I have found that blending ported and sealed subs is sooooo much easier using an analog high pass filter compared to using a digital high pass filter.
Now, this could be common knowledge around here I don't know but I haven't seen it before so I figured I'd post something in case someone else finds themselves in the same position I am - trying to blend ported and sealed.
I don't have actual ported subwoofers, but my mains extend easily below 20hz so the task is the same, trying to get the two types of designs to play well together. For music I normally run just the mains without subs and use the inuke dsp to boost the bass, but when doing a crazy demo like I did the other night I run the mains as large + subs at the same time and the results are fantastic!
The first person I heard mention that maybe a HPF was easier to implement to blend ported and sealed was Archaea. A few months back I was at his place and we were comparing 4 of my SI sealed subs to his ported Caps. When the comparison was over we tried blending them together and subjectively we preferred all subs playing at once. They measured well too (surprisingly since I had always heard how hard it is to blend the two together).
So, I started thinking about adding ported subs to my setup. I borrowed Jonathan's Caps to make sure i could blend the 2 types in my room before diving in and having d_c build me some ported monsters.
Well, all was fine blending the SI's and Caps (after doing lots of experimenting with sub distance settings on minidsp) until I put on a high pass filter using my minidsp. All hell broke loose with the frequency response and not just around the HPF frequencies. Frequencies were affected as high as 70 hz!!
I mentioned this on the forum and a few of you mentioned that a HPF can really mess up the response when trying to blend ported and sealed. I called Archaea and he mentioned that it could be the fact that in his room we were using an analog HPF (Behringer mic2200) and in my room I was using a digital HPF (minidsp).
Around this time I saw a picture of the 215's for the first time and all thought of getting ported subs went out the window, my irrational/impulsive brain kicked in and I knew I had to have them just for how they looked, haha, but that's another story.
So, I gave up the ported sub idea. However, once I got the 215's I obviously had the same issue of trying to blend if I wanted to try running the mains as large and the subs at the same time. Once again, I dialed the subs and speakers in so that they played great together.
Here is a shot of just the speakers playing full range and no subs:
Here is a comparison of mains full range (black line) and mains run as SMALL (blue line) crossed over at 80hz:
^ Weird how my sealed setup drops off somewhat similar to ported around 12 hz, I assume I have good room gain down to 12 hz and then the roll off of my avr plus lack of room gain takes over?
Now, here is Mains Large + Subs with NO high pass filter (red line) compared to mains small crossed at 80hz (blue line) and mains only (black line):
So, everything is great right? Well, it is until you use a high pass filter with the inuke dsp which is powering the mains. Here is what happens with a digital high pass (black line). Keep in mind this was the BEST I could do with playing with distance settings.
Most of the time I had dips in 2 or 3 areas not just one like you see here. The blue line is an analog high pass filter using Archaea's Behringer mic2200 and what is really nice is that's with NO adjusting to the distance settings of the subs from what they are with the HPF off.
Now, I do lose a lot of output below 20hz using the HPF as compared to mains large + subs with no HPF, so the other night on some music tracks and movies that I knew didn't have a ton of stuff below 17hz (where Jeff told me to set the HPF) I didn't use a HPF and the amount of bass output was subjectively much more impressive than when I had just the 8 SI's. I also had things falling off the wall that have never fallen off the wall and my wife (who is a deep sleeper on the other end of the house) was woken up for the first time.
I had some kids (now in college) I used to coach come over for the first time for a demo that night and a couple of them are into car audio a little bit so I knew I had to push things a bit. I have experienced car audio when I was younger and had a decent little JL Audio setup myself so I'm familiar with how easy it is to pressurize a car compared to a room.
Still, these guys were impressed. Lots of laughing and shaking heads which is a good sign, haha. What I like to do on music demo's is keep creeping up the volume. Here is what happens with guests almost every time. They look at each other and laugh and shake their heads as the volume keeps going up until finally they stop smiling and look at me with a look that says, "I can't believe you are still turning that up you fing psycho!!" I keep turning it up until this happens. Ha, well I didn't think I would get that look with these young kids but I did.
Here is what I did for a music demo. I started just playing the 215's and turn up the volume to a pretty decent level, bass is hitting hard. Next I turn on the Crowson transducers and it's even better, and finally I turn on the subs and it's chaos. Haha, too much fun! Lastly I turned on the mbm behind my main seat - which really only affects the guy in that main seat - but I made sure it was the guy that has subs in his car!
Here are a couple of videos, this first one is 215's only:
That was using the inuke 3000 dsp.
Today I tried it with the 6000 and no mic2200 on the Bassotronics song. I made it to 8 over reference before seeing any clip lights at all, 215's large no subs. Also, that is with boosting the bass on the 215's by 7 db's using the inuke dsp like this:
Also, I think I could push it a little harder sine the output lights on the inuke 6000 were clipping before the input lights. If I adjust the trims on everything and get the input and output to clip at the same time I bet I'd get a few more db's.
Here is a video that shows the 215's playing large and then keeping them large and adding subs, all at 6 over reference. The 215's are again 7 db's hot, the subs are god knows how hot, I turned them up as loud as I could before just seeing clip lights on the CV5000 amp.
I turn on the subs right at the 26 second mark in the video.
Sorry about the horrible quality of the video, having the screen on makes the quality so much worse I guess.
The first video the audio doesn't distort much, but that's with lower volume levels than the second ^ video. There is absolutely none of that in the room, it sounds completely clean so I guess I'm over the limit of the iphone mic.
So, all should be well and good but it is not. The signal from my avr sub out and speaker outs is very weak (I have to have my CV 5000 amp cranked up almost all the way for example). So, when I put the mic2200 in the chain I have to crank up the gains on it or on the avr and the end result is a lot of distortion sound when I crank up the volume. When I take the mic2200 out of the chain there is no more distortion and everything sound great.
So, I need a new avr eventually that has a higher voltage on it's outputs or xlr outputs or something
OR - I just found out through DD that Jriver has HPF that can function as analog so I'll have to check that out too when I get a chance. I use Jriver as my music player (other than Spotify to find new music) but not for movies.
Oh, I forgot to mention, not only do the ported speakers and sealed subs blend perfectly at the main LP, but they do the same in the second row and the bar table area.
Ok, good lord that was a long post.