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Discussion Starter #1
Whilst browsing for some spare parts I noticed Jaycar (Australia) had a new Sub released this year. Produced for the brand Re/sponse, which is a pretty well respected brand here. They are only A$49. rated 225watts rms (500 peak) @ 8Ohms with an Fs of 31Hz. From the spec's they look like they'd make a pretty awesome music sub. At $50 I bought one to have a play with and thought I'd post my experience. These seem to be somewhere in the middle of the road as far as subs go so I am going to model and build a couple of enclosures (including one for the car) and we'll see where I end up.

First couple of graphs I have modeled using small enclosures:
graph.jpg

Yellow: 18.5 litre sealed enclosure.
Grey: 20litre ported enclosure tuned to 25Hz.
Red: 20 litre sealed with a linkwitz transform circuit, I expect I'll need twice the power in my amp and I haven't tested the driver yet for its compatability with this enclosure.

Next some happy snaps of the actuall driver and some more specifics on some of the enclosures.

Any thoughts or ideas?
 

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Hi Drf,

Too little info about the driver! I can't call the yellow and white curves "subwoofers". The red one seems much better but looks to be like quite theoretical for a 20 L sub (although I have now idea about the driver).

Any idea about excursion? FR?...
 

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Discussion Starter #3
Their are no excursion details and the freq graph that comes with the driver probably isn't that accurate.

freq.jpg

All the graphs are theoretical. The red one is after applying a linkwitz transform circuit. I honestly think I can get this sub to go halfway between the red and grey lines in reality, but I doubt I will get results as good as the red model. Remeber this sub is only about $30 american, so it is very cheap. Do you know how to calculate or measure the excursion with any degree of accuracy? I would be interested to know if this can be done. I will try and measure my own response graph for this driver but it will require some time for me to get my gear together.
 

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Without driver specs, it's not possible to expect anything.
 

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By eyeballing the graphs it looks like you have 18db of boost at 20hz in the LT circuit. This is going to seriously eat into your headroom.

For 30$ I would doubt it could handle much more then 200w. Lets say 256 to make the math easy :). With 18db of boost 4w at 100hz would mean 256w at 20hz. And my guess is that for 30$ you will run out of Xmax before you run out of thermal power handling.
 

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Discussion Starter #6
More than likely.

One of the major drawbacks to using a linkwitz transform is the reduction in headroom.
This maywell be moot point though because I haven't tested the driver to see if it can handle a transform.
 

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Discussion Starter #7
Well, I got it out of the box and this is what it looks like:

side.jpg

front.jpg

rear.jpg
 

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For the money paid...this driver looks pretty good it seems to have some excursion too :bigsmile:

Nevertheless without driver T/S parameters you'll have to make a trial and error until you reach the correct box. size / configuration... Sorry :hide:
 

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Discussion Starter #10
http://www.jaycar.com.au/productView.asp?ID=CW2199&CATID=15&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=396

Their website is a little backwards at times, I found this sub in their car audio section :no:.

Blaser the T/S parameters are provided, I thought when you asked about excursion and FR I didn't realise you meant T/S aswell. Anyways, the T/S is all in the link.


I have also started pluging 91-130 litre enclosures into winisd and the results aren't too bad.
 

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That looks quite nice for an inexpensive woofer. I wonder how it would do in something like a 3 way tower design, where it wouldn't have to play as low as a dedicated sub. On the other hand, it does look like it could still be used to supplement a small system, as long as expectations are reasonable.
 

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Didn't know if you caught it but that sub is shielded. The 2nd slug is a bucking magnet. Still looks like a good value sub though. Nice size spider and surround on it.
 

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Discussion Starter #14
Didn't know if you caught it but that sub is shielded. The 2nd slug is a bucking magnet. Still looks like a good value sub though. Nice size spider and surround on it.
I did a little testing and that second magnet doesn't buck anything. The magnetic field from this sucker is quite strong and quite large. I believe* the idea with having a second ring is to extend the linear range of the VC without excesively increasing the cost of production.

Whilst I didn't get much time to play this weekend I did manage to get a new RS meter and am learning how to use it with REW. I did have ago with REW sometime ago but for the life of me I couldn't get it to work with my old gear.

*most logical explanation I can think of for having two rings slightly apart versus one large ring.
 

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Discussion Starter #15
I hate being a full time single parent :( , This weekend I only had time to throw the sub into a small sealed enclosure and have a quick play. The results weren't worth measuring so I when I get more time I will try a slightly larger enclosure and try a few test tones. From my experiments so far I don't think this sub is going to come anywere near its modeled predictions.
 

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Thanks for the link, drf. Out of curiousity I e-mailed them asking what the Xmax is. Hopefully they will reply.
The specs as shown are average for a twelve inch woofer. What separates the men from the boys is xmax, and not knowing that makes suitablility as a sub an unknown quantity. Even $30USD is too much for a pig in a poke. :huh:
 

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Looks like a wanna-be JL audio driver - which is cool because I like the dish cone look. I'm tired of dusk caps on subwoofers - I want more sexiness in my drivers. TC/AP, SS, and JL all do a good job of it and this driver doesn't look bad so why can't I have middle of the road drivers look good?!
 

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Discussion Starter #19
Well, as is usuall with all my adventures, they are taking a long time to piece together.

However I have managed to try a few enclosures and discovered that this sub really sucks in a 4th order bandpass box. I think there is just way too much tweeking to be done to warrant using this sub in this allignment. However I did try them out in some small sealed boxs. Red is the response I got without room treatment or equalisation.

twocheapies.jpg


As you can see its pretty ordinary. So I built this transform and power supply and wacked that in the mix.


ltransform.jpg ps.jpg

The Cyan is measured with levels set to 75 and the blue is set to 80.
 
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