Hi Bon,
You're insights are appreciated, it is good to be challenged and to question things.
The bowls are very stable - as you note they are designed for food and IKEA have been making that model for years. I built some full range driver kitchen speakers using two of them per sphere about 7 years ago and they still look great - and this was with no reinforcements or bracing rings.
Your point about vibrations is true and something I did consider, and this is why I am using PVC pipe rather than them for the subwoofers.
I have massively reinforced the fronts of these spheres using both bracing rings and structural epoxy, mainly because the vm752 dome weighs 9kg! So they need to take some serious weight.
You're insights are appreciated, it is good to be challenged and to question things.
The bowls are very stable - as you note they are designed for food and IKEA have been making that model for years. I built some full range driver kitchen speakers using two of them per sphere about 7 years ago and they still look great - and this was with no reinforcements or bracing rings.
Your point about vibrations is true and something I did consider, and this is why I am using PVC pipe rather than them for the subwoofers.
I have massively reinforced the fronts of these spheres using both bracing rings and structural epoxy, mainly because the vm752 dome weighs 9kg! So they need to take some serious weight.
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This is good to know. You seem to be on top of this issue. I hope to learn from following your progress.
Well I hope so! I am still concerned there will be a lot of weight through the lower sphere with the volt dome above, and it will mainly be in the front half so I am worried about the join between the two.....
But before I start to worry myself again, I have one of these arriving today:
Behringer NU4-6000 PA
The sub's are dual voice coil 2+2 ohm. So I figured wiring the two sub's in series for an 8 ohm load. The above amp will do 1500w into 8 ohms so should provide enough power.
I figured this would keep the damping factor higher than wiring them series-parallel for a 2 ohm load.
What do people think?
Great minds think alike obviously
I have one of these arriving today:
Behringer NU4-6000 PA
The sub's are dual voice coil 2+2 ohm. So I figured wiring the two sub's in series for an 8 ohm load. The above amp will do 1500w into 8 ohms so should provide enough power.
I figured this would keep the damping factor higher than wiring them series-parallel for a 2 ohm load.
What do people think?
. I have an NU-3000, NU4-6000 and NU12000. The NU4-6000 runs the mids and highs (Scanspeak 18W8531G00, D2905/970000), the NU12000 the parallel Peerless 830452 per side. I purchased the NU-3000 first to see how it compared with my reference class ab amps and was impressed enough to put together a suite for future projects. The big plus for me is the much more manageable weight and bulk once I found the sound quality to be acceptable. On balance, I find a good quality class ab power amp sounds a bit nicer to me, but that seems to be the nature of class D. On a watts/dollar basis the iNukes are great value. For bass they have a tight punchy, clean sound. They are ideal for sub-woofer duty. I have never got more than the 2nd power led to flicker within my hearing volume tolerance in a 6.7x7.5m room. The noisy fans are the only negative for me. Swapped them with Noctua NF-R8-1800 for whisper quiet operation. I have tried to get the iNukes to shut down. They run barely warm at extended high volume levels.
Great minds think alike obviously
This is exactly the kind of feedback I was looking for - Thanks Bon.
I will be using MC2 amps for the Scanspeak 7000, Volt VM752, and SB MW19P-4. Which are high quality Class AB amps that sound fantastic, however I wanted some serious juice for the subwoofers as they can take 1000W RMS each.
I plan on running the NU4-6000 in bridged mode for 2 x 1500W into 8 ohms I figure I won't need much more than that!
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Just as an aside - regarding the bamboo bowls I am using, I think the reason they are so structurally stable is pretty well surmised in this chart:
Of course bamboo block like this is also incredibly stiff and has a high internal damping factor.
All in, I have found it to be an excellent product.
[QUOTE
I plan on running the NU4-6000 in bridged mode for 2 x 1500W into 8 ohms I figure I won't need much more than that![/QUOTE]
Hi, I'm using an Inuke 3000 bridged for my 8ohm sub but I thought the 6000 was actually 2 bridged 3000's and had no provision for bridging? You should get around 2x 1200 watts out of it at 8 ohms. 2x 2000 at 4 ohms.
I plan on running the NU4-6000 in bridged mode for 2 x 1500W into 8 ohms I figure I won't need much more than that![/QUOTE]
Hi, I'm using an Inuke 3000 bridged for my 8ohm sub but I thought the 6000 was actually 2 bridged 3000's and had no provision for bridging? You should get around 2x 1200 watts out of it at 8 ohms. 2x 2000 at 4 ohms.
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I have used strand woven bamboo as a cladding for mdf speaker carcasses.
Wow Bon! beautiful speakers!
I see you have gone to great lengths to reduce cabinet vibrations too - that has to be the thickest baffle I have ever seen!
Just looking at those pictures though, I would be a little worried about cavity resonances - the incredibly thick baffle looks to result in a 4" 'tube' before opening out into the main cavity - did you route back the 'tunnel' before installing the mid driver?
I am always quite paranoid about cavity resonances in my baffle cut outs as I once had a problem with a very thick baffle that I couldn't pin down until I chamfered back the mid-driver cut out.
You are correct that the NU-6000 is 2 bridged 3000's and thus is not designed to handle 2 ohms but the NU4-6000 is a 4-channel amp, essentially 2 x NU-3000 in a single case.
Each channel is the same as in the NU-3000 and can handle down to 2 ohms. Moreover the channels can be bridged in pairs for higher 2 channel power but only down to 4 ohms. As Bushmeister suggests, running the 4 channels unbridged to each of the 4 woofers, maintains a superior damping factor and control of the woofers. In this mode the NU4-6000 can deliver 300 wrms into each of the 8 ohms or 600 wrms into each of 4 ohms. That is 2.4 kW rms total. I have confirmed these figures into my dummy loads but they got very hot, so it was only briefly tested at this level. The fans speed up with hard drive.
I try to live up to my signature line. The total wall thickness is 45mm approx.
I roundover the inner cut-out with the largest roundover router bit I own. No problems so far with uneven frequency response. I don't wish to hijack your interesting thread, so I won't comment further on my build here.
Right. Having come up with a joint between the spheres I am happy with, it is time to think about stands...
To this end 4 bamboo matching IKEA chopping boards. Mounted in mirror image (providing interesting bevelled edges) to give a 4cm thick fairly heavy base. Flexible adhesive between them also provides an element of cld, for what it is worth.
To this end 4 bamboo matching IKEA chopping boards. Mounted in mirror image (providing interesting bevelled edges) to give a 4cm thick fairly heavy base. Flexible adhesive between them also provides an element of cld, for what it is worth.
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I found some pics of the rear baffle relief of the mid-cut out.
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So I have now joined the second speaker. Structural epoxy bolts etc, by wrapping the magnet of the vm752 in cling film, installing it, then packing structural epoxy around the edge of the magnet at the bottom I have created a snug shelf to allow the weight of the driver to be transmitted to the reinforcements. In case you think I am being paranoid about all this, check out the size of the 9kg mid range dome....there isn't much room left!
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Hi all,
I am looking for some advice and help here.
Over in the full range forum, Fluid is making a full range driver array - in the same theme as OPC and of course wesayso's amazing Two Towers (I don't want to go off topic and pollute his thread with my worries!).
Wiring schemes have come up and interestingly there is a strong and compelling argument to avoid wiring drivers in series in the same shared, sealed enclosure.
Unfortunately I have bought 4 x Alpine SWR 10D2 subwoofers, which are 2Ohms dual voice coil sub-woofers.
My plan was to wire these in series - for an 8 ohm load.
They will be in a dual opposed push-push configuration.
I am now worried that this could result in some bad problems with the cone positions getting out of sync.
Anyone done this? Have people wired subs in series in the same sealed enclosure without issues?
Thanks for you advice and help.
I am looking for some advice and help here.
Over in the full range forum, Fluid is making a full range driver array - in the same theme as OPC and of course wesayso's amazing Two Towers (I don't want to go off topic and pollute his thread with my worries!).
Wiring schemes have come up and interestingly there is a strong and compelling argument to avoid wiring drivers in series in the same shared, sealed enclosure.
Unfortunately I have bought 4 x Alpine SWR 10D2 subwoofers, which are 2Ohms dual voice coil sub-woofers.
My plan was to wire these in series - for an 8 ohm load.
An externally hosted image should be here but it was not working when we last tested it.
They will be in a dual opposed push-push configuration.
I am now worried that this could result in some bad problems with the cone positions getting out of sync.
Anyone done this? Have people wired subs in series in the same sealed enclosure without issues?
Thanks for you advice and help.
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