I'm curious on the differences between the two. I would probably add Faital speakers to the Dually if that helps in the comparison.
I have a Faital loaded Dually. Never played a fEARless of fEARful, but overall I think it's safe to say they are full range and relatively HiFi. The Dually is very much a traditional/old-school sounding cab. The low mids short of bloom out of it rather than sounding fast, focused, and punchy. Also, there is really no air or glassiness about the high end. It does reach lower than vintage bass cabs, and the lows are fairly focused. Overall the Dually sounds fairly dark to me. This is partly because the Faital mids are very flat, and partly because 15s have pretty narrow dispersion in their highest range. To hear the full range response of a Dually you probably have to stand about 15' in front of it. I also have a couple of different size cabs loaded with old EVM18B. The Dually is more even, way more compact, and takes power way better. I like the mids and highs of the EVMs better...also they seem to have wider dispersion in the high range due to their curvilinear cone. 15PR400 EVM18B Notice how flat the Faital driver is compared to the rising mid response of the EVM. I personally prefer the sound of the EVMs but the Dually is way more capable if you need high SPL. If I were to buy a new Dually I would personally look into a Dually T which has a tweeter. Of course anyone who plays with drive will hate the idea of a tweeter. I don't personally think my Dually sounds great with distortion, and I normally play clean. IMHO, if you want a vintage sound, go with the Dually...If you want modern, full range, and relatively HiFi, go fEARless of fEARful.
Interesting. I remembered this post by Mr. Field where he compared those two drivers but came to the opposite conclusion, regarding dispersion. 18 inch bass guitar speakers... Me, I know too little about...the field to be able to reconstruct a 45° off-axis response curve from Figs. 3 and 4 of the EVM manual, only get the general gist. Your hands-on experience points to plots not telling the whole story. I remain very interested in that odd, mighty eighteen-incher.
I have a couple Bassic cabs and stack them to more-or-less form a Dually. I’ll agree they are somewhat darker sounding cabs but that helps get rid of some clank. I like having 2 Bassics instead of a Dually for having rehearsal/small venue cab options, and then throw the 2nd cab in the setup with bigger/outdoor gigs.
My observation that the EVM18B has wider dispersion in the high mids appears to be confounded. The driver's response rises as dispersion narrows, which creates a false impression. 15PR400 The Faital graphs shows off axis response is down by about -10dB from about 1.25k to about 3k. The on axis response is fairly flat to about 4K. Here is the EVM18B polar plot mentioned in the other post: My read is this shows the off axis (30 degrees) response is down by -10dB at 1.6k. Note, it's only down another 5dB at 60 degrees. The EVM18B has a significant peak in this range, that would compensate for the off axis drop off to some degree. To my ears the EVM18B sounds significantly brighter and more open then the Faital, but IMHO the Faital's high end actually extends a bit higher, especially on axis. The spec sheet lists the EVM18B sensitivity as 91dB 1W/10'. Keep in mind the charts above when you are considering how this driver might sound. Usable response is listed as 40hz-6khz (IMHO optimistic on the high end) The Faital 15PR400 lists a sensitivity of 99dB 1W/1m. Response is listed as 35hz-4000hz (I agree). In my experience the EVM gets louder with less power, but the Faital takes power a lot better, and gets way louder. So the sensitivity rating is a bit misleading as well, since the Faital's rating is way higher. Also, keep in mind the EV plans indicate the TL505 and TL405 are only rated for 100W.
If you are after a traditional sound, I think the Dually will be fabulous for these styles. I bought mine used. I has a tilt-back wheels on the bottom, and a handle centered on the top, back edge of the cab. The cabs tilts and rolls very easily, and it is so light I can lift it with one hand up over a few steps. Way easier to deal with than the Ampeg 810 I had years ago.
I've been looking at this builder's website. He has also been very responsive answering questions. fEARful/greenboy designs - Gigmaster Soundworks of W. MI
AFAIK the plans for the Dually are not publicly released. I suggest Googling "authorized greenboy builder"