agedhorse

9 hours ago, stevie said:

The specs for the Genz Benz custom PR300 are available online for anyone interested in seeing what the difference is. Faital Pro is a quality brand and any bass cab fitted with their drivers is likely to be very good.

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.

On 22/10/2021 at 05:52, ebenezer said:

I am using the genz benz 212 neox cab and very good it is, so whatever genz specified for the 12 pr300 is ok with me. 

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.)

22 hours ago, Beer of the Bass said:

As much as people complain about so many amps using the same few power amp modules now, at least there's a much better chance of a tech being able to source the right ICEpower module a few years down the line compared to proprietary ones unique to one model.

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.

7 hours ago, Dan Dare said:

 

Depends on the part. Many components won't be unique to a particular manufacturer - they buy them in - so a faulty resistor, for example, can be replaced by another of the same type/value.

 

 

You're right about this. Class D modules are machine built and components are small/tightly packed and even sealed, making repair all but impossible and replacement modules are not cheap.

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.

10 hours ago, martthebass said:

The GPU thing is crazy.  I was looking for a gaming laptop to use for astro image processing (as it's easy to add RAM/Storage) and couldn't get one in my price range at any of the physical shops.  However, online at one of the physical shops it was just a few clicks to get one delivered from central warehouse to local store.  So while there are shortages I suspect UK distribution is also an issue. 

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.

On 22/09/2021 at 00:31, chyc said:

Am I right in thinking that class d amplifiers get this HPF for free, or at least the amp's designers would need to explicitly build an amp to generate subsonic frequencies, which would make no sense?

 

 

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.

27 minutes ago, Downunderwonder said:

Consumers deciding between otherwise equal offerings lead spreadsheet manglers by the nose straight to the door labeled 'cheapest good components'.

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. 

6 hours ago, Chienmortbb said:

To be fair @agedhorse, I don't think the US is in anyway to blame here. Many months ago I was looking for some IRS2092 chips for a project and I was astounded when Mouser were quoting 18 months, they are are still quoting mid 22 for availability.

Everybody shares responsibility, and for many, many reasons.

5 hours ago, Bill Fitzmaurice said:

The US is having problems with the supply chain of everything from fuel to food for the lack of truck drivers. Many of those laid off during the height of the pandemic moved on to other higher paying jobs. One reason why ships can't off load their containers is the lack of trucks to transport them from the ports.

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.

15 hours ago, Phil Starr said:

It's interesting isn't it, lots of people have been speculating about the similarities between the Gnome, Elf and BAM's There are theories that Behringer/Cort and so on might be manufacturing them and badging them. The reality I suspect is that they all use the same chips/electronics and so end up with the same architecture. The same thing that drives the prevalence of the class D 300W/500W amps that everyone is producing now. I don't think people realise how narrow the first link in the chain is.

 

 

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.

17 hours ago, Chienmortbb said:

The current supply chain issues are likely to have a knock on effect on the availability of amplifiers. I have been looking at Power Amps for PA use and those that are out of stock are getting longer and longer lead times almost daily. 

 

The much publicised shipping problems will be having an effect but as I understand it , the biggest issues are with semiconductor supply. Industries such as the car industry use masses of  chips and may be getting priority over the MI and Pro Audio sectors. Some devices that I was using in a design have already gone to 18 months lead time and these are core items that cannot be second sourced.

 

Has anyone noticed a problem with bass amps recently?

Every day, and sometimes in the middle of the night in a bad dream that seemingly won't end.

23 hours ago, Gearguy said:

Eden bass amps were generic stinky poo. Made from the common solid state components available, Eden was a sterile, hard surface typical transistor design. NOTHING special in any way.  Eden failed not only because "NON" bass company Marshall had the bad idea to acquire them, but because their designs were basic , uninteresting, and hyped far beyond performance. With no organic appeal and a user base of jazzbos and weekend warriors, Eden was never embraced by the Pro bassists.

Good riddance.

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).

On 27/09/2021 at 03:59, paul_5 said:

Erm, a DI box is a cable adapter… 😄

Erm, no it’s not. 
 

A DI takes an unbalanced ground referenced signal and balances it. It also floats the signal from ground. It requires a TS input cable, not TRS. 
 

that amp has the balancing circuitry built into the amp, so all that’s needed is a TRS to XLR male adapter cable.

On 26/09/2021 at 13:15, TheRev said:

I use this with my EA Doubler. 

It was made by OBBM, following the description in the EA manual

 

Amazon have this balanced TRS jack to male XLR which should work, but it would be worth checking with the vendor to confirm that the TRS connections are wired as per the requirement in the EA manual.

 

https://www.amazon.co.uk/kenable-6-35mm-Balanced-Audio-Adapter-XLR-pins-Stereo-Plug/dp/B008JYF2CK/ref=mp_s_a_1_3?dchild=1&keywords=trs+to+xlr+male+balanced+adapter&qid=1632687056&sr=8-3

 

 

This is what you want, the terminations are standard.

No idea, I never saw that. Peavey used a black MEK glue that was really tough and hard. Usually the aluminum fractured at the edge of the dust cap where it became the lip that fit over the top edge of the bobbin. Once it stated cracking, the fracture would travel and the dust cap would kind of come apart. It's possible that Peavey used a different glue for the European market, the MEK glue was quite toxic and for the most part it's been phased out in the favor on more advanced adhesives.  

At one point, the industry tried CA adhesives, they didn't work all that well until new formulations came into being, and now some manufacturers use UV cure adhesives. 

Also, at one point, Peavey used a one piece dust cap/bobbin assembly, that was also problematic and expensive to form. These also fractured right at the edge:

Where the joint at the cone neck fails, if you do an analysis of the failure you will find that the glue itself was fine but the paper of the cone neck itself fails. This was before the industry recognized the need for reinforcing the cone necks in higher powered speakers, especially those with shallow cone profiles. Other manufacturers encountered the same thing, and one of my projects was the development of revised cones with reinforced necks for drivers that we had originally used throughout the company I worked for at the time.

The surround separating from the basket is more likely a production problem rather than a glue problem, this is also something that every manufacturer has to deal with. The dust cap separating from the cone is also likely a production problem since the glue used for that bond was completely different from the other glues. Back then, there were 3 different adhesives used. There were also issues with the aluminum dust cap fatiguing and actually fracturing around the glue line because the MEK glue was so hard and there was too aggressive heat treatment of the aluminum. This too was an industry wide issue, and one reason why manufacturers moved away from aluminum dust caps. They must be very thin (IIRC it's about 0.003"  (0.07mm) aluminum and it must be very stiff, therefore it must be heat treated to a high degree which makes it vulnerable to stress cracking. Even JBL had some issues over the years, and they were the first to successfully perfect the process. 

It's possible that there's a bit of magnetic debris stuck in the gap, or just as common would be bits of deteriorating foam from the magnet structure vent. To remedy this, two different methods are used depending on what the problem is.

1. Magnetic debris requires the use of folded over masking tape (sticky side out), and patiently running around the gap. It may take 5 or 6 iterations of doing this before it's clean.

2. Foam residue requires the use of a business card type paper stock, wet it with mineral spirits, and run that around the gap again and again, changing cards as needed. It may take a dozen iterations of this before it['s clean. Also, very gently clean the inside and outside of the voice coil to remove any foam debris that may have melted to the surfaces.

I have never heard of the defective glue issue, nor have I seen it, and I serviced a lot of BW drivers (both in and out of warranty). The assembly is generally very well done.

IF you need to buy a replacement basket, be sure to use the same part number that was originally used with the motor, there are some newer baskets that are not fully compatible with the old motors. They may physically fit (sort-of), but the power handling is no greater and the sensitivity ends up being significantly lower. You can always email Peavey support to verify that your basket and motor are compatible. IIRC, there were 3 different motor series.

Generally it has to do with timing issues, but with the protect LED on, it sounds like either something g else, or multiple problems simultaneously.

4 hours ago, Bigguy2017 said:

Yes, if you spray some Deoxit D5 on some black plastic, like a CD case, and let it evaporate it leaves a lube residue.

The lube residue is a very thin, almost microscopic layer. The D-5 is a 5% solution of Deoxit (red) and 95% carrier. If you were to place one drop on the surface and then remove 95%, you can see how little we are talking about.