I had started a newbie thread to get some guidance on how I could improve my 'HT woofage' and received tons of valuable feedback.
I have narrowed it down to building 4x subs with 18" SI woofers and Erich's 4 ft flat packs, probably 2 each co-located in the front and rear.
The DIY FAQ thread has great information for a newbie like me. Still in this thread, I am looking for more advice and recommendations for the amplification, as well as the wiring.
What amp should I be looking for?
Cooling fan noise of some of these amps seems to be a common concern. Are there any amps that are quiet or do they all require some sort of fan mod if you have to keep them in the listening area?
I already own a Behringer DCX2496. Can/should I use it or better go with another DSP? If so, one integrated in the amp(s) or as a standalone (miniDSP?)?
I hear that most of these amps do not offer a sleep/power safe mode and are always on. I do not like it and would like to use my AVR to trigger an on/off via 12V. Are there any amps that support this? If not, how do I best go about it? (I saw the threads for building or integrating relays.)
Do I need a separate circuit (or maybe 2) for the amp(s)? Would 25 Amp suffice?
On the drivers: do I need 2 or 4 ohm woofers and how do I best wire up them up (parallel, series)?
What size speaker wiring do I need? I heard 12 gauge throughout will be fine. Is this correct?
Any particular recommendations for binding posts? Anything special I should look for? What advantage to go with speakon connectors?
I'm a noob, but I'm researching my first DIY build which is similar to yours (2x SI 18's in flat packs) and I can help you with some info I've found.
First, I referenced this to figure out if I should get the dual 2 ohm or dual 4 ohm variant.
In your case you'd look down to four subwoofers, at the DVC options for whatever amp config you're using. Amp config in most cases would probably be mono (bridged), but it can vary, and so it's important to pick your amp first, I'd say.
For amp, the SI 18 is 600W RMS and apparently doesn't like to go over that according to data-bass.com, so your amp's gonna wanna do 600W * 4 = 2400W RMS. You'll probably want your amp to do somewhere more than that for headroom and the probability that the amp manufacturer overstated the RMS somewhat.
I read in your other thread that this is for a 7200 cu ft room? I'm not well versed on how that translates to output power at low frequencies, but if that means you can't reach below 10Hz due to the room size, then an iNuke6000 would serve you well. It's putting out approx 1800W per channel, so hook two subs to each channel. However, there's some peeps saying it rolls off after 10Hz, so if you do foresee yourself getting lower than 10Hz extension, the Inuke may not be optimal for you if what they're saying is true (not 100% sure on that).
If you get the iNuke, according to that crutchfield link you'll want to get dual 4 ohm so you can hook up two subs to each channel, and each channel sees a 4ohm load. However, if you get pretty much any other amp, with which you'll probably be mono bridging, you'll probably want a dual 2 ohm variant so the mono bridged amp sees a 4ohm load. You might wanna verify this though, I am a noob after all
Why would I want to go with 4 ohm over 2 ohm on amp and driver, if I seemingly can get more output with a lower impendance level?
You can go with a 2 ohm load on the amp but make sure the amp can handle that load. Some amps are only rated down to 4 ohms
DIY Sound Group: Information and Tips
Also, keep in mind that (I think) these are dual voice coils, so dual 4 ohm or dual 2 ohm.
Cerwin Vega CV-5000. According to specs has HPF at 5Hz so should go deep enough although there have been no tests so far.
Get 4No. SI HT18 D4s and wire each sub in series and two subs on each channel in parallel. A D4 in series = 8ohms. Two 8ohm loads in parallel = 4 ohms per channel.
This would provide 1800w a channel or 900w per sub which would be about right for getting a decent amount of excursion for a sealed HT18 in a 4.5 to 5cuft enclosure.The 600w power handling is based on the mechanical limits of the driver and not what the voicecoil can take thermally so modelling is the only way to know if the power is really too much. This driver can take quite a bit more than 600w in a sealed enclosure. A side benefit is that the amp would not be stressed out trying to supply power at 2ohms.
I have a CV-5000 and two SI HT18 D2s which will also provide a 4 ohm load to the amp. This amount of power should be OK in a 4cuft box but I will have to be careful not to pound on them and melt the voicecoils. I just couldn't help buying more power when the CV-5000 was about the same price as an EP-4000 here in NZ.
It always amazes me how pricing for the same products can vary so significantly by location. I did quick price search for a CV-5000 here in the US. It is about 2 twice as expensive as an EP-4000.
Quick update: In the meantime, I found a good deal for a pair of JTR Cap S2s. I think they will fit my ‘woofage needs’ quite nicely. So I will put my DIY project on hold for the time being.
Again, thanks everybody for all your recommendations and insights. Much appreciated!