Bill Fitzmaurice

It sounded good to me. The story behind it is that the Dead wanted to hear on stage the same thing that the audience did. That's why they stood in front of it. That would have been a mic feedback nightmare so what they did was to place two identical mics one above the other. What came out of the arrays behind them that went into both mics was cancelled out via a differential summing pre-amp, but they only sang into the top mic, so that wasn't cancelled. They got rid of the system because it took so long to set up and tear down that they need two, which leapfrogged each other around the country on their tour. That meant they had to pay for more crew, more trucks, and a lot more fuel.

It's not all wrong. Most of it is all right, because most of it is a line array. Where it differs from a modern PA line array is that each player had their own individual arrays for their instrument, along with the vocal arrays. It wasn't the best implementation of line array technology, not because it didn't work, but because it was much larger than it needed to be. That can be forgiven, because the Dead didn't have a blueprint to follow. As primitive as it might seem compared to a modern PA it was still far better than anything else that existed at that time. It would be another 18 years before Christian Heil invented the modern PA line array, although the first major installation using line array speaker technology was in St. Pauls in London in the late 1940s. Maybe. A few hundred years ago the Scots gave the Irish the gift of the game of golf. In return the Irish gave the Scots the gift of the bagpipes. The Scots didn't know it was a joke.

It looks big, I'll grant that. This is the kind of Frankenstein's Monster abomination that can only come out of a marketing department with no input whatsoever from an engineer. That was a common enough scenario in the 60s and 70s, but there's no excuse for it today.

I suppose if you know absolutely nothing about loudspeaker design it's impressive. I would have found it so, fifty years ago. But not forty years ago, let alone today.

I'll not bother with the 'whys', it's far too complicated a subject to be explained in a post. One basic bit of audio engineering that I've been shouting into the void for 20 years is that virtually any two cabs together will sound better than either on its own. The real question is whether any particular combination of cabs works better than, or even as well as, a pair of matched cabs. The only way to know for sure is to compare combination AA, AB, and BB side by side. How many actually do that? Virtually no one.

Everything. If you look at response charts for guitar versus bass drivers they both have steep roll offs, but guitar drivers tend to do so above 5kHz, bass drivers above 3kHz. That's mainly because guitar drivers have higher Fs, lower Mms and lower Le.

When I started playing in '65 there were no real bass tens, and very few real bass twelves. The original '69 SVT was loaded with guitar tens. That's why you needed two of them to handle the 300w head without farting out. In those days it wasn't easy to get what you wanted from one cab, or from two loaded with the same drivers, thus the practice of mixing began. But that hasn't been the case for a long time. Sure, there are still cabs that don't sound good, but you don't address that problem by mixing. You address it by getting rid of a cab that doesn't sound good by itself and getting one that does. Not loud enough? Get two.

That actually was valid when 10s went higher than 15s and 15s went lower than 10s, with 12s in between the two. That would have been for the most part before 1980. It may seem odd that so many bass players are still going by what was true 30 or more years ago, but not when you consider that a guitar player could be perfectly happy with a guitar and amp from 1959.

This is what you have in there currently: https://www.eminence.com/speakers/speaker-detail/?model=Beta_10A They weigh 3kg each. These are compatible neo replacements: https://www.eminence.com/speakers/speaker-detail/?model=Basslite_S2010 They weigh 1.6kg each, for a sum total weight savings of 5.6kg. IMO it's not worth the cost or bother to replace them. However, the Beta 10 is an entry level driver. The all important xmax is only 3mm, for a total displacement of 408 cc for all four drivers. There are 2x10s with more displacement, so they'll go louder than your 4x10, that are not much more than a quarter the weight of your OBC. IMO you should go cab shopping.

Cone area alone is almost meaningless. What matters is displacement, cone area times excursion. Most eights have less excursion capability than most twelves. It's easy to come up with a pair of eights that would have half the displacement or less of one twelve. All things considered displacement is a far more important spec than either driver size or thermal power capacity. It's the equivalent of going into a pub and ordering an ale by the color or the price, while not knowing whether the container is a pint or a dram.

It appears that the weight reduction is from going to thinner plywood of a lightweight species, probably Italian Poplar. Going to 12mm instead of 16mm would reduce weight further, but requires bracing that would drive up labor costs to install. I do all my DIY cabs with braced 3mm, 6mm and 12mm, as there are no labor costs. 😊

We still use the standard set by Henry VII on our side of the pond, whilst you've adopted that Napoleonic piffle. Makes one wonder who actually won at Waterloo. 🙄

Speaker size alone doesn't indicate what a cab is capable of. GR Aero doesn't publish the technical data which does tell one what any cab is capable of, so the only way to know for sure how these cabs compare is to take the time to try them, side by side. That said, all else being equal a 1x12 will usually outperform a 2x8. The problem is that all else is never equal.

It's better, but the gains by switching to the Beyma would still be minor, as would be going to a 4 ohm driver. The limiting factor here remains the amp.

Ported with a suitable driver might work better with at least 60 watts. With 15 watts it won't. You're in the realm of asking if it's worthwhile to put a set of Dunlop racing tires on an Nissan Qashqai. You may, but it won't go any faster.

If you just look at the specs it seems worse than it is. I modeled it and it's not bad. In a sealed box it's considerably better than the Beyma, which has too low a Q to work well sealed.

That driver isn't all that bad. To get something significantly better you'd pay at least three times as much, and with only 15 watts you wouldn't know the difference anyway. An eight would work better, but not in that cabinet. Look at your bass. It doesn't have a 24 inch scale, it doesn't have a .052 E string. That's because the scale length must be long and string diameter must be large to create long wavelength low frequency tones. The same physics of sound dictate that low notes at club levels from tiny speakers do not come.

One can't recommend a different driver without knowing what you have now. But don't hold you breath about a different driver being significantly better. The main difference between inexpensive and very expensive is how much power a driver can handle before exceeding both electrical and mechanical limits, and with only 15 watts you're probably already there.

Agreed, 100w and a minimum 10 inch speaker is the least that I'd consider. That may seem like a big jump, but to sound twice as loud as 15 watts you need 150.

Right. And part of the reason why an 810 seems to have more treble is because the height of the cab places the drivers up where you can hear the directional high frequencies that otherwise pass by below your waist. There is no characteristic sound based purely on driver size.

Do you know how to drain the power supply caps and why you have to?

I'm guessing that a power supply cap solder joint has come loose. When the amp is sitting normally the cap is out of circuit, when tilted it's in circuit. I'd re-solder those, then test the power rails to be sure there's no pulsing of the DC. Be aware that the caps will store a considerable charge, so if you don't know what you're doing don't mess with it.

No matter what's being played through youtube clips always sound like the teeny tiny speakers in my laptop.

At full power most amps don't put out twice the power into a halved impedance load due to power rail sag, but unless you've got a particularly anemic amp you'd seldom if ever push it at full power. At more reasonable levels the 6dB figure is spot on. The reason you get 6dB is because the amp puts out the same voltage into two speakers as it does into one. That results in doubling the system cone displacement, which gives 6dB additional output.

That's not how it works. How it does work is that by adding the second cab identical cab stacked on top of the first, with no changes to any of the amp settings, the output will go up by 6dB. That gives the same result as would quadrupling the power into the one cab, if it could take it.