If you'll be mounting each driver on opposite ends of a pipe you have plenty of options to play with! You could physically put a circular spacer in the middle of the pipe so you have identical but separate air spaces for each driver. You could wire up each driver's coils in series and use an output channel per driver. That will keep them completely separate and still have the benefits of force cancellation if you're that concerned about driver interaction.
Bushmiester, I'll make this short, so we don't hijack this thread. I have 4 12" subs in a common cabinet, wired series/parallel. Works just fine, no issues at all, except it's a pain to move. One each on 4 sides. It sits out in the room as a table. Yes, well braced. I built it about 15 years ago.
Thanks for your help guys - this forum is so useful as a sounding board!
Of course this is what I should do - I am just lazy! Also I haven't simulated dual voice coil drivers before - but I would imagine it would be straight forward - apart from having to measure each combination of series/parallel wiring.
I like this idea - I had thought about dividing up the space, but didn't want to use up more volume with a divider. The pipe will be approx 40cm long and wall thickness is over 10mm, so it should be very stiff, but a decent thickness MDF mid-wall would not only isolate the two drivers, but also stiffen the structure further - which is probably a good idea given the excursion of these subs.
Don't worry about hijacking this thread - it is of direct relevance as I will also document the sub-woofers on this thread. It is definitely reassuring to hear this.
Thanks guys - I think I will go with a central divider - it gives me peace of mind and should only enhance the enclosure with minimal loss of volume.
Of course this is what I should do - I am just lazy! Also I haven't simulated dual voice coil drivers before - but I would imagine it would be straight forward - apart from having to measure each combination of series/parallel wiring.
I like this idea - I had thought about dividing up the space, but didn't want to use up more volume with a divider. The pipe will be approx 40cm long and wall thickness is over 10mm, so it should be very stiff, but a decent thickness MDF mid-wall would not only isolate the two drivers, but also stiffen the structure further - which is probably a good idea given the excursion of these subs.
Don't worry about hijacking this thread - it is of direct relevance as I will also document the sub-woofers on this thread. It is definitely reassuring to hear this.
Thanks guys - I think I will go with a central divider - it gives me peace of mind and should only enhance the enclosure with minimal loss of volume.
Thanks for the consideration! Nice work on the enclosures so far.
In your XT bassed Synergy did you wire the woofers in series or parallel? They share the same sealed enclosure so that would be a way you could test the difference on something you already own.
My own view is that that the lower the number the drivers the less the problem. No harm in playing it safe with a divider though.
They were two 8 ohms drivers which I wired in parallel for a 4 ohm load - therefore no issues.
Your speaker build is excellent Fluid! I am really looking forward to hearing your listening impressions.
Whilst this build is using very high end drivers and some interesting shapes/materials, it is nevertheless a straight forward 4 way speaker.
The line array is next on my list, but not sure how I will sneak a line array past my wife!
Got a few days off now - so build progress will slow down somewhat.
Thanks! I hope to get them in place to listen more seriously soon but I will also be going away for a few weeks so that will probably delay things.
Ha, the XT Synergies are next on mine! I have the horns already and I have been eyeing the new SB 8" drivers with the plastic frame. Very cheap but still look good.
The arrays take up next to no floor space so they can be quite living room friendly, but there is no getting past how tall they are, the pictures really don't show it. The first time I stood one up instead of on it's back I thought hmm, these are bigger than I imagined
The fabric sock does a good job of disguising them, if you were to pick a colour that matched your walls they would disappear somewhat. They are a lot of work but I am sure you are up to the task given your previous builds.
If you were to need a speaker to dance to the arrays are excellent, no difference in sound at pretty much any height from standing to sitting, even sitting on the floor is not bad, probably would work quietly at night as there is a bass boost from the proximity to the floor.
Anyway, good luck with this build it will be interesting to hear your impressions when you are done.
Hi Fluid, and anyone else following either of our threads - Just a quick bit of info regarding wiring of subwoofers (which may or may not be applicable to other drivers in general). It is taken from JL Audio's website:
"It is far less desirable to make subwoofer to subwoofer connections in series. Due to slight and unavoidable differences between speakers and the high likelihood of uneven loading between different speakers in a car, there will be slight differences in the mechanical behavior of the two speakers in series. These differences in movement result in the creation of induced voltage (called back EMF) by the speakers across the series connection. This effect causes a problem when two speakers that behave differently are connected in series because the speakers can modulate each other (cause each other to move), resulting in distortion. The problem becomes more serious as more speakers are connected in series.
The following is a good experiment to show the effect of back EMF: connect four speakers in series and short the positive and negative input leads of the series circuit. Push down on one cone with your hand; you will notice that the three other speakers will move in the opposite direction of the one you are pushing. Now, reconnect the speakers in parallel, short the inputs and push down on one cone. The speakers will not modulate each other because each one is shorted directly.
Back EMF modulation is not a concern when the voice coils of a dual voice coil speaker are wired in series to each other because the coils are physically coupled on one moving mass. Therefore, they cannot possibly modulate each other because they cannot move independently."
So looks like I will be wiring each sub to 4 ohms and running a single sub off a single channel of the 4 channel amp, each in it's own enclosure - pretty much like building four subs and putting two back to back. No series connections for me.
"It is far less desirable to make subwoofer to subwoofer connections in series. Due to slight and unavoidable differences between speakers and the high likelihood of uneven loading between different speakers in a car, there will be slight differences in the mechanical behavior of the two speakers in series. These differences in movement result in the creation of induced voltage (called back EMF) by the speakers across the series connection. This effect causes a problem when two speakers that behave differently are connected in series because the speakers can modulate each other (cause each other to move), resulting in distortion. The problem becomes more serious as more speakers are connected in series.
The following is a good experiment to show the effect of back EMF: connect four speakers in series and short the positive and negative input leads of the series circuit. Push down on one cone with your hand; you will notice that the three other speakers will move in the opposite direction of the one you are pushing. Now, reconnect the speakers in parallel, short the inputs and push down on one cone. The speakers will not modulate each other because each one is shorted directly.
Back EMF modulation is not a concern when the voice coils of a dual voice coil speaker are wired in series to each other because the coils are physically coupled on one moving mass. Therefore, they cannot possibly modulate each other because they cannot move independently."
So looks like I will be wiring each sub to 4 ohms and running a single sub off a single channel of the 4 channel amp, each in it's own enclosure - pretty much like building four subs and putting two back to back. No series connections for me.
Further progress. Bases sanded back, treated to a few coats of finishing oil. Cones and buttons bolted on with sorbothane washers.
Central dividers and subwoofer baffles cut from 25mm MDF ready to glue up with the pipe.
Central dividers and subwoofer baffles cut from 25mm MDF ready to glue up with the pipe.
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Stands built up. Tweeter housings fitted and filled with two part epoxy to reduce resonances.
Trial fit on stands.....
Pipe finally arrived! Soon subs will start being built too.....
Trial fit on stands.....
Pipe finally arrived! Soon subs will start being built too.....
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Looking good
Cheers guys - this has been the most complex and difficult speaker build I have ever done. At many points I kept wishing it was BB ply box!
Thanks!
I have already measured the tweeter in situ and the 1/2 inch round over and hemisphere actually measures better than it did on the previous baffle on and off axis. Probably partly because the ring radiator has a fairly narrow dispersion anyway. But I was surprised how good it was. See a few posts back for wesayso's experience of rounded tweeter enclosures.
I've used black felt on baffles in the past and have some in a drawer, so if needed I can add it later - good idea! Will wait for final measurements.
Subwoofer tubes are getting close too. They are fairly imposing, but should fill in from 80hz down nicely!
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bushy, I agree with Bon's earlier posts, but at a 3kHz xover, the MF/HF C-C distance is a lot too far for my liking. Too much lobing.
No it won't. Both channels driven it was 1.08kW/8R/ch. Behringer make good sub amps $/W, but don't ever believe their specs.
DF is pretty much irrelevant but as the 6000 is already a bridged 3000, it's not rated for 2R loads.
Hi Brett thanks for stopping by to critique, shame it is all a little negative
Diffraction is not good if a tweeter is mounted on a disc or cylinder.
But this is neither of those, it is a half inch round-over transitioning into a hemisphere. See the photos, see the actual measurements I made in response to Bon's comments earlier in the thread (plus many more), see Wesayso's personal experience of mounting a similar ring radiator tweeter in a very similar 'pod' with actual measurements again on the thread he has linked which shows similar results to mine........
Second - regarding your C-C comments and lobing.
Again, I agree with you - the closer the C-C distance the better - basic physics, much like diffraction off a sharp edge of a disc is basic speaker physics 101. In fact - I have made a synergy horn (which sounds very nice) and is probably the ultimate way to avoid this problem.
However, I am not sure what you suggest here - perhaps you haven't looked at the many pictures I have posted, but there is ~6-7mm distance from the edges of the Volt VM752 and the SS 7000. They are closer now than they were mounted on the original enclosures. I am not sure how I can physically mount them closer, short of butchering a $300 tweeter and grinding the faceplate of the 7000 down.......suggestions? (postive please!)
If you are of the impression that I should have used a smaller faced tweeter (as I have in previous builds) then perhaps you have missed the point of this thread - it was to reuse the drivers from a previous speaker....and build a new enclosure for them as outlined in my first post......plus given the original WA Prestige sounded extremely good and I will be using digital crossovers which of course can help with the whole lobing issue anyway.......
Brett - I agree with your sentiments (again!) that the ratings may be a little optimistic (but over 1000w per channel is fine by me).
However, again you have missed a trick here - we are talking about the NU4-6000, NOT the NU6000......these are different animals, this very point has already been discussed in this thread earlier after someone made the same mistake you just have! Bon made some interesting points on the differences and gave some real world experience of the NU4-6000 amp with output testing results he had made. The NU4-6000 amplifier is a four channel amplifier, not 2 channel, and is capable of 2 ohms loads.
I appreciate it when people provide constructive criticisms and comments and come up with ideas that might be helpful (such as using rods to mount my dual opposed subs to help with force cancellation which I am now doing).
Brett if you can provide any useful comments - like how to utilize the NU4-6000 in a better configuration, given it is a four channel amp (which is what I actually asked -again earlier in this very thread), how to mount the drivers closer etc, then please feel free to chip in.
Surely this site is about trying to help each other and share experience/knowledge?
First - I also agree with Bon's comments!
Diffraction is not good if a tweeter is mounted on a disc or cylinder.
But this is neither of those, it is a half inch round-over transitioning into a hemisphere. See the photos, see the actual measurements I made in response to Bon's comments earlier in the thread (plus many more), see Wesayso's personal experience of mounting a similar ring radiator tweeter in a very similar 'pod' with actual measurements again on the thread he has linked which shows similar results to mine........
Second - regarding your C-C comments and lobing.
Again, I agree with you - the closer the C-C distance the better - basic physics, much like diffraction off a sharp edge of a disc is basic speaker physics 101. In fact - I have made a synergy horn (which sounds very nice) and is probably the ultimate way to avoid this problem.
However, I am not sure what you suggest here - perhaps you haven't looked at the many pictures I have posted, but there is ~6-7mm distance from the edges of the Volt VM752 and the SS 7000. They are closer now than they were mounted on the original enclosures. I am not sure how I can physically mount them closer, short of butchering a $300 tweeter and grinding the faceplate of the 7000 down.......suggestions? (postive please!)
If you are of the impression that I should have used a smaller faced tweeter (as I have in previous builds) then perhaps you have missed the point of this thread - it was to reuse the drivers from a previous speaker....and build a new enclosure for them as outlined in my first post......plus given the original WA Prestige sounded extremely good and I will be using digital crossovers which of course can help with the whole lobing issue anyway.......
Brett - I agree with your sentiments (again!) that the ratings may be a little optimistic (but over 1000w per channel is fine by me).
However, again you have missed a trick here - we are talking about the NU4-6000, NOT the NU6000......these are different animals, this very point has already been discussed in this thread earlier after someone made the same mistake you just have! Bon made some interesting points on the differences and gave some real world experience of the NU4-6000 amp with output testing results he had made. The NU4-6000 amplifier is a four channel amplifier, not 2 channel, and is capable of 2 ohms loads.
I appreciate it when people provide constructive criticisms and comments and come up with ideas that might be helpful (such as using rods to mount my dual opposed subs to help with force cancellation which I am now doing).
Brett if you can provide any useful comments - like how to utilize the NU4-6000 in a better configuration, given it is a four channel amp (which is what I actually asked -again earlier in this very thread), how to mount the drivers closer etc, then please feel free to chip in.
Surely this site is about trying to help each other and share experience/knowledge?
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There are tutorials about wiring two 4R DVC subs in series-parallel to maintain the 4R impedance of a SVC sub.
https://www.youtube.com/watch?v=r0BoN_8DBDs
Then the NU4-6000 bridged will run 600 watts rms into each pair. This is the same power as driving each 4R woofer with a separate channel but I would expect a difference due to the different damping factors. I have just been testing some ICE power amps for bass performance. The results are similar to those I got with the Behringers. Bass measures really well and is super tight. As a consequence there might be a sense of bass lightness. I found I needed to tweak the bass levels up by 0.5 dB compared to my usual set-up. It is quite audible. This is my evolving impression of Class D amps.
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