Add subs to ATC active speakers?


I’ve got ATC SCM19A active speakers, driven by a DSD using XLR interconnects I’m wondering if it’s possible to add subs without adding an external crossover. The DSD manual recommends using both the XLR and RCA outputs, but although from the write up it seems the reason primarily has to do with the 6 db difference in gain with XLR that many amps have. This is way beyond my knowledge level, but couldn’t the XLR signals be split between main speaker and sub, assuming an XLR capable sub, or the difference “equalized” in the set up if RCA were used for the subs? Just exploring what the possibilities are, if any. Thanks,


Yes - plug your speakers amps into whichever it is wired for, and the subs into the other, with adapters, if need be.


Not clear about the second half of your answer - “subs into the other, with adapters, if need be.” Subs into the other what? The dac-ATC connection is by XLR. I was wondering if splitting the XLR at the dac (Neutrik makes an adapter) or running both XLR and RCA to speaker and sub, respectively, would work. Are you suggesting another method, such as splitting at the speaker (in effect same as splitting at the dac)?


If you are running the DSD direct to your amp (no preamp), plug the RCA outs into the subs.


Either method of hook up is fine, XLR with splitter or RCA.

The sub will have a volume control so any difference in volume can be adjusted out. One needs to adjust the sub’s volume to blend in with your system in any event.


Thanks. The next question I have is, which subs to consider? This is a very modest sized living room (dining room at other end) and so looking at 8-10" speaker size, such as one of the REL Ti models (5 or 7). But I’m not sure what to make of the Neutrik Speakon interconnect they include. That is, the other end is often terminated with spade lugs for hooking to amps as if it were a speaker cable, which I assume is electrically different than either XLR or RCA. Or does it matter?

Update: I asked Music Direct and they said the Neutrik is a +/+/shared ground electrically vs. +/-/g for XLR, so RCA and using the low level inputs would have to be it on the REL.


I’m a fan of closed-box subs, and like JL Audio. Many are REL fans. Maybe if you can borrow one from somebody or a dealer, you can get an idea what you prefer.

The size thing is actually less about the room size than how low the subs go with musicality and authority. I would suggest 10’s at a minimum. You really only want them doing stuff under the lowest reach of your ATCs, which I would suspect go fairly low for their size.

Depending upon the room’s physical dimensions you will have more or less issues at various frequencies with integration.


Thanks. After reading a bit, sealed does seem better for audio, and model to model are much lighter, smaller and less $$. Someone on the ATC forum also suggested JL. Though much pricier than REL or SVS, a pair of e-110’s look like they would work well (I would only go with a pair). I’m also wondering about the SVS SB2000. As I read review articles, set up is the key, but then it always is. Jonathan Valin in TAS has a particularly insightful review in that regard in setting up the e110’s - I’d most likely get help, as I did with the ATC’s.


Let us know how it goes. Incorporating subs is work.


I have dual JL Fathom 110’s and can’t recommend them highly enough. I would also recommend getting dual subs as they significantly even out the bass in the room, minimizing bass “modes” or hotspots. Before I got dual subs, I could only really optimize my room for only one listening spot with others seats too heavy or lean on the bass. After I got dual subs, pretty much all the listening area gets pretty even bass, more or less. The JL EQ is pretty amazing and the support at JL is also pretty great. I’ve heard good things about the e-subs, too. Good Luck!


Thanks for the suggestion. The second I’ve heard for the Fathoms. The 110s have been discontinued and show as such on the JL Audio site (which might open the opportunity for good deals on a used pair). I’m guessing they have in effect been replaced by the e-110, which currently for practical reasons is what I’m watching for. I’d definitely would not go with other than a pair.


One thing I’ve discovered is that the better mid-priced subs that don’t use Speakon, such as SVS and JL Audio, have RCA inputs/outputs, not XLR. My DSD to ATC run is XLR, the latter being XLR input only. Given that I have two pairs of MG Audio XLRs, I have some questions:

- Does an XLR cable from the dac's XLR output lose its balanced nature when an RCA adapter is used at the sub?
- Does the unbalanced signal from the sub's output remain unbalanced to the SCM19A even if an XLR cable is used (with an adapter at the sub)? Would I need some kind of active RCA to XLR box or transformer?
- Is it likely that noise will be introduced in using the XLR cables and RCA adapters?


If you have a DS Sr., PS does not reccommend using both outputs, but if you have a Jr., you can run the XLR outs to the ATCs and the RCA’s to the subs, which is how I’m currently running my system since Redcloud. Though for convenience’s sake, I put a volume control in the line feeding the subs. The JL Audio “f” series has both XLR and RCA I/O.

Generally it is suggested that you use a “Y” adaptor cable on each leg rather than the way I’m doing it. Also, Paul prefers RELs, in part because they are connected via the speaker outputs rather than a line output, which then retains the character of the amp you’re using. My brother has RELs with his Graham LS 9/5’s, and they sound great. I used to own a REL, several HSU’s, B&K, etc. And I just eventually went off ported subs. A well made closed box like the JL tends to be more expensive and be heavier, yet smaller. I usually find them to be more musical in the lower registers, as they aren’t relying on a port to simulate lower notes, and you don’t get “chuffing” of the air coming out of the port (a proper sub like a REL shouldn’t have problems with that, though).


Thanks for the comment. Since my last post, I obtained a pair of JL Audio e-110 subs, MG Audio RCA interconnects and a couple of Cardas adapters. Asking and reading around, it became clear that the best approach is to run through the subs to the main ATC speakers, using or starting with a crossover point down around 55 Hz. I haven’t set the JL’s up yet, being focused first on putting the pieces together and other upgrades, as I hope not to have to set the subs up twice.

Beef, I don’t know if you play with fuses, but if so did you change the ones in your subs?


Have not gone down the fuse rabbit hole…yet ; )