agedhorse

Creasing of the cone will soften the suspension and change the moving mass because that crease will become the new hinge point. I have never tested a driver with mechanical damage like that and found the TS parameters to be anywhere near what they were originally. In fact, the change in TS parameters is one of the gold standards in assessing mechanical damage to a driver. It's used all the time when developing maximum power handling speaker ratings.

I think this is a great gesture of good will towards the industry as a whole.

The back view (showing the numbers on the cone) also shows fatal damage due to mechanical overpowering. This driver will be so far from spec that it won't perform well in the cabinet it was designed for. If you look closely st the front, you will see damage at the transition between the inside surround edge and the cone. Reconing or replacement are the only two options.

It's pretty expensive to support them myself in Europe, but there are a few qualified and authorized shops in the UK that I work with that have a nice track record.

Ask me about sewage treatment plants some day Paul

Thousands of tons (tonnes) of old school dimmers (resistance, auto-transformer/variac, and Triac/SCr based) have been scrapped in the last 10 years, as have tens of thousands of fixtures (instruments) due to the acceptance of LED dimming. The improvements in LED fixtures is really mind blowing, I designed one of the first high brightness room lighting systems about 15 years ago (called house lights in the theatre world) using at the time "exotic" 1 watt devices. There were almost 600 of them on custom made, plug together strips that were powered by redundant switchmode power supplies and zoned DC PWM dimmers. This room (a large custom home theatre for somebody in the movie theatre business) went from needing 4000 watts of halogen lights to only 600 watts of LED lighting. This was before there were any practical codes for LED architectural lighting, it was a proof of concept system that we built to commercial/industrial standards in order to pass design code review and inspection. LEDs are now twice as bright per watt, but this system is still in full operation without a service call in probably 10 years now. [/off-thread]

The triac and inverse parallel dimmers are based on reverse phase control of the 60Hz (or 50Hz for many of you) AC waveform. There is a PWM version that modulates the AC waveform by slicing up the waveform into tiny slices and eliminating slices throughout the waveform. There's also a type that converts the AC to DC and then PWM modulates this DC, either into an AC waveform or into a DC equivalent signal. Different companies have different ways of doing it (and different patents). LED lamps are usually dimmed by converting the AC to DC, then PWM'ing the DC voltage based on the RMS current rather than on the voltage since LED brightness is proportional to current through the device and independent of voltage across the device.

For conventional incandescent lamp dimmers, a few do, but most do not. For LED dimming, almost all use a form of PWM dimming,

Guys, I think you are (at least in part) misunderstanding some differences between how commerce is done the UK and commerce is done in the US, including HOW pricing is presented. 1. In the UK, your prices INCLUDE 20% VAT, in the US, our prices do NOT INCLUDE state sales tax (our version of your VAT), which runs between 9-10% average. 2. Importing into the UK costs roughly an additional 10-12% on top of this VAT for things like transportation, licensing, bonding, insurance, registration, and safety/EMC inspections and certificates. 3. There are some additional costs for warehousing, distribution and servicing/support which are generally covered by the importer of record, but of course this is a real cost as well. So, as an example let's take an amp that is advertised for sells for and sells for $1000 in the US and calculate what the real differences are... To the US consumer, this amp will cost approx. 1000 x 1.1 (sales tax) = 1100 USD which is the out the door cost to a US consumer To the UK consumer, that same 1267 GBP amp which has the VAT included Now, to look at why the amp is more expensive, we need to have the import costs of ~10% subtracted out because that's an ADDED COST of bringing a product into the UK, so now that's about 1140 GBP which would otherwise be the out the door cost to the UK consumer after the added taxes and fees levied by your government of our product. We do not have a choice in paying these added costs, which get passed onto the consumer in the end just like for all taxes. That said, all of the taxes paid by importers and yourselves go to cover things that do greatly benefit you, things like your extensive public transportation system, health care and retirement programs. You might be shocked to learn that many of us Yanks pay on average ~$1500-$2000 USD/MONTH for the same healthcare that you receive as part of your government services. While comparing prices might seem like you are getting the short end of the stick, it's nowhere near that simple... the grass is not always greener on the other side of the fence/pond. In fact, it's debatable that the stick is equally short on both ends Hope this helps.

Properly designed, any class of amp can be plenty reliable, but not well designed can affect the reliability of any class of amp. I have designed all types of amps, tube, solid state class AB and class D and haven't experienced any reliability issues (or unrepairable issues) on any of them. While many power sections of class D amps are not easily or economically repairable, often replacing the power module is less expensive than the labor and parts on a conventional tube or class AB solid state amp. Generally, the preamp and supporting assemblies are easily repaired BY A QUALIFIED service tech. Now the problem I am seeing lately is that many who call themselves techs do not have the knowledge, qualifications or aptitude to properly repair this gear. That's not a technology problem, it's a service tech problem. We are losing the really good ones as they retire out of the industry, not too many coming in to take their place.

Note that for musical instrument use, JBL recommends between 1/2x and 1x the thermal rating depending on how it's being used. See section 4 which covers the applications that would apply to bass guitar. https://www.jblpro.com/pub/technote/spkpwfaq.pdf

I believe that's the cost for the entire driver and horn, not the replacement diaphragm that I suggested (which is MUCH less expensive).

Your dealer or the service agent of record for your region can order a replacement diaphragm, there is no reason to replace the entire driver unless you prefer to spend additional, unnecessary money.

As Bill mentioned, low frequency extension is generally one tradeoff, another is power handling. As power handling increases, sensitivity generally decreases. The idea is that the SPL gain from increased power handling exceeds the SPL loss due to higher power handling (which it usually does up until a point). For instance, you may lose a dB in sensitivity to double the power handling. Regarding sensitivity specs, I typically use the average sensitivity from 50Hz to 5kHz for bass guitar because this seems to reasonably represent the bandwidth that most players perceive as "volume". Unfortunately, there are plenty of examples of sensitivity that are simply impossible to achieve using such metrics. Also, it's important to distinguish sensitivity at 1W/1M from 2.83V/1M because 2.83V/1M with a 4 ohm cabinet will result in numbers 3dB higher due to it now being the equivalent of 2W/1M rather than 1W/1M.

Your dealer would need to contact the distributor for your country. I do not know what the policy is for this kind of accessory

Correct, I should have been clearer in my explanation. The footswitch operation on the M6 is different, individual contact closures for each voice (1, 2, 4, 5) with 3 being default. Sorry for the confusion. The original concept of the switching on the M6 came from the guitar amp side of things where MIDI switchers and contact closures were commonplace. When a program change is sent via MIDI, it triggers the appropriate contact closure to enable that voice. With the M9, this was simplified and it kind of works in reverse, you set the voice you want to switch to on the voice knob, then the footswitch toggles between no voice and the selected voice. This is the tip contact, the ring contact is for mute. Hope this helps.

Just be sure you get the latching type.

Correct, applies to the M-6 only. [edited for accuracy]

This switching scheme was designed to be used with a variety of switcher boxes that are more common in the guitar side of the industry. There were a bunch of semi-custom products, but some stock ones too. https://mesahollywood.com/products/voodoo-lab-control-switcher Here's another, uses 2 x TRS that have to be broken out at the amp's end into 2 x TS: Here's another, I believe this breaks out to 4 x TS: Here's an example of the kind of product that would be used at the amp end, and a programmable MIDI footswitch would go on the floor with a single MIDI cable between the two. The box would provide the contact closures upon command by the MIDI signal. The guitar world is full of such devices, we had some too, but things have changed considerably over the years and they are in fact fading away: https://six4pix.net/product/midiswitcher/ We also made a 4 footswitch pedal with 4 outputs that could be connected through a single 4 pair snake terminated in 1/4"-TS plugs, I don't know much about the accessories, but customer service would know. Hope this helps

Because the gain structure is very similar between the two, and with the channel volume on the Shuttle 6.0 control set to ~1:00, the gain structure is the same. The results are virtually identical in the pre position and overall within a few dB in the post position. The DI circuitry is in fact identical. In case you don't realize it, I designed both of these amps. What the OP is experiencing is consistent with either the DI output level switch being set differently or the sound guy being unaware of the gain structure of his console's input channel strips.

The different preamps make no difference to the OP's situation.

With all 4 MOSFETs, it was capable of greater power into both 8 ohm and 4 ohm loads. There were many versions of these amps that used a similar output section, but it depends on the power transformer (thus the rail voltage) also. If the rail voltage gets too high (to achieve greater power into 8 ohms), then 4 output transistors may not be enough for the resulting higher power into 4 ohms. There were also different MOSFETS used throughout the production history, including special "double-die" parts. Over the years, there were some output stage applications that weren't all that reliable, and sometimes incorrect transformers were fitted in order to ship amps. Many of these unrelaiblities could be traced back to the liberal build philosophy rather than the circuits themselves.

The AH-100 links are for manufacturing to use this PCB assy. with a different model. This amp, from the photo, uses a single pair of output MOSFETS. Depending on the power supply (rail) voltages, it may very well be rated for 8 ohms minimum load only. Especially because it has a single speaker jack in what was a combo, and because Celestion confirmed that it was an 8 ohm driver.

You are going to need to do more testing and troubleshooting. There may be a small difference in DI level between the two different amp models, but not a huge difference.