AVS Forum banner

1 - 20 of 277 Posts

·
Registered
Joined
·
1,394 Posts
Discussion Starter #1
So I just added a second sub (Dual Outlaw LFM-1 EX). This is my first time with dual subs. I have been doing some reading and searching on the concept of level matching vs gain matching. Both really seem to have strong points. I think I like the concept of gain matching better, as to not have one sub run out of steam before the other.


Here is my situation. My room is sealed and pretty small. All of my seating is in the back half of the room (as is most people). Last night I gain matched each sub, and the sub in the room is 3.5 dB louder at the listening position than the one in the front of the room. I didn't have the proper splitter, so that is as far as I got. I am going to spend a ton of time this weekend trying all kinds of positions and measuring and listening.


Is 3.5 dB difference at the listening position too much of a disparity to effectively gain match? Would it be better, if I am going to gain match to put both subs in the front of the room to get a closer match at the listening position between the two subs? In my situation, might it be better to level match each sub at the listening position, since the room is so small, and I "think" I wouldn't push either sub into clipping anyway?


Thanks!

Greg
 

·
Registered
Joined
·
165 Posts
I have never gain matched my sub's, but I dont think 3.5 db is anything to worry about. Someone who knows more may chime in. I only level match my subs and If one poops out sooner I just turn it down a notch
 

·
Registered
Joined
·
1,706 Posts
Greg, as Haskin has said, I don't think the 3.5db is that noticeable. Personally, I am a fan of level matching identical dual subs, especially if you are using a calibration tool (such as Audyssey, Anti-mode) and have one LFE out signal Y-split to each sub. If you find that one sub is reaching its max with level matching, I would than use gain matching.


OTOH, with non-identical subs, GAIN matching the subs may help prevent the lesser sub from potentially maxing out (which would limit your sub set-up).
 

·
Premium Member
Joined
·
13,082 Posts
I am a proponent of gain-matching. I have 3 Submersives, asymmetrically placed around my room. I want them all to drive the room with same energy, no matter what the relative SPL's are at any one listening position. This ensures they all have the same headroom, and they are all contributing equally to the sound. I don't hear any directionality from any of the subs anywhere in the room, even if I stand or sit very close to one of them.


To gain-match identical subs, the most rigorous method is to move each sub to the middle of the room, place a mic very close to the driver, and measure the SPL. Then move each of the other subs to the exact same position with the mic exactly the same distance away, and set the level to the same SPL as the first one. I place tape on the floor around the first sub, so I can ensure the subsequent subs are located in the exact same place. I don't move the mic between measurements. This works for identical subs, and the level knobs should be at the exact same point, assuming the amps are consistent from unit to unit. It also works for different subs, but then you should expect different settings on the amps.


Mark Seaton was the one who suggested this method to me, and if it's good enough for him, it's good enough for me.



Craig
 
  • Like
Reactions: rossandwendy

·
Registered
Joined
·
1,394 Posts
Discussion Starter #6
Thanks for all of the advice. I was really bought into gain matching. I spent a lot of time today trying everything. What I found in my room, is level matching worked better. In my room one sub in the front, and one in the back really sounds the best. When level matching I got a flat response down to 15hz. When I gain matching, the best I could do was flat to 20 Hz and a slight rolloff from there. I get that every room is different, but this is what worked in my room. I am not too worried about overdriving the sub further away, because my room is small enough that even a single sub in that position was probably enough. When I added the second, I added in 4.5 DB of headroom.
 

·
Registered
Joined
·
4,394 Posts
Gain matching for me.
 

·
Premium Member
Joined
·
13,082 Posts
I was at a friends house tonight and he has 2 small, 12" sealed subs subs. One was placed in the left corner, and one was placed on the right but in the middle of the front wall. (The front wall is much wider than the area were the AV system is, so the the right of the right speaker is mid-front wall.) The two subs were obviously receiving significantly different room reinforcement. We initially tried level-matching. We set both subs so their levels matched at the primary LP. This yield about an 8 dB higher gain setting for the mid-wall sub. We watched the Star Wars opening scene. Immediately we realized the mid-wall sub was distorting badly and we had to turn down the overall level to compensate.


Next, we tried gain-matching. This allowed about a 3 to 4 dB increase in *system* level over the level-matched system, while retaining excellent sound quality for the entire system. This, yet again, reconfirmed my belief in the gain-matching technique.


Craig
 
  • Like
Reactions: rossandwendy

·
Premium Member
Joined
·
13,082 Posts

Quote:
Originally Posted by Kimwyn /forum/post/19338378


Please ignore my ignorance but what is gain matching?

See Post #5 above.
 

·
Registered
Joined
·
4,394 Posts
Craig,


I gain matched (using the Anti Mode) my quad Empires a couple of days ago. I have two under the TV firing to the front (10 ft to the seat) and two to the rear of the seat (6 ft from the seat), firing forward. Big improvement over level matching with bass clairity and mid bass slam sounding the best that I have ever heard in my room. Audio thru the system has improved greatly also with gain matching of subs. So much detail that I am watching clips all over again just to see what I have been missing. Finally, just want to say . . . gain match your sub(s) and don't worry about the spl at the seat as the bass will be there.


Bill
 

·
Registered
Joined
·
1,394 Posts
Discussion Starter #12
So as with most things audio, I can't leave well enough alone...and I am glad I can't. I spent tonight moving around my subs and gave gain matching another try. With my subs in their new spots, gain matching measured better and sounds a heck of a lot better.
 

·
Registered
Joined
·
824 Posts
I have a quick question and there are several people in this thread that I respect when it comes to subwoofer info. I've changed from having my dual Epik Sentinels on opposite sides of the room, which sounded great, to stacking them in a corner due to wife's request.


I'm splitting with a Y to both, so I don't have to run dual sub cables, and have a question regarding calibration. I'm using the Audyssey on my Onkyo 707 and I'm wondering if I should just hook them both up and calibrate like normal or if I need to do something different? At this point in time I don't have an SPL meter and am relying on the receiver.
 

·
Premium Member
Joined
·
13,082 Posts

Quote:
Originally Posted by irishluck73 /forum/post/19356129


I have a quick question and there are several people in this thread that I respect when it comes to subwoofer info. I've changed from having my dual Epik Sentinels on opposite sides of the room, which sounded great, to stacking them in a corner due to wife's request.


I'm splitting with a Y to both, so I don't have to run dual sub cables, and have a question regarding calibration. I'm using the Audyssey on my Onkyo 707 and I'm wondering if I should just hook them both up and calibrate like normal or if I need to do something different? At this point in time I don't have an SPL meter and am relying on the receiver.

If they're co-located, (stacked), they should be gain-matched. If you don't have an SPL meter, your only option is to set the amplifiers to the same volume/level setting. Assuming the amps have the same gain structure, this *should* be gain-matched. However, you will now have at least 6 dB more output from the corner-loaded, co-located subs, so you'll need to use the receiver's auto-calibrate to calibrate the combined levels. If Audyssey sets them to the negative limit of it's range, you'll need to turn each sub down by the same amount and re-run Audyssey until you get the levels within the trim range of the sub channel.


Craig
 

·
Registered
Joined
·
686 Posts

Quote:
Originally Posted by craig john /forum/post/19357379


If they're co-located, (stacked), they should be gain-matched. If you don't have an SPL meter, your only option is to set the amplifiers to the same volume/level setting. Assuming the amps have the same gain structure, this *should* be gain-matched. However, you will now have at least 6 dB more output from the corner-loaded, co-located subs, so you'll need to use the receiver's auto-calibrate to calibrate the combined levels. If Audyssey sets them to the negative limit of it's range, you'll need to turn each sub down by the same amount and re-run Audyssey until you get the levels within the trim range of the sub channel.


Craig

Craig,

What if you have dis-similar subs....at unequal distances to lp? When I gain matched in this scenario, one sub was over powering the other.
 

·
Registered
Joined
·
824 Posts

Quote:
Originally Posted by craig john /forum/post/19357379


If they're co-located, (stacked), they should be gain-matched. If you don't have an SPL meter, your only option is to set the amplifiers to the same volume/level setting. Assuming the amps have the same gain structure, this *should* be gain-matched. However, you will now have at least 6 dB more output from the corner-loaded, co-located subs, so you'll need to use the receiver's auto-calibrate to calibrate the combined levels. If Audyssey sets them to the negative limit of it's range, you'll need to turn each sub down by the same amount and re-run Audyssey until you get the levels within the trim range of the sub channel.


Craig

Thank you very much! Pardon my ignorance but I thought co-locating and corner loading was to achieve the 6db increase? If you match the volume settings on the subs, auto-calibrate afterwards and bring the 2 subs in line with Audyssey's parameters than wouldn't having just 1 sub corner loaded suffice or be the same thing? Or is this simply for gaining more headroom?


I'll be trying this later today. I'm also getting an SPL meter in the very near future.
 

·
Registered
Joined
·
1,394 Posts
Discussion Starter #17

Quote:
Originally Posted by irishluck73 /forum/post/19358176


Thank you very much! Pardon my ignorance but I thought co-locating and corner loading was to achieve the 6db increase? If you match the volume settings on the subs, auto-calibrate afterwards and bring the 2 subs in line with Audyssey's parameters than wouldn't having just 1 sub corner loaded suffice or be the same thing? Or is this simply for gaining more headroom?


I'll be trying this later today. I'm also getting an SPL meter in the very near future.

The purpose is not to increase the sub by 6dB. It is to gain 6dB of headroom and make your sub/subs 6dB more capable than they were before. If you choose to run your subs hotter than calibrated, that is your choice, and the second sub will help in those efforts, but your calibration philosophy should be the same whether you have one sub or four subs.


I chose to seperate my subs rather than co-locating, but my goals were different than adding 6dB of output.


I hope that helps.
 

·
Registered
Joined
·
824 Posts

Quote:
Originally Posted by ******* /forum/post/19358914


I hope that helps.

That helped a lot! Prior to this week I had my subs separate but the wifey wants to utilize more space in the living room now. Between my job and a 9 month pregnant wife I don't have as much time as I'd like to research and learn about everything I'm interested in. Great explanation and it's appreciated!



The only thing that looks odd is going from BJC subwoofer cable to the Radio Shack splitter, much thicker cable from BJC.
 

·
Registered
Joined
·
824 Posts
I dialed both Sentinels down to 3 o'clock on their gain setting and ran Audyssey. It came back with -3.5 so I bumped it up 4db to get some heavy hitting bass. Thanks a bunch for the help!
 

·
Registered
Joined
·
4,394 Posts

Quote:
Originally Posted by irishluck73 /forum/post/19359126


I dialed both Sentinels down to 3 o'clock on their gain setting and ran Audyssey. It came back with -3.5 so I bumped it up 4db to get some heavy hitting bass. Thanks a bunch for the help!

Gain setting dialed in on a sub at 3 o'clock is pretty high. You mean 9 don't you?
 
1 - 20 of 277 Posts
Top