Originally Posted by gpmbc
Quaxtros if Jeff says it then it is. And by that I mean with people questioning if the driver can do 4" peak to peak and if the amp can do the stated output, with Jeff being the source I say all day yes. Jeff is not a hype man, it's just not his personality. So when he puts it out there that one of his products has a certain capability count it all good. I think you will be in awe of what a box that size puts out. I still am and I have 4 times less power for the peaks than you will.
I can appreciate your enthusiasm for this fine product. Similarly, I can appreciate your feelings regarding Jeff not being a hype man, "it's just not his personality"
. I do not know Jeff as you do, so I cannot make any claim as to his propensity to embellishment. As far as we know, these numbers may be supplied from the driver OEM, or marketing dept., we just don't know. Hell, it doesn't even matter where they came from.
Like many that frequent AVS, I've been in driver search mode for quite some time. So, us in that mindset have a general idea of what's out there, what's theoretically possible. We also are familiar with driver weak points, and typical driver compromises that allow for more performance in one area, while forgoing performance in a different area.
So, upon first seeing the web-site specs for the Cap driver, I really sat up and took notice. An 18" driver with a 4" peak to peak stroke is phenomenal. DIYers salivate over such displacement. There have been discussions regarding inflated claims, although wrt the 4kw amp, I'm entirely satisfied with the thorough explanation given. However, I'm still somewhat perplexed with the 4" peak to peak claim. Jeff offered a description including some exterior driver basket measurements. I thanked him and let it pass.
Now, reading your enthusiasm, and assuredness of these numbers being good, just on Jeff's word. I, like many here, am not in that position of blind trust with any AVS poster regardless who it is. Trust, but verify was a common cold war slogan in the 80s. I can't speak for anyone else, but it has served me well.
The first bullet point is as follows;
◦massive excursion 18″ subwoofer (30mm xmax each way, 4″ peak to peak)
That is the first prominent feature listed. I'm simple, and oftentimes I need to break things down into their components. I like to move slowly and be prudent. According to my wife of a quarter century, I still make mistakes, but I don't miss much.
The math is as follows;
Xmax= 30mm which is ~1 3/16"
Doubling Xmax, 60mm, gives us the total stroke, which is the peak to peak of the magnetic circuit. Drivers can exceed Xmax, and are physically limited by Xlim, or Xmech. This represents the point of which mechanical movement is limited by physical means. In some drivers, this is where the former or voice coil encounters the back plate.
Xlim is the amount by which the voice coil can move in one direction before this hard limit occurs. In other words it is the "excursion limit"
Xmax is the amount by which the voice coil can move in one direction, while staying in the linear part of the magnetic circuit.
Now the claim of 4" peak to peak travel equates to 102mm. The reason this first made me take notice is that 102mm is 170% of Xmax. That's significant. Is it out of the realm of possibility? I don't know. That's why I posed the question. I was glad Jeff responded to this here
. However his explanation left me with additional unanswered points.
Regardless, it a very strong performer, at a very attractive price accompanied with a the normal industrial chic minimalistic style.