Class D Amplifier(s) for SWARM Subwoofer System

The crown is a pro amp, designed for driving PA systems. The XLS series is class d. They will drive 2 ohms no problem. I’d still run the subs in parallel. The power at 2 ohms is 775 watts/channel. The likely reason they’re popular for subs is the also have a built in crossover. I use one in my Jam studio to drive the monitors, sounds great, I also use one to drive the speakers in my living room tv system driving Totem Sttafs. Sounds great there too. They aren’t my choice for my main system, but I use one to drive my subwoofer in my home theater and it’s excellent.

if you’re worried about age, buy a new one ($550 I think). The used ones aren’t that old though, so it’s not an issue so long as it wasn’t abused (which some are if they are used in a pro/gigging system.

@peter_s Why not get the sub amp that Duke recommends? It works quite well (I use one in my system at home) and has the crossover built in and its far less money.

@atmasphere  Hi Ralph. Good to hear from you. I actually do have two of those Dayton amplifiers that Duke recommends. Each amplifier runs two subwoofers in series, so the effective impedance is 4 ohms. But the output is way too low to balance my 87 db efficient mains, which are driven by VAC Phi 200 monoblocks. The JL Audio CR-1 subwoofer offer has much more flexibility… Allowing me to mix RCA and balanced inputs, and outputs, allows me more flexibility for the signal balance between the mains and the subs, and has all the controls on the Dayton amplifiers as well. This will help me greatly as I try different equipment, its universality.  it will also allow me to use some more powerful amp, and hopefully get a better SPL balance between the two, so I think it is a win all around. I have the CR-1 on the way.  Make sense?

@peter_s I'm puzzled why the sub output is so low. My main speakers are 98dB and the Daytons with the Swarms have no troubles keeping up. With the limited power you have with the VAC and the 87dB of your speakers, this should be a walk in the park for the subs and amps. So I think you have a setup problem or an outright malfunction.

BTW I don't think the Dayton puts the subs in series- they are parallel for a load of 4 Ohms. I use a set of Jensen subwoofer transformers to convert from the balanced output of my preamp to the single-ended input of the sub amp. Works a treat.

@atmasphere HI Ralph.  I am puzzled too!  I agree that the volume matching SHOULD be a walk in the park.  I am also using Jensen transformers to convert the balanced output from my preamp to the SE input of the Dayton amps. It is the ISO-MAX PC-2XR.  Perhaps this is the issue, from the spec sheet: "Converts +4 dB balanced signals to -10 dB unbalanced".  Maybe the Jensen is removing too many dB???

Regarding series/parallel - Duke told me that there are two versions of the Swarm subwoofers.  In one version, each sub has an impedance of ~6 ohms.  In the other, ~4 ohms.  I believe the four ohm model is meant to be set up as two "pairs" wired in series. For each pair, the "intermediate" sub has two pairs of speaker terminals, and the only resistance (3.7 ohms on mine) is b/t the two positive terminals. The other sub has just one pair of speaker terminals, also with ~4 ohms across the pair.  So the signal "passes through" the  2x-terminated sub (energizing that speaker), then passes through the 1x-terminated sub, and then back via the negative terminals of the 2x-terminated sub (which are simply strapped together)..  The two 4 ohm subs in series provide 8 ohms effective.

Regarding the Dayton amps, I had previously asked Duke why one would use two amps rather than one, particularly since you are only using one channel on each amp and the presented load is a benign 8 ohms.  His answer is below:

"There is a worthwhile spatial-quality benefit from using two amps. You can drive the two speakers on the left-hand-ish side of the room with one amp, and the two on the right-hand-ish side with the other amp, and then use the phase controls on the amps to put them 90 degrees apart in phase.  This simulates the sort of phase differential you would get at your two ears in a large acoustic space.  So in effect the playback room's inherent "small room signature" is suppressed.  This "unmasks" the low-frequency acoustic space information on the recording, so you have more of a sense of the venue acoustics on the recording (whether they be real or engineered or both)."  

The only flexibility I lose with the CR-1 is adjustable phase. I'm not sure which will be better - using the two Dayton amps with 90 degree phase  offset, or using the CR-1 with it's better flexibility paired with a pair of Hypex NC400 amps I just bought to power the subs.  I think the flexibility of the CR-1 could be fairly valuable.

Thoughts?