connecting sub for both 2-channel & multichannel

[majac777]

Hello,

What is the best way to connect my MartinLogan Dynamo 10 sub so I can use it in both 2-channel stero (for music) AND in multichannel for HT?

Current setup: Onkyo 805 AV receiver, Axiom M80s for mains, Axiom VP100 center speaker, and my old rig speakers for R & L surround.

The Onkyo AVR has a single Sub-Out. The MartinLogan has R & L inputs, and a separate LFE input.

I'm a little confused about connecting it properly for two different uses.

Best Regards, Majac777

 

[jostenmeat]

You can simply use the same lfe connection for both uses. (Although there are some that think that speaker-level is "best", whatever). The issue is where you might want to x-over. For HT, 80hz is good, because there is audio info up to that point that is meant for the .1 sub only (will never reach towers even if x-over'd lower). I find, however, with music often a lower x-over is better. You might need to experiment.

*Also, are you running the mains as "large/full-range". You will have very negative effects if running large + sub for music. Phase and amplitude issues. For HT, its fine, actually preferred.

Easiest and most expensive way is to buy a nicer bass management unit than what the Onkyo probably has. Anything from affordable Behringers to the very user friendly, capable, and expensive Velodyne SMS-1. Ive heard great things about Outlaw's, but they are dc'd. Some like the Velodyne will offer presets for different uses, while also improving (evening out) bass response at the primary listener's position. The OSD will visually show you (Wish I had one ).

I've never had hi-level inputs on the sub before. Maybe you can have both hi-level and lfe connected at the same time, flick a switch (or two?) between HT and music? Ideally the sub's x-over is engaged for music, and disengaged for HT (while using lfe input). Sorry, that I am unclear here, but something to ask about or investigate. This would only work if the hi-level was still "passing-thru", but without x-over engaged during HT.... I think*, right?.... Also, this is assuming that the mains are always set to large.

best wishes.

 

[Kolia]

Use the LFE connection

Like Jostenmeat said, your receiver should take care of the signal and Xover point for 2.1 operation.

Make sure that, if the sub's Xover isn't by-passed, it is set at a higher frequency than that of the receiver.

Question for Jostenmeat: why do you say running the fronts has large would be a problem?

 

[majac777]

I've never had hi-level inputs on the sub before. Maybe you can have both hi-level and lfe connected at the same time, flick a switch (or two?) between HT and music? Ideally the sub's x-over is engaged for music, and disengaged for HT (while using lfe input). Sorry, that I am unclear here, but something to ask about or investigate. This would only work if the hi-level was still "passing-thru", but without x-over engaged during HT.... I think*, right?.... Also, this is assuming that the mains are always set to large.

best wishes.

The way a local HT tech advised me is: use a RCA Y-splitter...the single end to sub-out on the receiver; one of the two RCA-outs (split RCA) to LFE input on the sub, and the other of the two (split) RCA-outs to either the + or - input on the sub. His rationale is that if I'm listening the stereo music (with the AVR set to 2-channel stereo)...the sub's LFE will not be active and I'll have the advantage of adjusting the crossover on the sub..

and when I'm using HT (Dolby or DTS 5.1)...the LFE kicks in on the sub and the +/- input on the sub in not active (provided the recevier is set for 5.1).

Kind of confusing eh? Hope he's right.

Anyone have any input about this?

Thanks, Majac777

 

[j_garcia]

The sub doesn't care...so the guy at the shop is not entirely correct. It is true that there is no .1 channel in stereo sound. Howver, if you are listening in stereo, unless you have some kind of "pure direct" or "source direct" mode turned on which bypasses bass management, you WILL get the sub in your mix as long as you have your speakers set to small and sub = yes. This is fact.

The Onkyo 805 should have some of the latest bass management on the market...I highly doubt the problem lies there. I've setup a number of previous Onkyos and this sort of thing has never been an issue.

 

[jostenmeat]

Hm. Assuming the dealer is right on all counts in how it works, you will effectively be getting low-pass only still (again, assuming mains are always full-range). No high pass filter for mains. *Now, really, do what pleases you, but not giving the mains a high-pass while engaging sub is generally not recommended. (For Kolida too, oh nice rig btw) the phase and amplitude issues I mentioned will generally expose themselves as muddy and unclear lower registers. You should understand that 2.1 audiophiles that use towers rather than bookshelves seem to be crossing-over as low as the hi-20's to as high as 40-ish hz. At least, that's what I've perceived. (The few people that use my speakers in 2.1 rig seem to like at it around 28hz). Again, if it sounds good to you, who is to argue. I've tried low-pass only already, and while I do enjoy some of the added things that come more into the foreground (I think jazz walking bass for ex), things are just too muddy, unclear, and inaccurate for me. Waiting on either a BM unit and/or nice Audyssey system. Speaking of:

I knew that the 805 is supposed to be quite a nice piece (60 amps, MultiEQ right?). I've set up a few Onkyo's already in my extremely limited audio experiences, and the ones I've seen do not have continuously variable x-over, nor "flick-of-a-switch" x-over presets. Even in my own pre/pro, even if the limited settings of 40/60/80 etc were good enough, it would be a downright pain to turn the tv on each time, check the OSD, change x-over setting for every time I went back and forth from HT and 2-ch. Well, this was perhaps the half-baked reasoning behind my statement, "Easiest and most expensive way...".

As far as frequency response correction, j_garcia is right, the Audyssey should do a better job on its own that even an SMS-1. I've never set one up, so I have nothing else to offer, and I do not know how truly flexible they might or might not be. It will work a larger area as well, not just for one perfect sweet spot. Time domain correction they call it; identifies and corrects overhang that would not necessarily show up on a simple level meter, if what I understand is correct.

A lot of blabber, but not much substitution for trying for yourself!

 

[AVRat]

Just use the single LFE connection and set up the speaker x-overs appropriately in the receiver. Onkyo's "Pure Audio" disengages the video a display circuitry only. The "Direct" mode allows minimal audio processing. Whether it affects bass management is not explicit in the manual, but I doubt it. See pg. 76

 

[jostenmeat]

Just use the single LFE connection and set up the speaker x-overs appropriately in the receiver. Onkyo's "Pure Audio" disengages the video a display circuitry only. The "Direct" mode allows minimal audio processing. Whether it affects bass management is not explicit in the manual, but I doubt it. See pg. 76

I guess my input/warning is completely dependent on the OP's inclination to apply hi-pass to the mains or not. I guess we should assume that he is? If BM applies in the receiver, then yes. But my impression about the dealer's recommendation does not seem to be the case for the music part of the equation, if what I am gathering is correct...

Low level input to sub (w/ its own x-over engaged) + hi level output to speakers. OK, then, lets say OP never adjusts x-over level in receiver (assuming it IS set to something). Now all of a sudden we might be talking about stacked cross-overs. Right? Careful majac.

Of course, following AVRat/garcias' recs would make sure this is all a moot point. I think I was attempting to cover certain ideas in light of getting the best performance possible in the both the separate arenas of HT and music...
if not a big deal, yep, set it to some level in the receiver, and be done with it.... again, assuming mains are not set to "large"....

majac, are you planning on running mains as "large" or "small"?.....

 

[majac777]

Hello,
thank you all for your feedback! FYI, I spoke with MartinLogan service rep today about the best way to connect the Dynamo 10 sub to the Onkyo 805 AVR; the issue being: best connection for stereo music vs. DVD 5.1 movies. I did take his advice, I just would like to know if it makes sense with you all:

Placed a RCA y-splitter into sub/LFE out to the AVR; used a single RCA cable on one of the two splits to the LFE input of the sub. Used another RCA cable on the remaining split from sub-out to the + (R) input terminal of the sub.

The rep told me that the Dynamo 10 has onboard circuitry to sense what signal format is coming to it, and will automatically use the LFE for 5.1 signal input, and the + (R) input for non .1 signal.

Every thing sound OK to me.

Does this jive with you all??

Thanks, Majac777

 

[j_garcia]

Yes it does make sense what he is saying, my issue with it is that it seems completely unnecessary. In fact, the only difference between those two inputs on the sub most likely is the fact that one uses the crossover and the other does not; otherwise they are both receiving the same signal since it is analog after all. The sub doesn't "know" what is being sent to it at all or what format it is in (which is line level analog in both cases), it just amplifies whatever signal it gets. Your receiver should be taking care of all of the sound that is .1 (LFE) as well as what is not .1 via it's own bass management.

I have seen a few receivers that automatically set the mains to large and sub = none when the playback mode is Stereo, however these seem to be very rare compared to the vast majority that don't work like this or at least have the option of turning that feature off. I haven't used the 805, but as I said I have configured a number of Onkyos and they have all allowed the use of the sub with the mains at all times even in stereo mode.