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Post subject: 4x12-Not Loud Enough!?
Posted: Fri Mar 25, 2011 1:55 pm
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Location: Charm City
I know it seems that I come here only with tales of woe and misadventure, but I'm new and still learning and need some guidance. Finally got around to installing speakers in my first 4x12, an empty Fender DT 412. Put two 65w alnicos on top, two 100w ceramics on the bottom. Had to do some soldering ( first time in 25+ years!) as clips were not an option on some of the terminals. All drivers are 16ohm and wired in parallel to match the desired 4 ohm load of my 85w DSR. Problem is that this cab is not as loud as I imagined it should be, not as loud as when paired with my 2x12 or 1x15, not as loud as my Twin. Cab also sounds kinda dull, bassy and lifeless, with some buzzing/farting from one of the aluminum domed alnicos on some bass notes. Posted this on another forum, and the good folks recommended the 9v battery test to check polarity of terminals, and to check ohmage of speakers with a multimeter. Did that. All drivers moving out with battery test, all speaks read from 12.6-13.8ohms. Is there something else I could have overlooked, or done wrong? :?:
As always gang, any comments or suggestions are much appreciated! Thanks, yours Fenderly, O.


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Post subject: Re: 4x12-Not Loud Enough!?
Posted: Fri Mar 25, 2011 11:25 pm
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What brand and type of speakers?

Possible cold solder joints?

Have you measured the cab's overall impedance at the input jack?

IIRC the Fender (nee Sunn) 412S cab had a goofy dual-input plate on the rear that permitted 8Ω x 2 stereo operation or 16Ω mono only via a pair of self-switching jacks. For your purposes that switching and wiring should be dispensed with and reconfigured to provide a 4Ω total load only via a single standard jack.

Pics of your wiring job would be helpful to sort this one out.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 4x12-Not Loud Enough!?
Posted: Sat Mar 26, 2011 3:23 am
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Thanks, Arjay. Drivers are two alnico GT1216's on top (research showed these were made by Eminence for Sunn cabs in the '70's) and two ceramic Jensen C12 K's on bottom ( I know these get some mixed reviews, but I kinda liked'em in the reissue Twin, and got them at a very reasonable price). The DT 412 is a solid closed-back cab, and speakers mount from front, so I can't really post pix of wiring without unwiring and removing speakers. Didn't notice anything particularly goofy about input plate, two input jacks and plate reads "Parallel Inputs", I'm assuming this is for adding an additional cab for a "Monster Full Stack."
Thanks for your replies and help, cordially, O..


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Post subject: Re: 4x12-Not Loud Enough!?
Posted: Tue Apr 12, 2011 6:09 am
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Joined: Tue Apr 12, 2011 5:35 am
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nyquilcoma wrote:
I know it seems that I come here only with tales of woe and misadventure, but I'm new and still learning and need some guidance. Finally got around to installing speakers in my first 4x12, an empty Fender DT 412. Put two 65w alnicos on top, two 100w ceramics on the bottom. Had to do some soldering ( first time in 25+ years!) as clips were not an option on some of the terminals. All drivers are 16ohm and wired in parallel to match the desired 4 ohm load of my 85w DSR. Problem is that this cab is not as loud as I imagined it should be, not as loud as when paired with my 2x12 or 1x15, not as loud as my Twin. Cab also sounds kinda dull, bassy and lifeless, with some buzzing/farting from one of the aluminum domed alnicos on some bass notes. Posted this on another forum, and the good folks recommended the 9v battery test to check polarity of terminals, and to check ohmage of speakers with a multimeter. Did that. All drivers moving out with battery test, all speaks read from 12.6-13.8ohms. Is there something else I could have overlooked, or done wrong? :?:
As always gang, any comments or suggestions are much appreciated! Thanks, yours Fenderly, O.



what is the ohmage of all speakers individualy? You have to be careful. most of those were I belive 4 ohm total. So you would have to either have 4 16 ohm speakers or only use 2 8 ohm speakers and leave two dummies. This is very important. Power supply 101, the load ohmage has to match the power supplies ohmage. Get this off and you will eventual ruin your amp. If you get your ohmage down to 2 or less you are headed for disaster.


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Post subject: Re: 4x12-Not Loud Enough!?
Posted: Tue Apr 12, 2011 2:55 pm
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Joined: Wed Mar 31, 2010 12:48 am
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Since you've already ascertained that each of the four drivers is 16Ω and that they are correctly wired and phased, the only other possible scenario is that one or more of those speakers is bad. My money's on those two Sunn pie-plates. Try this:

Disconnect two speakers from the array simultaneously and play the amp to see if the tone improves. Start with the Sunns, then the C12K's. Try one of each as well. If you've got a bad one, sooner or later you'll isolate it by the simple process of elimination.

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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