Help with SI 18" sealed

[Shrader]

Noob here, I am planning a another sub build, I am ordering (2) 18" SI subs for two separate 21" sealed cabinets. The question i have is, do I order the d2 or d4 subs, and what would you guys recommend for an amp? I built a CSS trio 12, but that was more or less a kit, need to know what wiring i will need from my Denon 7.1 receiver to the amp, and what I will need from the amp to the subs? this is a low budget build, so what amp is the best bang for the buck? the amp will be in a closet so to speak, so not worried about fan noise, also how much power to each of the subs? Thanks for any advice guys!

 

[rojo]

Are you talking about Stereo Integrity HT18? Cool. Those look like great drivers. Are you wanting one amp to drive both subs? If so, get the dual 4Ω voice coil drivers and wire them up as 2Ω per cabinet. Then run both cabinets as stereo on a 2-ohm-stable amp. The Behringer iNuke 1000 (or the one with the DSP) is nice if you want to connect amp to speakers using Speakon cables; or... well, that's the best budget solution, really. You'll need Speakon cables and terminals for your boxes. To connect from AVR to amps... well, someone correct me if I'm wrong, but I think you can just use an RCA -> 1/4" TRS cable. If you want to be able to control each sub's volume, you'll need a splitter somewhere to split the LFE signal from the AVR into two TRS plugs, then run the amp as stereo.

On the other hand, if you want one amp per sub, get the dual 2Ω voice coil drivers and wire them up as 4Ω per cabinet. Then run one sub per amp in bridged mode. You'll get more power this way, but it's also more expensive.

FWIW, 500 watts is more than plenty in my 2300 ft³ room, and my CSS sub has a much lower sensitivity than this SI sub. I think you'd be fine just getting one amp and driving the subs in joint stereo config.

If you'd rather stay traditional and use lamp cord to connect amp to subs, get the dual 2ΩVC drivers, wire them 4Ω per cabinet, and attach them in stereo to the Behringer Europower EPQ1200. If you don't already have Speakon cables or RCA/TRS adapters, the cost would be about the same via either avenue, and the Europower solution nets you 100 more watts. The more I think about it, I think I like this route better.

 

[Shrader]

thanks for the reply. I was looking at the crown xls 1500? just for ease of connection,would that work? and yes one amp for both speakers is what I was after. What is all this 2-4 dual ohm stuff? lol. how do I wire a d4 as a d2? is there a site or wiring diagram here that can point me in the right direction?

 

[rojo]

The Crown would work, but it's more expensive. The SI subs are rated at 600W RMS power handling, so the Crown might be a bit overkill at 775Wx2@2Ω. Then again, a little extra overhead never hurt anybody if you can afford the difference.

The driver you are looking at is a dual voice coil driver. That means the single driver has two pairs of + and - terminals. Remember your CSS kit, how there was a single speaker wire going from a - to a + pre-wired from the company? That's a series connection. Wiring two voice coils in series doubles the impedance rating, so wiring two 2Ω voice coils in series results in a 4Ω load. It's called "series" because the electrical path goes in series into -, out a + and into another -, then back out the final + and back to the amp. The signal path is twice as long as a single coil, so it's double the impedance.

The other type of connection, a parallel connection, means you are basically attaching both pairs of + and - on the driver to one pair of + and - on the amp. This halves the load rating. So wiring two 4Ω voice coils in parallel results in a 2Ω load. The amp has to drive twice the load of a single coil, so it's half the impedance.

And the lower the impedance, the more current is drawn. You don't want an impedance lower than the amp is rated to handle or it'll burn up.

There's probably an excellent graphic somewhere that illustrates this, but I'm too lazy to find it. Just look on Google Images.

Now. To squeeze the most power out of whatever amp you choose, go with the lowest impedance rating that amp will support. For the iNuke and Crown amps, that's 2Ω per channel. The Europower is only 4Ω stable in stereo mode. But if you pair it with the correct load, a pair of 2Ω dual voice coil subs each wired in series within its own cabinet (netting 4Ω per channel), it'll provide wattage rivaling the other two amps.

Clear as mud?

So in summary, if you get the iNuke or Crown amp, go for a pair of the 4Ω version of the driver and plan to wire them in parallel (two runs of lamp cord from the cabinet terminal to the driver). If Europower, go with the 2Ω instead and wire them in series (one run of lamp cord from terminal to driver, and a single wire connecting the - of one voice coil to the + of the other). Whatever impedance you choose will either be doubled or halved, depending how you wire it.

 

[Shrader]

Thank you rojo, i think i got it now lol. I think i can spring for the crown amp, just have to save up a couple weeks worth of beer money is all! I will be sure and post up some pics when the build starts.

 

[BoredSysAdmin]

I would highly recommend going with xls1500 due to better build quality, more power (si18 could definitely take much more than 600w), easy connections and lastly silent unless driven hard

 

[darien87]

I would second the XLS1500. I bought one recently and love it. Gobs of power and I've never had the fan turn on.

I used to have a Behringer EP4000 and it broke twice. I'll never buy another Behringer amp again. Their amps are cheaper for a reason.