Tired of small scale OB, going big..Selenium 15PW3-SLF-15 questions.?

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I am about to order abunch of Selenium 15PW3-SLF-15 drivers for OB bass driven temporarily by a pairof BASH 300S plate amps which go to 150hz 4th LR. I am then to use TT 12" Alnico for mid bass & B & C DE10 for for up top & may try othe CD's till I am happy up top. SET will be used on TT & CD. Question is ...How many 15" Selenium can I go without crazy low ohm. I would like 4- per side, but wiring this for no less than 4-ohm load I have not done before. WAF is NO factor in any of this,I have dedicated play room. I wood use my 45 for low volume listening & 300B for maore oomph..bi-amped at very least & maybe tri. Thanks for any help. $ 500.00 is budget for bass driver excluding shipping.
Can I please get a suggestion for the configuration of the 4- per side Selenium 15PW3-SLF. So many ways to do it. I thought of just vertical line like AJ's, but then Magnetar's config looks good. I also thought of just a horizonal line, side by side mounted about 3" about floor or so. I am to order these drivers this weekend & a minimum of 8 will be ordered. Any help would be very cool...
thanks...J & G
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If you are cutting them off with a plate amp, the need to have them vertical is not critical as it is with drivers carrying higher frequencies. You need to consider the room and how the drivers will load in your environment ie: close to the floor will use that plane to reinforce, but it usually comes down to where things will fit when using that many drivers. Usually with 4 per side the need to reinforce is not as critical either as you have lots room to EQ.

Polar plots for 4 OB: s in point source arrays can be seen in the picture 1(1). Observe the polar plots show only the first wave front from the arrays and only localisation conclusions can be discussed.




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Hi J&G,

The big system with 8 18" woofers on OB sounded quite nice. It got plenty of basss, that's for sure, but it was the depth and spatial vividness of the soundstage that I thought was fairly special. I used to demo the system to my friends by playing the "drum dance" music on the third track of the soundtrack CD of "House of Flying Daggers." I had a lot of fun listening to that track loud. It is a pity that I had to take that system apart when I moved from the Chicago area to the Bay Area.

If you don't mind, and if you have not yet placed the order for the Selenium woofers, I'd like to suggest that you check out another woofer. Kevin Haskins at DIY Cable is developing a 15" woofer for OB use, and based on the numbers given, it could be a much better choice for OB use.


One parameter that I consider very important is the Fs of the driver. It is hard to EQ the response of a woofer on OB past the Fs of that driver, so it pretty much defines the bass extension. The DIY Cable OB woofer, with an Fs around 20Hz, will allow you to get nearly another octave of bass below the 37 Hz Fs of the Selenium driver. Its Xmax of 22mm is also a big plus, and needed to allow the woofer to play down low.

Hi Kurt,

That woofer looks good but it takes over 10 times the power for the same SPL. Sure you lose some of the low end with the Selenium but it's not that bad at Fs 37 Hz. I can only imagine the power needed to drive Kevin's woofer down to 20 Hz after you factor in the EQing. I'm wondering if his woofer isn't better suited for IB rather than OB.
Fortunately watts for bass come cheap these days and Joe I believe has 300 of em on each end, if I am not mistaken. I think that one or two of Kevin's drivers with those BASH amps would be plenty. I have been looking at that driver and it appears best yet suited for OB. I once heard the XBL^2 7 inch in those RAW HT3 here, and was completely dumbfounded by the amount of clean, tight, dry bass they delivered. .... we are talking about 15 inch versions of those, here.

I am signed on for a pair to try when the order arrives, FWIW.

TT Alnico 10 forthcoming.

Joe, did you have a look at the TT Ceramic 8?
The RAW HT3 driver is from Bob Reimer of CSS . Does Kevin's share the same bloodlines? I know those two know each other quite well but I wasn't aware of any connection. My main concern was the power requirements to achieve 20 Hz in an OB. To me that seems staggering whereas the Selenium, although one octave less seems a more reasonable choice.

That's hard for me to say in that I know both of them and would like to support their products but something tells me that Kev's woofer is an IB candidate.

Perhaps I should bow out of this. It's not in my interest to turn you away from which ever driver most suits your needs. Good luck whichever choice you make Joe.
hi Cal,

They are both indeed off the train from Wigginsville.

Again, bass watts are cheap these days, and the newer driver can be made to do as it's told. I could of course be wrong, but I really like that stout driver, and the amount of power required to EQ something like the Selenium down to where you want it will not be very different from that which is required for the new one, with a stated Fs almost one octave lower. There is a thread on it over at www.audiocircle.com which is hard to find as it is a "child" of some sort.
Room is about 20'x20'x8' w/ no WAF factor. I think I will cover that 1st octave later down the road. I am concerned about 40hz up to get correct which will take me a wjile, then I'll go for the 20-40 gig. I am not stead fast on a 150 hz XO as I have 2 OB's running much higher XO 500-600.. but this one will have TT 12" alnico version for the mid & CD for most likely around 2k up..somewhere around that. Maybe 5k if TT is truelly behaved.but then beam..so might have to chop her low. Hope Lynn Olson will get his TT 12 testing done so I really know, but am fairly set on using them. Seems the Selenium will cover a few more octaves cleanly which could be drastically in my favor for simple XO's & pulling it off. Which I do now & don't really know what the hell I am doing...*s*. Also I have many nice PP Tube amps I would also like to try for the quad of 15". MY BASH plates get crappy quick on anything up in the 100hz range, great controle but sonics just suck... in this XO range.I have however had nice results with PP tubers on high eff OB drivers of large size XO around 500-600. I love CD horn in the mix so that is definately going to be in there. SET's will be running my mids & top end so I gotta be carefull. I am hopeing the TT 12" will do me justice for mid bass & stay behaved enough for simpel XO & no notches. Hey Dan PM me on the TT 12" you are running I must see if the love affair is still on or over with them for you. Thanks for all help in this matter.
J & G
Love affair more like lust. Exchanged the 12 for the 10 which are to come. I am interested in a much higher XO point here. I am also interested in the Ceramic 8. My room is much smaller, and so whatever I wind up with will be scaled appropriately. I was thinking along the lines of my Hafler 9505 for bass, and one of those Renko bass crossovers from www.creativesound.ca which have been tried and true.

None of this is carved in stone. Except hemp-in-the-middle.
Hi Cal,

Yes, the efficiency of Kevin's woofer is quite a bit lower than that of the Selenium. Nevertheless, I expect that the efficiency will be somewhat better if four of them are used together in a 2x2 matrix close to the floor. By the way, I only used 6dB bass boost at around 30Hz with the OB system with four 18" woofers per side, and those woofers were in a verticle line and had a Qts around only 0.4.

I suggested that J&G check out Kevin's woofer because I myself would love to have OB bass extension down to 20Hz and thought everyone elso would feel the same way. ;) If I am going to build a serious OB system using drivers like the TT12", I'd want the system to have impressive bass extension by itself, and 20Hz sounds like a good number to me. Bragging right is important, you know.

Kevin's woofer does in many ways resemble the Dayton IB woofer, which is the one I would have chosen to use in my own "ultimate" OB system, until I saw Kevin's post about his new OB woofer earlier this week. I guess I am saying that I don't see the distinction between "IB" and "OB" woofers. Brute force EQ and a huge reserve of SS power should be able to solve everything, at least in the bass! ;) A couple years ago I helped a friend build his OB speakers using one Dayton IB woofer per side (plus EQ), and I was quite impressed by how deep and solid the bass sounded. Using four such drivers per side should be quite nice.


I did check Kevins OB driver out, it is impressive. Qts of almost identical, but much lower fs. I do like the idea of much less EQ if possible. but for 8 I am @ over 1k for the 8. I could do it, but man,,...got many other drivers to get. like 550. for the 12 TT's & the CD/waveguide combo. & a bunch of other stuff. Also I should say that a BIG concern is that 80hz has to hit me hard in the clean OB way. I know it can be done, so I am scared to go under 4-per side. I got the weekend to think it through, then I will order. I dought I can wait all weekend though without pulling trigger on the bass drivers.. I am perposelly not getting the TT 12's 1st so I make sure I get the proper bass drivers for the scale I want. I know as sure as ****, that if I start with mids & CD. etc,, I will screw my self on the OB bass. I have a seriouse addiction to OB, OB hybrid systems as I am sure without dought this is territory that has miles & miles of undriven road ahead. All to fun & thanks.
I guess I am missing some of the details. I understand you want four Selenium woofers per side on an OB crossing over at about 150 Hz. You are looking for bass down to 40 Hz where some other sub will take it down to 20 Hz. I think I saw you were planning to use tube amps and probably a passive crossover. So a few questions come to mind.

1. How are you planning to get bass extension in an OB with a relatively low Qts driver?

2. How big of a baffle are you planning?

3. What is the efficiency of the midrange driver and how are you going to mate the summed woofer efficiency to the midrange driver?

4. Are you planning to use EQ with the low Qts Selenium?

5. What design work have you done ahead of time before buying the drivers to make sure they are the right choice?
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