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· Registered
1 Posts
Discussion Starter · #1 ·
Hi Everyone,

I would certainly appreciate it if someone could please give me some suggestions on how to fix a problem I'm having with my home theatre system.

First a bit of background. I have a Marantz SR7500. Speakers are JMLab Focal Chorus 726 S, with a Martin Logan Dynamo 700 sub.

The Marantz on screen menu for the speaker setup is such that the sub is 'yes', all speakers are set to 'large', surround back is set to 'speaker c' (I am using this to bi-wire my front's), LPF/HPF is '80hz', and bass mix is set to 'both'.

The problem is that I know a signal is being sent to the sub as the standby light comes off and when I do the speaker test and turn the volume up on the onscreen menu, I hear a very faint rumble from the sub.

I'm using a digital coaxial cable from the 'sub preout' on the back of the Marantz going to a y-connection which goes to the left and right input on the sub. The volume on the sub is at 6 and the crossover is set to approx. 56hz. The phase is set to 0.

If anyone has any helpful suggestions, I'd certainly appreciate it.

· Super Moderator
59,148 Posts
Try setting the speakers to small, the crossover on the AVR to about 40Hz. The crossover (LPF) on the sub shouldn't matter if you're using the LFE (right) input on the sub, but set it to "max" (120) just in case. Set the sub's "crossover" switch to LFE. Remove the "y-connector" and connect the sub cable to the right LFE input directly, as shown in the sub's operating manual. The AVR should be adjusting the crossover, not the sub. The sub volume should be around 12 o'clock. Have you run MRAC and does it run properly with the proper tones coming out each speaker?

Are you complaining that you don't get enough rumble from the sub, or that the sub is rumbling when it shouldn't?

You may wish to simplify and forget about bi-wiring since it rarely makes any difference, but you should be able to leave it if all of the above makes things work properly. Just as an FYI, with most AVRs if you set the front speakers to "large", the sub will not come on if you listen in "stereo" mode. If you wish to utilize the sub when listening in "stereo", you need to set the front speakers to small. I realize your speakers are not "small", but there is nothing wrong with setting the AVR output to small with a low crossover to the sub. Your speakers will still be well utilized.

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