Bill Fitzmaurice

[quote name='Jack' timestamp='1487097023' post='3237076'] Same cab, seal one hole and use 1 speaker?? I assume the 4 ohm load wouldn't be ideal for your combo though..... [/quote]Agreed. OP, the purpose of speaker modeling software is to make sure of the result before you cut any wood, or order any drivers. Chalk this up to a lesson, albeit an expensive one, learned. Start from scratch, do it the right way, and see if you can sell the drivers to recoup some of your losses.

[quote]The dimensions of the cab I built work nicely to stack the little Ashdown.[/quote]Doing that doomed the result. The BP102 needs at least twice the volume you allocated to work well. Stuffing two of them into that size box pretty much guarantees boomy response, with not much low end. You can salvage that box by leaving it sealed, which won't give a better result but at least it shouldn't be boomy. Otherwise it's back to the drawing board, I'm afraid.

If the cap was blown it would only affect the high frequencies.

The power rating of a driver means very little. If what you have sounds good leave it alone.

The number of cast tens still in the Eminence catalog today is a very short one: none. The only 16 ohm steel frame ten is the Delta 10B. What you have may be the discontinued Gamma Pro tens, impossible to say. Eminence would know.

Chris used a guitar combo amp for the highs and distortion.

Raggae isn't about deep lows, it's about humped midbass. That's what sealed cabs deliver and why the SVT has always been the benchmark raggae cab.

[quote name='3below' timestamp='1484862420' post='3219294'] Further inspection revealed widespread glue failure. [/quote]That could be the case for the OP as well. If visual inspection doesn't show a problem the best way to identify it is to test the drivers individually out of the cabinet using sine waves.

Is the cabinet lined?

The amp is far more likely the source of that noise than the speakers.

[quote name='alexclaber' timestamp='1484669867' post='3217350'] Yes but that works both ways. Once you exceed Xmax the amp cannot drive the cone with the same motive force because BL (magnetic field strength multiplied by metres of coil in the magnetic field) drops as more coil leaves the gap. [/quote]+1. By far the main issue with providing more voltage swing than the xmax can make use of is heat build up. When you factor in thermal compression as well it becomes obvious why thermal failures predominate

[quote name='alexclaber' timestamp='1484656628' post='3217193'] Bear in mind that plenty of bass cabs with low excursion (<3mm) drivers are tuned to ~60Hz and used with amps in the 300W+ range - if they were behaving as suggested by these graphs people would be replacing all the drivers after their first loud gig. [/quote]Even if they did there's another consideration. Going beyond xmax doesn't cause damage, reaching xlim/xmech does. The Beta 10 has 3mm xmax, with 8.6mm xlim, so there's a lot of room for overshoot. The BP102 with 6.2mm xmax will go a lot louder than the Beta 10, but with 10mm xlim there's a lot less overshoot capability, so despite the higher output capabilty of the BP102 you're far more likely to see them creased than Beta 10s. A minimum 2:1 xlim to xmax ratio is prudent. If that much is not available then it's wise to not only high pass but to limit the maximum voltage applied to the driver as well. That's seldom seen with electric bass rigs, but in high end PA it's SOP.

[quote name='markstuk' timestamp='1484582603' post='3216481'] I was looking at driver spec sheets (3012ho) and noted that the impedance appears to go into tens of ohms at low frequencies. Does this not limit the amount of power your amp delivers at low frequencies ? [/quote]Speakers are voltage driven devices, not power driven devices. An amp will deliver a constant voltage into any load.

[quote name='Phil Starr' timestamp='1484409190' post='3215285'] I had some of the old Motorola piezos which sounded OK. Bill will know but I think CTS may have taken on the Motorola plant when they stopped production. They weren't widely available over here when I checked quite a few years back. The cheap Chinese made piezo's are definitely inferior both in sound and reliability. I decided in the end that a conventional horn driver and crossover were always going to sound better. [/quote]Motorola piezos were dismissed back when they were the only game in town, to some extent rightfully so, because they were never properly employed. Motorola sold their piezo business to CTS, and they were still disrespected until a few years after CTS went out of business. That changed when NOS Motorola and CTS piezos started to command premium prices, often ten times that of the Chinese versions. Then the same people who had never endorsed piezos changed their tunes, and said that the NOS Motorola and CTS were fine but the Chinese brands were junk. I still have some NOS Motorola and CTS on hand. Some Chinese brands, notably Goldwood, work better. Piezos properly employed work just as good as compression drivers. But to get piezos to work well they must be used at least in pairs, as they lack the voltage capacity to be run singly at high volume. They also must have a real crossover, one that employs a resistor to offer the crossover a resistive load. That resistor can't be 8 ohms to use an off the shelf 8 ohm crossover, as the insertion loss is far too high. There's no off the shelf solution, it must be custom configured. I have yet to see a single commercial manufacturer who properly employs piezos.

There is a right way and a cheap way to load bass cabs with tweeters. Care to venture which method is the most commonly employed?

If it's a piezo you can't use an LPad. Read this: http://www.baysidenet.tv/catalog/pdf/piezo.pdf Note that not all piezos are alike.

Insert an LPad between the crossover and tweeter. Google it.

[quote name='Lw.' timestamp='1484237779' post='3213865'] So - are we damaging our expensive ported cabs or not? [/quote]When's the last time you had to replace a driver due to mechanical damage?

The vented 2512 should be about 2dB more sensitive in the lows than the sealed BP1525, without the hump that causes boom, giving it the advantage unless you have more than 250w on tap. Then the higher Vd of the 1525 gives higher output, though you'd need a way to contend with that boom, such as a parametric EQ. I don't care for the SM212, or for that matter most European offerings, as they lack a rising response into the midrange. That's OK crossed over at less than 2kHz to a midrange driver, but IMO only then.

What does a comparative modeling of the two show you? Yes, the BP1525 will deliver a good low end in a sealed cab...if it's at least 4 cubic feet.

An 8 ohm 110 would keep the same power in all three drivers. If you were going to a 112 or 115 it would probably be better for that to be 4 ohm.

[quote name='AndyRoo' timestamp='1483712605' post='3209463'] [size=4][font=Arial, sans-serif]is this one thirds/two thirds power splitting based on the max head power (i.e. 500W, which would put 160W into the 8ohm and be fine but 333W into the 4ohm cab and ultimately shred it subject to “Alex’s first rule”) [u]OR[/u] is this power splitting based on the power at the overall impedance (i.e. 500 * 2/2.667 = 375W)[/font][/size] [/quote]It's based on the impedance. The problem here is that the 210 will be doing most of the work. Depending on what you're adding it might not be all that worthwhile. A second identical 4 ohm 210 would be the best option.

From 1965 I've only had four amps, and while I've built hundreds of speaker cabs of all types I've only used perhaps eight.

[quote name='gary mac' timestamp='1483204546' post='3205418'] I used a Markbass 12" cab with my Big Baby, I'm sure Alex from Barefaced would be horrified but it honestly sounded, to me, great [/quote]And how did it compare to using two BB? I'm going to assume that you didn't try those two options side by side. The fact of the matter is that unless grossly mismatched any two cabs will sound better together than either does alone. Chances are a matched pair will work better than a mis-matched pair, whatever they are, as one will likely be a weaker link in the chain.

[quote name='Dan Dare' timestamp='1482530204' post='3201361'] Could sustained current delivery be the way to measure "heft"? [/quote]Absolutely.