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Discussion Starter · #1 ·
Hey everyone, I've been out the loop for a few years now so I don't know whats hot these days. I originally was trying to talk my buddy into building a sub rather than buying a Polk sub. Then I stumbled upon the closeout on the SI HT 18's and started thinking maybe it's time I try something new



I currently have 2 SDX 15's in passive radiator boxes running of a single EP2500 which is honestly more than I need but that hasn't stopped any of us before LOL. So Since the SDX's are dual 2's I am getting about 600w to each sub and can't get the full potential out of the EP2500. I was thinking I could run 4 SI HT 18's in a couple dual opposed boxes and give each sub about 500w, but I really don't want to dump $800 into subs I don't need. I am more than willing to go with a pair though if they offer greater performance than what I currently have.


What do you guys think about 2 SI 18's vs the 2 SDX 15's? Is it a worthy upgrade?
 

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Quote:
What do you guys think about 2 SI 18's vs the 2 SDX 15's? Is it a worthy upgrade?

If I understand your question correctly I would say no! Looking at things from a driver to driver perspective taking thermal limits into account sealed or vented along with spl versus max spl your better off approaching the situation with what you have and adding more power. Depending what you have going now, I might be able to make a good case building two new enclosures and a new amp though whether PR or traditional venting.
 

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There is no replacement for displacement! (Sorry, I just had to say that! LoL!)


Have you modeled the CSS15" versus the SI 18HT's? You could sell your current CSS subs and with the money that you make off selling them, you could likely afford four of the SI 18HT's which I can assure you that it would be a massive upgrade going from two CSS 15" drivers versus four SI 18' drivers!
 

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Discussion Starter · #4 ·
I haven't modeled anything. I have rebuilt my computer 3-4 times since the last time I used winisd. I don't it or any of my old files anymore. I should probably download it and get back to it. I thought about adding power as you suggested. It looks like I can get the inuke 6000dsp for $400 from sweetwater. Are there any other better options to get more power than the 600w I get out of the EP2500 @ 4ohm?



Marty, I don't think I would be able to get that kind of $$ out of the SDX's but I sure do like the sound of Quad 18's
 

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I have had both and listened to them side by side. The si18sealed with 600w and sdx15 ported to 19hz with 1200+ watts. The si goes much deeper. The Sdx, I feel, has a better sound quality. Also, it's not tuned as low, so really it's apples to oranges in my comparison. When I modeled them however, the si ported and tuned to 19hz, had a significant advantage over the sdx in both spl while being able to go lower while using half the power. The si tuned lower is even better. In the end, I still like the sound of the Sdx better. I like the sound from my Lms ultras more, but that's a different story...
 

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Are there any other better options to get more power than the 600w I get out of the EP2500 @ 4ohm?

I don't know a lot about this except for the wiring diagrams but conceivably can't a guy bridge the EP and run both sets of leads to the amp and end up with 1/2 of your 4ohm bridged mode which would be 1200w per sub 4ohm?


The 6000dsp would serve you well of course, no doubt about it. In relation to your first question though, I did sim them both in sealed and vented in different size enclosures and stayed true with your original question or conclusion after talking it out with yourself. If you ever do decide to sell your drivers there are people out there searching for them and I could give you some leads. Marty was correct of course in 4 SI taking out 2 SDX.
 

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If the SDX15 is also XBL2.... Those motors are glorious.


The SI 18HT has 5.3 liters of displacement and the SDX15 has 4.7 liters of displacement. By going from a pair of SDX15 to a pair of SI 18's, you go up 1.2L (12%) from 9.4L which isn't insignificant, but also isn't a huge amount.


With those numbers, I would stick with the SDX15+PRs unless you go up to 4x SI18HT. ..but only if you find the SDX lacking substantially.
 

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Quote:
Originally Posted by Anthony_Gomez  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411338


If the SDX15 is also XBL2.... Those motors are glorious.


The SI 18HT has 5.3 liters of displacement and the SDX15 has 4.7 liters of displacement. By going from a pair of SDX15 to a pair of SI 18's, you go up 1.2L (12%) from 9.4L which isn't insignificant, but also isn't a huge amount.


With those numbers, I would stick with the SDX15+PRs unless you go up to 4x SI18HT. ..but only if you find the SDX lacking substantially.

Hey Anthony, glad you stepped in. Could you read my question in my last post and comment on? I'm thinking a guy can run two sets of leads off of the EP and splitting the load and still staying at 4ohm. Is this so? Oh and a guy can push the SDX harder with more power since it will take the power and has the better xmax. You know that though of course.
 

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Quote:
Originally Posted by steve nn  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411271


If you ever do decide to sell your drivers there are people out there searching for them and I could give you some leads.

I'm one of those guys
 

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Well, two 4ohm subs can be run as 4 ohms stereo, 8 ohms series (mono bridged) and 1 ohm parallel (mono bridged). With dual 2ohm VCs, you could also rewire those to parallel 1 ohm, for a 2 ohm series (mono bridged).


So, 750 watts per driver is about all you can get with this amp and dual subs. You could run a single sub at 2400 watts though
 

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Quote:
Originally Posted by steve nn  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411271


If you ever do decide to sell your drivers there are people out there searching for them and I could give you some leads
I even had someone already contact me for when I sell my Tumult (and I didn't even post that I was selling it!) :-D Those XBL2 motors are special!
 

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Quote:
Originally Posted by Anthony_Gomez  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411435


Well, two 4ohm subs can be run as 4 ohms stereo, 8 ohms series (mono bridged) and 1 ohm parallel (mono bridged). With dual 2ohm VCs, you could also rewire those to parallel 1 ohm, for a 2 ohm series (mono bridged).


So, 750 watts per driver is about all you can get with this amp and dual subs. You could run a single sub at 2400 watts though

Ok so you can't run two sets of leads off of 4ohm bridged and stay at 4ohm then. I was once told you could but I'm not up on all that admittedly. I do know about running in series though. Some guys live and breath amps around here and really know their stuff. I definitely fall short.
 

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Quote:
Originally Posted by Anthony_Gomez  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411446


I even had someone already contact me for when I sell my Tumult (and I didn't even post that I was selling it!) :-D Those XBL2 motors are special!

I get that same issue with the SDX lol.
 

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Quote:
Originally Posted by d_c  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24411417


I'm one of those guys

Sorry
Two of my keeper drivers are the 12 and 15 SDX.
 

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Hey Scott. To be fare I put the SI in a 10cf enclosure because the 18 likes a little larger enclosure and evens things up more for the SI as apposed to the 8cf enclosure with the SDX. I went 1100w with the SI and 1500w with the SDX. I was so zeroed in on your drivers though I made no mention of running a dual PR option, and it's nice to come across another member who rolls with the PR option.

 

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Discussion Starter · #16 ·

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Originally Posted by steve nn  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24412255


Hey Scott. To be fare I put the SI in a 10cf enclosure because the 18 likes a little larger enclosure and evens things up more for the SI as apposed to the 8cf enclosure with the SDX. I went 1100w with the SI and 1500w with the SDX. I was so zeroed in on your drivers though I made no mention of running a dual PR option myself and it's nice to come across another member who rolls with the PR option.

I unfortunately only have 1 PR per sub. I was planning doing 1 sub first, then the other later. Then I ran into trouble finding 2 more PR's So each box is tuned to somehting like 10 or 11hz. I new I should have just bought them all at once. I have the 18" PR's that are basically a circle of MDF connected to a thick cardboard tube acting like a coil. I can't even remember where I got them it was either CSS or AE speakers. I think after hearing all the comments I will see if I find a matching pair of PR's and sell my EP2500 to get the inuke 6000dsp. I can say that the current setup is more than needed in my room but I feel like switching it up, its been too long.
 

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I dunno?? Not sure where you found your PR's but I do remember seeing them some time ago though. What you need with that kind of power and excursion is two high excursion 15" PR's per driver and not anything micky-mouse. One of the links I'm providing are the CSS PR's.. they're loaded from the outside so they admittedly have a different look, priced well though and 33mm Xsus. You would still need to confirm the PR's would take what the SDX can dish out though at 1500w whatever PR's you went with.


I know what you mean by build though. I guess it's in our DNA


http://www.creativesound.ca/

http://aespeakers.com/shop/catalog/index.php?cPath=24

http://tcsounds.com/product/drivers/vmp-passive-radiator/
 

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Quote:
Originally Posted by scotthulbs  /t/1519899/si-ht-18s-an-upgrade-from-css-sdx-15s#post_24412505


I unfortunately only have 1 PR per sub. I was planning doing 1 sub first, then the other later. Then I ran into trouble finding 2 more PR's So each box is tuned to somehting like 10 or 11hz. I new I should have just bought them all at once. I have the 18" PR's that are basically a circle of MDF connected to a thick cardboard tube acting like a coil. I can't even remember where I got them it was either CSS or AE speakers. I think after hearing all the comments I will see if I find a matching pair of PR's and sell my EP2500 to get the inuke 6000dsp. I can say that the current setup is more than needed in my room but I feel like switching it up, its been too long.

That is AE/Stryke PRs. I know because I have a pair of 18" ones
I think mine are tuned to ~ 18hz in a ~22-23" cube. If you are not in a rush, I'll be selling them off in a few months, faster if I get a flatpack for the new subs and not buy MDF and build my on..but I don't have any tools for that right now lol. John at AE can make up new ones for $130 each + shipping iirc.
 

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Thinking about it not trying to pull a sale from Anthony or AE, but be the devils advocate, is to spend your $$ on building two new enclosures or FP if you will, and the amp you're going to have to get one way or another. No matter how you go you're going to spend the $600-800 anyway.
 
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