Bill Fitzmaurice

Since the dome is paper it was probably re-coned with a 2226 kit. Not ideal, but it still works. As to the wife, a man should have as many amps as his wife does shoes. 

Judging by the vintage if loaded with JBL it's probably an E140. If you don't see a 10cm diameter aluminum dome it's not JBL. 

According to Fender: Compact and lightweight (16 pounds) sealed enclosure with removable grille. Given the size and power chances are it's an inexpensive high Qes driver, so there wouldn't be any point in porting it. 

Thanks. Celestion hasn't been known for PA drivers for DIY but they're getting very strong in that market.

They're very light, as they are built from 12mm plywood and the drivers are neo. The exact weight depends on the plywood species, but they're going to be lighter than most commercial offerings. Like any sub they should cross to the mains between 80 and 120 Hz. 

Celestion hired me to design compact lightweight enclosures for their TSQ 1845 and 2145 drivers. They're now posted on the Celestion site as free PDFs with youtube videos. 

https://celestion.com/blog/build-this-18-inch-bass-reflex-enclosure-featuring-the-tsq1845/

https://celestion.com/blog/build-this-21-inch-bass-reflex-enclosure-featuring-the-tsq2145/

1 hour ago, Davy said:

@Phil StarrWe use in ear monitors which sound sooo different to the main PA sound

They shouldn't. The room affects the PA of course, but standing close enough to the PA to take the room out of the equation your in-ears should sound very close to the same.

3 hours ago, Al Krow said:

 

Seems to be the key point here, thanks. Please remind us why that is Bill - sound reinforcement from the walls?

Allison Effect, the cancellation from the reflection off the rear wall. To prevent it the subs must be close to the wall, the mains far from it. When both are the same distance away it's unavoidable. 

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I suspect 8/10 pub / bar bands in the UK put their tops on poles above their subs due to space limitation issues. But if the only downside is directionally locatable frequencies and bands aren't fussed about the losing the ability to put subs anywhere, then no particular problems crossing over at a higher frequency than the usual 100Hz when using a bass combo as a sub?

See above. Since you can put the sub anywhere that relieves some of the space concerns. By dint of using a bass combo as a sub it is a sub, and the same placement rules apply. 

7 hours ago, Al Krow said:

 

It's an interesting one, 'cos there's an argument that tops are completely fine with going down to 60Hz? So why cross at 100Hz?!

Because the sub probably has more available output from 60-100Hz than the tops. Crossing lower than 100Hz with tops that are on stands also brings floor bounce cancellation into the equation. 

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crossing over at 150Hz (because the bass combo can easily handle up to this) would be more beneficial than 100Hz.

No, as that results in directionally locatable frequencies coming from the subs. Then you lose the ability to put the subs anywhere, which should never be below the mains unless there's no alternative. 

Once again, port shape ...doesn't matter, though narrow slots should be avoided. That's as far as sound is concerned. From a construction standpoint I use corner ports, as they do double duty as bracing for the baffle, top, bottom and sides. 

2 hours ago, Paddy Morris said:

 it's just for 3x vocals and blues harp really. Possibly a tiny amount of mic'd guitar amp, just to sharpen it up.  And trombone, when he's available to play. But the instruments are mostly all backline.

That being the case you don't need the subwoofer bottom cab of a Bose clone, even as meager as it is. You do need two speakers, for even coverage. Size being the issue a pair of powered 8" or 10" loaded mains will do, and you'll get a lot more value for the money with those than with mini line arrays, which tend to be terribly over priced. Another advantage is you can use them with your existing sub when the need arises, and add them to your regular system for outdoor gigs. 

4 hours ago, MostLow said:

 it seemed like it had a lot of (unnecessary?) bracing in it.

Bracing is seldom unnecessary, unless you're building with 36mm plywood. My personal cabs are built from 3mm and 6mm plywood, which is possible because they use necessary bracing. 

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perhaps TL606-type cabs

Sure, if you want state of the art circa 1984. 😲

Port shape (duct actually, the name 'port' is incorrectly applied to ducts, but it's part of the lexicon now) doesn't matter, though narrow slots should be avoided. The area of those ports looks to be far too small. 

It would also result in chuffing, as the port area would be too small. 

7 hours ago, Downunderwonder said:

You could possibly make use of your LDS cabs as they sit by adding a high pass filter into your amplifier.

 

And / or, stuff one of the ports to raise the tuning.

 The cabinet is simply far too large, so it doesn't provide the necessary restorative force to prevent over-excursion. That mainly relates to the driver Vas. For the K140 that's 297 L. For the 3015 it's 153 L. 

That diagram shows the 3015LF, not the 3015. The 3015 works best in 70 liters/2.5 cu ft (net) with  200 cm2 port area 35cm long for 45Hz tuning. 

In 60 years of playing I never had an amp failure, so it wasn't worth it to me to carry another piece of the heavy iron that ruled for the first 40 years or so. But given how small good amps can be had today if I was to keep a spare it would be one of those midget amps rather than a pedal. 

Without detailed specs on the woofer and tweeter one cannot construct an ideal crossover. If you have the impedance of the drivers you can use an off the shelf crossover that will still be better than what you have, for instance https://www.parts-express.com/Eminence-PX-BII-3K5-2-Way-Crossover-Board-3-500-Hz-290-636?quantity=1

The APT drivers were changed years ago from a proprietary non-standard attachment to a standard 1 3/8" screw on. The horn in your picture looks like the old design. A picture of your driver would confirm if it's the new design. 

Hum is almost always caused by grounding/earthing issues with the wiring and there's seldom anything you can do about it. 

That's not a crossover. A crossover splits the low and high frequencies, sending the lows to the woofer, the highs to the tweeter. That's just a high pass filter, and a very poor one at that. It's what's called 1st order, meaning that it attenuates below its knee frequency at a rate of 6dB per octave, which is totally inadequate. I never use less than 3rd order high pass filters, which attenuate below the knee frequency at a rate of 18dB/octave. That makes them over ten times more effective in reducing low frequency content to the tweeter that leads to high distortion and blown tweeters. 

Search 'sound analyzer app'. I can't recommend one as I don't have iPhone. 

I get whatever tonal changes I want with technique and occasionally the tone control on the bass. I seldom touch the amp on the fly. I do adjust the amp at sound check because close to half the result is dictated by the room. I always go out onto the dance floor to hear what it sounds like there, and if there's an FOH I check it there as well. I never trust the sound man to get it right, unless said sound man is me. 

The reason I said to take the RTA playing an open A is that your tone is a product of the amp EQ and the speaker. By using pink noise with the amp EQ flat you remove the amp EQ from the equation. You want the PA EQ to not only duplicate as much as possible the effect of the speaker but also the effect of the amp EQ. There's also the matter of whether the amp is actually flat when the EQ is set to flat. Most amps have built in voicing, so flat EQ may not give a flat result.   

Most top acts tend to over-use subs as well. I'd say three out of four FOH mixers have no idea how to mix bass. The fourth is a bass player. ☺️