You could check the group delay if you care. I think this tuning is OK, while I also wonder why one would use a larger enclosure than necessary. And at the risk of becoming boring, what are your plans for subwoofer integration?
Did you readjust the port tuning for each volume? I still like the smaller volumes better, they look more linear to me. But then, I prefer bass to be a little dry.
I will do that today, thanks for pointing this out. Honestly I don't have anything to compare the results too, so won't be sure if what I'm looking at is acceptable or how it can be improved, but I'll read up on it.
As for the 'larger volume', I started this project being assured by two people with considerably more experience that this driver could work in an 84L enclosure, so I tried everything I could to make that work, but it was obvious that it was ridiculous. So I cut the volume in half and figured I would start from there and work my way smaller, approaching the Vas of 26L, which is what I was attempting yesterday. I was surprised to see the woofer response changing so little as I reduced the volume, and that it looked best to me at 42L. Sub integration will be with my REL T7/x, I'll play with the cutoff frequency starting around 70Hz and moving up from there. The REL integrates seamlessly with my current setup, I hope the same will hold true with these speakers.
I didn't do any adjustment, I wanted to see how the ports responded as I reduced the volume before changing anything (2 x 75mm x 36mm deep). I expected the tuning to rise a bit as the volume decreased, which it did, though not quite as much as expected. But it definitely got more unruly and ragged as I reduced the volume, and looked pretty smooth at 42L, very close to the resonant frequency of the driver. It really looked to me like the 42L with this port arrangement was pretty dialed in but honestly I don't know what I don't know. Looking at the response curves at the three volumes I tested, the linearity is nearly identical and the 42L response is just extended a bit lower, all else looking about the same. I can remove the smoothing and have another look, maybe there's something I missed. Yes of course obviously there is a lot I'm missing due to lack of experience, but I'm trying to figure this out with what I know so far. Once I get group delay figured out, I'll be able to adjust after including that data in my assessment. I'm sure this all seems pretty basic to more seasoned builders, but for a novice it seems like an endless labyrinth, and I haven't found a really solid guide that proceeds in a linear fashion that isn't excluding a whole bunch of other factors and maybe oversimplifying things a bit, understandably. As with other things I've done, I'm prepared to accept a fair amount of failure and mistakes, while trying to learn from them. But the reason I'm here is to learn from more experienced builders and hopefully save some time by bypassing a few of those errors. To markbakk and others, I'm not trying to be stubborn, I'm just ignorant. I scour the net for information, learning relationships between different T/S numbers, and am reading David Weems and Vance Dickason, but I'm a tactile learner and things don't stick well until I get physically involved. My dream would be to work side by side with someone who could answer the myriad questions I have every day but at 60 and living in a rural area this is highly unlikely! I appreciate the guidance and patience offered so far on this forum, and will keep plugging along.
That's reassuring to hear Neon, I'm sure with a lot of experience, knowing which variables to focus on becomes second nature, and so for now I'm trying to include as many as I can while remaining sane. As a beginner, it's natural to focus on FR, but I understand phase and group delay are important to understand, which I don't quite have a handle on yet. I do understand how important they are though. Here are the group delay graphs at 42L and 31L, again from what I understand, the 42L group delay looks pretty good (?) Should I be concerned about the negative GD below 70hz? I'm beginning also to see why a HP filter could be a good idea to limit excursion below 70hz.
OK guys, a bit of an update. After making a new box and running new measurements, then looking at the results, I'm going to move on and work with a driver that is going to get me closer to what I want. Right now that looks like the Beyma 12XA30ND, a 12" coax. I've run some early box sims on WinISD, and it looks like this driver is what I was hoping the Radian to be in the first place. So lesson learned - you can't get blood from a stone, as my mother used to say. The Radian is really designed for small monitors, and from lack of understanding of T/A parameters, I was led to believe it could do well in a 60-90L enclosure and perform reasonably well in the bass region. I spent a lot of time trying to turn a chicken into an eagle, so I'll cut my losses, sell the Radians, and continue to learn. I've got lots of questions, so I'm going to start a new thread around the new driver. I want to thank everyone who has chimed in here, I've learned a lot from everything that's been said.
Cheers!
Bryan
Cheers!
Bryan