Subwoofer: Front pre-outs vs. SUB pre-out

johnphoto

New Member
I'm revamping my entire setup. I have a new-old-stock Marantz SR8001 (2007, HDMI sourced and switched), and a new-to-me James EMB-1000 subwoofer.

According to the what-works-with-what chart in the receiver's manual, there's supposed to be SUB output under almost all conditions, including the analog direct setting. However the subwoofer only ever kicks in (green light) when the source is specifically 5.1 or 7.1 encoded (blurays and DVDs, SACDs, some broadcasts etc). (Also with processed 5.1 effects). Never with unprocessed vinyl or CDs, even when the frequencies are there that should activate it (e.g. organ music). With vinyl I'd rather stay away from processing, otherwise what's the point?

The receiver has a full set of pre-out RCAs. Since I listen mostly to music, and mostly watch movies without a lot of explosions, my solution right now is to connect the subwoofer via the front L & R pre-outs instead of the SUB pre-out. This of course totally works with music. But does this mean that when I watch something (movie, SACD) that has LFE encoded, I won't get it; or are the low frequency effects always present in all channels? Using the LR front pre-outs, should I tell the receiver settings that there's no subwoofer, and do a new Audyssey speaker setup? (If I leave the receiver thinking there's a subwoofer I could simply change the cable to the SUB-out for a Hollywood-type movie).

Settings on the James EMB-1000 subwoofer: I have the crossover set to variable (~100) as opposed to bypass. (My new-to-me mains are a pair of elderly PSB 800 towers with decent bass response).
 
If you're going to use the system as-is then set the L/R speakers to "large" and tell the Marantz that you have no sub. Low (i.e. effects) frequencies will not be sent to both L/R and sub out.

Unfortunately you then lose the high-pass filter for your mains, which means some frequencies will be reproduced by both the subwoofer and the L/R speakers, unless you carefully adjust the sub's low pass filter to start cutting out where the mains come in.

However, you might try AVSForum; there are almost definitely members there with that receiver that can give you info on how to get it working properly (assuming it's not defective).
 
SR8001 is a great receiver, still today. I have an SR5001 since new, these days is in a secondary HT system. Run your sub from the sub pre-out. If not mistaken you can adjust settings for it using the OSD, where you can access all kinds of settings and adjustments for HT and music.


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The manual seems to provide unclear, if not conflicting information, in different areas.

Usually when Source Direct or Pure Direct is engaged bass management is disabled so the sub doesn't work with 2-ch analog or straight up PCM input signals. The chart of audio modes vs. input signal type vs. output channels seems to bear that out (and seems to match your experience).

That said, looks like there is a "Bass Mix" setting wherein the manual says the sub will work with analog and PCM if you set fronts to Large, sub to Yes, and Bass Mix to Both. Guess I'd give that a try if you haven't. OTOH, if Source Direct and Pure Direct disable bass mangement, not sure how that could work. It's easy enough to try though...maybe get lucky. There's that darn conflicting/unclear meaning stuff again.

If that doesn't work then I think you'll have to go as suggested in the previous post. There are two ways to do it. Use the front L/R pre outs to the sub L/R line level inputs (do not "Y" the receiver L/R outputs to the sub's LFE input). Or, use the L/R speaker level inputs connected in parallel to the corresponding speaker. You could connect the sub either to the speaker teminals on the receiver or at the speakers themselves. Of the line level or speaker level connection method, I would use whichever is more convenient for hook-up and wire/cable on-hand. There is no distinct advantage to using the pre outs in this case.

Also, as previously mentioned, to use the L/R pre outs or speaker level connection, you'd set sub to No and front speakers to Large. However, this means all bass and LFE will go full range to your front speakers. That can be pretty demanding of the speakers when watching movies even at moderate volumes. The setting of the sub's low pass filter/frequency control should be a bit higher than the low end capability of the front speakers. Unfortunately, the sub's low pass control will have zero effect on reducing bass (no high pass filter) going to the front speakers.
 
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Just one question the OP had that hasn't been specifically answered...

If you use the Front preouts, you can still limit the bass going to the center and rear/surround channels by setting the desired xover freq on the AVR.
 
In addition to that, is the clarification of subwoofer vs. LFE.

Subwoofer bass = "normal bass". That being the bass that's, say, present in the channels of a stereo recording or in the left, center, right, surround, or back channels.

LFE = discrete channel of Low Frequency Effects (hence, designation "LFE"). This is a dedicated channel, the .1 in 5.1, 7.1, etc., LFE is independent of subwoofer bass.

Setting speakers to Large or Small dictates whether they get full range signal (large) or signal that is high pass filtered (small).

If the front speakers are set to Large and sub is set to No/Off, then the front speakers:
-get full range signal present in the front L/R channels
-get bass from all small speakers, according to the high pass filter settings selected
-get the LFE
 
OP here: Thanks for all the advice. I did an auto setup telling the AVR that there was no subwoofer and connecting the sub to the AVR LR Front pre outs, but nothing from the sub. I now have the speakers set up manually, with distances and dB offsets from the auto setup and all speakers (except rear surround) set to large; sub to no; sub connected to Front pre outs. And perhaps crucially, with bass mix set to both. Kind of an amalgam of the suggestions you all were kind enough to make. Works well, I'll stick with it for a while. Music bass is terrific.

Sorry to reopen a subject that has been done to death; I couldn't find anything covering my particular situation. The chart in the manual was puzzling, suggesting that the sub should almost always be there with analog and stereo. Maybe the manual just left unmentioned the need to set up in the ways we've discussed.
 
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The manuals are not written to cover every possibility that people can dream up. They cover the normal operations and conditions.

If you want sub on analog sources in direct modes you have to cheat, as you did. Direct means you don't want any processing. Bass management is done in the digital processing. So, you can't tell the processor "no processing" then expect to get bass mangement. That is not expected operation of the unit.

Myself, I find using the settings that facilitate bass mangement provides more benefit to me than the direct modes do.
 
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