agedhorse

If you knew how many tubes marked 7025's are in fact just plain 12AX7 in "different clothes" (counterfit), you might be surprised. If you knew how many tubes we reject because they are either out of spec, noisy or microphonic, you might be surprised. If you knew where these rejected tube end up, you might be surprised. If you knew how many issues related to a user or tech not understanding the concept of correctly biasing an amp, you might be surprised. Preset bias and "matching tubes for that bias level" is an essentially foolproof way of being able to change out power tubes without the need to re-bias, as well as keeping fingers out of the electronics. This way the bias is exactly as the designer intended. Your comment about "bullsh*t marketing" is uncalled for because it's based on your lack of knowledge of why these decisions were made. You don't have to agree with them, you don't have to buy our amps either, but calling it bullsh*t isn't right.

Glasgow Studio Electronics is another good option IME.

Yes, the folks at Westside are excellent, and run a tight ship.

With the ongoing COVID case numbers throughout Europe, parts and materials from that region is remaining a serious challenge. Materials and shipping from Asia remains a nightmare, with some regions getting worse rather than better. Eastern Europe (a major source of tubes) is getting worse, which compounds tube shortages from China’s issues. South America (another source of speakers and materials) is also not improving as hoped for. Some things in the US are improving, but backorders and global parts shortages are impacting our abilities to produce finished goods as well. Ultimately, we are all in this together. That’s how a global economy works.

Yes, that's the best option. If there's hum due to a ground loop, most PA companies carry XLR pin 1 lift barrels for that purpose.

With your Streamliner, you have enough power on tap to destroy those speakers. Beware.

Least likely is either ported or sealed next to a folded horn IME.

Yes and no. The original specs posted by the seller were not correct because he was advertising them as stock 12PR300’s when in fact that was untrue. Eventually, that “oversight” was addressed. The published TS parameters, as you know, only describe elements of the low frequency performance of the driver. The mid and high frequency performance characteristics are not described. I don’t believe that correct information was ever provided (though the incorrect info bounced around quite a bit. This is because of an issue when somebody bought some of these drivers and they sounded quite different from the stock model in spite of the paperwork showing them being “identical “. Created some ill will.

There were 2 versions of the NeoX 212 cabinet. The original version used a custom Eminence driver and the NX2 version used a custom Faital driver. While the low frequency parameters are reasonably close, the mid voicing parameters are different as the goals for the cabinet line evolved.

I can be general, but correct I can't get specific because these techniques are in fact still used in commercial products being designed today. One of the biggest challenges with any driver is balancing the desired characteristics with their side effects or negative attributes. Sometimes, this works in the designer's favor, but often they can conflict. The critical part of this is correctly identifying the attributes you wish to exploit and those you wish to minimize. It's easier said than done of course, and sometimes, it's simply an impossible set of compromises and a different approach in needed. One characteristic that's VERY important to bass players is the midrange voicing, and how that voicing integrates with the tweeter. This is also heavily influenced by the polar pattern of the driver which is governed in part by the diameter of the driver but also by the cone/dust cap shape, material. Another characteristic is how well the driver tunes in the desired cabinet size. Different choices of soft parts results in different parameters that can make a driver more or less friendly to a particular range of cabinet sizes. This means that if the goal is a smaller than average cabinet size, TS parameters may be adjusted through the selection or tailoring of soft part properties. Another property that a designer can address is what happens to the VC as it enters and exits the non-linear portion of the magnetic field and the shape of the magnetic field fringe is shaped, specifically the ends of the VC, and how the inductance and the VC current interact with the fringed fields. Note that the fields are often not perfectly symmetric, this can become a blessing or a curse depending on the goals and the component parts. Xmax is something that comes up a lot in LF driver discussions, there are different definitions, sometimes different goals and sometimes different mechanisms depending on what parameter the designer is more concerned with. For example, it's possible to design a driver with more robust mechanical suspension parts than the basic Xmax might suggest depending of the characteristics of the fringe field performance, as well as long term ageing and mechanical reliability metrics. While the AES power rating standard is a 2 hour "must survive" test, I typically use a 200 hour "must survive" test because the companies I design for have longer warranty periods and the customers of those products typically have greater expectations. This is just a little bit about what goes into designing a driver.

To clarify this often propagated and unsubstantiated "rumor", the Genz Benz products did not use a stock 12PR300. The soft parts were customized for our design goals with the stock metalwork. The difference is significant and for our goals worth the effort and cost of customization.

Message me and I will help you sort it out. If the job isn't done right, you can indeed end up with a mess. I do not have any replacement PCBs left, ironically in all the years I have serviced these amps, I have never needed a replacement board but I have seen plenty damaged from failed repair attempts that would have been a simple, inexpensive job for a QUALIFIED tech. They are a double sided PCB with plated holes, damage the plating and you have a problem. Due to chronic issues with blue LEDs from what were well qualified suppliers/brands, we moved to using CREE parts due to their much higher overall reliability (of course they cost more too, but that wasn't the reason we used the parts we did use, CREE didn't have this part available until years after the amp was designed.)

Yes, All of ICEPower’s modules going back almost 20 years by now are still in current production and available to authorized manufacturer’s service centers.

There are many parts that are no longer available as the manufacturers of such parts discontinue them and there are no other sources. The most common parts are pots, jacks, switches, relays, and some opto-electronics, plus many lateral and vertical MOSFETs (though for some applications there are still some reasonable substitutes but they don;t work in all applications). Beware of counterfeits however, especially semiconductors. The world is awash with counterfeit MOSFETs, most aren't even the type that they are labeled (lateral in particular). From a company that supports their products, replacement class D modules are often reasonably priced. Not are they generally impractical to repair, the act of repairing them invalidates their safety certifications because they are a specially certified part (reinforced insulation between the primary and everything else) and must be tested for compliance after the repair. The European manufacturers of these modules are quite clear about this and won't even repair them at the factory. It's a bit like rewinding a transformer, if you can't certify it (properly), it can't legally be used in a repair for the same reason. It's treated as an integrated component. The EU is more strict about this than most regions.

Or, they had inventory from orders placed months ago and you were lucky to find them.

I spend some time each day tracking down parts and production schedules that have been upended by one thing or another related to this matter. Just as a glimpse into the manufacturing world, here's the availability of SMT resistors from a large supplier of parts for all industries (including ours): https://www.trustedparts.com/en/search/tt-electronics/M55342K12B I have had nightmares less scary than this.

Yes, it’s a very real thing.

No, a class D amp can reproduce DC if the designer wished it to, just like a class AB amp. In fact a class D amp generally has higher performance at low frequencies. The HPF has to be designed into the amp, the same as for any amp.

This is basically what has driven most companies down this path, it the consumer won't buy it because of price alone, then price will become the overwhelming driving factor.

Everybody shares responsibility, and for many, many reasons.

Everywhere in the world is having these problems. For slightly different reasons, but no region is unaffected.

The problems are global, not related to our side of the pond. We have European manufacturers that can not build components for exactly the same reasons we can’t… unavailability of raw materials and component parts. This has nothing to do with our side of the pond. Transformer vendors (of line frequency parts) today can’t get materials in production quantities without long delays. Lamination steel of all grades, bobbins, terminals, insulation tubing/tapes and TCOs are all impacted. This has nothing to do with our side of the pond. Transformers “wound” in back street shops are not an option for real manufacturers because for the EU market, they MUST be designed, certified, constructed and tested to YOUR EU safety standards. The factories must also be inspected at least quarterly by a nationally recognized test lab inspector.This has nothing to do with our side of the pond. Currently that would be IEC 62368, it’s a European standard, and it’s not optional. All power and output transformers must comply. The shop must be registered as an approved manufacturer by the NRTL that’s responsible for certification of compliance. This has nothing to do with our side of the pond Test labs globally, including in the EU, are backed up with extremely long lead times. This has nothing to do with our side of the pond. Regarding tubes/valves, there were as many western European manufacturers of tubes as US manufacturers back in the day. Now, there are no US or western European manufacturers, they are all built in eastern Europe and Asia. This has nothing to do with our side of the pond. The global shipping industry is heavily impacted. We are experiencing very long delays and prices that are ~10x higher than before. This includes products originating from the EU as well. We use a lot of European components and materials, we struggle with delays due to our European partners inability to source materials, shortage of labor and shipping. This has nothing to do with our side of the pond. This is a global issue, it’s almost certain that delays and shortages will continue for maybe even a year or two at this point as manufacturers work through their back orders. This has nothing to do with our side of the pond.

The commonality of parts is not just a recent thing, it goes back 50+ years to the use of common tubes/valves, semiconductors, pots/switches, knobs, etc. There are commonly accepted architecture based on years and years of development and then refinement, architectures that didn't work out get dropped by the wayside and the successful architectures live on. Every designer has their own take on several basic power amp architectures for example. Every day, and sometimes in the middle of the night in a bad dream that seemingly won't end.

Yeah, too bad it took them forty-something years (and tens of thousands of amps) to "fail". Plenty of pro bassists used them as well.

The protective earth ground is never lifted from the chassis, it’s not allowed (via a switch or otherwise) under any code for a class 1 safety certified device in any region that I am aware of. Lifting circuit ground is different, though generally goes hand in hand with transformer isolation on unbalanced applications (including ABY boxes).