Best Sub Driver for small enclosures (1 Viewer)

[Shawn Solar]

I've just went through just about all these posts and I'm really impressed with the 1203 from BP. It is just about what I am looking for. I was goig to go shiva but I really like the small enclosure volume it needs. If I get one I probably build that 80L enclosure tuned to 20hz with a flared 4" port 25"long.
I may of missed it but what kind of internal bracing will this baby need and what kind of depth will I need to acommodate the port?

 

[ThomasW]

If you're making a tube sub then no bracing is needed. If you're going to use a box then something like this appropriate

 

[Brian Bunge]

I have some questions for Jon concerning the 48L enclosure using an LT circuit. I remember you said you were getting 102dB @ 20Hz. Was this anechoic response? Also, what values were you using for Fb and Qtc in the simulation? And last question (for now) what kind of power were you requiring? I'm toying with the idea of using the 1203 in the 48L enclosure with Adire's HS500 amp. I think that's the model number. It delivers 700W into a 4 ohm load and looks like an excellent choice if you're wanting a sub with a plate amp. I just wonder if the LT will require more power than this at 20Hz and if so would something like the BFD be a better choice over the LT circuit?
Thanks,
Brian
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[Jack Gilvey]

I'm certainly not Jon, but...

I'm toying with the idea of using the 1203 in the 48L enclosure with Adire's HS500 amp.

You too?

 

[Brian Bunge]

Jack,
The reason I was wondering about the Fb and Qtc is because I thought Jon's specs. were done using an LT circuit. So I just wanted to run the same simulation. I just wanted to see if the LT could be used with this driver and the HS500.
I'd really be interested in the shelving EQ that Jon talked about also. This was passive EQ correct? It would be great if Jon would design this and allow us to use it.
If I model the 1203 in a 48L cabinet with an Fb of 20Hz and a Qtc of .5 I'm getting around 101dB at 20Hz anechoic. That's only 7dB down from 80Hz anechoic. I have to implement a subsonic filter around 14Hz with a Q of .7 to keep the power requirements around 711W at 20Hz. Does anyone see any problems with this? Would I just be better off with a BFD instead of the LT?
Anyway, if I do this it will be for a friend since I'm definitely planning on using the 1803 in my system. I caught my dog taking a peek at it yesterday while I was measuring the mounting depth. I imagine she was just wondering when she could get a chance to chew on it!
Brian

 

[Jack Gilvey]

quote: I'd really be interested in the shelving EQ that Jon talked about also. This was passive EQ correct? [/quote]
From what I understand, a shelving eq is an active circuit the eq curve of which would appear similar to that of the Bassis (with the "shelf" below Fc) but without the corrective "notch" characteristic of LT circuits.
Power-wise, the HS500 should work fine as long as you keep your Fc/Qtc/volume requirements in line with its power. Its already got an infrasonic filter, Fc of 18Hz I think. Some articles recommend the use of one, since the power/excursion requirements below 16Hz get so extreme, although the actual amplitude of such signals when encountered are almost never at the level assumed by the simulations.
I think I remember something on the Basslist about S. Linkwitz himself not recommending the use of one. I don't recall the specifics, but it will change the shape of the rolloff, effecting the Qtc/transient response that was the goal in the first place (?). Not sure on that one.
I think this combo would best the small Velodyne mentioned, principally in freedom from the dynamic compression in the low bass caused by the limiters in servo subs.
quote: . I caught my dog taking a peek at it yesterday while I was measuring the mounting depth. I imagine she was just wondering when she could get a chance to chew on it![/quote]
Actually, in the right light, and from a dog's perspective, in kinda looks like a fire hydrant. Better keep the door shut.
[Edited last by Jack Gilvey on November 12, 2001 at 07:07 AM]

 

[Brian Bunge]

Jack,
Thanks! Actually this guy is wanting to replace to HGS-10's. I'm thinking this will still best them! What do you think? So maybe I won't worry about a subsonic filter since the amp already has one.
Luckily both my dogs are female so they don't "lift their legs"! I imagine the 1803 would make a nice food bowl for them though!
Brian

 

[Jack Gilvey]

I don't have anything with which to model a pure shelf-type eq, but looking at a LT with an Fsc of 20Hz, Qtc of .5, in 48L looks very good with 75w in the "Power Applied" box. The excess excursion and power requirements seen below 16Hz would be taken care of by the filter, but they may not be a real-world concern anyway.
As always, a larger box will lessen the power required, which is always a good thing, as there's less potential for distortion from the amp, and less chance of power compression and driver non-linearities due to voice coil heating (which can be fairly pronounced looking at LSPCad). (More conjecture )
In 48L, you're only looking at a Qtc of 0.4, which is well below that which Jon recommended for eq-ing with a parameteric. Might be most feasible, since one should be used anyway, to start with just a BFD, and see how that goes.

 

[Jon Hancock]

Hi guys,
Sorry I wasn't able to keep up with the discussion this weekend, but family stuff sort of swamped me- daughter's big cross town rivalry game, 19th birthday party for my girl friend's older son, well, you get the idea!
First, the calcs I did for the BP1203 were with Unibox, which give anechoic results, and the output is limited by cone excursion in a sealed box. The larger the box, the slower the roll off because of the lower Q, and the less demanding the EQ curve. With a driver with a VC heating capability of roughly 1 kW (pretty unusual in a 12!

)
you can get away with playing games that required Bag End, in their EQ's subs, to use complex limiters with adaptive thermal modeling. Still, it's interesting to see what the bigger box and a port buys you.

Because of the EQ required to deal with the high VC impedance of TC-Sounds, it's likely that a more comprehensive equalizer like the BFD is the way to go for the BP1203 as opposed to a simple shelving EQ circuit (which can be done as a passive inline filter, or in the feedback loop of an opamp buffer). The shelving equalizer approach has worked very well for me with Audax Pro woofers and Shiva's and Tempests, but they have a more normal impedance curve.
We got very nice results with the BFD equalizer on the AS-15; Thomas, who's a bit spoiled by his IB subs, thought it was some of the best bass (EQ'd) that he'd ever heard from a sub- by that, we both mean deep, clean, accurate, and balanced octave to octave.
Since I want to equip a master bedroom with a "mini-HT sub", doing the small box for the BP1203 is a no-brainer.
Now, the interesting question may turn out to be, which is better- an HE-15 in a 3 cu. ft. sealed box, or the AS-12 klone in 80 L with a port? On sheer output at 20 Hz, the AS-12 wins, as the HE-15 will "only" muster about 106 dB anechoic at 20 Hz. But then, at 16 Hz the HE-15 will still muster a fairly impressive 102 dB- nothing to be sneezed at. And the transient response will be critically damped- essentiall perfect. But it will gobble much more power than the AS-12 doing it.
Which is better? You decide. I'll let you know what I think after I've tried them both, just like we did with the Stryke cube design and our homegrown AS-15.
I'm working on a full range speaker project with a magazine deadline to meet, so I won't be getting into the construction of these sub cabinets until Thanksgiving week at the earliest- maybe not until Xmas, becase there's also an amplifier project, which may manifest as a mod to a commercial line up.
Best regards,
Jon
[Edited last by Jon Hancock on November 12, 2001 at 10:53 AM]

 

[ChristianT]

Ok, I need some recommendations from you sub gurus out there. Here is my situation.
16" sonotube, BPD 1203, 4" flared port. My calculations (approximately) put the tube at 29" and the port at 25" for a 20Hz tuning point in an 80 liter enclosure. But the 1203 has a 7 1/4 " mounting depth and I have to place the 25" long port on the other end of the tube. Obviously they will not both fit. Is there any way to place some sort of material in the enclosure to reduce the interior net volume so that I can cut the tube longer and still get the 80 liters? Should I use multiple smaller ports? Any other recommendations?
Thanks,
Christian

 

[Brian Bunge]

Christian,
You could cut the sonotube longer and add an internal endcap to make the internal volume to 80L. Then just add another endcap on the exterior with the port extending from the exterior endcap through the interior one. That way you have the right port length with the right internal volume just in a taller piece of sonotube.
Does this make any sense?
Brian

 

[ThomasW]

The easiest and lightest way to remove interior volume is by getting some styrofoam insulation from one of the home center stores. Comes in sheets 1-1/2" thick, and weighs practically nothing. Cut circles that are a snug fit with the diameter of the tube, glue them in place with caulk/hot glue/whatever....

 

[ChristianT]

I was under the impression that the entire lenth of the port needed to be inside the enclosure. If I understand the idea correctly, wouldn't the internal endcap idea defeat the lengthing of the sonotube? Am I mistaken?
Thomas,
If I use the styrofoam approach, should I still measure the port length from the inside of the endcap?
Thanks,
Christian

 

[ThomasW]

Well no the port doesn't need to be totally enclosed by the box. It can stick out quite a bit if you don't mind the stovepipe look.
When using dual flares (a must with the 1203) the port length is measured from the end of one flare to the end of the other flare, it is unrelated to the endcap thickness.
[Edited last by ThomasW on November 12, 2001 at 05:23 PM]

 

[Ville Javanainen]

Hello again
How much does the 1203 itself weight?
Will the Behringer Ultracurve Pro work like Linkwitz Transform filter with 1203 in sealed 48L box?
How about the SQ of 1203 in sealed 48L box when eq-ed?
Is the sound tight and fast?
Since my room is so little, about 3m x 3,7m, I think that SPL of 1203 in 48L with eq should be fine..
EDIT:
How's the output level at 80Hz with 1203 in 48L sealed box eq-ed? Is it clean and tight?
(And sorry for bad English..)

 

[ThomasW]

Gee, I thought this thread was long gone
No the Behringer will not function as a LT circuit. But if you use the 1203 in a box 33L or larger you won't need a LT circuit. But you will need a regular EQ unit.
Don't have a 1203 but I have a 1503 and it weighs about 40+lbs or so. There isn't a big weight difference between the two.
With a proper amp it will be plenty loud in your room

 

[Ville Javanainen]

But how is the SQ of 1203 in sealed eq-ed?
And how's the output level at 80Hz with 1203 in 48L sealed box eq-ed? Is it clean and tight?

 

[Jack Gilvey]

Is it clean and tight?

Yes.

 

[Ville Javanainen]

Damn that those Blueprints aren't available in Europe yet..
Another driver which I'm considering is Infinity Kappa Perfect 12.1

 

[ThomasW]

I have a friend that used one. It's a pretty good driver but more like a Shiva than a BluePrint.
Scroll to the middle of the page to see his sub.
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