Bill Fitzmaurice

You need a bluetooth transmitter, or a pre-amp that has one built in. Google them.

Technically speaking the difference between 236 and 450 watts is less than 3dB, which is audible, but just, so TC thought they'd get away with their subterfuge. TC engages in this specmanship for no other reason than greed, wanting to maximize sales through false advertising. They didn't anticipate anyone actually testing their amps. Not at all surprisingly many actually came to their defense, in effect saying they didn't care if they were lied to so long as the amps sounded good. The idea that people don't care if they're lied to so long as they hear what they want to hear is hardly confined to audio. 😒

And you've got TC Watts, where their lame explanation for the blatant exaggeration was 'Well, no, it's not actually 450 watts, but it sounds like 450 watts'. 😒

Someone who really really knows what he's doing isn't fooled by the smoke and mirrors. You actually can cheat an honest man, but it's very difficult to cheat a man who's well informed.

Why? Because the competition does it. No one wants to lose a sale because they didn't play the same numbers game as the rest. 

The actual maximum SPL could be accurately predicted using speaker modeling software if one has the driver Thiele/Small specs, the exact enclosure details, and the thermal and mechanical compression data. Thermal power compression is the result of the heating of the voice coil. When it heats its resistance increases, which causes a loss of efficiency. The hotter it gets the greater the loss. Mechanical factors also reduce driver efficiency as power is increased. The main culprits are the spider and surround, which lose flexibility near the limits of their extension.

But thermal and mechanical compression data is by and large unavailable, so we assume that these losses result in 6dB lower maximum SPL than a linear swing voltage to SPL calculation predicts. Manufacturer data is usually even further off, as they never consider the driver mechanical voltage limit, only the thermal limit.

Where peak power is concerned that's never a part of the equation. Cone excursion is always calculated using voltage swing, never power.

2 hours ago, Phil Starr said:

Even worse is the piezo tweeter which can be wired with no crossover at all and almost inevitably sounds awful. Not a surprise, they are only £2.50 retail.

Piezos can sound very good, when correctly employed. The trouble is I've never seen them properly employed in commercial cabs. I run them down to 2kHz at high output with very low distortion. But even in a 1x10 I never use fewer than six of them, and only with a real crossover.

Non-budget PA cabs do come with semi-decent specs. But 'non-budget' means two thousand quid and up. Even then the numbers don't always add up. For instance, maximum SPL claims are seldom measured. They take the 1w/1m sensitivity and calculate the max SPL from that. But that calc doesn't take into consideration real world issues, like thermal power compression and driver excursion limits. And if they're using peak power for the calculation it's bogus anyway. Experienced acoustical engineers are aware of these shenanigans, and knowing the full driver, enclosure and amp specs can make accurate performance predictions. The other 99.99% of users are at the mercy of the marketeers. 🤥

Marketing. They also use 'music power', 'peak music power', and my favorite, 'peak music power output'. It's all bovine excrement.

I never slap and always use tweeters. However, mine are effective from 2kHz, so they operate nearly a full octave lower than average. The reason is that there's a lot of content in the 2kHz-4kHz range. While woofers for the most part have response in that region it's with very narrow dispersion. Tweeters have wide dispersion there, so I don't get the high frequency laser beam effect. Above 8kHz there's little I want, so I roll that off with my EQ. As to why commercial cabs have such a high crossover to tweeters, back when they were first introduced tweeters capable of going to 2kHz were both rare and expensive, so 3.5kHz to 4kHz capable tweeters were used. That practice should have ended back around the turn of the century, but it didn't. 

The subs to tops ratio isn't a problem per se, but the fact that those Bose barely qualify as subs is. And then to place the line source tops side by side instead of stacked, with the subs split to either side and not wall loaded, indicates that his technical knowledge base consists of the Bose advertising and no more. What's worse, though, is that the Bose manual makes no mention of how to employ multiple units, or how to properly employ subs. For that matter the very design that pretty much forces users to mount the tops above the subs is totally flawed. It's why friends don't let friends buy Bose. 🤥

This brings up an important point: one person should be in charge of all things PA, the one who knows the most about it. That tends to be the bass player, as the challenges of our amplification forces us to become knowledgeable about it. We don't have the luxury of being able to plug into just about anything and have it sound good. Besides, we're just smarter. 😄 

What's not been mention is that cab power ratings are thermal. In the vast majority of cases they run out of mechanical power capacity at well below their thermal rating, in many cases at no more than half the thermal rating. AFAIK the only brand that gives their mechanical rating is Barefaced. The good news is that when the mechanical limit is reached the driver will distort, giving you fair warning to back off the volume. But that does you no good if you use distortion effects, so if that's the case you have to be very cautious.

Never use 1/4" connections when there are XLR available, for a number of reasons. If your singer isn't comfortable with that give him one of these: https://pixabay.com/vectors/loudspeaker-man-boy-holding-1459128/

I'd say you're fine, as the only people who'll be listening to you are those close to the stage. The rest of them near the bar aren't there to hear you, they're there to drink and with any luck not go home alone. I've played many places like that where if there was any comment about the sound it was that it was too loud and was interfering with people's conversations at the bar.

The problem isn't the power ground, it's the signal ground. With unbalanced 2 wire interconnects the signal ground and power ground are connected, which can lead to ground loops. The usual cure is lifting the signal ground at one end of the connection. You never lift the power ground. Properly configured 3 wire balanced connections don't have ground loops, as the power and signal grounds are not connected.

You need to use a combination of lowered gain on the amp and lowered volume on the bass. Amps with passive and active inputs get around this by padding the level of the active input, but it you only have a passive input you have to do the padding yourself.

https://www.ranecommercial.com/legacy/note110.html

For sure the Bassman was a POS. The amp was a slightly modified Bandmaster, the speaker was an un-modified Bandmaster. In '65 there wasn't much else to choose from. The first speakers that managed to handle my Bassman's 50 watts were a pair of Kustom 4x12 columns. 😲 Being 30 years before there was an internet my first exposure to the science of speakers was when I found Olson's 'Acoustical Engineering' at my college library, which prompted me to start designing and building my own speakers in 1969. That Bassman was the last factory made speaker I owned.

1 hour ago, mike257 said:

For a wedge mix - I'll start off with each persons own instrument/voice in their wedge, plus anything that isn't making its own loud noise on stage

+1, with a caveat. Upper midrange and high frequencies are very directional, so no matter how loud they may be on-axis they can be impossible to hear off-axis. Guitars with proverbial laser beam dispersion are the most obvious example, but it applies to every instrument, even the bass. You can stand behind a bass cab and hear the lows perfectly well, but the mids and highs not at all. A perfect monitor mix high passes above the frequencies that are audible without going through them, while providing the mids and highs that otherwise can't be heard. This applies to mains as well. Even in smaller venues the reason for putting everything through the PA isn't volume, it's dispersion.

4 hours ago, BassmanPaul said:

Well Fender do short circuit the output when no speaker jack is inserted. I still say that the correct tap for the load is best all around. Any thing else I see as abuse. in an emergency you could get away with it and I've done so myself many times. It's not something I recommend as a regular basis.

Fender shorts the output because that doesn't hurt valves, while running with no load does. Every valve amp should do the same. Using the tap with the same rating is nice when you can do it, but when you can't using the tap that's closest to the load without being lower is perfectly safe. That's again because valves are the opposite of SS. SS is rated for the minimum load impedance, valves are rated for the maximum load impedance.

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I’m going to run it with just the 4 ohm cab I think .. seems like the better approach 

59 years using valve amps tells me otherwise. My first Fender was a '65 Bassman. I bought it new.

You don't need anything below 100-125Hz as you'll hear that from the mains, and if you put it in the monitors it will make everything muddy. I run the same mix as out front, as I'm mixing from the stage and want to hear in the monitors what the audience hears. I run just loud enough so everyone can hear everyone else.

Back when we didn't know an ohm from a watt we used to run our Fender amps with 4 ohm taps with 1 ohm loads with no ill effect.

Valves are the opposite of SS, they work better into a lower impedance than the tap rating. With a 2.67 ohm load use the 4 ohm tap. Realistically it won't make much difference, other than for peace of mind. Where you'd have an issue is using an 8 ohm load on a 2 ohm tap. That could lead to premature output valve replacement.