agedhorse

Just wanted to update on Mesa availability in Europe... Mesa bass gear will be featured as part of the new Gibson Garage showroom in London which will be up and running early next year. That's when the re-launch of Mesa in Europe will occur, and it will give players to try out some of the new gear locally if they don't have a dealer near by and happen to be traveling through London:

https://www.gibson.com/en-US/Blog/News/are-you-ready-for-the-gibson-garage-in-london

On 16/09/2023 at 23:46, Phil Starr said:

B&C don't really make instrument speakers so this might be an acquisition adding to their range. I don't know about how Eminence are distributed in the States but maybe this would help B&C in a big market. Perhaps there are some economies of scale they hope to achieve. I wonder if @agedhorse has any inside information or other insights? 

This was not unexpected, manufacturing in the US or Europe is difficult without governmental support. Different countries in the EU support different industries which is why we see a concentration of speaker manufacturers in Italy, Class D amp manufacturers in the Netherlands, etc. This is how individual countries achieve critical mass which indirectly benefits them through increased employment and tax base. China has been doing  this for years...

110V, 115V, 117V are all legacy voltages dating back decades. 110V DC was the original Edison standard, 110V AC was the Tesla standard. Between WW1 and the 1960's, the voltage crept up until 120/240V became the defacto standard for the US and Canada. Some designers never changed their 115V or 117V templates, so you do see these referenced from time to time.

On 08/09/2023 at 10:28, BassmanPaul said:

Traditionally the US has been 117V not 110V. Here in Canada we operate at 120V.

 

US and Canada are 120V +/-10%. 

12 hours ago, Chienmortbb said:

I agree, but many "better" manufacturers do. RCF and QSC are prime examples, whereas Martin Audio quote the real power with the peak power added for information.

 

Turning my own argument on its head, Martin are a better manufacturer and RCF, QSC are not.

I was referring to bass amps in my reply. Bass amps intended for more professional applications are in general rated using RMS metrics.

Moving over to the pro audio side of things, powered speakers marketed towards the general masses are often rated using peak but any numerical rating is disingenuous because to the heavy (and complex) limiting algorithms used to protect the drivers. When you get to the more pro side of things you see more RMS metrics used, though more often I am seeing peak power along with RMS.

It's a slippery slope, the marketing guys have to market against others who are already doing it or they feel at a disadvantage.

15 hours ago, Chienmortbb said:

A well designed Class D amp will generally be cleaner than a Valve amp designed for bass or guitar. Howeve a Valve amp may have compression built in.That will give more distorted watts (compression is distortion) and valves/transformers have the effect of taming the nastier sounds from a clipped amp. However the extra power will be marginal. 
 

Often the difference is in the inflated figure sone manufacturers quote. Remember many class D amps are designed with the consumer market in mind and are fighting the PMPO* mentality. 


*Peak Music Power Output.

 

 

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.

14 hours ago, Chienmortbb said:

Interesting that you say 25 watts when many guitar amps and a few valve/ tube amps for bass are rated at 30 watts. I will admit that I do not know the original spec on Jacks and Plugs  but I know many are rated at 500mA @ 50V. That ties in with 25 watts. 
 

I have seen it argued that if the electric guitar were invented today, the Jack would not be the connector of choice. The case for a different connector between amp and speaker is even more compelling. I must admit that I had never considered flammability as an issue. 
 

As a self-confessed nerd, I did consider buying the IEC standard but at just over £400/$450US it is a luxury I can do without. That would go a long way to a Mesa Subway😀.

 

I have seen it suggested that not using compliant equipment might cause problems with Public Liability Insurance(I don’t know what it is called in the USA). Have you heard ?

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.

2 hours ago, Stub Mandrel said:

Well given the number of fires caused by inadequate speaker connections I'm not surprised action had to be taken...

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. 

2 hours ago, squire5 said:

My amp is the Laney RBG400 which has a lot less inside than that pictured by DGBass.Ive managed to oontact a guy in Lisburn N.Ireland.Says he'll take a look at it.

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)

53 minutes ago, Downunderwonder said:

Not sure we're still talking about OP's amp. The pic is from the helper.

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

6 hours ago, Chienmortbb said:

It’s true that electrolytic caps can degrade but that is unlikely to be the cause if the failure happened suddenly. Also sudden failure of electrolytic capacitors is often visual in that they will either deposit electrolyte close by or bulge/explode.

 

De-L it is available in Europe but it is very expensive. In my experience, as pots age and are used, two things happen. Firstly, parts of the track flake off causing debris that disturbs the wiper causing crackles and noise. There is also a chance that dust from the outside world gets into the pot and similarly disturbs the wiper and makes the pot crackle. As De-Oxit is specifically designed for cleaning and lubricating pots , I am sure it is better than switch/contact cleaners. WD 40 should not be used anywhere in an amplifier.

 

Another issue with pots is that a result of the track material flaking off, the track wears out. This is the only way I can see that a pot could cause hum, where a pot becomes open circuit. 

As for a DIYer trying to fault find, it is best to leave it to the professionals, they have the knowledge and equipment to fault find.  Laney’s service department are helpful and I would consider ringing them as it may be quicker and cheaper in the long run to send it to them.

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. 

On 22/08/2023 at 06:57, DGBass said:

A loud hum on the speaker output usually means something has gone on the output section of the amp, its usually an indication of a dc signal which shouldn't be there. But not always! Laney amps of this era are fairly simple to repair and parts can be found for them easily online. If an output transistor had failed, it would usually take out the fuse as well, so it may be a failed coupling capacitor or even a dry solder joint on one of the caps. Vibration over a long period can rattle things loose and from Laney bass amps I've worked on before, they seem to be sparing on the hot glue to keep big caps fixed and stable on the circuit board.  The pic below is from a bigger 300w version of your combo that had similar issues. The big black bits with 5/22 on them are the coupling caps. If they move or feel wobbly at all it could be they've worked loose. Any good amp tech would find an issue like that very quickly. Can be diy but as with anything electrical with dangerous voltages present, you have to be careful and not get yourself electroplated. If in any doubt, an amp tech is the way to go. Any amp is worth repairing if its cheaper than buying something to replace it. 🙂

 

 

 

 

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.

19 hours ago, Baloney Balderdash said:

Could be something as simple as the pots needing a cleaning.

 

Any additional crackle when any of the pots are turned?

 

If so a fix could turn out to be as quick and easy as to spraying some electronic cleaner inside them and giving them a series of wiggles back and forth.

 

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.

3 hours ago, Chienmortbb said:

What do the new standards say about 1/4" jacks for speaker use?

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. 

After all the suggestions on TalkBass about "bad caps" being the cause (which for the most part is an absurd guess), it turns out that bad caps is unlikely the cause because bad caps don't "heal themselves", nor are they fixed by "ritualistic healing", or even burning at the stake.

It may have been that the cause was unrelated to the amp itself, but was present at the input along with the signal. This is why we do troubleshooting rather than "guess-a-shooting".

If the problem is gone (the noise floor of that amp wasn't particularly low to begin with), it may be best to leave well enough alone rather than create entirely new problems. If it ain't broke, don't break it...

On 21/07/2023 at 06:57, RikiB said:

I was told it’s plenty loud enough as it’s class AB and not class D but my GK legacy is lots louder.

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!

1 minute ago, RikiB said:

Putting a bass head on a bass cab is pretty normal and would expect it to not cause any problems. Maybe vibrating over time could cause some problems but this is house volume not gig volume so far so if it is that then the head isn’t fit for purpose.

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.

2 hours ago, dmccombe7 said:

Pre-amp tubes can give you a sore one if not careful. Safer in a way than power amp tubes but still care is required at all times.

Dave

Not much safer given the plate voltages are fairly close.