Bill Fitzmaurice

It's nothing new here. Dodge, Buick, Oldsmobile, Pontiac,Chrysler, Plymouth, Chevrolet, Cadillac, all were originally stand alone companies before being consolidated under the General Motors and Chrysler Motors companies in the early 20th Century.

7 minutes ago, Al Krow said:

 why should it matter if there is a cancellation notch centred at 42Hz?

That was just an example.  There will always be a cancellation notch where the speaker radiating plane is 1/4 wavelength out from the wall. The frequency depends on the distance, the longer the distance the lower the frequency. There are two ways to eliminate it. One is flush mounting the speakers in the wall, which isn't an option for the most part, although it is common in theaters. The other is to not have the speaker 1/4 wavelength from the wall below the speaker baffle step frequency (where the baffle is 1 wavelength in dimension, and dispersion goes to less than 180 degrees). For the 30 to 300Hz frequency range that's roughly between .3 and 3 meters. That's more or less impossible to do with large 3 way full range speakers, and is one reason why they've pretty much been replaced by separate subs and mains. You can place subs close enough to the wall so that it's not 1/4 wavelength out at any frequency within its pass band, and tops far enough away from the wall so that they're not 1/4 wavelength out at any frequency within their pass band. But you can't if they share the same footprint.

Wall or corner loading doesn't just give more output in the lows, it also prevents boundary reflection sourced cancellations. If your sub is two meters out from the wall you will have a cancellation notch centered at 42Hz. That's non-negotiable.  As for the notion that wall or corner placement will give too much low end that's what volume controls are for. Some 75% of the energy required of PA comes from the subs. Anything you can do to improve the efficiency of the subs via placement will give cleaner output from both the subs and the amps driving them. Aiming the subs at the wall or into a corner makes for even lower distortion, as distortion manifests as harmonics in the directional frequencies above the sub pass band. They're attenuated by aiming the speaker backwards, while the output in the sub pass band is unaffected.

I've been stand mounting my tops for thirty years and have yet to have a mishap. Perhaps it's because I have my Rottweilers stationed below them?

If you have in ears exclusively there's no need for the precautions required with floor and/or side fill monitors.

You absolutely neither need nor want anything below 100Hz in floor monitors. Whatever is down there you'll hear from the mains or subs, because they're omnidirectional below roughly 200Hz. Having content below 100Hz in the monitors can even reduce overall low frequency output, because the distance between the various sources can result in phase sourced cancellations. All you want from monitors is the directional mids and highs that you can't hear from the mains.

The main advantage to knowing the science behind low frequency production and dispersion is you can walk into a room and know where you'll get the best placement results just by looking at it. If you don't understand the science then your sub placement will be like playing darts...while drunk...and blindfolded. If you don't care about the results just hope that the audience doesn't either.

The seemingly small number of Eminence employees is because they source most of their components from Asia, so the Kentucky facility is mainly used for R&D, assembly and marketing. They opened Eminence Dongguan as it didn't make sense to have components shipped to the US for assembly and then shipped back to Asia. I don't see much changing with the new ownership, which was precipitated by the retirement of CEO Bob Gault. What's most likely for now is business as usual, with B&C being the parent of B&C, 18 Sound and Eminence, much like Harmon is the parent of JBL et al.

I've never encountered a situation where the sub and top could not be separated, as the sub can go pretty much anywhere. They don't even need to be facing the audience, or even able to be seen, because they're omni-directional, and the long wavelengths they produce aren't blocked by obstacles.

It had four notch filters for feedback control. Their frequencies weren't adjustable so they weren't very effective.

On 15/09/2023 at 13:28, Chienmortbb said:

No like me a relic of the 50s.

I bought my first SM58s in 1973. I doubt they were around much before that. They were an updated version of the 565. They were the first low impedance mics I owned, before that it was all high impedance, with 1/4" plugs. Mixers as we know them today hadn't been invented yet. The only mixers that could use low impedance mics were recording and radio broadcast mixers. I had to add another gain stage to the first generation Shure Vocal Master we were using to get it to work with the 58s. 

1 hour ago, Al Krow said:

 

But if you're putting subs behind the mics in order to have them close to a wall you can get awful low end feedback. 

It's not likely, with the exception of drum mics. But two points. First, sub output is omni-directional. Be they in front or in back of you the mics will still pick up the same content in the sub frequencies. Second, there's no need to put them in back of the band to wall load them. They can go off to either side, as not only are the subwoofer frequencies radiated omni-directionally, they're also not directionally locatable with our hearing. No matter where they are the directional cues for their content won't come from them, they'll come from the harmonics of the low frequency content which  comes from the tops.

If you're at all serious about PA the comments made here by Downunderwonder, Phil and myself are Gospel. Where low frequencies are concerned getting it right with PA is far more complicated than with bass amps, as nothing about how sound below 100Hz works is instinctive. You have to be taught. The guys who automatically put subs under mains split to either side have not been.

On 12/09/2023 at 04:45, Jakester said:

Like you, I've seen a lot of comments suggesting that subs under tops is less than optimal, but whenever I've played venues with that setup, it's never been a noticeable issue.

Lots of things aren't particularly noticeable if you're not able to make side by side comparisons. When you put subs under tops you not only lose boundary loading, by not have them close to a wall, you also can have cancellation notches when they're 1/4 wavelength out from a wall. If they're split by less than two wavelengths you will have power alley comb filtering. That's the science, and the science is never wrong.

There are three reasons why people put subs under mains.

#1: "That's how everybody does it".

#2: "It's the only way we know to do it".

#3: "We don't know any better way to do it/we don't know why it's the wrong way to do it".

Now you know.

Replacing drivers is both a science and an art, and if you don't know what you're doing you shouldn't attempt it. For instance, the 250 watt rating of your cab is thermal. In most cases what limits a cab's output isn't the thermal rating, it's the mechanical rating. You could load it with a pair of 300 watt drivers that have no more mechanical capacity than what you have now. How would you know? You have to be an expert to make that determination. IMO if you want to get the most possible from a 2x10 and you're not an expert spend the money and get a Barefaced. They have the highest mechanical capacity available.

It shows how in the manual. Of course if you actually read the manual you run the risk of this:

I don't see the point either when there's plenty of PA oriented forums, but it seems more than a few members here seem loath to go to them.

Use ten loaded mains and either fifteen or eighteen loaded subs. You can't do it right with full rangers. Mains need smaller woofers for midrange dispersion and they have to be pole mounted for projection. Subs need to be on the floor, clustered not split, preferably close to a wall for loading. For small gigs leave the subs at home. You can't do any of that with all in one box PA cabs. As for owning the PA, if you do you can get gigs providing sound that will pay for it.

Assuming you're only running the board and not playing as well you've got to ride the sliders. If not then you've got to hire someone to do so.

Agreed. It seems out of place where it is now.

Where voltage conversion is concerned it's far more likely that it's done with dual primaries rather than multiple output taps. When there are multiple output taps that's usually to provide more than one voltage supply, as in one for the tube B+, one for the tube heaters, and in the case of hybrid SS/valve amps three for the SS voltage rails, +,- and earth. 

https://www.electronics-tutorials.ws/transformer/multiple-winding-transformers.html

I'm not overwhelmed by Lebihan's knowledge base: “If you think of where Sunn came from, that was an environment where amps just weren’t loud enough – the Kingsmen had the same issues with being heard as the Beatles and Stones. They just needed a louder amp, and that’s what the Sundholm brothers put together – a loud amp, using completely different technology". The problem everyone had in the 60s wasn't the amps, it was the PA. The PA wasn't able to be heard by the audience, and there was no such thing as stage monitors so performers could hear each other or themselves. Sunn amps didn't use different technology either, it was quite commonplace. The only thing that made them louder than most amps of the day was the ported cabs loaded with JBL, as I mentioned already. That advantage didn't last long. The 200S cab was totally outclassed by the Altec or EV loaded Ampeg V4B cab, which really was a folded horn, and the similar designs by Acoustic.

The last thing a marketing department will tell you is that you only need one cab. Their goal is to sell you as much as they can, not what you actually need.

15 minutes ago, dclaassen said:

Seems these cabs work really well with the amp, as they should since they are part of a factory matched stack.

That's the advertising claim, but how often do you see truth in advertising? About as often as you see an honest politician. 😄

It's possible that the power transformer has dual primary windings that will allow it. A schematic would probably show if that's the case. Singapore is a tech center, so finding someone knowledgeable shouldn't be difficult. 

In case anyone wonders why a 9x10 the answer is impedance. If you use 8 ohm drivers you can't wire eight of them for an 8 ohm load, you may only get 1, 4, 16 or 64 ohms. You can wire a 9x10 as triplets in parallel, the three groups in series for an 8 ohm load. Or you can wire nine 4 ohm drivers for a 4 ohm load. That gave Ampeg more driver options than the 32 ohm they used in the 8x10.

It has to be for the look. The actual need for those died with the invention of the true electric bass specific ten and good PA.

I'd get the 212. The vertical driver placement gives wider midrange dispersion than a 410.