agedhorse

Better manufacturers do not rate using peak power or PMPO, they use RMS at whatever duty cycle is appropriate for the product.

Never directly measure the output of a class D power amp with a sound card input. Most are BTL (bridged) and there is no ground reference. If you try to ground the speaker minus terminal through the sound card you have a good chance of destroying the amp and/or the sound card. Generally such measurements are made using differential probes and the subtract function on the scope, or a 1:1 measurement isolation transformer capable of the voltages and frequencies required.

25 watts, 30 watts even 50 watts or 100 watts, it depends on the rated load impedance. It also depends on the interpretation and if the product is classified for ordinary or instructed users. There is a lot of gray area, which varies by region. Just because it's allowed in one region doesn't mean all regions. The IEC 62368 standard is just about the most miserable reading ever. I feel awful whenever I open the manual, and if it wasn't for all the politics within (and between) the IEC member bodies, it could have been simplified to 1/4 of its content. Compliance is generally required in order to import goods into a foreign country. Each country or region is different and those differences are contained within the "National Differences" section of the reports, things that are specific to each region. For example, China recognizes the IEC 62368 standard but has (many) additional requirements regarding labeling. Japan has labeling requirements but also the submission of Hipot test logs bu serial number. The Nordic countries have additional labeling language requirements in addition to the EU. It goes on and on, in nauseating detail.

It’s the EU that are driving these changes. It is what it is, it’s actually very minor compared with some of the other items in the regulations that we have to design around.

Good choice, hope yours doesn't use those output devices (may not be the output devices, but the originals are pretty much unobtanium unless Laney's service network still has service inventory available)

I was addressing the Laney in the picture. If that’s not the OP’s amp, that’s another matter.

Correct on all accounts. Fortunately, the track flaking off or delaminating from the substrate is very rare these days with any of the name brand parts, though I'm sure it can occur with knock-off pots from China and India (for example). The DeOxit D-5 used in TINY amounts is generally safe and effective (IF the problem is due to a pot, which in this case is almost 100% likely it's not). PCB cleaners contact cleaners and such are generally damaging to pots and also surrounding plastics like the housings of header connectors, switches, etc. WD-40 is just nasty and like silicone products don't belong anywhere near electronics.

I see the results of DIY repairs regularly, generally the first thing that comes to mind is "what were they thinking?", followed by "why?" followed by "what the hell?". You talk about saving money, but in reality most of the time when an amp (I only service Genz Benz, Genzler and Mesa) comes into the shop without somebody monkeying with it, the amp falls into the $100-$125 (USD) flat rate repair cost. When repair attempts are made that result in additional work and clean-up of the mess (most of them), it automatically doubles the cost of the repair because now EVERYTHING is suspect and a lot of additional disassembly, inspection and follow-up needs to be done in order to fully warranty the repair. I immediately recognized that you are a DIY enthusiast. Gaining appreciation for the inner workings of an amp starts with education and learning before attempting to repair something that they are unfamiliar with. The DIY "industry" is full of folks who claim to know more than the (real) experts, talk up a good game, yet anyone who really understands electronics can see through the crap pretty quickly. It's just how it is. Now the Laney amp in question uses a unique Sanken STD series output device that's been out of production for quite some time. It's unique not just because it's a Darlington device, but because there's a bias offset and thermal compensation diode built right onto the die and is an integral part of making a Darlington output device work well in a linear output circuit. This is something that an experienced and qualified service tech should know, but VERY uncommon in general. Seeing the date written on the filter caps suggests that somebody has already been into the amp and did a "cap job" (so rarely do caps less than 40 years old actually fail that this is immediately suspect as the root cause of damage) that may be causing or contributing to the symptoms. The bigger question an experienced tech would ask is "what else has been messed with, and what other damage may have been caused?" This is why there is no way to diagnose this amp over the internet, no matter how good the intentions might be. Also, the majority of these parts being sold over the internet (eBay, Ali Express, etc.) are fakes, counterfeit knock-offs. OnSemi made a similar part (not a Darlington, nor is it pin for pin compatible) which is also essentially out of production.

Since it’s a direct coupled output topology, those caps can’t possibly be coupling caps. Therefore, the rest of the information provided is suspect.

This is a quick way to ruin a set of otherwise good pots. Cleaning pots requires only the tiniest spray inside AND the only product I have tested that didn’t create longer term problems is Caig DeOxit D5. There may be something similar in Europe, but the majority caused damage to the test pits over time.

This is another "it depends" answer and how the test lab applies the regulations (there can be a lot of gray area and interpretation, especially in MI audio). Under 25 watts probably isn't going to trigger anything but as power increases you begin to run into limits of connectors under the abnormal conditions clauses. This covers things like maximum continuous power until temperatures stabilize, 1/8-rated power into 1/2 the lowest rated load impedance, 1/8-power into a shorted load, etc. (the amp can fail under these tests but can't create a hazard while doing so). Another thing to consider is the connector and/or the opening in the chassis can become a potential ignition source (level 2 or 3) and this becomes more likely as the power levels increase. This is why the new chassis jacks for the SpeakOns are now rated at UL 94V-0 flame spread, the hole in the chassis is large enough that the jack acts as a flame spread safeguard. I deal with this stuff every day in my regulatory engineering work (I'm a product development engineer, an EE by education, but do regulatory engineering about half time). It's unbelievably complex, I'm constantly working out the engineering justifications and solutions as well as interpretations in order to comply with the safety and EMC regulations as well as working with the test lab engineers on what are reasonable interpretations for the regulations as they apply to different products. It's anything but black and white.

It depends on the size of the piezo crystal and how it’s implemented. Many passive piezo pickups are just fine driving a 1M input impedance and can sound better under that load.

This is a VERY complicated subject, and the blanket statements that are being made by the marketing materials have 3 distinct differences that are quite vague and misleading. 1. There is a difference in the general ratings between the PowerCon and SpeakOn connectors because the applications are very different. Since the PowerCon is used on the AC primary, specific clearance and creepage values have been updated in the new IEC 62368- standard. Since the SpeakOn is used on the secondary side of the AC system, the clearance/creepage values are not the same issue as on primary applications. On the AC primary side connectors, there is an additional need to be able to break the current without arcing since in the event of a subsequent short circuit, the available fault current (and power) is many times higher than on the secondary, which impacts PowerCon differently. Since Neutrik manufactures mating PowerCon cord sets, they must be compliant as well and that's a different matter entirely. How Europe handles the mating SpeakOn plugs is yet to be seen, but my feeling is that it's more bark than bite since Europe is already flooded with Chinese knock-offs of all kinds of products requiring certification (and for good reason) without any meaningful consequences to the violators AND there is a willing market of consumers focused on cheap rather than safe. 2. On the SpeakOn connectors, specifically the chassis jacks, since the chassis cutout is so large, AND because on a typical bass amp the speaker signal is classified as a potential ignition source PIS3, the housing material must have a specific flame spread rating of UL 94V-0 which is a VERTICAL spread rating and much harder to meet than the older UL 94HB which is HORIZONTAL and what the older housings were made from. The same applies to the older version of some (but not all) PowerCons. This requires different molding materials for the housing of the jack, though sometimes the older jacks can comply based on the specific application and lack of proximity to other PIS components, or by component testing. This is application specific and both the determination and the testing is convoluted. 3. On the SpeakOn specifically, changes in current ratings were also made, updates to both the continuous and duty cycle rated currents which are used in the application of designs under the new IEC 62368-1 safety standard without the need to do additional testing of the connector. Also, the speaker application rating is based on both short current (for contact current density) and long term under the audio power derating requirements, so while the contact rating may be 15 amps RMS, on the older connectors which are rated as continuous, the new connectors are rated for higher contact current density, but use 50% duty cycle rather than continuous. The new connectors specifically address contact robustness for very high pro audio power amps, not like what we see in bass amps. Much if this is addressed within the finished amplifier's certification procedure, it's a long and VERY expensive process. For example, on our guitar amps (we don't use 1/4" jacks for speaker outputs on the bass amps), most 1/4" jacks do not need to be V-0 rated due to their locations within the amp, but the speaker jacks do because the signal is at PIS2 or PIS3 levels. We had to separately approve the jacks we use to insure that they met the flame spread rating before they could be used in a location requiring this protection. This is one of the many reasons for the delays in certification approvals in Europe. We have many amplifier models and many components that needed to be evaluated and in a lot of cases tested separately before being tested in the finished amplifier because they are custom parts.

With a low powered speaker, a strong motor and just a couple mm of VC overhang, it’s possible to make a very efficient driver using a 4” coil and a tighter than average gap.

Be sure to use SpeakOn cables with genuine Neutrik plugs. Some knock-offs can damage the amp’s jacks.

It’s not due to the difference between class AB versus D. That’s a false premise to start with.

Turn the gain/volume up!

Correct, it’s the most common configuration, and a player would have a reasonable expectation that the head can be operated on top of a cabinet.

Not much safer given the plate voltages are fairly close.

Yup, this was also suggested Saturday on your TalkBass thread asking for help on the same amp... post #19. You could at least have the courtesy of following up there with your resolution IMO.

Maybe not, no way to know without a little more troubleshooting. The good news is that we do still have the newest PH 10" driver (8 ohms) in stock.

At this point, we don't know if any of the speakers are damaged yet. We do know that one is (very) incorrect.

Sorry, I wasn’t feeling well for a couple of days and missed this. First, a professional service technician that made that kind of mistake (substituting a 4 ohm driver for an 8 ohm driver in a 410 needs to hand in any credentials he may (or may not) have. That’s a bone-head error in judgement, just like choosing a BP-102 which is about the worst driver I can think of for that application. The original vendor for the earlier PH cabinets went out of business, the parts for those drivers are no longer available. The closest match to the drivers in your cabinet is the Legend CA-10 (8 ohm), and the drivers are wired series-parallel. Note that wiring so the polarities are correct is essential. If you need a diagram, message me and I will get it for you. This is why I always recommend verifying that the cabinet you are buying used is really what you think it is, I see folks get burned all the time.

A piece of heavy carpet might help, but some of this is going to be caused by the acoustic coupling between the speaker’s acoustic output and the top diaphragm of the riser. A high pass filter is one tool that may help, a parametric eq is another tool, turning down a bit might help too.

The GX-5 is an easy amp to repair for a qualified authorized service center. They have also proven to be extremely reliable over the past ~20 years or so. I don't recall any of the ~100 GX series amps that I had installed ever failing, they were at least as reliable as the RMX amps, but in a smaller (shallower) package. That said, the reduced cost of manufacture of some new amps can make them less costly to purchase in some cases.