Two Subs...Gain Matching vs Level Matching - Page 9 - AVS Forum | Home Theater Discussions And Reviews
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post #241 of 262 Old 02-05-2015, 06:35 PM
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^^


I was afraid you might say that, the 2 subs I am building are the only speakers I will have that exceed the size and weight of the K-horns I have! Moving them about will not be much of an option.

I am building a screen wall at the front of a 21x16 room, the DTS-10's will fit behind the wall/2.40:1 AT screen between the L-C-R towers that are also behind the screen. Due to other constraints the only location might be at the rear of the theatre, but that will take up space that would compress the seating position quite a bit and interfere with the rear surrounds.


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post #242 of 262 Old 02-05-2015, 07:55 PM
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Make some sub risers with wheels. It makes moving my large sub a breeze. You can take the subs off once in the final location. I leave the subs on the risers.
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post #243 of 262 Old 02-06-2015, 08:58 AM
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Quote:
Originally Posted by Al Sherwood View Post
^^


I was afraid you might say that, the 2 subs I am building are the only speakers I will have that exceed the size and weight of the K-horns I have! Moving them about will not be much of an option.

I am building a screen wall at the front of a 21x16 room, the DTS-10's will fit behind the wall/2.40:1 AT screen between the L-C-R towers that are also behind the screen. Due to other constraints the only location might be at the rear of the theatre, but that will take up space that would compress the seating position quite a bit and interfere with the rear surrounds.


Well, if it's any consolation, a buddy of mine has a room that is almost the exact same dimensions and we found that front corner placement of his duals provided the best response (although he sacrificed a bit in seat-to-seat variance)...you may be just fine with those monsters up front.

In the future, you could always put another smaller sub in back solely to smooth the response.
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post #244 of 262 Old 02-06-2015, 09:34 AM
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Originally Posted by Alan P View Post
Well, if it's any consolation, a buddy of mine has a room that is almost the exact same dimensions and we found that front corner placement of his duals provided the best response (although he sacrificed a bit in seat-to-seat variance)...you may be just fine with those monsters up front.

In the future, you could always put another smaller sub in back solely to smooth the response.

Thanks that makes me feel more confident that it won't be a complete fiasco!


I will have to take a tape measure out and check but there might be a possibility that the DTS-10's could fit positioned to the outside of the L-R speakers since the mouth of the horn can be positioned a few different ways.


This construction picture shows a couple of the options for the mount (only one port open in operation), as you can see if they will fit I could put the mouth right in the front left/right corners.


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post #245 of 262 Old 02-06-2015, 09:43 AM
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Have you downloaded REW and got yourself a USB mic?

You're gonna need it.


BTW - very jealous of those subs.
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post #246 of 262 Old 02-06-2015, 11:15 AM
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Yes, I have REW and a EMM-6 from Dayton Audio with an Icicle USB adapter in preparation for all of this.


As for those subs, thanks, but I still need to build them (that was a pic from the forum), same with the room, now that my kitchen is done the wife gave the nod to the HT.


Years ago I built (and still have) a pair of SpeakerLab K's they are pretty much exact replicas of the Klipschorns, even ran a home built center that used the same components as the top horn but now with Atmos begging to be experienced I have gathered a whole new set of speakers, all Klipsch except for the subs to build the HT back up from scratch. So I have a lot of work ahead of me yet!

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post #247 of 262 Old 02-07-2015, 07:22 PM
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Originally Posted by Alan P View Post
If you are not getting a gain of ~6db when you add the second sub, you've got phase issues.
I decided to just go with the single ES250P instead of running it along side my SUB12. It just never sounded right no matter what I did. I think I had a phase issue and switching either sub to 180 never gave me a balanced result. It actually sounds good and smooth now running the single. Guess I'll have to pick me up another 250 if I really want to run dual subs in the future.

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It's strange that your subs calibrate closer though....usually (because of the extra delay introduced by the sub's electronics) the calibrated distance will be further than the actual.
Funny you mention that. Running the single sub now calibrates to 10 ft compared to 6.3. I also just replaced my Venue Voice with a S-Center II. I've got to say, my system has never sounded better.
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post #248 of 262 Old Yesterday, 01:14 AM
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Read through this thread but still a bit confused as to how gain matching works with XT32 and 2 sub pre-outs. Using dual subs each connected to their own pre out the levels are different after running Audyssey. Do I add the 2 levels together and divide by 2 to get the middle? OR are you supposed to use only one sub pre out with a Y connector? If you using a Y connector you don't get the benefit of individual distance settings?
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post #249 of 262 Old Yesterday, 07:18 AM
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Originally Posted by kevbo123 View Post
Read through this thread but still a bit confused as to how gain matching works with XT32 and 2 sub pre-outs. Using dual subs each connected to their own pre out the levels are different after running Audyssey.
Some room correction systems such as Audyssey treat dual subwoofers independently, and gain matching isn't really applicable after that independent processing is applied (at least in my opinion).

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Do I add the 2 levels together and divide by 2 to get the middle?
Only if you want to undo what Audyssey is doing.

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OR are you supposed to use only one sub pre out with a Y connector? If you using a Y connector you don't get the benefit of individual distance settings?
Only if you want truly gain matched subs at the expense of any individual processing between the subs. You are correct that you will lose the individual distance settings. The best you can do to compensate is to adjust the phase control on the subwoofer(s) to account for the difference in distance.

If it were me, I'd gain match the subs before running Audyssey (with both subwoofer pre-out levels set identically and all other Audyssey subwoofer processing off or bypassed). Then I would run Audyssey and let Audyssey do its thing. If Audyssey processing is bypassed you then have gain matched subs. With Audyssey processing on, you have the subs independently adjusted (level, EQ, delay, etc.) to what Audyssey has determined is best.

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post #250 of 262 Old Yesterday, 12:21 PM
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Quote:
Originally Posted by kevbo123 View Post
Read through this thread but still a bit confused as to how gain matching works with XT32 and 2 sub pre-outs. Using dual subs each connected to their own pre out the levels are different after running Audyssey. Do I add the 2 levels together and divide by 2 to get the middle? OR are you supposed to use only one sub pre out with a Y connector? If you using a Y connector you don't get the benefit of individual distance settings?
- Gain match the subs
- Run Audyssey and check to make sure the sub trims are in the acceptable range, if they are not not, adjust sub gains equally (using SPL meter) until the trims are acceptable
- Adjust both sub trims in AVR equally to get to your desired SPL

EDIT TO ADD: The sub trims post-Audyssey will most likely not be the same. As long as you adjust the trims equally post-Audyssey, they will remain gain matched.
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post #251 of 262 Old Yesterday, 12:40 PM
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Unless you have subs of far different quality you will not hear a difference and you have better things to do.
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post #252 of 262 Old Yesterday, 01:12 PM
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Quote:
Originally Posted by kevbo123 View Post
Read through this thread but still a bit confused as to how gain matching works with XT32 and 2 sub pre-outs. Using dual subs each connected to their own pre out the levels are different after running Audyssey.
It works the same basically except if you're trying to get a lower post room correction sub level offset from which to raise afterwards from within the receiver to run both sub's a bit hot. Basically you gain match both sub's to 79 or 82dB beforehand then run the first mic position skipping the first step where you're asked by Audyssey to level match the subwoofers( do that and your no longer gain matched.) After finishing the other mic positions and saving the Audyssey corrections you go into the manual speaker settings under levels and check both subwoofers corrected level offset. If sub #1 is a -4dB and sub#2 is a -9dB you take the difference between them and divide by 2. That's a -2.5 to sub#1 and a +2.5 to sub#2 making both sub's -6.5dB and you are again gain matched and nothing with Audyssey's other corrections are affected.

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Do I add the 2 levels together and divide by 2 to get the middle? OR are you supposed to use only one sub pre out with a Y connector? If you using a Y connector you don't get the benefit of individual distance settings?
See above for the first question and you are correct for the second. No need for a Y splitter using the technique described above😉.
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post #253 of 262 Old Yesterday, 01:56 PM
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Unless you have subs of far different quality you will not hear a difference and you have better things to do.
Then it's a good thing for the poster that hearing a difference isn't the thought process behind gain matching sub's and if the prerequisite for always learning something new was that you first shouldn't have anything else better to do then we would never expand our knowledge/skillsets . These are all just individual tools in our audio toolbelts. Some have a more immediate impact or make an audible difference and others are more situational but having the knowledge to do it isn't a waste of time. Especially if he's got buddies with mismatched sub's or he himself does in the future. "Teach a man to fish and he can feed a village."
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post #254 of 262 Old Yesterday, 03:01 PM
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LOL ok do it to "learn something new". Or learn something new that is more useful. Whatever.
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Quote:
Originally Posted by Madmax67 View Post
It works the same basically except if you're trying to get a lower post room correction sub level offset from which to raise afterwards from within the receiver to run both sub's a bit hot. Basically you gain match both sub's to 79 or 82dB beforehand then run the first mic position skipping the first step where you're asked by Audyssey to level match the subwoofers( do that and your no longer gain matched.) After finishing the other mic positions and saving the Audyssey corrections you go into the manual speaker settings under levels and check both subwoofers corrected level offset. If sub #1 is a -4dB and sub#2 is a -9dB you take the difference between them and divide by 2. That's a -2.5 to sub#1 and a +2.5 to sub#2 making both sub's -6.5dB and you are again gain matched and nothing with Audyssey's other corrections are affected.



See above for the first question and you are correct for the second. No need for a Y splitter using the technique described above😉.
In my Onkyo I don't have the ability to skip the step where you calibrate the subs levels individually. Do you mean just don't make any changes?
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In my Onkyo I don't have the ability to skip the step where you calibrate the subs levels individually. Do you mean just don't make any changes?
Correct. Sorry, didn't elaborate that better. Basically you ignore it for all intents and finish that measurement and see where the room correction set the subwoofers offset. If acceptable finish the other positions. If not raise the sub levels equally if identical sub's then rerun until the desired offset under -12dB is reached. I gain matched mine to give me a -6dB offset then raised it +4dB and didn't have to correct for different sub level offsets as my old Denon receiver doesn't set levels/ distance separately like Audyssey XT32 with Sub EQ HT does.
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LOL ok do it to "learn something new". Or learn something new that is more useful. Whatever.
Lol, back. Again, what's more useful in your opinion or more useful to you in particular isn't a cookie cutter definition of what's more useful to all . Whatever is right. I've got "more important" things to do than keep explaining this so have a nice day doing whatever you deem more important than this. By the way God forbid this helped someone else other than the poster directly because that might actually be...... Important to them and not you?
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Lol, back. Again, what's more useful in your opinion or more useful to you in particular isn't a cookie cutter definition of what's more useful to all . Whatever is right. I've got "more important" things to do than keep explaining this so have a nice day doing whatever you deem more important than this. By the way God forbid this helped someone else other than the poster directly because that might actually be...... Important to them and not you?
Nice bike.
booooorrrrring

Old bike. Got to update that pic.
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booooorrrrring
Yes, I'm starting to strangely feel that way too for some reason😏.

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Old bike. Got to update that pic.
Among other things. Good luck with both.
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post #260 of 262 Old Today, 12:11 AM
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Originally Posted by Alan P View Post
- Gain match the subs
- Run Audyssey and check to make sure the sub trims are in the acceptable range, if they are not not, adjust sub gains equally (using SPL meter) until the trims are acceptable
- Adjust both sub trims in AVR equally to get to your desired SPL
Thanks - the mistake I made was that my sub furthest away trim was lower than what Audyssey deemed acceptable. This is because my near field sub is much louder and had to turn the furthest one right down.

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Originally Posted by Madmax67 View Post
It works the same basically except if you're trying to get a lower post room correction sub level offset from which to raise afterwards from within the receiver to run both sub's a bit hot. Basically you gain match both sub's to 79 or 82dB beforehand then run the first mic position skipping the first step where you're asked by Audyssey to level match the subwoofers( do that and your no longer gain matched.) After finishing the other mic positions and saving the Audyssey corrections you go into the manual speaker settings under levels and check both subwoofers corrected level offset. If sub #1 is a -4dB and sub#2 is a -9dB you take the difference between them and divide by 2. That's a -2.5 to sub#1 and a +2.5 to sub#2 making both sub's -6.5dB and you are again gain matched and nothing with Audyssey's other corrections are affected.
Thanks for confirming the divide by 2 and adjust method.
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If I had that fire power, I would level match level match and use attenuators to correct levels. In most rooms those sub will not be mis-matched enoug to just gain match. Steam is all filled in the back room and you won't run out unless you don't balance the system.
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Originally Posted by kevbo123 View Post
Thanks - the mistake I made was that my sub furthest away trim was lower than what Audyssey deemed acceptable. This is because my near field sub is much louder and had to turn the furthest one right down.


Thanks for confirming the divide by 2 and adjust method.
No problem. You almost had it figured out but it's the difference between the two you divide then adjust not the sub offset levels themselves. Most times they are the same anyway post correction but with one near field they'll probably be different. No biggie.

EDIT: Afterwards if you like you can raise both sub levels several dB from within the receivers manual speaker settings if you want a bit more bass but again raising them equally and staying under 0dB in the level settings.

Last edited by Madmax67; Today at 10:04 AM.
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