Bill Fitzmaurice

0dB is the approximate threshold of hearing as was defined by Bell Labs when they invented the audio decibel, which is a tenth of a bel. Care to guess where bel came from? At the same time they quantified 1dB as the minimum difference that the average person could hear, but that varies from person to person and frequency to frequency. The threshold of pain also varies from person to person and frequency to frequency. Our hearing is most sensitive in the vicinity of 500 to 1kHz, both with respect to intensity and pain. In the midrange we might feel pain at only 115dB, in the bass it might be 140dB. Where hearing safety standards are concerned 'A' weighted metering is used, as it's most sensitive in the same region as our hearing.

It looks fine. Much ado is made about inductor orientation, but it's moot with that much spacing.

That's SOP with monocoque construction.

If pressure on the back stops it I suspect the glue joint between the back and the brace has failed. A couple of screws would fix that.

Many amps do color the sound, via built in non-defeatable EQ known as pre-shaping. That was usually the case with valve amps, which could not be set to flat response. It's less common with SS, but even those in many cases have pre-shape, even if just by dint of high passing the signal at 30Hz or so. Speaker coloration is almost always present. The main effect of speaker modeling tools is to use EQ to emulate the inherent coloration of various speakers for playback through speakers that actually have flat response, Hi-Fi and high end PA. Between amp and speaker coloration the practice of setting all the EQ knobs at noon to give flat response doesn't work. Not that you'd want it to, as flat response is as desirable as flat beer. At the very least boost in the low frequencies is a must, necessary to compensate for the response of the instrument, which isn't flat either.

I remember in the 80s when CDs were introduced everything from receivers, tuners and amps to speakers and even wires were labeled as 'Digital Ready', giving the impression that you needed to upgrade to play CDs. The only change that had been made to the gear was the addition of the 'Digital Ready' sticker. 🤥

There are two considerations. First is the small signal response. In that case the halving of impedance results in twice the power delivery. But at full power you don't get twice the power delivery, as power supply sag at full power prevents that. This applies to almost all SS amps, no matter the class. Not that it matters all that much. As already touched on perceived loudness isn't linear with respect to power. Quite a bit more, perhaps 150W. But that's at full power, which we very seldom use. Why? Because of another subject not yet touched on, the actual power handling capacity of the speakers. That's hardly ever what's listed, which is the thermal capacity. What really matters is the mechanical capacity, which tends to be half the thermal capacity or less. Power, whether it be that of the amp output or the speaker thermal limit, is insignificant. What we engineers concern ourselves with is the amp voltage swing and current capacity and the speaker excursion capacity.

The reason there are no truly digital amps where our needs are concerned is a speaker can't make use of a digital signal. Many amps have some type of A/D conversion of the input signal, which is amplified by pulse wave modulation that requires low pass filtering before the speaker can make use of it. That makes them quasi-digital. AFAIK PWM amps were called Class D because when invented in the 1950s it was the next available letter in the alphabet.

Speakons are rated for amperage, not impedance. Amps are rated for impedance loads. Any amp will put out a flat signal if the applied EQ gives a flat signal, be that the internal or external EQ or a combination of the two. But unless you have a method of measuring it you can't know.

A single Beta 10 is OK for practice or coffee house gigs, but that's about it. Long xlim means you're not likely to destroy it with more than 50 watts but it's not going to sound good. The Sovereign 8-225 isn't much better, having less cone area. The Sovereign 10 is worthy, being nearly the equal of two Beta 10.

There is, but the term is very loosely applied to amps that aren't fully digital, like Class D. Maybe they're TC watts. 😄

Don't do that. Always unplug at the amp first.

It says the power supply is 32v 5A. That's 160 watts. I very much doubt that it operates at close to 200% efficiency. 🤥

It could be the caps, but it's more likely a loose component joint on the power amp PC board. They can be almost impossible to spot, so hitting them all with a soldering iron and a tiny bit of solder is one way to be sure all that joints are good.

I'm familiar with battens, I've used them extensively in home building, just not in speakers within recent memory. I went to monocoque in the 1990s.

I haven't used corner battens for 30 years. They're not required for assembly, and the corner joints are the strongest point of the cab, so they don't add any bracing. The material used for them is much better employed as cross bracing.

Batten?

Like this? Airhead optional.

Of course, but they'd have to be longer to maintain the tuning. WinISD will tell you how long.

Span is the key. My benchmark is to not have more than an 8 inch/20cm un-braced span.

12mm plywood is all you need, if it's properly braced. Thinner than 12mm can be done, with curved panels, which increases their resistance to vibration. Knowing how to brace cabs requires a fair amount of building experience. Sandwich constructions can work, but require even more experience to be successful. My personal cabs are primarily made of 3mm and 6mm plywood, but I had 30 years of cabinet building experience when I designed them.

The fundamental of the E is 41 Hz, but we don't hear just fundamentals, we also hear harmonics. They actually are most of what we hear, so electric bass cabs generally start rolling off their response around 60Hz. One reason why bass can be overpowering through large PA systems is the subs go a lot lower than bass cabs, so it takes a well trained hand in the FOH to get it right. Good engineers know enough to high pass the bass channel at 60Hz or higher. The best engineers tend to be bass players themselves.

I bet Alex did some market research and found that players tend to regard tall narrow cabinets as odd, so he stayed more conventional. If you're as old as me you remember when PA columns ruled. They were driven from the market by trapezoid cabs made for side by side placement with an outward splay. Where dispersion was concerned columns were better, but buyers didn't know that and insisted on the trap cabs. Marketing and sales departments decided it was better to give the customers what they wanted than to waste their breath trying to educate them. I see that the Ashdown 310 is gone from their line, probably a victim of this very issue.

I load the 2510 into a 42 liter (net) box tuned to 50Hz. 22cm port of 100 sq cm area.

Anyone still doing that 30 years ago was not adhering to established protocols. Not that the electric instrument industry has ever given that much mind. 🤥