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 Post subject: Re: Subwoofer inequality
PostPosted: Thu Jun 15, 2017 10:53 pm 
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Charles Jenkinson wrote:
I've just bought a couple of lab 12's, 6-ohm version and there's no label on them saying what impedance they are


I'm sure it would say "Lab 12" or "Lab 12C" on the label.

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 Post subject: Re: Subwoofer inequality
PostPosted: Fri Jun 16, 2017 11:58 pm 
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CoronaOperator wrote:
Charles Jenkinson wrote:
I've just bought a couple of lab 12's, 6-ohm version and there's no label on them saying what impedance they are


I'm sure it would say "Lab 12" or "Lab 12C" on the label.


Attachment:
Lab 12.jpg
Lab 12.jpg [ 45 KiB | Viewed 297 times ]


They need to be clearly marked as "Eminence Lab 12" on the back of the magnet. If they are not, they are not genuine Eminence Lab 12s. They MIGHT be an OEM by Eminence, but chances are they are knock-offs.

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 Post subject: Re: Subwoofer inequality
PostPosted: Sat Jun 17, 2017 2:44 am 
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Mine are both as the photos show - they were somewhat cheaper than most who retail the lab 12 in UK but they look genuine, though there is a sticky tab where the lab 12 name is. I would have just thought it would have said how many ohms they are.


Attachments:
rps20170617_083604.jpg
rps20170617_083604.jpg [ 28.45 KiB | Viewed 289 times ]
rps20170617_083641.jpg
rps20170617_083641.jpg [ 21.74 KiB | Viewed 289 times ]

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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 1:54 am 
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Gig tonight went very well. The subs were rocking the place bass was felt about 20 ft out. Wasn't crazy. It nice. I used 4 t60s and 2 dr280s for a venue I did a while back when I first got these there was a huge improvement. The stage and table behind the subs shook like crazy. I even made sure there was a good gap between the subs and table/stage. I reduced the limited voltage by around 20v went from 65 to 85ish. Limited didn't hit as much as it used to which is probably good. Still had room for volume and only ran one amp for tops and one for subs. Starting to believe. I still think I need some more t60s just to get things less stresssed and extra volume. Looking to get two more soon. I'll have to figure out what I'm going to do about one sub still and wether I want to replace the lab12c's.

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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 2:01 am 
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https://ibb.co/dXdtyQ

https://ibb.co/bUxmJQ

Some pics of the setup.

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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 11:16 am 
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With the subs extending away from the wall like that, the last one is 81-108" from the wall (as well as that far from the first sub). Isn't this creating cancellations? Given the limited space (as always, everywhere!), would a 2x2 semi vertical stack make better bass, <40hz? To clarify: take the two currently farthest from the wall and stack them atop the two closest to the wall.

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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 11:41 am 
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Rich4349 wrote:
With the subs extending away from the wall like that, the last one is 81-108" from the wall (as well as that far from the first sub). Isn't this creating cancellations? Given the limited space (as always, everywhere!), would a 2x2 semi vertical stack make better bass, <40hz? To clarify: take the two currently farthest from the wall and stack them atop the two closest to the wall.


Ye I was going to do that but didn't want to deal with lifting those guys tonight it was only me i probably could of gotten a hand but it sounded pretty good.

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2x Crest Audio 5.0
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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 11:42 am 
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There's two walls in play there, one to the right, one to the back. Both have the potential to create nulls. OP, read the placement sticky.


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 Post subject: Re: Subwoofer inequality
PostPosted: Sun Jun 18, 2017 12:06 pm 
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Bill Fitzmaurice wrote:
There's two walls in play there, one to the right, one to the back. Both have the potential to create nulls. OP, read the placement sticky.


My biggest gig in a couple months for insomniac it will be very important it's a tent that has opening on all sides and they put the stage smack dab in the middle of one of the sides it's like an octagon shape. But they put the stage near a wall centered. What would be my best layout to get maximum bass there won't be any walls to really get close to should I stack my 6 2x2 I'm trying to get two more tubas built by then as well.

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10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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 Post subject: Re: Subwoofer inequality
PostPosted: Sat Jun 24, 2017 8:53 am 
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Looking at the location you're playing here, you also have the option to set them up near the dancefloor, stacked alongside the wall in pairs opposing each other with two feet between them,

The back and side wall which are now creating nulls have a lot less effect this way. DR280's can be crossed over low enough to not sound tiny. The innermost cab in the way you set up now has nearly no effect since it is fighting reflections of cab one and two comming from the side wall.


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 Post subject: Re: Subwoofer inequality
PostPosted: Sat Jun 24, 2017 10:39 am 
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I'm a bit weary about the DC resistances of the cabs being all over the place though. 8 to 9ohms is "acceptable" but 11 and 13 ohms? ..... Something is way off there because two series wired Lab12's ought to measure 8.6 ohms DC (2 lab12C's 6.2) and not much more then that. Have all connections been soldered properly? And most important, do all cabs have original eminence lab drivers or have four cabs been fitted with an alternative (perhaps OEM 8ohm?! because that's what it seem like) driver?


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 Post subject: Re: Subwoofer inequality
PostPosted: Mon Jun 26, 2017 1:17 pm 
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Location: The Neterlands / Holland
Charles Jenkinson wrote:
I've just bought a couple of lab 12's, 6-ohm version and there's no label on them saying what impedance they are (there are numbers on the back of the cone but it's not 'plain English' if you know what I mean), but I did a DC resistance measure with a cheap digital meter and they measured between about 4.8 and 5.2 ohms, exactly the same as the other pair of 6 ohms drivers I have.

Something doesn't feel right to me with respect to the vendor duty of care here. I know this is DIY and only the OP ultimately owns the solution here, but the manufacturer is responsible for their quality of output, and making the cabs all the same impedance and maintainable. Do they have any Quality Control measurements / pass off sheets - David's resistance check is a good standard test that could/should be on there. Maybe they have the set up space where you can get this all sorted out.

Maybe these drivers didn't make the quality test after production and are sold as B-quality through gray channels?

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 Post subject: Re: Subwoofer inequality
PostPosted: Mon Jun 26, 2017 3:31 pm 
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Think wrote:
Charles Jenkinson wrote:
I've just bought a couple of lab 12's, 6-ohm version and there's no label on them saying what impedance they are (there are numbers on the back of the cone but it's not 'plain English' if you know what I mean), but I did a DC resistance measure with a cheap digital meter and they measured between about 4.8 and 5.2 ohms, exactly the same as the other pair of 6 ohms drivers I have.

Something doesn't feel right to me with respect to the vendor duty of care here. I know this is DIY and only the OP ultimately owns the solution here, but the manufacturer is responsible for their quality of output, and making the cabs all the same impedance and maintainable. Do they have any Quality Control measurements / pass off sheets - David's resistance check is a good standard test that could/should be on there. Maybe they have the set up space where you can get this all sorted out.

Maybe these drivers didn't make the quality test after production and are sold as B-quality through gray channels?


I don't know, they certainly look genuine. They are from colossusxb as has been mentioned by others, and I previously bought one from him as well. My meter is only a cheap one as well, but also i don't think impedance and DC resistance are quite the same thing, eh.

I've lost the sub-plot (...aghem :D ) on this thread in general - Has the OP / vendor sorted this out?

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2xJ12L (3012HO) switchable/melded (viewtopic.php?f=30&t=18773)
2xT30 : viewtopic.php?f=30&t=20386

No sound is better than bad sound.


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 Post subject: Re: Subwoofer inequality
PostPosted: Thu Jun 29, 2017 10:07 am 
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Location: The Neterlands / Holland
Charles Jenkinson wrote:
Think wrote:
...........

I don't know, they certainly look genuine. They are from colossusxb as has been mentioned by others, and I previously bought one from him as well. My meter is only a cheap one as well, but also i don't think impedance and DC resistance are quite the same thing, eh.

I've lost the sub-plot (...aghem :D ) on this thread in general - Has the OP / vendor sorted this out?


Measure an other batch of drivers and see if the variation is normal. But I bet other members have allready done this and can tell you.
Quote:
DJStubbs wrote:
I have taken all apart except for one and one the red and black main wires were switched. Sad thing now is the last cabinet which was built by the same person has striped screws that will not come out so I cannot take the panel off. What I was thinking could I just alter a speakon cable and make it on one side red and black like normal and on the other side make it black and red? Because I don't think I'll be able to get that panel open to even see if the wires inside to the woofer are switched.


So a polartiy swap at 1 of the drivers or to the cab connector was the problem? If both drivers to the cab are reversed you could simply switch red and black at the cab connectors.

edit: if 1 of 2 drivers in the cab would be wired wrong, then you would get very litte output from this cab.

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 Post subject: Re: Subwoofer inequality
PostPosted: Fri Jun 30, 2017 1:06 am 
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Think wrote:
Charles Jenkinson wrote:
Think wrote:
...........

I don't know, they certainly look genuine. They are from colossusxb as has been mentioned by others, and I previously bought one from him as well. My meter is only a cheap one as well, but also i don't think impedance and DC resistance are quite the same thing, eh.

I've lost the sub-plot (...aghem :D ) on this thread in general - Has the OP / vendor sorted this out?


Measure an other batch of drivers and see if the variation is normal. But I bet other members have allready done this and can tell you.
Quote:
DJStubbs wrote:
I have taken all apart except for one and one the red and black main wires were switched. Sad thing now is the last cabinet which was built by the same person has striped screws that will not come out so I cannot take the panel off. What I was thinking could I just alter a speakon cable and make it on one side red and black like normal and on the other side make it black and red? Because I don't think I'll be able to get that panel open to even see if the wires inside to the woofer are switched.


So a polartiy swap at 1 of the drivers or to the cab connector was the problem? If both drivers to the cab are reversed you could simply switch red and black at the cab connectors.

edit: if 1 of 2 drivers in the cab would be wired wrong, then you would get very litte output from this cab.


Until further testing is done it seems like the polarity was the issue and i switched the red and black lead on one cable and marked the cable to use for further gigs. but it seems it was resolved. i will let you guys know if there are any issues.

_________________
10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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