[sam_cat]

Theile small params here:
http://www.imagedynamicsusa.com/pdf/...20d4%20V.2.pdf

I have a pair of these sat at home from a previous car stereo setup, am planning on using one (or maybe both) to compliment my current stereo.. Naim NAIT 3, CD3.5 and a pair of Dali lektor 1 speakers (tiny, and lacking the low stuff)

Dont want the cabinet to be too big, but am totally open to ideas. Ported/sealed but MUST be musical.

Planning on driving it with either a BK elec BSBPV300 or BSBPV500 (any ideas on which would be best)

Thanks,
Sam

(wont be building till the last week of this month, and may start off with a small sealed box as a test... Will put together a build thread)

[micb3rd]

This is a sub I know a lot about.

I have had one for review years ago and was good friends with the UK distributer.

These are not ideal in small sealed boxes, they end up sounding a bit hard and boomy. Larger sealed boxes like 1.7-2.0 cf sound better.

If you want depth and output then 2.5-3.0 cubic foot net tuned to 25hz is a good.

What frequnecy range do you want it to play?

[Moonfly]

Ive had a little play and ported designs seem like they are going to take a whole heap of figuring out, so for me sealed would be the way forward. In a box of reasonable size (small to moderate) though, with either 300 or 500 watts Win ISD says they will exceed xmax at max power very easily so that will need either figuring out or some care from the user.

Win ISD has these drivers already in its database though, so it's well worth you downloading it and having a play yourself. The 5 mins Ive spent playing with it is definitely going to be better using 2 drivers. This will help keep xmax under control and give decent output, but it seems far from straight forward at first glance. I'll have a play a bit later and see what I can come up with and post back if I find anything worth while. As for musicality, thats a toughy to figure out without a working test model for anyone who hasnt heard them before.

Hopefully one or two others will jump in and help out a bit.

EDIT: After some messing about I found something that looks to work well in a ported box. Using 300 watts input, and 2 drivers in a 125 litre box, with 2 4" ports its gives very good output to 20hz (19hz tuned). Anything below 15hz blows the drivers xmax but otherwise this would give nothing to worry about. The only catch is the ports need to be quite long but I wouldnt see that as too much of an problem in a this size of box although that sub might be too large for you, IDK.

What yo think Mic3rd

[micb3rd]

Moonfly your design would be fine, nice and flat if he wants good bottom end.

500 RMS to the pair will be fine, they are very complient and efficient woofers.

It basically boils down to how much space he wants to give up and what exact freq range does he want to play.

[sam_cat]

Originally Posted by micb3rd

It basically boils down to how much space he wants to give up and what exact freq range does he want to play.

Well... Space is a wee bit of a premium, but could build something of a reasonable size if it will make a big difference, just have to rethink some of the units in here.

Very tempted to start with a 50L sealed box, as around that size worked very well in the bus previous (although it was a pair of 50L boxes). Am aware that houses and cars are very different acoustically, in the car we have a lot of cabin gain.
I have a 50L enclosure to hand thats unfinished. If that doesnt work out then I can build something else.. Happy to have a play

Wont get much of a chance to work on the enclosure this weekend, but might snap a few 'before' pictures of the unfinished box and the sub.

With the ported enclosure detailed above, what size of port would I need if I went to a nicely made slot port (all clean curves and rounded off).

Thanks again,
Sam

[Moonfly]

If you dont use both drivers in a single box your going to have to give a little in the depth department, but if you made 2 single driver subs you'll get the same amount of spl. The only problem I see in the simulation is that a single driver is pushed to the point where xmax becomes a bit of an issue. Mic3rd seems confident that isnt an issue though and I'm in no position to argue with him. The other issue of course is that with 2 boxes, if your going to use plate amps then you would need 2, so costs increase.

IMO, you should build you sub to use both drivers to get the most performance and best value from your single amp.

For a slot port, its exact size will probably depend on the final size of your box. You'll want to keep the slot the same width as your box to make construction easy, and its height will change depending on its width. If your replacing a 100mm (4") port with a slot, the area of the slot needs to be roughly 78 square centimetres.

Ive just tinkered with something that might work for you:

Box volume would be 55 litres
Dimensions would be 400mm x 400mm with a height of 600mm
1 slot port at the bottom would be full width of the cabinet and 50mm high, and it would have to be 600mm long, basically to the back of the box and about 3/4 of the way up the inside of the rear panel.
Cabinet would be made from 1" MDF and this would leave enough room for a single brace.

That would give a tuning frequency of 25hz, and about 106db at 20hz in room max @ 300 watts, and its -6 would be about 26hz. This sub might struggle a bit with anything below 20hz though. Building 2 will obviously give you a bit of headroom, but if you want more depth the only way is to go bigger with the box. You could also add a high pass filter to protect the sub low down and help reduce the risk to the sub at 15hz and under, where its not doing much anyway besides hitting xmech, but that might be making it more complex than required.

What do you think?

If you want me to have a tinker with a dual driver design, I rather enjoyed working all that out

[micb3rd]

You subs are dual 4 ohm coils so if you wire it to 8 ohms then the BSBPV500 will make approx 300 WRMS.

Plus if you like what you hear then build a second subwoofer and double you power runing the pair in parallel to 4 ohms.

If it is hanging about then try the 50L box, if it plays the frequency range you want then build a second if you want more output.

If it does not go low enough for your liking then go for a ported design.

Have fun!

[Moonfly]

Makes sense Mic3rd,

[sam_cat]

Thanks for the input guys

Will start with a single sealed and go from there... In car a single sealed is brutal with 350wrms, so will be intrigued how it sounds domestically.



Thanks again,
Sam

[sam_cat]

BSBPV500 ordered, preliminary box partly built (rough and ready and oversized so I can experiment with different box volumes).

Piccies soon I promise.

[sam_cat]

On double checking the drivers they are both Dual 2 ohm, so with 1 I can easily show the amp 4 ohms but with both I can only show 8 ohms (or 0.5/2 but the BK amp isnt stable under those conditions)

[IronGiant]

I think you can run an amp panel with a higher resistance driver(s) so you would be OK with an 8 Ohm load, the amp instructions say

This amplifier panel is optimized for use with an 4 Ohms loudspeaker. Operation into loads lower than 4 Ohms will substantially reduce the life time of the panel

Could you not use one 2 Ohm voice coil per driver to give a 4 Ohm load and leave two coils unused? I can't remember/figure out what implications this would have on the sound output though.

Dave

[micb3rd]

The BSBPV500 will be fine at 8 ohms but you will get around 330 WRMS out of it. Shame you can't run both drivers at 4 ohms for full power though.

I look forwad to the pics.

Originally Posted by IronGiant

Could you not use one 2 Ohm voice coil per driver to give a 4 Ohm load and leave two coils unused? I can't remember/figure out what implications this would have on the sound output though.

Dave

It changes the Q params of the driver so the box size and freq responce changes.

DVC = 2 fields with 2 coils.

No Power to coils you get nothing.

Power to both coils (wired in phase) you get both coild driven so full in phase motor force.

Power both coils (wired out of phase) you get out of phase motor force and just power going though to the coils!

Power one coil and leave one open (some of the Q params change) and you get one coil being driven and the other doing nothing so you get half motor force and one coil moving with a reduction in control.

Power one coil and short one coil (some of the Q params change) you get one coil moving but with the shorted coil resisting so you get half motor force but second coil damping the movement.

So you can run one coil and short a coil but you will have less motor foce and your responce curve will change.

You do loose output from only running one coil and your themal power handling is halfed as you only using half the windings on the coil.

Me personally I prefer to run both coils powered but at a higher impedence.

[sam_cat]

The instructions with the IDmax subs say to never run just one coil on a dual voice coil sub, so that idea is out the window.

Have just done the first run of the built prototype and all I can say is wow! No setting up other than tweaking the gain/eq to make it sound right to my ears and its sounding really good already! tweaked the eq down so the bass became non directional (and its roughly around the lowend dropoff point of the main speakers), and tweak the gain such that it sounded correct.

Stuck Massive Attack Angel on and at everything from low volume to cranked as loud as I like to listen to it confirmed that this should work wonderfully!

Dont think I will be needing to run both drivers..



What are my options now for more complex setup/intergration?

Thanks,
Sam C

[micb3rd]

Originally Posted by sam_cat

The instructions with the IDmax subs say to never run just one coil on a dual voice coil sub, so that idea is out the window.

Have just done the first run of the built prototype and all I can say is wow! No setting up other than tweaking the gain/eq to make it sound right to my ears and its sounding really good already! tweaked the eq down so the bass became non directional (and its roughly around the lowend dropoff point of the main speakers), and tweak the gain such that it sounded correct.

Stuck Massive Attack Angel on and at everything from low volume to cranked as loud as I like to listen to it confirmed that this should work wonderfully!

Dont think I will be needed to run both drivers..



What are my options now for more complex setup/intergration?

Thanks,
Sam C

Nice, are you running one or two subwoofer drivers?

[sam_cat]

Originally Posted by micb3rd

Nice, are you running one or two subwoofer drivers?

Just the one driver, and with the gain turned up a bit it makes stuff in my kitchen rattle (2 rooms away)



Just uploading some pics now.

[sam_cat]

Click a picture to open the larger version (through Flickr).

Box is 18mm ply, except the face the driver is on which has an additional 2 layers of 6mm mdf bonded to it (as I ran out of 18mm ply, would normally run a double thickness)

Front view of the rough prototype box (you can see some of the bracing here)

Exterior is 500mm high, 345mm wide by 414mm front to back
Interior is 468mm high, 313mm wide by 368mm front to back
Rough calcs thats about 54 litres/1.9 cubic feet

Rear view of the rough prototype box (the white stuff you can see is silicon, wasnt happy with how well some of the faces fitted so ran a bead of silicone around the joins a few days ago)

Amp in place

The subwoofer, Image Dynamics IDMAX 12 D2

And the rough box in place

[sam_cat]

Just watched The Dark Knight and listened to a few tracks.. Very impressed so far

[sam_cat]

Originally Posted by Moonfly

Win ISD has these drivers already in its database though, so it's well worth you downloading it and having a play yourself. The 5 mins Ive spent playing with it is definitely going to be better using 2 drivers.

Just pulled this down, have used it before for modelling enclosures for in car.

It doesnt have the IDMax subs, only the IDQ's, so will have to tap the details in myself.. Going to knock up a couple of experiment sealed boxes, aiming to try a QTC of 7.07, 1 and 5.

Thanks again,
Sam C