agedhorse

For audio output power, the VA term is simplified to watts because the amp is modeled as a close to ideal voltage source and for practical purposes it’s easy to measure RMS voltage, square it and divided by the nominal impedance (simplified to resistance) to calculate power.

So many players I have worked with (as a pro audio provider) over the years have passed. That’s one of the sad parts of a long and very busy career, lots of fabulous music, and I wouldn’t trade my job for anything.

You probably can’t hurt anything but there’s no guarantee.

I kind of doubt it. I don't know which pins are dropped as to how the adapter is wired. Since I can't find any docs on the original 7 pin wiring diagram, I would be just guessing and there's no need to guess wrong here. All I can find is this information on the 4 button footswitch and 5 pin DIN wiring:

There is one pin that's connected to circuit ground and 4 pins that are pull-down pins connected to the opto-isolators for each function. The footswitch circuit works by connecting each of the function pins to ground which will switch the function. A QUALIFIED tech will be able to identify the correct pins and not damage anything.

On the Presonus boards they use 2 separate inputs (mic and line). By the spec sheet for the Studio Live 16, the input clip point with the trim control at unity is +12dBu and rotating it counter-clockwise from unity increases the input clip point by 15dB to +27dBu which is 17 Volts RMS and 48 Volts P-P. I believe this is an error in the manual because it exceeds the power supply rails. This is complicated a little bit because the signal block diagram doesn't match the console silk screen values, but even using the -6dB from unity headroom yields +18dBu which is 14dB of headroom on a +4 nominal signal. +18dBu is 6V RMS and 17V P-P Note that it's important not to throw numbers around without understanding the units. Peak, P-P and RMS are all differentfro the same signal. I don't see how you can overdrive the input if you are using the board properly.

Non-clipped output power in rms metrics.

The video world moved way too fast for my comfort level, you could be qualified one year and completely unqualified to design new products the next year as the technology changed and the big player drove the market. It's hard to have a 40 year career in the video business as a designer/engineer IME based on friends of mine who followed this path.

To respond to the message I received calling me a liar, here is where the test conditions for normal conditions are defined in the IEC 62368 regulations (for the EU). The input power to be labeled is defined to be the input power under these normal conditions (or greater if the manufacturer chooses a more stringent duty cycle because of the application). For example, for the amps I design for bass and electric guitar, I typically use more than double the minimum required under the regulations but for acoustic guitar it will be a little less than double: Also, may I ask why there's so much rudeness here? For those interested in learning, I'm providing information that most players clearly don't understand or haven't been exposed to. For those of you who don't want to learn, why challenge the facts is such a manner?

Our hope is that the Mesa showroom will also be complete by that date, but I don't know the details. There are containers of Mesa products that have already been shipped, so we are all hopeful that this date remains correct.

First of all, these additional discussions can be valuable for those who are open to learning. that’s why some of us put in the effort to explain things the way we do. Of course the additional information are going to be frustrating for someone who is struggling with the facts yet continues to post incorrect information as though they know what they are talking about. Clearly I poked that bear here, sorry for that. The term RMS power is defined by industry convention to be power based on rms voltage and current, it is a descriptor which is well understood and accepted by the industry. It’s also been accepted by all of the regulatory agencies (safety and EMC) for audio equipment testing. Hopefully this isn’t going to be controversial as well.

Actually, Bill’s correct on this. This example has nothing to do with clipping (in this universe anyway)

Yes, and so do I Bill, but you already know this.

A HPF can certainly help by reducing the level where the cabinet is most vulnerable to mechanical damage. A compressor might also help, but too much compression increases the average thermal power which may place the cabinet at risk due to increased thermal power. With compression, a little can go a long way.

You may disagree with my comments about the 1/8-rated power designation for labeling, but it’s fact not opinion. Its part of every global safety regulation and in order to legally place the CE mark under the CB scheme regulations, the power consumption that’s on the label must be the minimum of 1/8-rated audio power or higher IF the manufacturer intends for the amp to be used at higher average duty cycles. Every product that complies with CB scheme (IEC 60065 or 62368 with national differences) is required to be marked in this way. I do this regulatory stuff every day as part of my design work.

No, that is not what it means. That is the power that is drawn by the amp at 1/8-rated audio power in rms metrics, into the minimum rated load. It's a minimum labeling requirement by the global safety regulations (assuming that it does comply with IEC 62368-1. The actual amount drawn can't exceed 200 watts but may in fact be less to account for any duty cycle additions beyond 12.5% that the manufacturer wishes to address. It's fairly easy to take that power consumption number and calculate the approximate rated audio power... Since the average efficiency of a SMPS + class D amplifier is 85%, take 800 watts RMS, multiply it by 0.125 and divide the result by 85% and this number must be less than 200W. (800 x .125)/.85 = 118W which is less than 200W. Now is this amp a good idea for a 200 watt/4 ohm speaker? It's perfectly fine as long as you don't have an accident, have a lapse in good judgement or have unrealistic expectations of the speaker's capabilities. It's one reason why we see blown speakers, nobody's perfect.

I haven’t heard this, my understanding is that Mesa gear will be there for the opening. I’m not directly involved with the marketing side, especially international marketing, so things may have changed related to the construction or the phasing in of the brands owned beyond Gibson branded products themselves. I will ask and see if I can get updated info.

Yeah, sometimes it happens that way. Maybe a bad solder joint, maybe it was simply a bad connection that was corrected as a byproduct of the repair. Since there were thousands (6227 to be exact) amps built with those values without a problem, it should be obvious that it wasn't a problem. They don't have to be the same values as Marshall used, why would the?

The values of the components had nothing to do with your problem, it’s not a Marshall amp. The fix was just a lucky byproduct of the “repair”.

Correct, this newer format was also used on some other bass products too (though not identical). There may have been other differences as well to the way the logic was handled. I don’t have the docs for the later one handy. I would look for the correct footswitch rather than attempting to modify the 5 function one.

Do the two foot switches say M-Pulse? Do they have the same number of pins on the DIN connector?

Try the valve before screwing with anything else. I don’t recall if all M-Pulse models used the same foot switch or if there were differences. I will look to see if I can find the info, but don’t attempt to bodge something together because the switching system could be damaged by an incorrect connection. This was from an era when a lot of changes were happening to our entire switching protocols (including guitar amps).

Almost certainly the valve with the white getter coating.

Solder is lead free. Note that it’s a custom bushing diameter. The correct part is available from the factory. I haven’t heard how the follow-up service network will be implemented yet. I will post the information when it becomes available.

There are quite a few possibilities, but by far the most common cause is the amp falling on its face. We are in the process of setting up a new service network throughout Europe, including several in the UK. The factory is closed for the holidays, but I can contact one of my coworkers to find a service solution for you. You can message me and I will get you the info.