Pearless XXLS 12 with passive radiator

**imbeaujp** · **10-20-07, 08:45 AM**

Hello folks,

I am a new member and I would like to discuss about a subwoofer project using pearless XXLS 12inches driver and passive radiator. I am going to build 2 subs. The subs will be drived by a Rotel RB-1080 and EQ with a Behringher FeedBack Destroyer Pro. Those subs will complete my HT system (5 Yamaha NS-1000 Studio Monitors).

If you have any recomendations regarding the cabinets:

- physical dimensions (total volume, with or wihout drivers ?)
- stuffing (yes or no ?)
- Material (recommendation)
- Driver and passive alignement (back to back ?)
- Etc...

I will post pictures of the building process and keep you inform of the final result.

Thanks !

JP

**tweeksound** · **10-20-07, 11:30 AM**

I am still in the early stages of learning sub design.
I'd love to see some pics and learn from this project.

It seems like a good idea to use some amount of stuffing but that might be a case by case thing.

I know that you should pay close attention to the impedence relationships between your amp and speaker as this is what willl determine the damping factor and the tightness and accuracy of the sub.

Good luck and keep us posted!

**warnerwh** · **10-20-07, 04:34 PM**

The first thing I would do is go for a 15" driver, they are only slightly more expensive and offer way more performance. That is of course you don't already have the drivers. Then again it may be worth selling them to finance different drivers. A 12" is kind of small for HT as you're trying to reproduce super low frequencies, say 12-15hz with authority.

I'd not worry about the damping factor, as long as the load is 4ohms or more you'll be more than fine. As a matter of fact many people here, maybe most, use pro audio amps for their subs. Last night on Ebay I found the Behringer EP 2500 for 250 shipped. This amp seems to be the favorite. It does need it's noisy fan replaced but this is very easy and cheap. The Rotel is worth 600 so you'll make a profit. That's what I believe most people would do, much more power and less money, not to mention less heat.

Being HT only a passive radiator of ported is what I'd do although when it comes to excellence a sealed imo is superior but you lose output capability. When you try to reproduce 16hz with power it takes alot of juice, the Rotel is pretty underpowered. Remember that every time you half a frequency the driver has to more 4 times as much! So you want a driver that can move mass big time and the POWER to drive it. Many here use multiple 15's and lately many are building them with 2 18's. These are high quality high output drivers being used btw, not wimpy ones.

When it comes to designing the box it depends on what you can get away with size aestetics etc. There is a program called WinIsd you can download for free. You can design a subwoofer with it but be sure to get someone else's opinion before you build.

If you cruise around this forum you'll find build threads with pictures. Also at AVS and HTGuide there are subs people have built. At HTGuide if you go to Missions Accomplished under the Mission Possible forum there's a thread with subs with pics and build threads. Read Read Read.

Hope this helps.

**WillyD** · **10-20-07, 08:36 PM**

The XXLS drivers are definitely good.

But with the Dayton RSS315-HF on special for $109, I'd go for it, that is if you want a 12". But like Warner said, these days the preferred drivers are 15" or 18". That isn't to say you wouldn't be pleased with a couple of 12s though.

Do you have any enclosure size restrictions?

**imbeaujp** · **10-21-07, 09:07 AM**

Thanks for thoses fast reponses !

I got to let you know that I alerady bought the Pearless drivers and passive radiators. So I am looking for some good advice to use that components.

I am going to build 2 subs (in stereo) because I think that multiple drivers is better than juste one big sub. Depending on the results, I am ok to add 2 additional subs but I really think that 2 will be ok.

I will try the RB-1080 to drive 2 subs in 4ohms (I alerady got that amp). It has an impressive 1000 damping factor and more 400 watts in 4 ohms. So it think that i will confortably reach the maximum XXLS 12 power rating (350 watts).

Feel free to correct me in anyway.

JP

**mpiotro** · **10-21-07, 09:37 PM**

I highly recommend Unibox for modeling different sub designs (also a free download). I really like the excursion plots that are automatically graphed so you can see how your changes not only affect output but what the drivers are doing at all frequencies.

**JCD** · **10-22-07, 12:33 PM**

Quote:

imbeaujp wrote:

Hello folks,

I am a new member and I would like to discuss about a subwoofer project using pearless XXLS 12inches driver and passive radiator. I am going to build 2 subs. The subs will be drived by a Rotel RB-1080 and EQ with a Behringher FeedBack Destroyer Pro. Those subs will complete my HT system (5 Yamaha NS-1000 Studio Monitors).

If you have any recomendations regarding the cabinets:

- physical dimensions (total volume, with or wihout drivers ?)
- stuffing (yes or no ?)
- Material (recommendation)
- Driver and passive alignement (back to back ?)
- Etc...

I will post pictures of the building process and keep you inform of the final result.

Thanks !

JP

So, some general observations..

Physical dimensions -- I'd go here.. it looks like they've already calc'd it for you.
Stuffing -- probably, but be aware that it adds to the "perceived" volume of the enclosure. Someone smarter than me can hopefully chime in on this one.
I'm assuming you're asking what the box should be made out of .. 3/4" MDF. And double up the front baffle.
Alignment -- I'm not sure it matters (again, I'm hoping for someone smart to jump in), but if I was going to do it, I'd probably have them on opposite sides of the enclosure.

Good luck.

JCD

**imbeaujp** · **10-22-07, 01:08 PM**

Thank you !

I would like to be more specific regarding box volume calculation. Manufacturer said 33 liters with a passive radiator (thanks for the link). But do we have to consider the driver volume inside the box ?

I mesure the driver volume this morning (Put them in a plastic bag and use real water displacement) : The main dirver is less than 3.5 liters, the passive is less than 2 liters. Roughly, the will use 5 liters. So do I have to consider that volume: build a 38 liters box to get a real 33 liters ??

Thank you !!!

**Mike P.** · **10-22-07, 01:53 PM**

Yes, you add the displacement of the driver, passive radiator and the bracing. The final net volume should be 33 liters.

**warnerwh** · **10-22-07, 11:52 PM**

Maybe I'm missing something but my SS RL-P 15" only uses about .2 liters of space inside the box. This driver is very heavy duty and large. How could that driver be 3.5?

**WillyD** · **10-23-07, 02:31 AM**

Quote:

warnerwh wrote:

Maybe I'm missing something but my SS RL-P 15" only uses about .2 liters of space inside the box. This driver is very heavy duty and large. How could that driver be 3.5?

Your Rl-p 15 actually displaces closer to .2 cubic feet of volume, not liters. So, 5.6liters.

**warnerwh** · **10-23-07, 04:17 PM**

Thanks Willy, you're correct.

**kano32** · **10-31-07, 11:10 AM**

Here's a link to North Creek Music. They designed a sub w/passive radiator and the cabinet plans are included. The only problem is that it's for the XLS not the XXLS. However, the cabinet listed on the North Creek site would be about the right size and it gives you a starting point. I hope this helps.

http://www.northcreekmusic.com/Thunder/ThunderInfo.htm

**imbeaujp** · **10-31-07, 12:22 PM**

Thanks for the link !

**Owen Bartley** · **11-01-07, 11:42 AM**

JP, it looks like you're getting off to a good start with this early advice. Now that you have your necessary enclosure volume, you can play with the dimensions until you get a shape that works for you (don't forget if you go ported, you'll also have to subtract the volume of the port, ideally). --Nevermind, just re-read that you're using a PR and have it accounted for already. Don't forget to use lots of bracing, especially on the larger panels, and subtract that volume as well. Do you have to make this a specific size to fit in somewhere, or did you have a shape in mind? I'd second the opinion of putting the driver and PR on opposite sides of the enclosure, but I think I've seen a few downfiring subs with the PR on one side. Keep us updated!

**imbeaujp** · **11-01-07, 02:01 PM**

Thank you verry much O.J. !

Realy appreciate your input on this project.

I do not have any limitation on the physical dimensions but I do not want to create a big monster. I think that de final design will be around 16X16X16 in a back to back drivers/passive configuration. But I am ok if someone recomend another design.

The 2 subs that I am going to build will be used to add deeper bass for my 5 Yamaha NS-1000. I want to go as low as 18Hz. I am looking for Stereo HI-FI bass and HT. So I think that the passive radiator concept will respect all thoses requirements including reasonable dimensions.

I am waiting for my Behringer FDP and Microphone to start this project. So any recomendation is welcome ! I will post picture soon.

JP

**Owen Bartley** · **11-01-07, 08:39 PM**

Just looking at the numbers again JP, and I know that alignment specifies 33L, but when I think about it, that's a pretty small box. Generally, the larger the box is, the lower it can play, but I'm not sure if you'd have to change the mass of the PR if you changed the volume, or if that is already an "ideal" alignment. I guess if you can get the TS parameters of the driver you can model some different options, which is a good way to learn what the various changes do to the sound. It has been a while, but I remember it helped me a lot when I was working on my Tempest.

**imbeaujp** · **11-06-07, 08:28 AM**

Hello folks,

Here are all the data I got to build my project (PDF). I am trying to use unibox to get final dimensions but this is my frist time and I am not sure how to use it...

If someone could help me on that (unibox), it will be appreciated !

JP

**Owen Bartley** · **11-06-07, 09:58 AM**

JP, it's been a while since I've used Unibox, but I think I just started plugging in numbers and figured it out as I went, it isn't too bad from what I remember. Have you put all the easy data in yet? (T/S parameters, etc.)

I just grabbed the program and did a quick model using your drivers, and maybe I'm not remembering things right, but I'm getting an F3 of 44.87 Hz which isn't too impressive.

In any case, the actual dimensions themselves don't matter that much, it's the internal net volume that's important, and you can calculate that just by playing with the numbers. Roughly calculating, in internal cube of 13 x 13 x 13 inches gives you about 1.1728 cubes (33.2L - google conversion). Then you'll have to account for the driver and PR volume, so you'll need a little bigger.

I hope I'm not steering you in the wrong direction here... anyone want to give a second opinion?

**imbeaujp** · **11-07-07, 12:46 PM**

Hello all and thank you for your support on this.

I recieve today all the components to start my project !!!

Behringer DSP1124P
Peerless XXLS12 Sub (2)
Peerless XXLS Passive (2)
Behringer 8000 microphone
RadioShack SPL
And the software : Unibox and REW

I will try unibox today to get the final parameters and I will build a prototype this week-end.

JP

**imbeaujp** · **11-12-07, 07:35 PM**

Hello again !

I did my first try with unibox last week-end. Hope I did it the right way...

If someone could check that I really appreciate it.

Thanks !

Here is the graph:

**imbeaujp** · **01-08-08, 01:07 PM**

Hello folks !

The 2 subs are now done and I could start some mesurements with RoomEQWizard !

I placed the subs under my front speaker to make a first test. Here are the graphs :

The first one is without EQ and the second is with some filters, just to check out how to use the BFD... I will do more serious work this week-end. First with speaker placement and then with some EQ

JP

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