Class D Amplifier(s) for SWARM Subwoofer System

@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?  

I dunno, if the designer recommends two Dayton amps I’d be hard pressed to go another way and really liked Duke’s explanation of the benefits of phase adjustment — thanks for sharing that.  I understand all situations are different though.

@audiokinesis Hi Duke. I’ll reach out to you offline to discuss troubleshooting on the Daytons. I should have reached out earlier to you about this concern. I am running two balanced outputs from my VAC Signature 2se preamp, one to a pair of VAC Phi200 monoblocks and the other to the Jensen ISO-MAX PC-2XR, which converts the balanced to SE signal (and +4 to -10 db conversion). I am guessing that Ralph is doing the same, but require confirmation. I will report back on this thread as more is known. I can definitely try the LFE inputs on the Daytons.

It looks like there is no way to bridge the Daytons to get more power (since I am only using one channel per amp) - but another option would be to use both channels and run one sub per channel.

@peter_s , it's not apparent to me where the lack of gain is coming from.

With the JL Audio CR-1, do you have plenty of gain?

The Dayton amp just has a single channel.  The two sets of output terminals on the back are both connected in parallel to that single channel. 

Duke