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-   -   JL Audio Fathom f113 Question (https://www.audioaficionado.org/showthread.php?t=45431)

Cohibaman 03-27-2019 09:50 AM

Quote:

Originally Posted by crwilli (Post 958741)
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.



: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

crwilli 03-27-2019 10:15 AM

Thanks Mike! I am okay now ;)

crwilli 03-29-2019 02:44 PM

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

Cohibaman 03-29-2019 03:59 PM

Spoke with Randy several times. He is fantastic!

Audiophilehi 03-29-2019 04:07 PM

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?

crwilli 03-29-2019 05:26 PM

Quote:

Originally Posted by Audiophilehi (Post 959090)
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.

jbaudio68 03-30-2019 02:13 PM

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?

crwilli 03-30-2019 02:38 PM

Quote:

Originally Posted by jbaudio68 (Post 959184)
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.

jbaudio68 03-31-2019 01:18 AM

Quote:

Originally Posted by crwilli (Post 959188)
Change nothing but set your CR-1 to L + R instead of stereo. That way the CR-1 sums the two channels.



Ok thanks!

jbaudio68 04-05-2019 12:03 AM

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!


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