7.2 Set up from a 7.1 Receiver

Posted by: Bigdog76

7.2 Set up from a 7.1 Receiver - 02/06/13 01:22 PM

Is adding an additional EP500 Sub as easy as adding a male to dual female RCA splitter out of the back of the receiver to add a second sub? How does that effect the MCACC (Pioneer Sc-27) calibration when the receiver only sees one subwoofer? and cannot differentiate on the distances that it sets the sub and speaker levels ect? People have told me I can just add the spitter but this made me think about the calculations the receiver makes on the speakers.
Posted by: cohesion

Re: 7.2 Set up from a 7.1 Receiver - 02/06/13 03:02 PM

If you use a splitter there would be no way to properly do the automatic calibration. You would need to arrange the subs such that they were about the same distance from your listening spot and calibrate levels manually.
Posted by: SirQuack

Re: 7.2 Set up from a 7.1 Receiver - 02/06/13 08:02 PM

That is not totally correct. I have successfully calibrated 3 subs in my room. Most Audyssey versions, as well as offerings from Pioneer and Yammy's only have the ability to calibrate one sub. However, that does not mean you can't do a great job and get the room sounding awesome.

Basically you first want to calibrate each sub manually, making sure they are the exact distance/position away from the primary first measurement location. My 350's are within .5" of distance from the primary seat, where I took the first reading. Next, you have to manually run the dB test tones and calibrate each sub independently, one by one, to the exact same SPL in dB's, I think I used 78dB's. Keep in mind, when they are combined, the dB's will increase by about 3dB's, so you might want to measure them a little lower, so when combined they will be where you want them.

In my case, I run Audyssey just on my 2 350's, which are up front, spread out between my M80's from all 8 locations. I also initially calibrated my EP600 to the same dB's as the 350's and it is placed in the back of the room.

I've tried including the EP600 when running Audyssey, but I get better results, just adding it after the fact and run Audyssey just against the 350's. The internal DSP of the 600 makes the distance settings difficult, normally it comes back at 25ft, when actually 8ft. This is normal for DSP subs, but when the 350's are 9ft away things get crazy. Averaging distance does not help either.

Anyway, yes can get fantastic results with a receiver and splitting out the subs. Another option is to just daisy chain them from sub to sub.

Receiver line out to Sub 1 line in, Sub 1 line out to Sub 2 line in. That is if your subs have dual RCA jacks.
Posted by: dakkon

Re: 7.2 Set up from a 7.1 Receiver - 02/06/13 09:16 PM

I have dual EP-600's and i am just using a y splitter.. I my processor doesn't have any room correction for the subs. With 2 600's i don't think there is much need for room correction... the same should be true with a pair of 500's.. I say just buy a second 500 and enjoy it...


I will say with a pair of 600's the whole damn house rattles.. Room correction.. Ble.. House correction!!.. laugh
Posted by: Amie

Re: 7.2 Set up from a 7.1 Receiver - 02/08/13 04:34 AM

Funny - I was over at Axiom yesterday filming a video of Andrew Welker talking about this exact subject! **spoiler alert** He suggests in the video that you get each subwoofer sounding great on its own in the best spot for it in the room, and then you hook them together. EG calibrate each individually, as a single subwoofer, and then get the splitter out and do final tweaks from there.
Posted by: nickbuol

Re: 7.2 Set up from a 7.1 Receiver - 02/08/13 09:50 AM

That is what I've heard too. Mixing a decently tweaked sub in with one that sounds like crud in your room maye fix some things, but also make others worse. Calibrate each individually. Depending on your subwoofer options, this may be as "simple/limited" as finding a good location in the room (subwoofer crawl) and setting the right gain and then doing the same for the second sub, then splitting and going from there. You ideally want them at least the same distance from the listening area even if they aren't in the same location so that delays are calculated correctly, and then calibrate them as "one."

My Onkyo TX-NR709 has two subwoofers out, but my understanding is that they are nothing more than an "internally split" signal, meaning that I have no independant control over them via the Onkyo. That is more of a limitation of the Audyssey MultEQ XT. You need the Audyssey MultEQ XT32 to be able to control each sub independantly. I know that isn't directly related to the original question, but since others may have difference receivers, it should help with their questions too.
Posted by: cohesion

Re: 7.2 Set up from a 7.1 Receiver - 02/08/13 03:44 PM

Originally Posted By: Amie
Funny - I was over at Axiom yesterday filming a video of Andrew Welker talking about this exact subject! **spoiler alert** He suggests in the video that you get each subwoofer sounding great on its own in the best spot for it in the room, and then you hook them together. EG calibrate each individually, as a single subwoofer, and then get the splitter out and do final tweaks from there.


Of course Andrew's suggestion is good but he is essentially saying to manually position and tune each subwoofer rather than use an automatic calibration like Audyssey or MCACC. The op was asking about using the MCACC automatic calibration that is a feature of his Pioneer receiver. Like Audyssey, MCACC will attempt to correct for room-related issues like modal points. It also sets delay and level for each speaker. I would use this for the other speakers only and then follow Andrew's suggestion for the 2 subs. Probably this could be accomplished by setting subwoofer as none before running MCACC.
Posted by: CatBrat

Re: 7.2 Set up from a 7.1 Receiver - 02/08/13 04:50 PM

Why not just run MCCACC/Audyssey with all subs attached and running? (With volume control set to the same level on the amps). It should give correct results for the mic placement(s), I would think.
Posted by: JohnK

Re: 7.2 Set up from a 7.1 Receiver - 02/08/13 11:01 PM

Brian(Bigdog), one of the contributing problems in this area is terminology. There's no "7.2" currently in existence(despite manufacturer labeling of receivers with two sub outputs); there's only one .1 LFE(low frequency effects)channel and using multiple subs in the channel can't change that. Using two center channel speakers in a 7.1 system doesn't make it 8.1 and two subs don't make it 7.2.

This one channel can't be calibrated independently for level and distance delay for two subs by most receivers(including your SC-27). If the subs are the same model and at the same distance from the listener, the one set of adjustments done by the auto-calibration should be entirely satisfactory. If not, the levels of the subs should be matched manually(not by ear but with the aid of an SPL meter)before the auto-calibration. The auto-cal will then correctly match their levels with the main speakers. The distance delay set by the auto-cal won't be accurate if the sub distances from the listener are significantly different, and probably the best that can be done is manually adding the extra distance to the farther sub after the auto-calibration.

There are receivers such as higher cost units using Audyssey Sub EQ HT which send separate level and distance delay settings to the two subs connected through the separate outputs and then after the calibration make room EQ corrections to the composite output of the two. Dr. Kyriakakis has discussed this among other factors in his excellent thread here . Among the findings were that separate room EQ adjustments to the two subs weren't as good as a uniform set of adjustments to both.

As to the location of the multiple subs, the best location for each individually isn't the point, but rather locations where they have opposing acoustic parameters such as to reduce the effects of room modes. The research of Dr. Toole and his associates at Harman indicated that mid-points of opposite side walls or the front and back wall, or diagonally opposite corners gave good results.