stevie

So this is your sixth? One can't help wondering what happened to the previous five.....😊

The Kappalite 3015 used in the BF Compact works from about 60 litres up. It's probably a better bet than the Faital Pro if your cab is on the small side.The BMS 15N620 works in a 50-litre cab (I had one in an Ashdown Mini 15) and is in a different league to either of those. Unfortunately, it costs more, but it is available in 4 ohms if you can find one.

Before you can figure out whether your replacement driver of choice will work, you need to calculate your cab's internal volume. Faital Pro is a quality brand and the driver you mention is used in a few high-end cabs. However, its parameters tell me that it needs a reasonable volume to perform properly - and combo cabinets tend to be on the small side. My guesstimate is that you'll need at least 70 litres. I should point out that I don't have hands-on experience with that particular driver. There are a few alternatives that function well in a relatively smaller volume, although the ones I'm familiar with are more expensive. Also, if you're going to double the power handling of the driver, you need to make sure that the porting is adequate - or alter it. Bear in mind that you'll likely have to take a jigsaw to the driver opening to accept a slightly larger chassis. You can easily measure that beforehand with reference to the Faital spec sheet.

It's going to be a giant killer!😁

Overall, a very nice little cab. I compared it with a fairly expensive 12" commercial cab (which shall be nameless) and it sounded much better to my ears, although rather on the lean side. To its credit, it made the 12" cab sound bloated. I think this will surprise people when John's amp is fitted.

To troubleshoot the dip, I measured the cab at 30 degrees off axis. If the dip is caused by reflections from the cabinet sides, the effect will be reduced. The fact that the driver is dead centre in a square baffle will make matters worse. The dip has indeed disappeared on the off-axis measurement, which proves that the cabinet is the source of the problem. This is not something I would worry about personally, as it's very likely to be inaudible.

Finally, the on-axis frequency response curve. It's quite sensitive for an 8" driver - about 94-95dB - and extends up to about 3kHz. There's an ugly dip at 1.5kHz which requires further investigation. It's either a driver fault or it's being induced by the cabinet. I suspect the latter.

Here's the response at low frequencies. -10dB down at 50Hz is quite respectable for this size of box. I've been using the same driver in a larger cab for practice at home for the past few years, and I know it will go lower in a larger cab. Nevertheless, it sounded good on audition, with a lean but tight bottom end that should be easy to fatten up with a touch of eq. Much better that than bloat and boom.

John dropped his cab offwith me a couple of days ago, and I ran a set of measurements on it this morning. It all looks really good. First, the impedance curve. It doesn't reveal any problems and shows a tuning frequency of about 61Hz. I also did a nearfield low frequency measurement, which is more accurate, and that says tuning is at 58Hz. For a very small cab like this, that's fine.

Normally, applying any kind of paint or lacquer to a driver will dampen the top end response, as Phil explains. However, I did measure a blue Ashdown 15" driver a while ago and the top end was all there. So it seems that they (and Sica) know what they're doing.

There's quite a bit of info on this cab on Talkbass. From what I can gather, none of the smaller drivers is sealed; they share the same airspace as the 15. That's not great for the six-inch drivers in particular and might be why so many people on that forum are trying to repair them. To make matters worse, the crossover only works on the horn.

This is a more advanced project than fitting a different driver in an existing box. You're going to have to integrate three different drivers and get them working together seamlessly. Your best bet, as Steve has alluded, is to find out what the existing drivers are, get the spec sheets, and try to locate the nearest modern, neo equivalent. Keep the existing EV crossover (which also might be in need of repair, by the way) and cross your fingers. Unless you're lucky enough to pick some up secondhand, you're looking at a minimum of £400 for new drivers. If it works, you'll not only have a much lighter cab, but it will also handle more power. If it doesn't work, you'll just have to resell your drivers and swallow the loss. Interesting project though.

Check out funkle's build thread here: That's for the CNC cab kit, but the same principles apply if your cutting your own panels.

You'll find the plans and the parts list on page one of the thread, @martyy. Build the cab without the horn and compression driver if you find the electronics a bit daunting. Add them at a later date if you want.

I'd be reluctant to blame Westside without knowing what deal they had with Mesa. As far as I can tell, prices in the rest of Europe were comparable with those in the UK.

Quite probably. 😊 It wouldn't be the first time.

And the 650W drivers are?

The cone reproduces different frequencies by vibrating at different speeds. At low frequencies it moves in and out, say, 40 times a second. To reproduce high frequencies, it moves in and out at, say, 2,000 times a second. To reproduce a low frequency and a high frequency at the same time, it has to move in and out 40 times, while simultaneously moving in and out 2,000 times a second. That's just to reproduce two frequencies. When a speaker is asked to reproduce a musical signal, it has to reproduce many different frequencies simultaneously.

Yes, that's quite a useful test track for highlighting differences. I might start using it myself.

Looking forward to your comments.

... and black and white TV.

There's an interesting comparison here of the RCF 745 and its wooden cabinet equivalent, the NX45: The benefits of the wooden cabinet are clear to hear, with the 745 suffering badly from boom/tizz. Surprisingly also, vocal reproduction on the NX is fuller and more natural. At least that's what I'm hearing. As Russ mentioned on a previous occasion, the differences would probably never be noticed by your average punter, although for many (including yours truly) that's never been a criterion. Thoughts?

Bit late, but I'm fairly sure that the CN112 and 112EXT use the same 12" driver. So they should sound very similar.

It was a long time ago - the details are lost in the mists of time..... I just recall it as being a bit of a mess and not at all helpful. So, did it get you reading, @Coilte? As I'm the only one in this thread who didn't get on with it, I agree with your "to each their own".