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15" Simple Reflex

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mrspeedy View Drop Down
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    Posted: 22 June 2012 at 1:55am
Hi, 
I'm after a bit of advice regarding the pair of single 15" reflex cabs that i made many moons ago.

The build, well, i knocked up a 120L box, ported it with 3 large ports and stuck a Celestion FTR-15-4080F in it.

I thought they were awesome to start with, but now I have heard other small 15" reflex subs and I'm a little disappointed with mine! 

I run a pair of 18" w bins rated at 500wrms and 1k peak @8 ohms and i run them of a Pulse 1100.
Those cabs will take all of the pulses power which measured at Abletronics on a like for like amp was around 850 watts.
If I stick nearly full power into my '600 watts rms, 2.4kw peak' celestions, I can hear the cones bottoming out and they dont really have much in terms of general bass output to be honest.

HPF is at 38hz by the way.

Here is a picture of one of the cabs hopefully showing the ports, rough lengths and just what the cabs look like:




Below the ports and above the driver on the inside of the cab, if you imagine a piece of wood which splits the cab into 2 chambers (1 chamber with the ports, and 1 with the driver). I cut a circle of roughly slightly less than the diameter of the box in that divider as a way of bracing the cab.

Could it be that there is too much port gap, ie making the driver seem as if its in free air? 
Or is the driver just not that great in this box?
Don't get me wrong, they're great little cabs but I just think the output of the box may be hindered slightly by the design of it?
I'd be grateful for a quick opinion!

Thanks
Toby


Edited by mrspeedy - 22 June 2012 at 1:55am
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Muckerbarnes1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Muckerbarnes1 Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 2:04am
Toby, Pulse 2x1100 on sub is pants. Try a better amp to start with.
Billy Dawg.
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mrspeedy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrspeedy Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 2:09am
Knew that was coming!
I used to run them from a Cerwin Vega CV2800, (which was matched to the subs) I will test them with this amp tomorrow!
However I have run the 1100 with my 18's for a while now and I like how it sounds!
Could it be the celestions are a bigger/heavier driver to move and the pulse can supply the power but just cant supply the grunt? 


Edited by mrspeedy - 22 June 2012 at 2:27am
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Tony Wilkes View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tony Wilkes Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 7:06am
When you built the boxes originally did you calculate the ports and actually measure them when they were built?

From memory when I used that driver a few years ago it was in a 80l Net box tuned to around 45 hz.

Not the greatest of drivers,

Tony
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mrspeedy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrspeedy Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 9:51am
Hi Tony,
I used winisd and it calculated those ports for me, whether there was an error in some driver spec that I inputted I'm not sure?
I was just wondering really if there was anything that looked apparently odd with the boxes, they are tuned to 48 Hz IIRC.
They're great for little gigs but you do wish you had more sub at the end of the night!

Hope that answers your question, I didnt do anything with port length either as win isd didn't tell me to so I left them standard out of the packet.

Edited by mrspeedy - 22 June 2012 at 9:52am
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Muckerbarnes1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Muckerbarnes1 Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 10:06am
Toby is the 120L you state an internal volume, or is this the outer.
 
Give us the box measurements outside, and others.  This driver Ihave never used, but heard. Never been impressed, but as usual the specs outweigh the goods. 
 
Is the surround on the Celestion sticky Tony ( or Toby) as the surround looks Muller, like my torn ones.....
Billy Dawg.
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mrspeedy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrspeedy Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 11:40am
The box is a 120L internal volume, external dimensions are as follows:
(WxHxD) : 49cm x 66cm x 52cm

They do have a 'shelf' like brace with the circular cut out which braces the box and theres a brace below that directly behind the magnet which has a semicircular cut out (1/2 the depth of the cabinet) otherwise identical to the shelf above (just half of it).
In the corners there are 45 degree angled fillets (40mm x 40mm).

The surround is hard, a glossy hard finish but allows flex.
Sorry Malcom but whats Muller? 




Edited by mrspeedy - 22 June 2012 at 11:43am
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GekoMusic94 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GekoMusic94 Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 12:19pm
I think the problem is the tuning frequency... What's the lenght and diameter of the ports?

Giacomo. Smile
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odc04r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 12:39pm
Your tuning frequency may be too high causing unwanted extension under it and lack of bass extension. A bad combo.

Do you have the tools to make an impedance plot of the cabinet? It's not as bad is it sounds.

A sinewave generator (can use PC and program), Voltmeter that is half accurate measuring RMS voltage, and a good accuracy medium power resistor. 2 multimeters make it even easier.

This will tell you exactly where your tuning frequency is. WinISD is a good guess but won't get it perfect.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Muckerbarnes1 Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 1:00pm
Originally posted by mrspeedy mrspeedy wrote:

The surround is hard, a glossy hard finish but allows flex.
Sorry Malcom but whats Muller? 


 
Muller manufacture software ( cones, surrounds, spiders). Often the same software is on similar speakers. The surround on your Celestion looks the same as a 15XB, but thats another story.
 
+1 on testing the box tuning. If you find a download PDF of Loudspeaker Design Cookbook by Vance Dickason, or better still buy this bible, then there is a section on box testing. This will help you far more than any PC sim junk.
Billy Dawg.
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mrspeedy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrspeedy Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 2:49pm
Giacomo, 
Port diameter of 10cm
Port length of approx 12cm

Ok guys cheers i'll take a look, if my tuning frequency is too high then what needs to be done in the way of adjustments to the box or are they scrap Cry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote infrasound Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2012 at 2:57pm
Originally posted by mrspeedy mrspeedy wrote:

Giacomo, 
Port diameter of 10cm
Port length of approx 12cm

Ok guys cheers i'll take a look, if my tuning frequency is too high then what needs to be done in the way of adjustments to the box or are they scrap Cry


No, just need longer ports.
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