields for ventilation and preventing access to the tubes. We got dinged on that pass because the amount of force specified for the standard finger allowed it to touch the hot tubes by being pressed through the speaker cone to touch the tubes.
There is a similar requirement for a stiff wire probe not being able to touch any hazardous voltage, even applied with some force; think a kid poking wires into holes in the amp. An amp with a high voltage wire behind a non-closed-body jack would fail this test.

It takes a special kind of person to be a safety engineer. I respect them, but don't understand them.

[bepone]

[
In the USA, there is no law that all products must be certified, for safety or for RFI/EMC. It's voluntary.

thx for clarifying that.

it is unbelievable to me that one begginer with very limited knowledge, and safety procedures can build guitar amplifier or ten of them which can be lethal , and put in the market without any problem

[pdf64]

Yes, it seems unfair to consumers to let the market regulate their safety.
On the other hand, it seems all but impossible for DIYers in our region to ever build stuff for sale, eg as a side line. The financial and administrative burdens on doing so (whilst keeping in compliance with the regs) being rather onerous.
The net result is stifled entrepreneurship and high costs for the good guys, whilst little guys put themselves at risk by carrying on and hoping they don’t get caught out, and bad actors still seem to happily import hazardous / downright dangerous stuff from the far east that significantly undercuts legitimate vendors.

[R.G.]

it is unbelievable to me that one begginer with very limited knowledge, and safety procedures can build guitar amplifier or ten of them which can be lethal , and put in the market without any problem

Oh, they do have problems. They just don't know they have them. And the system does have the advantage that someone >>can<< start up their business by building only one unit, and may grow over time if they work hard and carefully. So it lets single people take chances and grow a business from nothing. It's risky, but then starting a new business is always risky.

As I mentioned, the real enforcement is by lawsuit. The system is complicated. It seems like nonsense to many people who have never seen it work.

In the USA, in general, anyone can sue anyone for any reason. And for any amount of money. Judges will usually dismiss the truly stupid or baseless ones, but if there is any real damage involved, the lawsuit usually proceeds.

It is quite expensive to be sued. A person >>can<< defend themselves in a civil lawsuit for damages, but there is little hope of them winning. As a result, if you're sued, you had better hire a lawyer. Hiring a lawyer to defend a civil suit for damages will usually cost about US$10,000 to start, and may cost much, much more if the case actually goes to trial. If you are sued, it will cost you the approximately $10,000 to defend yourself to start with, and up to about US$100,000 if it proceeds to a full trial. A complicated case can cost both the person suing and the person being sued an unlimited amount and take years. Two companies suing each other can cost each company millions each.

As a famous example, a lady bought a cup of coffee at a McDonalds drive-through window and spilled it on her lap. It was very hot, and she was burned. This resulted in the McDonald's coffee lawsuit (https://en.wikipedia.org/wiki/Liebeck_v ... estaurants). There are many such examples.

A single person making amps could easily be bankrupted even by having to hire lawyers to defend themselves. The real tragedies are when people don't understand how this works and accidentally hurt someone. I shudder inside when I see a guy making and selling amps with real safety issues inside, or even worse, a single guy repairing amps and leaving a safety issue inside. If someone gets hurt, even years later, they can be sued into bankruptcy. And guys who make or repair amps often don't know all this.

There are a couple of defenses. One is to be "immune to lawsuits" by having no money to pay. If you have little money, it's not worth the cost to the person who got hurt to sue you. another is insurance. There are ways to buy liability insurance that would defend and pay the legal fees and damages; but this is an ongoing expense on its own. This is why most of the big-money lawsuits are against companies or wealthy people - they have money enough to pay.

In practice, this all works out to mostly keep hazardous stuff off the market. Mostly.