Bill Fitzmaurice

This question comes up often enough on my forum that I added an FAQ reply: When should I bridge? The answer is almost never. Forget about the silly power ratings that manufacturers post for bridged output, that's just advertising piffle aimed at the unwashed masses. Bridging isn't about power, it's about voltage swing. You use it when your amp doesn't have enough voltage swing to drive the speaker to its displacement limit. Nine times out of ten that's because the speaker has a high impedance, say 16 ohms. The tenth time is when your amp is rated at less than a quarter the power output that your speaker is. If you do bridge when you don't need to the doubled voltage swing quadruples your chances of blowing drivers. Bridging into multiple cabs also can cause the amp to overheat, as bridging typically doubles the amp minimum load impedance, while using multiple cabs lowers the load impedance. Not likely. There may be tens with a thermal rating of 600 watts, but I'm not aware of any that will take more than half that before reaching their mechanical limit. Also, power amps are intended for PA use, where plenty of headroom is desirable. That's not necessarily the case with instrument amps.

It's not what you meant, but clipping is clipping, no matter where it occurs in the signal chain. It can be bad for tweeters, that's why guitar cabs don't use them, but will never hurt a woofer. http://www.bcae1.com/2ltlpwr.htm

That's the Myth of Underpowering, and it's just that, a myth. If amp clipping, or clipping anywhere in the signal chain, hurt woofers guitar players would be swapping them out at every break. Clipping is only potentially dangerous to tweeters, because the high frequency content is abnormally high. And we don't play sine waves.

Farting out occurs when the combination of power and frequency attempts to force the cone to travel beyond its mechanical limits. The cure is to reduce the volume and/or low frequency EQ. The cab power rating doesn't indicate whether an amp can push the cone too far because that rating is thermal, not mechanical. Cone excursion goes up as frequency goes down, so a 500 watt signal may not cause over-excursion at 500Hz while a 50 watt signal at 50Hz may. The simple answer to farting out is that if one cab won't handle the combination of volume and bass EQ that you use you need two or more cabs, or one cab with more driver displacement. https://barefacedaudio.com/pages/how-speakers-move-air-volume-displacement

No. Let's say the frequency is 100Hz. That means the cone must go from rest to full outward excursion to full inward excursion and back to rest 100 times per second. If it does so over a distance of, say, 6mm it must move six times faster than it does over a distance of 1mm. How cone velocity can affect the result is explained here: http://www.readresearch.co.uk/loudspeaker_papers/klipsch_modulation_distortion_article_1.pdf

That's what Chris Squire did as well. I doubt he used a crossover. He probably just plugged into both. Most amps of that period had parallel input jacks, making it very easy to daisy chain amps.

Xmax is the distance the cone can travel before distortion becomes severe. The longer the xmax the louder it can play. The best way to compare different drivers is with speaker modeling software. The program I use the most for sealed and ported cabs is WinISD 0.7. With it you can see the effects of the box size and tuning, and see Maximum SPL, which is determined by both the voice coil power limit and xmax.

Neither of those are 200 watt, so I suspect those in the video are B102 or BP102. The magnet in the video also looks too large for the frame to be a twelve. It's true that one doesn't need a 32Hz F3 for low B, no more than does anyone need a 41Hz F3 for low E. But low B is still more demanding than low E, so I'd want at least 6mm xmax for low B use. 6mm xmax is usually going to cost more, but my philosophy is buy once, cry once.

For -3dB at 40Hz would require an internal box volume of 300 liters, exclusive of the space taken up by the port and the drivers. You don't necessarily have to go that low, a 50Hz F3 from a net box volume of 200 liters would suffice. But with less than 200 liters the low end would fall off rapidly. There's also the matter of the 4.4mm driver xmax. That's adequate for the most part with a low E, but not with a low B.

That's ported. Measuring frequency response is done with software, like HolmImpulse, and a USB measurement mic. The Beta 12 is an entry level driver, so whether it's adequate for your needs only you can say.

With a proper balanced interconnection there's no need to lift the ground, that's one of the advantages of balanced. That said, not all devices are correctly configured. Have a look here, scroll to page 216. https://www.yumpu.com/en/document/read/25666510/ranenote-collection

There's no point to bi-amping similar speakers. The difference in the low frequency limits would have to be close to two octaves to make it worthwhile.

+1. One can be perfectly fine with a 30 watt Ampeg B-15. One thing you can be sure of with respect to watts: the more someone dwells on their importance the less they understand about amplification. They probably can't even recite Ohm's Law from memory.

Assembled in the US from components sourced in Asia. That's not the same thing as made in the US, not that anything is, any more than is anything made in GB.

Maybe. The problem when you use non-specific subjective terms is that there's no real definition, and therefore no agreement, on what it means. That greatly increases the difficulty of realizing whatever it is that you're trying to get.

And the downside? 😊

That had little to do with mineral rights, which American and other companies can and do get from the Greenlandics. It had to do with the Northwest Passage. Thanks to the global warming that Trump labels as a hoax it's gone from 19th Century fantasy to 21st Century reality. In theory whoever controls the sea lanes within Greenland's territorial waters would have a strategic and economic advantage as more and more commerce goes through those waters from Asia to Europe. As usual Trump didn't think it through. It never occurred to him that the inhabitants of Greenland wouldn't go for it, even if the Danes did. If there's a change from the status quo for Greenland, currently an semi-autonomous possession, it will be to full fledged nationhood. It wasn't the most harebrained idea Trump ever had, but that list is a very long one.

If you're familiar with the innards of a vintage valve amp you've got perfboards that components are mounted to, with discreet wiring to the valves, pots, transformers, jacks and so forth. Even if the perfboards were loaded with their components in Asia, probably Viet Nam, that would still leave a lot of wiring to be done. Making a big deal about them being hand wired is advertising blather, because that type of construction can only be hand wired. It's a completely different form of construction from circuit boards, which can be configured so that all the components, including the pots, jacks, valve sockets and power supply, are directly soldered to the boards, usually via wave soldering. In some cases there's only one board, so there's very little plugging in to do.

Without measured response charts SPL ratings are worthless. The figure could be a broadband average, it could be at the highest point of the curve. What you can assume that it's not is the SPL at 80Hz, which is where bass cabs should be rated.

Assembled in the USA means assembled from parts made in Asia. That applies to just about everything these days.

Despite the rare earth name neodymium isn't rare and it isn't all that difficult to refine. China is the main producer, for the same reasons China is the main producer of just about everything. The Chinese decided to take advantage of their near monopoly and jacked up the price. In response other countries have ramped up their mining and refining. The US is predicted to exceed Chinese production within the decade, while Australia, India and even Greenland are stepping up production. As for its use in the loudspeaker industry, that's a mere drop in the bucket. The main consumers are the auto industry for use in motors for electric vehicles, and the wind power electric generation industry for use in generators.

Double post, tried to delete the second one, I guess this forum software doesn't have a provision for that.

The clip indicator is probably reacting to the in initial attack. Since it's a power amp, not an instrument amp, the indicator is probably calibrated with the expectation of the signal being compressed.

Your 60s unit was hand wired too. 😉

If they weren't isobaric they'd be even larger. They may not seem small today, but they were by the standards of their time. This is a quote from the Linn product information sheet: Each speaker has two of each drive unit fitted – i.e. two bass, two mid and two treble. The second bass unit is hidden inside the cabinet, behind the visible bass unit and this forms the basis for our patented Isobarik equal-pressure bass system. This means that the front speaker behaves as if it is in a much bigger enclosure.