My New Fi Q18 Sub Project -Input Wanted Please

**Martianpc** · **08-09-09, 10:43 PM**

I stood the box up on its end, with the port up near the ceiling and I think it is actually a bit better, I also moved it into the absolute corner. However I am noticing the box is not braced as well as I thought, it seems to resonate some. I am going to try adding some foam inside the box and bracing it better before scrapping it. since it would be near impossible to add more bracing to a finished box, I am going to run some threaded rod through it and loctite some bolts on it nice and tight then silicone the holes the rods go through. I do not care about the look really for this room as I am sure when I can make a better room I will make a new box. I picked up a RS meter so I am going to learn to REW and see what I can get for some information.

**Ricci** · **08-10-09, 02:09 PM**

Couple of things here. I just re-read your post.

You have your EP2500 plugged into a power conditioner. Unplug that first off. Pro amps in no way need to be plugged into something like that. It will simply rob them of power. (example is the breaker tripping on it).

It sounds like you have some bad room acoustiucs going (you can have nulls which will rob you bass) and also some box resonances which as Mike noted could be tied to the very long length of the box putting the 1/4 wave into the passband of the sub or bracing. This stuff would be the sound related problems that you noted. It's all room and enclosure and sub placement in the room.

The output problems which you have noted could be related to the amp, you could try jacking up the SW channel level on your Onkyo if you wanted to since it has plenty left to go. One thing that doesn't make sense is that you've said that the sub got over excursioned with the Hulk which has nasty ULF content 5-15hz so watch it if you don't have a HPF and you've said that the sub isn't as loud as you thought it should be, but yet the amp you've also said is not clipping and the power conditioner breaker has tripped? The really low stuff 5hz-25hz is not going to be loud even at 115db. Not like the regular 40-60hz stuff. It just don't work that way. If you see the driver flailing away and/or the port has air rushing out of it then there is some major low bass on that part and the sub is trying to reproduce it. Bass like that is more of a presence, or tactile feeling than a sound that you hear with your ear. If it's loud you'll just notice things vibrating wildly and feel it. It won't be like WOW that's loud! even with a pair of big 18's. Have you tried regular music type tracks without the super low stuff to see what those sound like?

Question. Do you come from a caraudio background?

**dradius** · **08-10-09, 02:26 PM**

Your sub is set to 0 in the onkyo config? Bump it up. It made a big difference for me.

**Martianpc** · **08-10-09, 06:00 PM**

Quote:

Ricci wrote:

Couple of things here. I just re-read your post.

You have your EP2500 plugged into a power conditioner. Unplug that first off. Pro amps in no way need to be plugged into something like that. It will simply rob them of power. (example is the breaker tripping on it).

It sounds like you have some bad room acoustiucs going (you can have nulls which will rob you bass) and also some box resonances which as Mike noted could be tied to the very long length of the box putting the 1/4 wave into the passband of the sub or bracing. This stuff would be the sound related problems that you noted. It's all room and enclosure and sub placement in the room.

The output problems which you have noted could be related to the amp, you could try jacking up the SW channel level on your Onkyo if you wanted to since it has plenty left to go. One thing that doesn't make sense is that you've said that the sub got over excursioned with the Hulk which has nasty ULF content 5-15hz so watch it if you don't have a HPF and you've said that the sub isn't as loud as you thought it should be, but yet the amp you've also said is not clipping and the power conditioner breaker has tripped? The really low stuff 5hz-25hz is not going to be loud even at 115db. Not like the regular 40-60hz stuff. It just don't work that way. If you see the driver flailing away and/or the port has air rushing out of it then there is some major low bass on that part and the sub is trying to reproduce it. Bass like that is more of a presence, or tactile feeling than a sound that you hear with your ear. If it's loud you'll just notice things vibrating wildly and feel it. It won't be like WOW that's loud! even with a pair of big 18's. Have you tried regular music type tracks without the super low stuff to see what those sound like?

Question. Do you come from a caraudio background?

Yep I do come from a car audio background. I used to compete for Team Maxxsonics and used RE audio MT subs. So my experience is mostly over 150db, not really in HT building down low.

I understand that sub 20hz I wont hear really, my disapointment is that I dont really feel it much either. The sub moves a lot but it doesnt seem to feel like much. I feel like I do need a HPF but I am unsure as to which one. I want to EQ and see how that helps, so I am looking at BFD but if I remember right the 99 dollar one does not have the HPF in it. I will try to jack up the level on the amp and the Onkyo when I get a LPF, I am terrified to crank it and relax for a movie because it could bottom out (The Matrix Reloaded highway scene did it too). I think that I have the possibility to bottom out in the 20's though as well with enough power. I am going to try REW on this when I can get a usb sound card then I will brace the box better with the threaded rod, put some foam inside of the box and try it again. If it still sounds like junk then I will just scrap this box and make a sonosub. I priced it and I can get 30" sonotube locally for 15 per foot.

What EQ/HPF would be a good fit for me (budget is important)
For now I might engage the 30hz HPF on the EP2500 just to mess around with maxing the amps power out without fear of over excursion.

**Mike P.** · **08-10-09, 06:23 PM**

Quote:

my disappointment is that I dont really feel it much either.

And you won't for the most part. The feeling is the tactile effect, which is hard to produce in a basement with a cement floor and walls. It took a pair of 15" subs and a pair of 18" subs for me to get there.

**Martianpc** · **08-10-09, 06:28 PM**

Bummer to hear, I will focus on making what I have as good as possible, and maybe in the future make a new enclosure tuned a bit higher, say 18hz.

**Martianpc** · **08-11-09, 11:00 AM**

Ok, I am getting frustrated, I plugged the amp right into the outlet, no power conditioner anymore, on the amp I engaged the 30hz HPF just to try some things. Watched the highway scene in Matrix Reloaded again, when the two semi trucks collide head on the subs makes its WHAP WHAP WHAP sound again even with the HPF at 30hz. The amp clip lights didnt flash at all. Either I am just getting way to much power to the sub, or I have another problem I would think. Something just seems really off with all this.

Should I just make a 650 liter sonosub? -could my box just be really junkie?

**Ricci** · **08-11-09, 12:04 PM**

Refresh my memory here. What is your enclosure dimensions, and port dimensions and tuning? Your driver is a D2 vc? How much excursion would you say is going on when you get the WHUP sound? Is it 2" or more p2p? You are correct a driver also has a peak in excursion above the tuning and with enough power it can be overexcursioned there. Did you say that you engaged the 30hz HPF on the EP2500 and it actually got worse?

Something is up there. You are sure that the amp is not heavily clipping? (I know I keep asking you this but hey...

) Did you try some music that doesn't go very low, just tight and punchy bass? Try cranking up something like that and see what happens. Are you sure that the nasty sound comes from the driver itself, nothing loose, or rattling around somewhere?

At this point I'm thinking that either you have a defective driver, or there is something set wrong on your amps dip switches. I don't have one of the EP's so I don't know just by looking.

Mike,

You use an EP don't you?

**Martianpc** · **08-11-09, 01:59 PM**

Quote:

Ricci wrote:

Refresh my memory here. What is your enclosure dimensions, and port dimensions and tuning? Your driver is a D2 vc? How much excursion would you say is going on when you get the WHUP sound? Is it 2" or more p2p? You are correct a driver also has a peak in excursion above the tuning and with enough power it can be overexcursioned there. Did you say that you engaged the 30hz HPF on the EP2500 and it actually got worse?

Something is up there. You are sure that the amp is not heavily clipping? (I know I keep asking you this but hey...

) Did you try some music that doesn't go very low, just tight and punchy bass? Try cranking up something like that and see what happens. Are you sure that the nasty sound comes from the driver itself, nothing loose, or rattling around somewhere?

At this point I'm thinking that either you have a defective driver, or there is something set wrong on your amps dip switches. I don't have one of the EP's so I don't know just by looking.

Mike,

You use an EP don't you?

My Enclosure is 72" long, 23" tall and 23" wide

The port is 3.25 inches wide, 21.5 inches tall, and 42.4" inches deep.

this makes my tuning 14.54hz and my driver is a Dual 2 ohm.

Amp is an EP2500

Engaging the 30hz filter did not make it worse, it made it better, however it did still managed to WHAP with the fiter engaged during the Matrix reloaded semi truck head on crash scene. I have made two videos. The first video shows the sub WITH the 30hz HPF on the amp engaged. The sub did NOT make a WHAP sound this time despite having the same amp and receiver volume settings as it did the previous time when it did WHAP while the filter was engaged. In the video it would have WHAP'ed at about 1:36 into the video had I just had it a bit higher I think.

The second video shows the exact same scene, only the filter is not engaged this time and the sub DOES make the sound, it appears to have a lot of excursion. The amp DID NOT clip according to the status lights at all. I should also note that when I have had my clip limiter engaged the WHAP sound will still happen. The WHAP occurs at 32 seconds into this second video

. I have not done much testing with music, although I should do that. When I did the little I have played the sound was somewhat lackluster.

I am slightly afraid of cranking anything on this system as I do not want to damage the sub. I was very quick to roll the volume off after making the second video where the sub bottoms out.

http://www.youtube.com/watch?v=gXCVSr6abMQ

http://www.youtube.com/watch?v=8257FRL8ZyQ

**Mike P.** · **08-11-09, 03:39 PM**

What SPL readings are you getting, I can't really see in the videos.

**Martianpc** · **08-11-09, 03:51 PM**

in the second video when the sub WHAP'ed the meter read 125 right afterwards. Granted, the meter is next to the sub. for most of that video the meter would show 110 - 118 during the intense bass sections. Obviously it would not show when the level was below 110 with it set to the 120 range.

**Fi Audio** · **08-13-09, 03:20 PM**

Definitely looks like it is pushing the limits of driver excursion. Judging from the meter jump off the box Id say that there is definite bottoming going on. I will need to measure clearances but I seem to recall it soft bottoming (spider hitting top plate) on the 18 before a coil would hit the back plate. Ill need to take all info provided and see what sort of power in the box would get you to that point, but if you had a voltmeter and current clamp you could test as well.

My concern isnt as much the bottoming right now as the earlier statement that the older box sub was louder... just isnt making sense there in the grand scheme of things.

Thanks,
Scott

**Martianpc** · **08-13-09, 11:26 PM**

Unfortunately I do not have a clamp meter. I dont really understand it either in terms of the output. I am really starting to think my box just may have too many flaws that when combined with my lousy room are making larger problems. I may convert the box into a sealed box and see how that does, reducing its size after displacement to 7 cubic feet. If that is not good I may just make a sonosub and see how that does. I don't really like this box as a whole so that may be a better option anyway. Although I hope the driver didnt get damaged by bottoming out.

**Martianpc** · **08-16-09, 10:22 PM**

I got REW up and running, although getting it right with an X-Fi card is a pain in the butt. Here is my measurement. I am not sure if I am doing everything right but I think I am close, my graphs come out somewhat consistently each time at different volumes, just obviously louder or quieter.

Used the RS digital meter, creative x-fi card, rs cal file. I left my graph line of my sound card cal in the graph.

**weverb** · **08-17-09, 10:21 PM**

Is this a sub only graph or sub and mains? I am wondering if those nasty peaks at 55 and 85 Hz. have your set-up off. What I mean, do those peaks have you thinking the sub is calibrated correctly compared to the mains.

**Martianpc** · **08-18-09, 10:58 AM**

Your right, I forgot to disconnect my mains. I undid them and have done some new measurements. One with the eq off and then one where I used my Onkyos built in EQ to try to smooth things... I also re positioned the sub and it sounds better this way.

**weverb** · **08-18-09, 11:39 AM**

Any reason why you are using a 60Hz. crossover? Looking at those two graphs, the second one looks really good. The first one looks like the low end is "boosted" a lot.

There looks to be at least a 8dB difference when you look at the values at 30Hz. (green ~ 90dB versus purple ~ 98dB). Maybe that's adding to your bottoming out problem.

You still need to also look at a graph with the mains on too. You need to check to make sure they are blending nicely with the sub.

**Martianpc** · **08-18-09, 11:58 AM**

Quote:

weverb wrote:

Any reason why you are using a 60Hz. crossover?

I actually do not have a 60hz crossover, it is an 80hz crossover in the receiver. I have adjustments for 25hz 40hz, 63hz, 100hz and 160 hz in my receiver. I turned the 25 and 40 down to -6 my 63 is at +1, my 100 is at +6 and the 160 is at 0 I think. This is all shown in the second graph, the first one *purple* has no EQ.

**weverb** · **08-18-09, 12:16 PM**

Quote:

Martianpc wrote:

I actually do not have a 60hz crossover, it is an 80hz crossover in the receiver.

Gotcha.

Is it starting to meet your expectations? Are you still having troubles?

**Martianpc** · **08-18-09, 01:49 PM**

It is ok on some levels, not great, Definitely not worth the extra cost and size I had to go to from my Klipsch. I think my box needs more bracing still. I have decided that I am going to make this a sealed box when I can get a circular saw and reduce it to 7 cubic feet. Add some bracing and see how that sounds, and use it like that until I can make a sonosub. While I have gotten the output up at some frequencies I just dont feel that it really sounds too good as a whole.

**weverb** · **08-18-09, 01:55 PM**

Have you done a graph with the mains since the last green graph? Have you verified that it is still calibrated equally/balanced (75dB) to the mains? Have you tried Wayne's house curve?

http://www.hometheatershack.com/foru...ed-how-do.html

**Martianpc** · **08-18-09, 02:19 PM**

Quote:

weverb wrote:

Have you done a graph with the mains since the last green graph? Have you verified that it is still calibrated equally/balanced (75dB) to the mains? Have you tried Wayne's house curve?

http://www.hometheatershack.com/foru...ed-how-do.html

Not yet, I need to match it, I have calibrated the system to 75dbs but I always have to take my readings at about 85 or REW says that my levels are too low. I dont really understand why we calibrate to 75 db, things are pretty quite at 75 and it doesn't seem like a realistic listening volume.

I am going to try his house curve, I unfortunately do not have a BFD yet and my receiver is pretty limited in its EQ options. Not mention on higher frequency bass my box is resonating.

**SQCherokee** · **08-18-09, 09:59 PM**

do you happen to have some sort of bass boost/lfe enhancement turned on? My yamaha has a music/movie enhancment that I could see potentialy bottoming a sub during large peaks.

**Martianpc** · **08-18-09, 10:09 PM**

Not that I know of, I think mine is a matter of too much power for the amount of airspace it has.

**Martianpc** · **08-24-09, 01:25 AM**

I have decided to make it into a sealed box. I used a jigsaw to cut to but the box apart and then to cut off my end panel and seal it. The Jigsaw I used was a black and decker... What a POS. the blade kept coming out of the roller track and made my cuts get messed up, needless to say, the edges are not as perfect as I would like although I was able to get close enough to not have gaps that couldnt be taken care of. I will see how this does sealed and if it is not what I am hoping for then a Sonosub will be made.

Heres a cell phone pic...

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