Balanced or unbalanced output to subs?


#1

I’m setting up a run from a DS to a pair of JL Audio e-110 subs, which have RCA inputs/outputs. That run, after using the e-110 crossovers, will carry on with RCA-to-XLR adapters to ATC SCM19A active speakers, which only take XLR. In setting up the DS to sub runs, I have a choice between using XLR-to-RCA adapters at the Directstream’s XLR outputs or using its unbalanced outputs (RCA) and using adapters only with the subs to ATC runs. I’d been planning on using the latter option, since generally the fewer the adapters the better. But the question has come up: assuming good quality adapters with either option (Cardas, Purist Audio Design), but not wanting to buy both to compare, is there any reason to expect SQ to favor one approach over the other in terms of signal quality?


#2

You can connect both the XLR and RCA outputs of the DS at the same time. Run a set of XLRs to your speakers and a set of RCAs to the subwoofer. That way you are not running any adapters. Even though it is a compromise to run them both at the same time, it is less of a compromise than the adapters.

Unless you have a wiring issue you have not explained, you only need to run in and out of the subwoofer if you desire or need to use the sub’s crossover filter to cut the bass frequencies out of your monitors.


#3

https://www.cs1.net/products/jensen_transformers/SC-2NR.htm

Use this to drive high-level to your subs. Best $200 I’ve spent in a long while.


#4

Guess I wasn’t clear enough. I’m running through the JL subs, using its crossovers, to the ATC’s. No desire to run parallel to the speakers or put anything in the path, unless it’s something like the DSPeaker Anti-Mode 2.0. Though even then, I may opt for some acoustic paneling instead.


#5

The two most logical reasons to run thru your sub are because of equipment placement, or need for the crossover to limit the bass signals going to the main amplifier to free up some power. Your speaker system has a built in amplifier and the natural role off is about where a sub would take over anyway, 6db down at 56Hz.

If you are willing to try it your mid and high frequency detail should be better running XLR direct to your speakers. You get two advantages:

  1. The higher level, 2.8 volt, signal available through the XLR should give you better signal to noise ratio.
  2. The common mode noise rejection native to an XLR cable should lower any RF you might pick up in the cable run.

I think it would be worth a try. I will be quiet now.:no_mouth:


#6

The best reason to run through the subs is to let each set of speakers do what they’re best at. While there is no harm or added expense in trying a parrallel run to compare, what I’m trying to figure out with this post is what I asked: does using the XLR outputs with RCA adapters make any difference with just going RCA to the subs and only adapting after that.


#8

Hello Highstream,

I run ATC SCM50’s with a single JL Audio Subwoofer Fathom F113v2 with one pair of quality XLRs direct from the back of the DS. I have a two small 1m long “Y Leads” going onwards from each ATC to the left and right inputs at the back of the JL. The JL is sited centrally between the ATCs.
I have no pre-amp.
This sounds the best my stereo has ever sounded. The deeper tones of the JL augment the ATC50s and using its software can tune to my modest room. I considered 2 x smaller JL subs, but felt the control of the Fathom software was prudent in a smaller room some 3m by 4m. I was not happy with the single ended arrangement for the sub, duplicated from the back of the DS alongside the XLR cables.


#9

Sean, Thanks. So you’re crossing over the sub via the software to limit its range but not the ATC’s? It sounds like the Fathom’s software did for you what something like the DSPeaker Anti-Mode 2.0 does, but perhaps better.


#10

No! Both the ATCs and the single JL get the very same full range XLR signal from the back of the DS.
I let the ATCs do their full range thing without hinderance using all the DS signal width.
The Fathom, gets the full signal range too, but does its own software controlled thing once it has assessed the room, and then all I do is turn the sub “volume” and “crossover point” up or down so that it appears to my ears to be just under the bottom of the ATCs.
I wanted to hear what is on many film soundtracks and electro tracks with is often fairly low. This greatly adds to the space and sound environment, which the ATCs on their own do not really fully deliver.
I had considered going to ATC100s or 150s but my room would not take it…but the control afforded by the Fathom software overcomes this. I should say I have fairly advanced treated “listening studio” really, bass traps, ceiling and wall control all professionally assessed and measured.


#11

Ok. Since Fathoms are beyond my price class, I suspect the closest I could come to that with the e-110’s would be inserting something like the Anti-Mode 2.0 between the DS and both speakers, since it has both XLR and RCA outputs. That way at least the Anti-Mode and ATC’s would get XLR and there would be overall room correction as if it were one 2.0 system, with the ability to tweak the sub on the fly if I want.


#12

Sean, Thanks for your suggestion. Your Fathoms have not only the software to help, but also XLR inputs. In my case, running in series through the ATC’s first would still mean using adapters.


#13

hlg3, Just so I’m clear, is your suggestion to run in parallel from the dac, using both its XLR and RCA outputs, or to run in series but going to the ATC’s first?


#14

Actually I liked the way the E110s are made with their one piece face plate etc. I strongly considered a pair of those. However the control of the software to suit less than perfect room was needed so a Fathom it was.


#15

I only have the one! Dual L and R inputs.


#16

I could neither handle price nor weight of the subs with balanced connections and software, and didn’t want to deal with Speakon.


#17

Run them in parallel from the DAC. The XLRs will go straight to the speakers and the RCA’s to the subwoofer.

Because of the variables in your system, you have to make a decision on a compromise.

The variables I see are as follows:

Running through your subwoofer limits you to single ended cables (RCA.) This compromises the feeding of the signal to your speakers because they take only balanced (XLR.) The RCA to XLR conversion causes at least two issues; the adapters will cause signal loss (some manifestation of fidelity) and a single ended signal is half the voltage of a balanced signal (signal to noise ratio.)

Although JL Audio makes a great quality product, I doubt the quality of the preamplifier pass through is up to PS Audio’s standards, contributing to a loss of fidelity.

Running both outputs of the DirectStream DAC is also a bit of a compromise. Paul and others have said running both sets of outputs imbalances the signal traveling through the XLR cable because both sets of outputs are being driven by the same output transformer thereby increasing the impedance on one leg of the signal. This might affect the noise rejection properties of the XLR balanced output.

Your decision comes down to which will work better for you. The way is to try them both, and see which works better.

My 2 cents is:

Your speakers naturally roll off where your subwoofer takes over, so there is a compatibility you can take advantage of. If you do not have problems with your speakers distorting from trying to produce bass frequencies they are not capable of, then there is little reason to run through the cross over of your subwoofer.

The quality of the signal getting to your speakers is probably going to be better with a direct run of (somewhat) balanced signal through an XLR cable than it is coming from the RCA output of the DirectStream through the two connections and crossover components on the subwoofer and then through an additional adapter to make it fit the XLR input on your speakers.


#18

Thanks for laying it out. Looks like I got in deeper than anticipated.


#19

To keep everything balanced XLR, you also might consider going with a studio sub such as the Dynaudio 9S (the one I use) which has balanced inputs and outputs with an adjustable crossover.

I run my signal direct from the DS to my sub balanced, low passed at 80Hz to the sub and then high passed at 80Hz balanced back to my mono block amps which are also balanced.

This works very well in my system with no gain mismatching.

Most studio subs have balanced inputs and outputs.


#20

Thanks for the suggestion. Mine is an all active system, no separate amp, and I’ve already got the e-110’s. Had I known about the the Dynaudio’s I might have taken a closer look, although being a Danish manufacturer they are pricey new in the U.S. and there isn’t much of a second hand market for any of their current home or pro subs here. It’s also appears that they are focused more on working with other Dynaudio speakers.


#21

You may want to look at getting the JL Audio CR-1 crossover as it will solve all your problems and will allow you to use xlr to your speakers and rca to your sub.