Dual opposed Shiva sub with inuke1000dsp

Hey everyone, I have been lurking on this forum for a while and thought it was time to post a bit about my first DIY project (and ask a few questions :) )

I have chosen a closed box subwoofer for simplicity and dual opposed to minimise enclosure vibrations should I fail a bit in the building part. It's made from an old bed and closet, not perfect but a lot thicker then MDF (33mm sides, top and bottom, 26 mm front and back, dual parallel 26mm bracing) and less heavy. Rabbet joints are used everywhere (makes the cutting less critical and every part is glued in 2 dimensions) The cutting was horrible since I didn't have acces to a table saw, so it needed a lot of shaving and sanding and it's going to need a healthy amount of filler before everything is done.


[IMGDEAD]http://s22.postimg.org/osvhyf9kh/Ingredients.jpg[/IMGDEAD]

[IMGDEAD]http://s15.postimg.org/s37qo5lor/glueing_1.jpg[/IMGDEAD]

[IMGDEAD]http://s18.postimg.org/4lf4nv5h5/glueing_2.jpg[/IMGDEAD]

[IMGDEAD]http://s22.postimg.org/mpu9i8oj5/glueing_3.jpg[/IMGDEAD]

The back of the subwoofer (bottom on the last 2 pictures) has a compartment to fit an inuke1000DSP, the hole in the bottom (front in pic 3) is for ventilation. Although I know the various different ways I could wire up the amp I just can't get my head around what would be the optimal way.

The way I see it, correct me if I'm wrong, there are 3 usefull ways of wiring up the 2 dual 8ohm voice coil drivers. The power I quote below is RMS/max power of the inuke1000 as found in the manual, I haven't found any power tests of the inuke1000 on the net.

1) Drivers and voice coils in parallel resulting in a 2 ohm load for which I can use 1 channel of the inuke to drive it at 380/530W

Pro: using only 1 channel for almost the same power

2) Drive the woofers separate (dual mono) with voice coils in parallel resulting in a 4 ohm load for which I can use 2channels of the inuke for 2x210/320W

Pro: maximises "max" power, more options to control room modes by the 2 spaced drivers using slightly different DSP settings on the 2 drivers or allows me to use only one driver in an enclosure twice the size (for the lullz)

3) Voice coils in series with drivers in parallel resulting in a 8 ohm load for which I can use the bridged inuke at 1x430/570W

Pro: maximises RMS power, highest damping factor.

The differences in power are small and I'll probably never use it that loud but it bothers me that I can't figure out an optimal way.

Are my assertions correct, am I missing something, is it just academic or will I be able to hear a difference between the 3 options?
 

Attachments

  • 2013-03-16 18.58.27.jpg
    2013-03-16 18.58.27.jpg
    282 KB · Views: 411
  • 2013-04-04 19.03.17.jpg
    2013-04-04 19.03.17.jpg
    264.1 KB · Views: 65
  • 2013-04-04 19.03.36.jpg
    2013-04-04 19.03.36.jpg
    257.4 KB · Views: 58

18Hurts

Member
2010-11-21 11:20 pm
Let me break this down...

You are going to make a single subwoofer in a push-pull type so it will cancel the vibration leading to less stress on the box.

Since a push pull needs to have both woofers operating with the same signal, I would wire it bridged mono.

The dual voice coil subs can be wired in series for a 16 ohm coil (8 + 8)
then wired in parallel for an 8 ohm final load. Bridge the amp so it will happily run along at 4 ohms each channel.

Have fun and a loud sub is always a good way to meet new people... :eek:
 
Thanks. I don't use that driver any more, too small. :D

Pity you life two hours from here.
I'm always hoping to know someone around here, with shared speaker related interests.

You can't go wrong with your design, sealed with DSP is all you need. This result will depend on your drivers. Which Shiva's will you use?
For sound quality you could reverse one driver but this rarely looks good, if ever. (one driver magnet out and connection reversed)
What is your goal with this sub?
 
You can't go wrong with your design, sealed with DSP is all you need. This result will depend on your drivers. Which Shiva's will you use?
For sound quality you could reverse one driver but this rarely looks good, if ever. (one driver magnet out and connection reversed)
What is your goal with this sub?

It's the Shiva-X

Re: DC resistance of VC 3.65 Ohms
Le: Inductance of VC 0.90mH
Fs: Resonance frequency 20.0 Hz
Qms: Mechanical compliance loss 3.20
Qes: Electrical motor loss. .55
Qts: Total Q of driver .47
Mms: Moving mass 171g
Cms: Suspension Compliance 0.38 mm/N
Vas: Stiffness of driver scaled by cone size 125L
Sd: Area of the cone 491 cm^2
Vd: Total Diaphragm Displacement volume 2.65L
BL: Motor Strength 11.9
X-Max: One-way linear excursion 27mm
Pmax: Maximum power (music, not RMS) 600W
SPL: Sensitivity db/1W/1M 84.4
Volume Occupied by Driver .15 cubic feet or 4.25L

The cabinet is 555mmHx620mmWx555mmH net volume is 95l, sketchup model:

[IMGDEAD]http://s8.postimg.org/e5q2pvbvp/Subkast_1_crop.png[/IMGDEAD]

[IMGDEAD]http://s4.postimg.org/g3l43ccbx/Subkast_2_crop.png[/IMGDEAD]

The goal of the sub is to have some fun building it and will probably be used 80% music 20% HT. I have another thread about it at HTforum.nl. The guys there where a great help in selecting an optimal bang for the buck driver, I got the Shiva for 110€ a piece.

The cabinet is filled, so after the last round of sanding this afternoon I will test it for the first time before painting, I'm quite excited to hear the result.

A week ago I stumbled upon a public sale of some Pro sound drivers from sound projects, I got 2 15" neo drivers for a next project but I will have to measure the T/S parameters first. They are used in the SP15 PA subs and are normally sold for 370€ a piece. (SP-1504)

I was thinking about playing around with hornresp to see if I could make a tapped horn with them.
 
I just tested the sub and... it's obscene. It's not the loudest I have ever heard, but for a home setting it is more then enough and I'm very happy with it considering I didn't spend a lot of time fiddling with the DSP. The test was in the basement so a lot of things where rattling.

I didn't expect to feel so much vibrations on the cabinet though, you can put a glass of water on it no problem, maybe I was expecting to much (or little)

I wired the coils in series and the woofers in parallel, amp was bridged.
 
No one has any idea on the pro or cons for the wiring? I intend to try them all out but I would like some explanation on why one would sound better then the other.



The way I see it, correct me if I'm wrong, there are 3 usefull ways of wiring up 2 drivers with dual 8ohm voice coils. The power I quote below is RMS/max power of the inuke1000 as found in the manual, I haven't found any power tests of the inuke1000 on the net.

1) Drivers and voice coils in parallel resulting in a 2 ohm load for which I can use 1 channel of the inuke to drive it at 380/530W

Pro: using only 1 channel for almost the same power

2) Drive the woofers separate (dual mono) with voice coils in parallel resulting in a 4 ohm load for which I can use 2channels of the inuke for 2x210/320W = 420/640W

Pro: maximises "max" power, more options to control room modes by the 2 spaced drivers using slightly different DSP settings on the 2 drivers or allows me to use only one driver in an enclosure twice the size (for the lullz)

3) Voice coils in series with drivers in parallel resulting in a 8 ohm load for which I can use the bridged inuke at 1x430/570W

Pro: maximises RMS power, highest damping factor.

The differences in power are small and I'll probably never use it that loud but it bothers me that I can't figure out an optimal way.

Are my assertions correct, am I missing something, is it just academic or will I be able to hear a difference between the 3 options?
 
It's how I wired it up for the first test. Option 2 and 3 should be the same then despite the slight differences in quoted power if I understand correctly.

Some pics of the painting in progress:

[IMGDEAD]http://s23.postimg.org/n53qtc97v/Paint1.jpg[/IMGDEAD]

and a dried up drip :mad:

[IMGDEAD]http://s12.postimg.org/6l8yk83yl/Paint2.jpg[/IMGDEAD]
 
Looks well braced, and fairly inert. I'll take that over perfect paint any day! {^^}

Definitely, acoustic performance is priority number one, two and three. But I want it to be pretty too :eek:. The paint is actually a temporary solution. I started playing around with some fractal design software in order to make a drawing which I'll have printed on a huge sticker to put on the sub after it's finished. But it was going to take a lot more time to make a nice drawing then I first anticipated (Isn't this always the case). So I just took some leftover paint so it looks okay in the mean time.