Speaker/Subwoofer Adjustments

Until a few days ago, I was pleased with the audio and video playback of my HT. I must admit though, "I'm a tweak head!" For some reason I always feel if I made one more tweak, it would look or sound better. Anyway, both the ML Aeon i's and Descent came with the patent ML spikes. However, I didn't feel the need to install them because it already sounded great.

Well hold on to your seats boys and girls (speaking of girls, why aren't there any in forum)anyways, after installing the spikes on the fronts, I played one of my favorite movie and audio demos

David Benoit (Every Step of the Way) GRP, track 3 Key to You and 4 Remember what you Said David Benoit, Every Step of the Way, GRP, track 3 - Key to You & 4 - Remember what you Said. I've loved this CD since the time of purchase (1988) but never have a heard it sound this good. Mind you now, I still haven't installed any acoustical panels or traps....I think many of you would be amazed on the tightness of my sound stage and detailed imaging. With the spikes added to Aeon's, they sound like a totally different speaker. In short, they've completely disappeared in the room. Even the wife notice!!! That's gotta stand for something! :-)

Then came Master and Commander, chapter 4 (Under Attack). All I could was take a deep breath, close my eyes and say, thank God for good sounding HT. I was again completely blown away at the detail now audible in my system. By far the cheapest tweak even done.

Now came the coup de gras; placing the spikes on the sub. Until now, I believed to get the tightest LFE from my sub was definitely going to require installing traps of some sort. I don't think I can put into words how excited I am about my system right now. The low end in my theater is so quick and tight, I had to lower the level a notch. I still may need to add a couple acoustical panels; definitely don't need traps, but on a scale from 1 to 10 my system is a 12

One question for the group. How do I determine the best setting for the ML Sub? These are the options:

Phase: 0, 90, 180, 270 (I have it set to 0)
Low Pass Filter: 40hz or 70hz (I have it set to 40hz)
Level: set to 5
25hz Level: 0 to +12bd or 0 to -12db (I have it set to 0)

For phase, the rule of thumb is usually to play a test tone and try each setting - the one that seems loudest is the one to use.

For the low pass filter, I'd either disable it or set it as high as possible - the 990 is providing you with bass management already, so you don't need a second crossover getting in the way. With the 40Hz setting (assuming for a moment that you don't have all of your crossovers in the 990 set to 40Hz as well), you are throwing away subwoofer signal - probably a lot of it. If there's a way to disable the crossover, use it. If there isn't (and with a max setting of 70Hz I really hope there is), set it as high as possible.

The level should be fine at 5. That's where I tend to start, and then fine-tune the sub trim in the processor's settings.

The 25Hz level sounds like an EQ at 25Hz. I'd probably leave it at 0 like you are.

Thanks Gonk. Unfortunately, there's no way to turn off the low pass filter. And set to 70hz, it gets really boomy..yuck. Other suggestions?

I was going to really be disappointed in Martin Logan if they had actually messed that up (home theater sub has to have a way to disable its crossovers), so I grabbed the Descent i manual . At least on the Descent i, the "LFE in" connection on the sub bypasses the low pass crossover. Then I realized that you have the original Descent (not the Descent i, which has a 50Hz filter and a couple other controls that you didn't mention having on your sub), so I chased down that manual . Sure enough, page 7 confirms that the LFE input still bypasses the low pass crossover (whew!). I'd recommend connecting the 990's subwoofer output to that input. ML also suggests using that 25Hz filter to tweak the sub if you are having trouble getting the sub and mains to blend together well (either too little bass or too much) - if you're getting "boomy" bass, you may need to try dialing the 25Hz filter down a bit. You might also tinker with the crossover settings in the 990.

WOW...you know, any other time I'd feel bad when people know more about my equipment than I do but for some reason this time I don't. Thanks Gonk...I'll make that change tonight and let the Outlaws know how it turned out.

Well Gonk, I made the change and was sadly disappointed. Bypassing the LowPass Filter in ML Descent and allowing the 990 to manage the bass was not pleasant. Now I'm not saying the 990's bass mgmt failed because I still haven't done the update :-( I know, shame on me but will doing the update really make a difference in performance or will it just provide more controlled mgmt?

After making the change, it was now apparent the sub was located in the right corner of my theater, it lost its quickness and suddenly became boomy. And increasing the level made it worse .....it sounded like my 1990 Kenwood rack system....don't mean to offend anyone. Bottom line, it wasn't good at all. Needless to say, I changed it back to allow the ML Sub to manage the bass and like that, I had my system back. Woohoo!!!

So school is open...besides yelling at me for not doing the update, what else should I do?

The update will only matter if you are operating in a way that runs afoul of some bugs - it's been long enough that I've forgotten what the problem arrangements were, but I don't think your system is currently one of them (although they did also do some nice things in that firmware update ).

Two questions about your current setup: what crossover points are you using on the 990, and what crossover point are you using on the Descent?

990 setup:

small & 40hz on the fronts
small & 120hz on the center & surr
LFE Only for the Sub with the ML LowPass Filter set to 40hz

When you say "LFE Only" you are talking about the 990's subwoofer setting right? The sub cable is running to the Descent's left or right input? If that's the case, the one thing that I worry about is the fact that you are completely throwing away everything between 40Hz and 120Hz on the center and surround channels, plus anything above 40Hz in the LFE channel. Can you try the 70Hz setting on the Descent? That would at least decrease the size of the hole in your low frequency.

Yes....LFE only in the 990. Yes the sub cables are connected to the Descent left and right input. When I try the 70hz setting on the Descent, it gets boomy. Is there anything i can do to reduce the boom and accomplish what you're recommending?

Nice system EJ!

I would recommend installing the firmware update on the 990. It makes life a lot easier both for setup and regular use. And a question, did you make sure the 25 and 50 Hz settings are zero on the Descent? If either is too high, this would definitely cause booming.

As it says in the Descent manual try either letting the 990 do all the bass management or use the standard 2-channel hookup between the Aeons and Descent. What you are doing is mixing the two, and as Gonk recommends it is good to avoid double sets of crossovers.

If you let the 990 do the bass management just make one connection from the 990 sub output to the LFE input on the Descent. According to the Descent manual this bypasses the internal Descent crossover settings but still allows you to shape the bass with the 25 Hz and 50 Hz level controls. Again start these at zero. You could even use a balanced connection for this.

The other option is to use the Descent crossover by doing the 2-channel hookup between the Descent and the Aeons as described in the Descent manual. If you do you need lots of long cable runs. Then you configure the 990 with NO SUB and the fronts as LARGE. The 990 will divert the bass from the center and surrounds to fronts, and the Descent's crossover will handle splitting it appropriately between the Aeons and the Descent. Again you can use still the 25 & 50 Hz levels to control deep bass and boominess.

Between you and me, I would try the first set up consistently before you give up on it. Adjusting the sub levels and settings with knobs on the sub is very tedious -- you need a friend to sit by the sub and turn the knobs and switches while you listen and measure.

Thanks wolverine.....I'll give it a try.

Let us know how you work it all out.

The AVIA Gudie to Home Theater DVD has a good subwoofer set up section with test tones. I used it to set phase and the sub level (while keeping the sub outpt on the receiver at 0 dB). You don't need the AVIA to set up the other speakers but I found it invaluable for the sub (and for the TV). It's $38 on amazon.com, which may be less than the sub cable that you use and will probaby do more for the sound

Ok Gonk, I took your advice and went with the connections you recommended; 990 Sub Out to ML LFE in, bypassing the ML crossover.

New 990 Settings:

Fronts = Large @ 40hz
Surrounds = Small @ 120hz
Center = Small @ 120hz
Sub = LFE Only

Sub Settings

1. Phase @ 0
2. Low Pass Filter is now disabled
3. Level @ 5
4. 25hz Level @ +3

I just made the change so not allot of listening time. I did briefly listen to a few of my favorite regular and SACD's and I have to say the immediate experience wasn't pleasant. I did play with the 25hz level a bit and successfully got rid of the "BOOM" but I can't find that quick, tight, disappearing bass I used to have....its there though....just needs a little more tweaking. Maybe a need to reposition the sub....?

Threw in a couple movies and immediately I could hear the difference in the dialog and mids. I actually had to go into the 990 and dial them down a bit because they were now so prominent. "That was pleasing!" The low end response remained almost as quick and transparent as the previous setup but I had to adjust the 25hz level to get the umff I wanted.

Only because I was impressed by the video sound reproduction will I live with this setup until I've done some real critical audio listening. Audio playback is a very important part of my HT, so this has to work.

Any suggestions ?

With the fronts set to large, two-channel sources played back in stereo should have no subwoofer present. Obviously if a surround mode like PLIIx is used, that changes things.

I'm starting to wonder if you don't have some room problems - the fact that you get "boom" and/or start having problems integrating sub and speakers as soon as the sub starts reproducing anything about 40hz really seems out of place. My SVS 25-31PCi gave me a little grief in this regard at our old house (crossed fronts at 40Hz so the sub wouldn't intrude when listening to music in two-channel), but it was better behaved in our new house (although the LFM-1 blended better still, as I mentioned in my LFM-1 review) and it wasn't as bad as what you are describing. You're just having way too much trouble getting the sub to play nicely with the rest of the system, and the most likely explanation at this point is room effects. Fixing it acoustically (sub placement, bass traps, and other acoustical treatments) is an ideal approach, but it's tricky business. You might actually want to consider something like an SMS-1 at this point (in which case I strongly recommend Outlaw's SMS-1 Guide to walk you through setting it up optimally).

So besides your assumption of needing acoustical treatments, you think changing the fronts to small would improve bass response in audio playback?

Yeah, I think setting the fronts to small would probably help with bass response for two-channel playback.

Another question (possibly been asked before and dismissed for some reason I can't remember)... Have you tried a lower crossover for the center and surrounds? The Cinema i is rated to 80Hz and might perform well with a crossover of 100Hz (maybe even 80Hz), and the Monitor Audio Bronze surrounds can get down to 65Hz (which might work well with an 80Hz crossover).

Gonk, once again you were right. Changing the fronts to small (this forces the 990 sub trim to "yes") made a significant difference in 2-chnl audio playback. I like it! Good thing I tried all these new settings before moving anything around!! That would've been a nightmare. Now I'll try tweaking the center and surround crossovers as you suggested. I'll let you know this evening how it goes.

Thanks again.

I am glad you finally got things all worked out. This is actually what I meant above by but I should have added to set the fronts to small. Sorry!

I agree with Gonk about trying lower crossover settings for the center and surrounds. Listen to some 2-ch source that should have a centered bass guitar with PLIIx, change the center crossover and see if the bass player is centered or appears to move over toward the sub.

Also, you can also adjust the 2-channel subwoofer offset which changes the sub level if there is too much or not enough bass in stereo compared with multichannel.

Gonk, after making the changes to surrounds and center xover, I decreased the sub trim in the 990 but slightly increased the 25hz level on the ML sub to +6bd.

Now, audio reproduction is excellent (Upsample or Bypass). A/V reproduction has never been a problem however since making the xover changes, the center and surrounds are more defined.

Thanks

Glad to hear that you got it working!