Critical Q Sub Question

needtubes

Member
2003-05-24 9:23 pm
I have a Blueprint 1503, and despite being in love with the Ascendant Audio Avalanche 18 and wanting to buy one, I am trying to make my 1503 more appealing. I tend to buy impulsively when I see something I want and often live to regret the decision later. I have a feeling that's what will happen with the 18, since I'll have to have a large enclosure built, which will cost more money...

I have done some experiments with UniBox and WinISD modeling my 1503 in a Critical Q enclosure. UniBox calls for around 116L to accomplish this. I used my existing enclosure, stuffed a few things in there to cut down some of the volume, and sealed up the port. It worked out ok... Sounds pretty good, but still is a bit too boomy for classical music.

I was wondering if this sort of sub is recommended and if my driver is suited to this kind of enclosure. It is still not as clean and articulate as I would hope on some songs, but on others, it is amazingly clean. I suppose it just might not like some songs... :rolleyes:

Would upgrading to the Avalanche 18 from the BP 1503 be a good move sound-wise? Could I expect quicker response and better overall sound quality? If necessary for testing, the T/S parameters for the 1503 are:

Fs: 25.52
Re: 3.93
Qms: 4.46
Qes: .41
Qts: .376
Sd: 737 cm^2
Vas: 92L
Xmax: 25.9 mm
Pe: 1000 W
Le: not known for sure... I've heard its around 3, but have also heard it approaches 10 mH...

Thanks for any help or advice. :)
 
Stuff the enclosure with loose polyester or fibreglass, that will damp the resonance of the driver making it sound less boomy.

I would also look at different locations for the enclosure in your room, big dips/peaks in the response that can be caused by the room can also make some songs sing while leaving others sounding flat or even bad.
 
needtubes said:

Would upgrading to the Avalanche 18 from the BP 1503 be a good move sound-wise? Could I expect quicker response and better overall sound quality? If necessary for testing, the T/S parameters for the 1503 are:

Thanks for any help or advice. :)


Some say the BP subs are noisy but loud. The avalanches are meant to be more linear,while the specifications reveal a good amount of damping for sealed or ported (qts~0.38)

www.mfk-projects.com
 
I currently run a BPD 1503 as well. I run mine in an IB install though. Moving up to the AAA18 is not going to gain you a lot of SQ unless of course you are pushing your 1503 to it's limits. Up at the top end of their limits, the AAA18 will screetch out ahead, but not by much.

As mentioned, build your box right, use heavy stuffing, and find the best, acceptable location for the sub to help alleviate room nodes, which is probably your biggest culprit overall....as is usually. If placement doesn't do the trick, then the BFD is by far the best upgrade dollar you can spend on your sub system.

A couple of questins for ya...

1. Which amp are you powering your 1503 with currently?

2. Does your 1503 get loud enough or are you just wanting to improve on the SQ end of the spectrum?

As far as someone saying "the BP subs are loud but noisy", this is simply heresay and is probably based on one or two faulty installs, rather than the driver itself. I have installed many BPD subs, for 2-channel and HT use, including my own IB, and haven't had a complaint yet about a "noisy" sub, unless they are being pushed to their limits of course.

Noidster
 

needtubes

Member
2003-05-24 9:23 pm
I haven't picked up a BFD yet... I am waiting to decide between getting multiple things (the BFD and some other stuff) or getting the Avalanche 18 and an enclosure.

I reworked my 1503 enclosure and sealed it up better. I am not sure if it made a huge difference. I am currently running a Nady Audio XA-1100 as the amp (using only one channel instead of bridged because of heating during music). It does get plenty loud for me (I am not a loud listener, really), but I find it to be a little sluggish during some rock songs and a little too boomy for classical. Home theater is where its forte is, but it still suffers in HT soundtracks. It has never been run very hard.

I have it in the best possible location (emphasis on possible- lots of other stuff in the way, so this is the only place it can be, but luckily, it is just about the best as well). it is about 2 feet from a corner, along the wall by my right main speaker.

I've been told that the sound quailty difference between the Blueprints and the Ascendant drivers is amazing... But I won't know for sure until I get the driver and have a box built (if I do go this route). So it is a toss-up for sure. I like the idea of having an 18, though...
 
Well whatever you do, you need to hurry up and decide because the AA drivers won't last long at their current discounted prices.

Have you stuffed your makeshift sealed enclosure with any fiberglass, polyfill or the likes yet?

As far as the difference between AA and BPD, I would hardly say "amazing". Is there a difference yes as mentioned before, but not amazing. I have heard an IB using dual BPD 1804 drivers and one using the AA A18 drivers and both were amazingly awesome. Niether of which I would say was better than the other. I would be willing to bet that most folks in a blind a/b comparison couldn't tell the difference repeatedly.

Anyhow, whatever you decide, if it comes down to you wanting to sell your 1503 to help pay for the new driver, then please let me know...I want it....:)

Noidster
 

needtubes

Member
2003-05-24 9:23 pm
If I do upgrade to the Avalanche, I will have to sell the 1503, but was worried no one would want it. Now I know it will have a home...

I am trying to make up my mind this weekend. If I decide to sell, I will definitely let you know.

I will look into stuffing the box a little more, but it is already at 5.3 cubic feet unstuffed. It will definitely be low Q sub.
 

needtubes

Member
2003-05-24 9:23 pm
After some work over the past two days, it does sound much better (unless I am imagining things). I was kind of hoping that nothing would help, that way it would make the decision to buy an Avalanche much easier. ;)

I stuffed the box with as much polyfill as I had around the house (probably 2 or 3 pounds) and stuffed the port before sealing it up. It sounded cleaner, but not quite there... So I bridged my amp just for the heck of it (I am also relocating everything in my HT to more convenient locations, and when I moved the amp, I just decided to bridge). Bridging the amp helped a lot. The sound is much cleaner more controlled. I've done experiments with the port cap off and on, but am not sure if there is a huge difference. In my opinion, it sounds more muddy with the port open, but I may be biased since I know when the port is open or not. I need someone helpful to do a blind test, but no one I know around here is into audio...

I am worried that having it in a sealed box like this with all the stuffing (UniBox says it is a Q of .453) will cause the driver to bottom out easily during movies. I tested with the Council of Elrond scene on the extended edition of FOTR and it sounded fine and the cone didn't seem to be moving too terribly much at the level I was playing it (which was my normal listening level). I am always worried about my speakers moving when they play... I prefer that they don't move much at all (strange paranoia).

At the moment, I am beginning to think it may not be the best option to buy the Avalanche, since the BPD is sounding better. I could use the money in other aspects of my HT... my mains DEFINITELY need new speaker wire (they have 10++ year old Monster on them that is turning green on the inside). I may hold onto the BPD yet... More testing to do.
 
I am worried that having it in a sealed box like this with all the stuffing (UniBox says it is a Q of .453) will cause the driver to bottom out easily during movies. I tested with the Council of Elrond scene on the extended edition of FOTR and it sounded fine and the cone didn't seem to be moving too terribly much at the level I was playing it (which was my normal listening level). I am always worried about my speakers moving when they play... I prefer that they don't move much at all (strange paranoia).
I wouldnt use a sealed box with HT unless you know what your doing.

Just get winisd pro,input your driver,box,and power input and see what happens at 16hz

Mike.e
 
mike.e said:

I wouldnt use a sealed box with HT unless you know what your doing.

Just get winisd pro,input your driver,box,and power input and see what happens at 16hz

Mike.e

Take probably 90% of the ported "HT" subs out there and model them at 16Hz, you will see that the excursion is way off the charts. 16Hz is usally not even a plausible thing for most ported HT subs as they have to be protected by a rumble filter of sorts below tuning point...usually in the 25-35Hz range.

Of the many subs I have built and played with, sealed is my choice hands down each time, for several reasons.

The BPD 1503 sealed and the amp in question are a great combo, but as always, you just need to set things up correctly and then use caution when you are at the volume knob. I mean this set-up will yield somewhere in the neighborhood of 115db or so at 20Hz in-room I am guessing. Much louder than most folks will EVER push their system.

If it were me, I would be thinking of rebuilding the box to a smaller 3 cubes with moderate to heavy stuffing though. This will drop the overall boxsize considerably which equals better SAF, better power handling, and still have on overall Q of about .5 or so, which I seriously doubt you would be able to tell the difference from the current set-up.

Oh wait a minute, you are right, that is WAAYYYY to much power for that POS subwoofer, better just sell the Blueprint to me for something like the cost of shipping. :devilr:

Noidster
 

needtubes

Member
2003-05-24 9:23 pm
I am still quite tempted by the Avalanche... but if I could be happy with what I have, it would definitely be cheaper. I think I measured 100dB peak during the Council of Elrond scene. There was a lot of cone movement going on, but I don't think it was anywhere near xmax. I usually don't push subs very hard at all. I like my subs to have the ability to have high excursion, but I very rarely use it.

According to UniBox, I could even go with a 65 liter enclosure with heavy stuffing and still end up with a Q of .513, which will not exceed the xmax of the driver all the way down to 10Hz. That makes me feel more secure... but with my 16" sonotube, that means an enclosure only 20" tall, which would look a little oddly proportioned. So I may have to look into getting a real box anyway...

I think part of the sluggish sound may have been from my amp working harder than normal. After bridging it, the line level light doesn't even blink, except in really loud passages (ie LOTR material). It sounds much cleaner like this. Of course, I may yet decide to ultimately upgrade subs (though I'll no doubt be too late to purchase the Avalanches for a discounted price... the story of my life). I have more testing to do tomorrow to be certain.

Thank you for all the pointers. I'll keep on testing some more to see if things will get even better...