Norpus' first IB - Home Theater Forum and Systems -

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post #1 of 7 Old 10-17-06, 04:04 AM Thread Starter
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Norpus' first IB

Here is my first diy speaker project blog

IB Sub

My objective
was to do a double leap of technology by listening to other DTV forum members dreams last year and doing it first as an early adopter here in Australia. I had a lot of faith in these guys and their sub knowledge and enthusiasm btw (credits to Spearmint and Nobby)
Wanted never to worry about lack of quality bass - this seemed the ultimate bang for buck
Wanted to meet/exceed the THX spec for subwoofer of 121dB available output

IB Infinite Baffle Sub manifold with 2 x 18" Avalanche drivers, mounted in floor to minimise number of big black boxes in the room (WAF is positive).
Purchased imported drivers ex another forum member delivered on Saturday Feb 25, box constructed during the following week and installed Sat/Sun 5/3/06

Room location, in between mains. Hole is 650 x 610mm

Made manifold box from 2 sheets 18mm construction boxing ply (waterproof as under floor). Routered the manifold to allow flush fitting of drivers - in hindsight wouldn't bother with the hassle next time

The drivers weigh 20kg each - the magnets shagged my crt picture from over 1mtr away - total rainbow of colour needed degaussing after they passed by the screen hehe

The manifold went under floor - bottom half painted with bituminous paint as it is partly below ground level. and yes the box became bigger than I'd thought. Internally, it added 230 extra litres to my room

We needed to dig 7 wheelbarrow loads of dirt out from underneath to allow us to fit from top (not easy btw) rather than fitting drivers from under house crawling on belly (< 600mm clearance under floor).

We then lowered box in to hole and fitted the drivers leaning in from top (2 man op, not easy took 2 hours to get it right). Then used a strop over back to lift the box (now 80kg with drivers) into position whilst Mac drilled with coach bolts into floor joists on 4 sides. (The wires were left there untidied for Foxtail )

Roughly finished product ready for first test using 2ch of the Elektra theatre 7 until the behringers arrive. Needs paint touchup and tuning. Also a grate to fit over the hole so pieces of furniture don't fall in and damage the drivers (and yes I have tried that already by mistake with one of my mains ). Luckily I didn't get the 'oversized' 600x600mm return air grate I'd found on the web, as after building the box with 40mm walls, I found it was somewhat undersized and would have fallen in

Behringer A500 amp and FBQ2496 feedback destroyer to power it

Cost Summary (I knew you would ask)
Cost materials and labour - around $2.5K AUD (including 2-3 man-days over the week)
Cheap considering the quality of these drivers is superior than your average box woofer and it has been designed to outperform most box woofers for HT above the $5K mark (conservatively)

Yes they are overkill for my room, but hey I happen to like that concept

Last edited by norpus; 10-17-06 at 08:14 AM.
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post #2 of 7 Old 10-17-06, 01:20 PM
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Re: Norpus' first IB

Exciting project you have there! I remember reading up on the close-out Avalanche deals...but didnt understand at the time how a single driver could be worth $300... I wish I could go back

That behringer seems like a great amp for this application indeed. Hope you enjoy the end result.

If you don't have a BFD for your sub, get one fast!
If you don't have REW, get it now!
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post #3 of 7 Old 10-17-06, 06:02 PM Thread Starter
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Re: Norpus' first IB

Exocer wrote: View Post
Exciting project you have there! I remember reading up on the close-out Avalanche deals...but didnt understand at the time how a single driver could be worth $300... I wish I could go back

That behringer seems like a great amp for this application indeed. Hope you enjoy the end result.
Thanks, yes it was a bit of a pioneering exercise for me as I'd never seen or heard an IB before. Just talk on the net and a couple of mates who'd seen one

I also was not prepared to pay lots for drivers - they are twice the price here and more due to transport/import costs. I ended up paying well over $1000USD for the 2 Avalanches from a guy who imported 6 into Australia. So $300 is nothing - in fact thats what the lowly Tempest 15D8 cost me.

The behringer A500 is a great little amp for bang/buck ratio. However I have found it doesn't really have the grunt to run 2x18 fully. I suspect it is really only 150w rms or so. Hence it will be retired for something better soon - maybe something with phase control built in

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post #4 of 7 Old 04-23-10, 02:57 AM
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Re: Norpus' first IB

Thought I'd bump this one

This has got to the most insanely good bass system I have experienced. It never sounds strained and it just goes about it business without any fuss. Oodles and oodles of quality bass.

Source: SB Duet, Pre/Pro: Integra DHC-9.9, Speakers: SGR MT3FSL (active), Sub Amp: Crown K2, Subs: 2x SGR Maelstrom-X (125L Sealed)
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post #5 of 7 Old 07-16-12, 03:26 AM Thread Starter
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Re: Norpus' first IB

This 2x18" IB sub still works seamlessly and brilliantly

I haven't upgraded anything in nearly 3 years now on the system and the IB has been running pretty much daily for 6 years

I can't think of a better, stealthier way to do it (see attachment, can you see it under the middle rack? nope not a shadow)

About all I'd do is change drivers to some bigger meaner 21s (and then only have to turn it down further lol)

So, very happy to recommend diy IB as the bees knees


Last edited by norpus; 07-16-12 at 03:35 AM.
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post #6 of 7 Old 07-16-12, 08:08 AM
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post #7 of 7 Old 07-18-12, 04:07 AM Thread Starter
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Re: Norpus' first IB

ironglen wrote: View Post
Give us more pics!

What are those beautiful floor standers?

Thanks ironglen

The floorstanders are SGR Octagons - custom built locally by the Ralstons
These were S/N 001 of the fully active version. Harry had made several of the passives and then when his son Stuart began producing some fab new high quality multichannel plate amps I got to listen to the passives being transitioned to active. My avatar photo is of the green active Octagon prototype in my listening room (alongside the incumbent B&W802D), which I had for one week to decide.

Naturally, you can see I sold the 802Ds from the April 2008 photo (2nd one below) , and then in 2009 reduced the HT clutter out the door to how it remains now
It was a change - from ported 2 x 8" bass + IB sub, to sealed bass with extension flat to 20Hz without IB.
I loved my bass so the week's trial really was needed to recalibrate in my head my ideal 'norpus house sound' from ported to sealed.
The transition has been permanent - I have never desired to go back to the 100Hz port hump of the 802Ds, despite I did love those glorious pieces of timbered timbre.

Features already on the prototype which were nice were:
1. the finish is automotive quality and qty - 30 coats.
2. Isolation - custom made adjustable SS feet/spikes, also mid/tweeter enclosure separate and isolated by coned feet and isolation pads. SMB multilayer internal isolation material used (proprietary IP)
3. Bespoke twin 10" bass drivers with factory EQ to be flat in room at 20Hz (mine measured flat on install too)
4. 6 channels of amplification included, two 3-way crossovers
5. imbedded magnetically attached driver covers (not seen here as they are magnetically attached to the rear of the cabinets for 'storage')

On order, my Octagons were then hand built (took some months) and I watched intently every part of the build and the meticulous craftmanship that went into it.
Several nice features were enabled during the production and upgrades of my Octagon serial n0 001
1. amps taken outboard (so people could pick and choose amp style per driver)
2. allowing bass driver box to reduce in footprint, more WAF
3. new outboard commercial SGR amps (EL15S and EL30S as seen in photo) replaced plate amps, featuring several toggle switch options.
4. low level crossovers also removed from plate amps and in two separate small boxes
5. Chosen colour scheme to match my room was Bass unit as blue/black iridescent and the top module (which lifts off) is straight black

Whilst the Octagons are no longer in production due to the handbuilt nature and lead time being uneconomic, replaced by the easier to manufacture MT3F floorstanders, the bass enclosure is similar.
The tweeter is a revelator but the config and mids are different and I like them better.
I cannot see myself changing these out as they give me all I ask (and if I ever want to surf the floor, I just couple the 2x18" IB)

I guess you asked......


Last edited by norpus; 07-18-12 at 04:38 AM.
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