I'm contemplating re-building a pair of subwoofers I made several years ago. They are currently set up similar to the sono-subs in a passive stereo pair. Since I now have a digital HT, I have been thinking of going to a powered single-sub configuration.
So, with that in mind, that means I have a pair of 10" peerless subs to use. I have been toying with a half-a-dozen different ideas/configurations. Recently I've been toying with the idea of using the two in one box to help with the bottom end in a sealed enclosure, and thought maybe the push-push idea would be interesting.
Here's some specs/limits:
The woofers are 10" Peerless 260SWR (831727)
The maximum box size is in the 3 to 4 cubic foot range.
The box will be place in a corner in the room.
Transmission line, while a neat idea, is more than likely out. (I don't think it'll fit in the space requirements.)
The amp hasn't been purchased yet, but am currently looking at the ApexJr plate amp.
So, any thoughts on doing a push-push with these limits?
In push-push, do the speakers have to be back to back? (What about 90 degrees to each other)
Will having one speaker fire into the wall kill the push-push idea? (Up/down is out, as it will be used as a quasi end table as well)
Any other suggestions for other arrangements that would be fun?
Thanks for the help and info!
So, with that in mind, that means I have a pair of 10" peerless subs to use. I have been toying with a half-a-dozen different ideas/configurations. Recently I've been toying with the idea of using the two in one box to help with the bottom end in a sealed enclosure, and thought maybe the push-push idea would be interesting.
Here's some specs/limits:
The woofers are 10" Peerless 260SWR (831727)
The maximum box size is in the 3 to 4 cubic foot range.
The box will be place in a corner in the room.
Transmission line, while a neat idea, is more than likely out. (I don't think it'll fit in the space requirements.)
The amp hasn't been purchased yet, but am currently looking at the ApexJr plate amp.
So, any thoughts on doing a push-push with these limits?
In push-push, do the speakers have to be back to back? (What about 90 degrees to each other)
Will having one speaker fire into the wall kill the push-push idea? (Up/down is out, as it will be used as a quasi end table as well)
Any other suggestions for other arrangements that would be fun?
Thanks for the help and info!
I heartily recommend push-push. Chris & i are working on V3. Pic is V1 using 2 x Philips 12". The box is about 2.8 ft^3, and in the cases of V1 & V2 are both aperiodic (the drivers would really like to see bigger boxes). The top 2 images show the brace used to ridgidly connect the 2 magnets together -- the blue foam is closed cel and quite thin and provides just enuff to tightly couple the magnet to the brace. It is important that the drivers are on oppossite sides & tied together mechanically.
Both V1 & V2 (customer supplied Foster 12s) turned out really well. Both use drivers that are more intended for midbass use than sub use. They go low cleanly and integrate very well with the sats (in both cases a quartet of BD-Pipes with RS 40-1197s). The push-push loading means very little mechanical energy transfer to the box.
dave
Both V1 & V2 (customer supplied Foster 12s) turned out really well. Both use drivers that are more intended for midbass use than sub use. They go low cleanly and integrate very well with the sats (in both cases a quartet of BD-Pipes with RS 40-1197s). The push-push loading means very little mechanical energy transfer to the box.
dave
Attachments
I have two alternative subs for my new Nonsuch range. The Little Awesome and the Bigger Awesome.
The Little Awesome is like an oval barrel with the driver (Bandor 150) firing out of the bottom.
The Bigger Awesome is a Push-Push, comprising one Little Awesome mounted upside-down so that the driver fires upward and the other one normal-way-up on top of it, separated by 2" - 3". The sound comes out of the middle, between the two drivers.
Clear as mud? Sorry I haven't got any drawings to show you. I just figured that the vibration cancellation would be even more effective if I could get the two drivers close together.
Anyway, if you can figure out what I mean, I put this forward as another alternative because the drivers are in the centre so you could still put coffee cups on top.
If you don't want to go for this vertical approach, I still wouldn't recommend the 90 degree thing as you would lose the vibration cancellation benefit.
As for whether you can fire into the wall (presumably there will be a gap between speaker and wall), I believe that this depends on the highest frequency the speaker has to produce. Down in the deep bass I don't think the speakers will care (some disagree) but if they go above, say, 150Hz - 200Hz you may have a problem.
For the particular driver you're using and the volume required, Push-push would require double the box size of a single driver.
Hope this is helpful.
Steve
The Little Awesome is like an oval barrel with the driver (Bandor 150) firing out of the bottom.
The Bigger Awesome is a Push-Push, comprising one Little Awesome mounted upside-down so that the driver fires upward and the other one normal-way-up on top of it, separated by 2" - 3". The sound comes out of the middle, between the two drivers.
Clear as mud? Sorry I haven't got any drawings to show you. I just figured that the vibration cancellation would be even more effective if I could get the two drivers close together.
Anyway, if you can figure out what I mean, I put this forward as another alternative because the drivers are in the centre so you could still put coffee cups on top.
If you don't want to go for this vertical approach, I still wouldn't recommend the 90 degree thing as you would lose the vibration cancellation benefit.
As for whether you can fire into the wall (presumably there will be a gap between speaker and wall), I believe that this depends on the highest frequency the speaker has to produce. Down in the deep bass I don't think the speakers will care (some disagree) but if they go above, say, 150Hz - 200Hz you may have a problem.
For the particular driver you're using and the volume required, Push-push would require double the box size of a single driver.
Hope this is helpful.
Steve
7V said:
Like the attached image? A very interesting design thou from a cosmetic point-of view.
Face-to-face is harder to get good coupling. The only way i can think of would be to use somesort of driver attachment that couples the 2 drivers together, but i can see complications with assembly.
Best is magnet direct to other magnet & the frame rims also tied together. If you can bolt the two drivers together even better.
An externally hosted image should be here but it was not working when we last tested it.
If this had the magnets touching it would exemplify what i'm suggesting.
dave
Attachments
planet10 said:
I've seen this before, somewhere. Now, is the basket a contraption that is housing the drivers for some reason? Am I reading that correctly?
What I mean is: are those baskets the things actually absorbing the mechanical energy, or are the drivers still driving against each other?
Dave
kneadle said:
The ultimate push-push is based on the PEARL PR2 woofer.
The magnet assembly sits inside the basket and it is designed to be bolted thru the polepiece. This is a very rare driver. With more accessible drivers some compromises or other tricks would need to be enabled. But if you are getting an OEM batch of drivers it is worth thinking about using these features.
dave
So let me see if I have everything straight... to model the push-push I just use a two woofer in parallel configuration in the modeling software. (I'm switching between winisd and unibox) My only concern with the sealed box is that the software shows these drivers having an F3 of about 50Hz in a sealed configuration. Since they're being used for a combo system (HT and normal music) I'm a little concerned about the bottom end for music. Will the corner loading really help make up for the high F3? (I'll also be using the sub-out from the AV unit, a Denon digital, which I think starts a roll-off around 80Hz)
Also, when it comes to the physical connection between the two, it just really needs to be a tight, solid connection between them, and not necessarily actually touching magnet to magnet. (I know this would be better, but I'm just trying to clarify things) As to bolting the baskets together, what do you think about lengths of all-thread between the two, or would there be vibration problems? As to bolting through the pole-piece, I don't have enough experience/confidence to try that.
As to the gap between the one woofer and wall, we're talking only a couple of inches, unless a build a top that really stretches out.
On to Steve's (7V's) design, it sounds interesting, but a couple of questions. Have you had a chance to listen to it yet? How does it sound? Also, what's the air gap between the two subs, and is it open on all sides, or did you design it to be similar to a port between the two? (Only one or two walls open)
I know, I have a lot of questions, but right now I don't have the time to build it, only design it and I might as well get as many ideas as I can before I have the time.
Thanks for the help and suggestions!
Also, when it comes to the physical connection between the two, it just really needs to be a tight, solid connection between them, and not necessarily actually touching magnet to magnet. (I know this would be better, but I'm just trying to clarify things) As to bolting the baskets together, what do you think about lengths of all-thread between the two, or would there be vibration problems? As to bolting through the pole-piece, I don't have enough experience/confidence to try that.
As to the gap between the one woofer and wall, we're talking only a couple of inches, unless a build a top that really stretches out.
On to Steve's (7V's) design, it sounds interesting, but a couple of questions. Have you had a chance to listen to it yet? How does it sound? Also, what's the air gap between the two subs, and is it open on all sides, or did you design it to be similar to a port between the two? (Only one or two walls open)
I know, I have a lot of questions, but right now I don't have the time to build it, only design it and I might as well get as many ideas as I can before I have the time.
Thanks for the help and suggestions!
Schaef said:
No, I haven't had a chance to listen yet. I'm picking it up over the weekend from the company that's finishing the enclosure.
The gap is 6cm (2.5"). It's open on all sides (well 'cabineted' at the back of course), connected by four steel rods. If it isn't open you may have to increase the gap size.
Steve
Shaef,
If by "all-thread" you mean threaded rod, then yes, you could use this, but you would have to cut it to a suitable length to avoid the chance of the cone snagging on it. And vibration would be an issue, but epoxy should cure that, maybe silicone as it's less permanent.
I would do it with a long threaded sleeve if I found one at the HW store.
And for irony, I was looking around for pictures of woofers with frames suitable for this mod, and I found 2 with a perfectly shaped frame sitting on my shelf...2 old 10" cheapies that planet10 told me to consider a push-push for back in Dec.!
If by "all-thread" you mean threaded rod, then yes, you could use this, but you would have to cut it to a suitable length to avoid the chance of the cone snagging on it. And vibration would be an issue, but epoxy should cure that, maybe silicone as it's less permanent.
I would do it with a long threaded sleeve if I found one at the HW store.
And for irony, I was looking around for pictures of woofers with frames suitable for this mod, and I found 2 with a perfectly shaped frame sitting on my shelf...2 old 10" cheapies that planet10 told me to consider a push-push for back in Dec.!
Schaef said:
But what is the F10. With room gain this is a far more important number. Many a sub is designed to be flat way low in the modeling software and ends up being a big lump once it gets into the room.
The tighter the coupling the better, magnet to magnet is impracticle in most cases (but there are tricks). A bolt thru the polepiece in a driver not designed for such is potentially harmful to the driver (ie get the spacing wrong by a bit and you could pull the magnets off the drivers).
dave
leadbelly said:
all-thread (aka ready rod) is exactly what i had in mind -- sheathed on the inside with a couple layers of heat-shrink to kill off potential resonances -- it should be tight enuff that resonances will be fairly high in frequency, but the potential does exist for this to act like a guitar string.
dave
If anyone is feeling daring, you could use two woofers with center vented pole pieces. Carefuly cut away the dust cover, and you have a hole ready to accept a rod. Run the rod through the center of both pole pieces, and secure the rod with locking washers or nuts. If you wish, you can re-attach the dust cap to make everything look pretty. This would also work with the solid aluminum spacer between the magnets as was posted earlier. You wouldn't need any speacial driver for this configuration, as vented pole piece drivers are very common.
Any comments folks?
Any comments folks?
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