JL Audio Fathom f113 Question
 

I have 1 JL Audio Fathom f113 that I currently have one cable going from the amplifier output to the f113 mono input.

Would it be better or more importantly can you use 2 cables L/R output from the amplifier to got to the L/R inputs of the f113?

Thanks

Paul.......I use a single Fathom f113 in my living room system. I have both the left and right channel outputs from a McIntosh C2300 preamplifier feeding the subwoofer. Great results.

Dan....thanks for the quick response. I’ll do just that.

I only use one cable to my F113 v2 plugged into the ‘mono’ input. Just as the manual shows.

What is the advantage of using an extra cable on a mono signal?

I have only used a single balanced cable on my F-113's but I have used dual single ended input on other branded subs in the past. My experience has always been increased gain on the sub and overall better sound, but the subs were no where near the level of quality of JL Audio. Again, I have not used this method on my F-113's so not sure if that holds true on them or not.

JL Audio Fathom f113 Question
 

Mono signal?

In my system, my preamp feeds left & right to the crossover. The crossover feeds left & right to the subs. While you won’t be able to discern left vs right, especially with one sub, there’s definitely left and right information (albeit not like mids and highs). If you don’t have the second channel, you will not hear all the low frequency.

Kinda makes sense when you put it that way. :D

Thanks

Then why do they mark their connections this way? Attachment 58631 And why is one cable all you ever see when buying a ‘sub’ cable?

WTF?

JL Audio Fathom f113 Question
 

Probably because they are primarily used for home theaters where it really is mono? :scratch2: I’m not really sure.

I run stereo subs in most all my systems, theaters included.

Ivan,

How do you get stereo from 5.1 or 7.1?

This may surprise some folks, but those that have experienced my Theaters know that I don’t lack for Bass one bit.

I have never used the LFE output on any of my systems. I use top grade WW XLR splitters on my Left and Right channel outputs. One is for the obvious Left/Right primary speakers.

The other leg feeds my stereo subs via XLR Cables. Both of my Theaters have (4) subs / 2 left channels and 2 right channels; in each corner of the room. 2 Gotham V2’s in the rear, 2 Fathom 113V2’s in the front.

This method will also give all your SACD’s a Sub channel feed, where previously there was none. This has been my standard for over 15 years now. ;)

So what is the recommended connection for 1 sub in a 2 Channel system?

I use one cable from Output 1 on my C1100 left output to the left (mono) input on my Fathom. I can cobble together another balanced cable and connect both left and right Outputs if that is how it is supposed to be connected.

https://paragonsns2.imgix.net/wp-con...?w=1024&h=1024

Craig... on your C1100 use a pair of XLR’s (L&R) output to feed your Fathom; re-run ARO and season to taste. :beatnik:

+1

Brilliant!

I ran a cobbled together second cable(s) from my CR-1 Crossover. It does seem to have filled in the stage for the lower frequencies.

Now I am trying to figure out how I seem to be the only person who never saw or heard anything about connecting two channels to a sub. Hmmm.

Thanks :tiphat:

Lol. I felt the same way when I learned this too. It’s a great feature that McIntosh preamps have a 2nd set of XLR outputs to feed left and right subs or both channels feeding a single sub with the sub summing the signal internally. This way, if the mastering engineer mixed the bass guitar, for instance, completely into the left channel and the drums into the right (like some Beatles tracks are ....) well if you had a sub connected to the right XLR only, your sub would never see Paul’s bass notes if mixed in this manner, only your main speakers would see that signal. Bummer, right? Additionally, I know some seasoned listeners are convinced that there is some stereo information buried in low frequencies but that is a story for a different thread.

I am obsessing over this now. For prosperity to the potentially 1 other person who did not think about this...

All very logical but it seems to depend on where or IF there is a summing of the left and right LF signal. In most home theater systems, the processor with a LFE or Sub output does the summing internally. In that case, you only need one cable to connect to your powered sub.

However, in my case with a stereo ONLY preamplifier and CR1 Crossover, there is no summing done anywhere. Therefore, I need to run cables for both the left and right channels to my JL Audio Sub where the summing of both channels then occurs.

Man do I feel stupid.

:thumbsup:

No need to feel stupid, simply an oversight. If anything, you’re the one that turned me on to the CR-1 to begin with. Thank you for that, it’s a fantastic piece of gear!

Mike

Thanks Mike! I am okay now ;)

Well I guess I wasn’t okay with my cobbled together second cable connecting my CR-1 RIGHT output to my F113v2. When I did that, I noticed and remembered there is a switch on the front of the CR-1 labeled L+R and Stereo. That suggested to me that the CR-1 would sum Left & Right on the first setting and allow me to only use one cable. So I asked JL Audio. On their permission, here are the two very useful replies I received from Randy Wagner.

Bottom line - I will use one cable and have my CR-1 do the summing by choosing the L+R setting. Whew!!!

My first question -
“Does the CR-1 sum left and right channels before a mono cable is connected to a Fathom F113v2? OR

Should I run another left and right cables from my CR-1 to my Fathom F113v2?”

Randy’s first reply -

“Hello Craig,

Thanks for the question on the CR-1; my favorite home product!

Lets look at this answer by starting at the end and working our way back to the source of the signal.

All JL Audio powered subwoofer inputs are individually buffered and then summed to mono to the amplifier. So if you are running a single f113v2 in your system either of the inputs on the f113v2 are going to the mono amplifier on the Fathom.

The CR-1 does allow for "summing" the left and right main input signals at the outputs by switching the Stereo/L+R switch to the L+R position.

​

If you have one f113v2 then I would suggest the L+R mode for the subwoofer to feed the subwoofer. If you have two f113v2's you can try it either way and see if you detect any differences.

For about 40 years, recording engineers have been mixing "stereo" recordings via the multi-track method of several individual mono channels that are then mixed down to two channel "stereo". They have been mixing the lower frequencies of the bass instruments acoustic and electronic in mono from about 130 Hz and down which distributes the low frequencies equally to both channels.

The main reason for this is that bass frequencies benefit from larger square surfaces of speaker cones. If they were to put the bass player "left center" in the mix where he may actually be on stage, they are simply reducing the overall amount of bass by reducing the volume of the right channel's woofer cone. Results: less bass.

Since the lower frequency the more "omni-directional" humans perceive the direction from which it originates the win-win is maintaining a mono output for lower frequencies.

However, since the harmonics of the lower frequencies do reach several octaves above the CR-1's crossover frequency you will still perceive bass instrument directionality.

So, in most cases CR-1's are set up with the subwoofer output mode in the L+R position and a single output cable to each subwoofer connected.

I hope this is the information that you are needing.

Respectfully,


Randy Wagner
Technical Support Specialist

My second question
“Outstanding answer Randy. Thank you very much. You saved me the cost of a cable!!!

A quick follow up: While silly, would setting the CR-1 at Stereo and using two cables to the F113v2 accomplish the same thing. Eg the F113 does the summing?

Also, may I have your permission to quote your response and into the Audio Aficionado forum?

Craig

And his second reply -
“Hello Craig,

You are welcome. The answer is yes connecting both of the f113v2 inputs would be the same a feeding the L+R with regards to what signal is reaching the Fathom. The difference is that by engaging both the left and right inputs your increasing the input signal by about 6 db. You can simply turn down the master level control to reestablish the original volume level.

As for posting the answer you are more than welcome to.”

Respectfully,
Randy Wagner
Technical Support Specialist

Spoke with Randy several times. He is fantastic!

Ok....just to throw a fly in the ointment. If you only use 1 cable coming from your preamp then what happens if say a bass guitar is strictly mixed to the left channel and the drums mixed strictly to the right channel.

Wouldn’t you lose some bass information with just one cable?

It depends on whether you are sending a summed left + right channel signal to your sub. In my case, my CR-1 crossover does just that.

Ok so I thought I was doing this correctly but would appreciate input from the folks here. I’m currently running one xlr from my CR-1 to each of my f112 subs. My CR-1 is set to stereo and I plug each XLR into the left (mono) xlr on each F112. This is correct, yes?

Change nothing but set your CR-1 to L + R instead of stereo. That way the CR-1 sums the two channels.

Ok thanks!

Crwilli, I want to thank you for your help. It’s amazing what a simple flip of switch can do. By simply switching to L+R I’ve added a nice amount of bass without losing any clarity. Really impressive improvement— I really feel the subs now. Wow! Many thanks!

You should probably run the DARO again

So I finally got to running the ARO which required me to move The elf knobs to zero. Wow! Really good stuff! Thanks so much for your input.

Why? Changing setting to L+R only results in a change in signal level.

The ARO had me adjust the ELF knob to zero in order to run. I did not realize I had adjusted ELF and so was missing some bass. Otherwise, the change in signal level has been welcome and I can adjust bass via the sats/sub knob on my cr-1.

Because it’s really easy.

JL Audio Fathom f113 Question
 

This article below from JL Audio says that there no such a thing as stereo bass. One cable connection (mono) is all you need. The article is from March of this year and goes into lots of details about how to properly set up subwoofers. Beware that several of the points made contradict long held thoughts in the audiophile community (including the stereo bass).

https://jlaudio.zendesk.com/hc/en-us...&source=search

I especially like the following from the article:

“Simply connecting a subwoofer to existing main speaker (or amp) terminals is the worst possible way to do this. Everything scientific and acoustic about this method is wrong, from the additive delay issues, to the back EMF of the main speakers affecting the low frequency signal. “

JL Audio Fathom f113 Question
 

Barry is no doubt very knowledgeable but these recommendations/opinions are based on his experience and knowledge of the JL Audio Subs. It seems a little over arching for him to so thoroughly diss the REL subs which I THINK are connected to the speaker terminals(???)

I now drive my f113 from the speaker terminals from my PS Audio BHK 300 mono's to a Jensen Transformers SP-2SX - 2-Channel Speaker to Line Level Converter to the JL Audio f113.

The integration of the f113 with the PSA BHK 300's is much more seamless with the transformer.

https://www.jensen-transformers.com/product/sp-2sx/

Jensen makes great transformers and it makes sense to use them in this application.

Technically Barry is 100% correct and a myriad of REL owners are very happy with their setups, so go figure.

It just shows that “sounds great” and “technically correct” are not necessarily tightly related.

Barry also wants you to close off all of the ports in your speakers, essentially changing the design. I’m not doing that. :)