# SDX 15 with Passive Radiators



## Machahee (Dec 18, 2009)

Hey guys, new to this forum but I have been a lurker for a while now. I've been doing a lot of research on a sub build I would like to try and would like to get some info from people much more knowledgeable in the subject than myself heh. 

I'm looking at 1 SDX15 with 2 APR 15 Radiators being powered off an ED LT 1300. I've seen the plans of others where the box is roughly 6 cu ft in volume or slightly larger. I would like to try to get the box to roughly 5 cu ft or so if I can. I have modeled a 5 cu ft setup in winisd with 900grams on the passives which shows a tune of 19 hz. From what I can interpret the plot looks very smooth. 

I would like something really impressive for theater use but still be able to have a nice chest slam for music...so maybe around a 22hz tune? Any advice would be greatly appreciated. Thanks.


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## Mike P. (Apr 6, 2007)

Thge first thing is to find out if the ED LT 1300 amp is first generation or second generation. The first Gen. didn't have a Hi-Pass filter, the second Gen. has a Hi-Pass filter at 20 hz. Finding out which amp you will be using will determine what the best recommendation is.


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## mwmkravchenko (Jul 11, 2009)

> I would like something really impressive for theater use but still be able to have a nice chest slam for music...so maybe around a 22hz tune? Any advice would be greatly appreciated. Thanks.


Chest slam is also called body cavity resonance. It ranges from 150 to 170 hz. For comparison Kick drum is at or around 100 to 120 hz. The lowest string B flat on a six string bass is around 32 hz. SO chest slam is a function of how loud you are pushing upper bass lower midrange. Your sub is usually out of the picture up that high in frequency. The chest slam comes from the main speakers. If they do not have the cone area to get loud enough they are the culprits not the sub.

Mark


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## Machahee (Dec 18, 2009)

Thanks for the replys. Thanks for the defintion of "chest slam" I wasnt aware it was higher in the frequency band so I guess Im not too concerned about having that in the sub hehe. Yes I noticed that the amp has two generations, I would definitely be getting the one with the hpf built in with this type of arrangement.


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## Mike P. (Apr 6, 2007)

> I would like something really impressive for theater use but still be able to have a nice chest slam for music...so maybe around a 22hz tune?


It's easy enough to add or subtract washers from the PR's to find the best tuning frequency for the sub in your room.


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## Machahee (Dec 18, 2009)

Mike P. said:


> It's easy enough to add or subtract washers from the PR's to find the best tuning frequency for the sub in your room.


Right, it's one of the reasons I want to go with pr's for the tweakability. My main question I have I guess is will dropping roughly a cubic foot off the ideal cubic foot winisd recommends hurt much. From what I can gather is there will be a steeper roll off below 30hz but cone excursion seems to be ok still. Sorry for the simplistic questions I'm more accustomed to sealed boxes and playin with the size affects the q which effects the sound of the sub. Thanks again.
_Posted via Mobile Device_


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## mwmkravchenko (Jul 11, 2009)

A smaller cabinet will require more weight on th PR's. It will lower sensitivity and also create a bump in the midbass response. But the bump won't be that large of a peak. 

The grestest loss will be a db or two on ouput.

Mark


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## Mike P. (Apr 6, 2007)

There would be very little difference in output in a 1 cu.ft. smaller box.


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## Machahee (Dec 18, 2009)

Thanks guys that's what I was looking for. I just wanted to make sure I wasn't forgetting something. I was looking at the kit CSS has for the 15 and it has the Dayton amp bundled with it. Does that amp have a built in hpf? The savings with the bundle is nice even though it was out of stock as of yesterday.


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## Mike P. (Apr 6, 2007)

Yes, the Dayton amp has a 3rd order HPF at 18 hz as well as a single band of EQ.


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## Creative Sound (Mar 29, 2007)

Machahee said:


> Thanks guys that's what I was looking for. I just wanted to make sure I wasn't forgetting something. I was looking at the kit CSS has for the 15 and it has the Dayton amp bundled with it. Does that amp have a built in hpf? The savings with the bundle is nice even though it was out of stock as of yesterday.


Hi,

Apologies, I have stock and have adjusted the inventory flag. Stock on the drivers, however, is very low and we are working on the Mk II version which will require reworking the Quartet15 kit.

Bob


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## Machahee (Dec 18, 2009)

Thanks again for the info guys you have been most helpful. Hi, Bob thanks for letting me know that, was going to send you an email hehe. I'm not in a big rush really. I understand if you can't say but is there an ETA on when we might see the MkII Kit for sale? I would imagine it will be worth the wait!


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## Creative Sound (Mar 29, 2007)

Machahee said:


> Thanks again for the info guys you have been most helpful. Hi, Bob thanks for letting me know that, was going to send you an email hehe. I'm not in a big rush really. I understand if you can't say but is there an ETA on when we might see the MkII Kit for sale? I would imagine it will be worth the wait!


Hi,

For a variety of reasons the SDX15 Mk II is further away than I'd like. Should have a better idea in about a month and yes, it will be worth the wait!!

Bob


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## Machahee (Dec 18, 2009)

Sounds like I will be waiting for a little while! With all the wonderful reviews of the current generation of driver I'm very curious to see what you guys have up your sleeves!! hehe


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## Creative Sound (Mar 29, 2007)

Machahee said:


> Sounds like I will be waiting for a little while! With all the wonderful reviews of the current generation of driver I'm very curious to see what you guys have up your sleeves!! hehe


Hi,

In addition to the feedback we gathered over the life of the current generation there are now 2 designers working with me on this. It's likely that excursion, weight and cost will all go up. Decisions, decisions....

Bob


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## Machahee (Dec 18, 2009)

Hmmm decisions indeed!! Lol Do you expect to see another Passive kit with the new driver as well?


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## Creative Sound (Mar 29, 2007)

Machahee said:


> Hmmm decisions indeed!! Lol Do you expect to see another Passive kit with the new driver as well?


Hi,

That's the plan but if we can get power handling and output up significantly 1000 watt plate amps and 15" APRs might not cut it!!

Bob


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## Machahee (Dec 18, 2009)

Well I'm sure you guys won't let anyone down with it regardless hehe. I just put in an order for the quartet kit, was gonna do 2 of these but just gonna build one for now and upgrade my main room to the new drivers when they come available. I'll probably move this sub to a secondary room where only one sub will be necessary. You can never have too many subs hehe


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## Mike P. (Apr 6, 2007)

> You can never have too many subs hehe


My kinda guy! I have 8 subs, 6 are currently in use. :whistling:


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## Machahee (Dec 18, 2009)

Wow 8 subs and 6 in use!! That is most impressive! What subs are you running at the moment?


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## Mike P. (Apr 6, 2007)

The HT room has a pair of Mach 5 Audio IXL-18's and a pair of Ascendant Audio Atlas 15's. The living room has a IXL-15 and the workout room has a CSS SDX10. In storage is a IXL-12 and a Adire Audio Shiva 12.


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## Machahee (Dec 18, 2009)

Wow nice subs all around. A pair of 18's and 15's in the theater room? talk about effortless bass!! How do you have those setup?


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## Mike P. (Apr 6, 2007)

The 18's are against the back wall and the 15's are on each side of the couch, facing each other. Action movies are an experience!


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## Machahee (Dec 18, 2009)

Lol ya I can only imagine!!


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