# TRIO12 sub project started.



## longdrive03

Thanks for Mike P for his assistance in this project. I'm building a sub for an acquaintance to use in his research of the effect on subsonic frequencies on humans. I'm making a 24" (od) cube with inner 3/4" shell of mdf and outer 3/4" of Baltic Birch plywood. Yes, it will be heavy and he knows it. He will also take it to seminars and load and unload it.

Got all the mdf panels cut last night and glued, screwed and clamped the internal brace. I used pocket screws to hold it together while glue cures and it is clamped. So far no major screw ups.

Question: should I drill some 3 " holes in the brace panel under the top pipe claim (will be behind sub) to allow more free movement of air?

This baby will be painted black with truck bed liner paint with removable 15" grills to protect the sub/PR's during travel. I may build in some casters on the bottom to help him roll it. He's pushing it with a Behringer EP2000 amp which he will have to make sure doesn't push too hard with the 350 watt rating on the sub. More later. Any suggestions welcome.


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## PenginTamer

Well it is a very unique subject and also a unique design. To answer your question about the 3" porting holes- for personal use it really depends on your taste of sound or what it is you will be listening to (whether you want to use an enclosed box or a ported box). But for a project like this you may want to aim for optimal output from your sub. Consult a subwoofer enclosure calculator to figure out what size ports and how many you should be using. Won't let me post link but goto Google and type 'subwoofer enclosure calculator' and it should be the first link. Good luck!!


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## longdrive03

Sorry, but I guess I wasn't clear on the project. I'm using the CSS 12" woofer with two APR12 PR's. The photo shows the internal brace. My question was whether I should drill 3" holes in the brace to allow free movement of air inside the cabinet not as a port. The system uses two APR12's so there is no port. I just want to make sure I have enought openness in the brace to allow free movement of the air.


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## PenginTamer

That seems to make more sense. I would probably recommend you not drill the 3" holes in the internal brace- Too much air flow is a bad thing.. looking at the picture is seems as though the air within the box would make a circular motion between the internal braces if you did that (which would screw up the compression within each chamber..)
Something you've probably already thought of- build it without the 3" holes, you can always drill them later to try and achieve a different result, but you cant add them back in without building a whole new unit.


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## Mike P.

That is very robust bracing, how wide is the vertical piece?


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## ironglen

Judging from the drill bit, that section looks to be 5-6": probably 2" holes centered throughout the panels would open the interior and lighten the load without weakening the panels. Integrated/removable transport handles would probably be appreciated by your friend...


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## longdrive03

Good guess ironclad! 6" on the width in Mike P's frame. 5" open on each side. The 2" holes sound good since I have a 2" hole drill. I haven't hooked up the sub yet but it is impressive looking!!! So are the PR's.


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## longdrive03

Sorry!! Ironglen!!!!


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## ironglen

longdrive03 said:


> Sorry!! Ironglen!!!!


:foottap: Wait, I like ironclad better!

Looking at the Trio driver, it looks to be an excellent bargain, sure it isn't a cast aluminum frame, but with xbl2 and CSS's reputation it looks like a good one.


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## longdrive03

Ironclad (AKA Ironglen) I took your advise and drilled 2.5" holes in the internal braces. I like the look and layout. Wore out my Harbor Freight right angle drill adaptor but it was kinds old. I got the top of the inner shell glued on and will probably layout and cut the sub and pr holes before applying the bottom to allow the consruction adhesive to vent. Thanks for you help.


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## ironglen

Looking Good!

Those panels are primarily designed for rigidity in one plane anyways: otherwise you'd use something more robust than mdf.


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## longdrive03

Post Christmas update. Got my circle cutting jig made and got the two PR holes and one Sub hole cutout with T-nut holes drilled. Cold and rainy today so didn't do a lot today.


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## patchesj

Looking very stout! I would say add some wheels to the thing to help get it moved around, but you'll need to be careful or they'll add points of vibration. I have a Trio12 and that is a great driver for the money.


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## longdrive03

Thanks Patches. That's my motto "If in doubt build it stout!" I am planning to install four removable casters so he can roll this thing around on his trips. I'll also install a wooded riser on the bottom to help couple it to the floor. It is heavy now and will get heavier. Glad I won't have to unload it on his trips!! 

He plans to run the sub off one channel of the EP2000 and some music off another single speaker I'm building for him.


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## mwmkravchenko

Lookin right wholey!


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## longdrive03

i should name it the "Wholey Sub". I got the last panel on the inner shell installed last night and will start on the next layer of 3/4" baltic birch. I can't wait to get this puppy to the point I can listen (or feel) the bass).


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## longdrive03

Question: Has anyone used casters on the bottom of a sub to allow movement? If so how did it work? Did they rattle? I'm trying to decide if brakeable casters would work on this sub to allow my friend to roll it rather than carry it.


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## ironglen

longdrive03 said:


> Question: Has anyone used casters on the bottom of a sub to allow movement? If so how did it work? Did they rattle? I'm trying to decide if brakeable casters would work on this sub to allow my friend to roll it rather than carry it.


I think you could install removable casters that have a plate permanently screwed in along with a shaft-mounted wheel that is removable, perhaps like this.


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## longdrive03

Thanks Ironclad!

What about simple screw on casters that would be left on the sub? Would that degrade the low output? I was originally going to build a 1" frame on the bottom to help get it off the floor/carpet to couple to the floor and clean up the bass a bit. Would the four lockable casters serve the same purpose. My friend is trying to keep his costs down on the casters.

I may build him a simple moving dolly that fits inside the 1" frame so he can remove it when he puts it in his SUV to travel. 

I'm considering using some extra walnut grain formica on this puppy with black plastic corner covers to give it a tough outer coating. I'm using 15" removable metal grill frames over the 12" sub and pr's so they won't be damaged in transit. Maybe I should put some headlights on this thing!!!


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## ironglen

Yeah, those are costly. Just a quick grab on google...

I don't know how regular casters will do, I'd be concerned they would rattle on anything but a perfectly flat surface, unless you have a spongy-type mat for them to prevent such noise.


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## black_z

Interested in the results of his study!

Nice build, btw!


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## longdrive03

Thanks. Got a little warmer weather yesterday and today and got the cabinet built. IT IS HEAVY!!! Hooked up the speakers and they sounded great. My buddy has a signal generator program in hi laptop and I could hear down to 19hz and saw movement at 8Hz. This was outside in my driveway. Now sure how much powr we were pushing with the EP2000 Behringer but the CSS woofer never looked like it was working hard. At 13 Hz the PR's were moving quite a bit and the sub wasnt' moving that much. The cabinet barely resonates even at 13 hz. 

I will round off the corners, prime and paint with truck bed liner, install 15" snap on grill covers, apply plastic corner protectors, attach a 1" high picture fram base for bottom , attach four carrying handles and make a small caster dolly to fit in side the base to allow movement. 

I can't wait to get the finished product in a house to hear the low notes. I'll bet this baby rocks in a house.

Per Mike P I usally all 20 of the 45 gram washers on each PR. 

Question: How the do you know how much power your pushing with the EP 2000?


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## bambino

Definatly a solid build. Nice work.:T


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## Mike P.

> Question: How the do you know how much power your pushing with the EP 2000?​




Either an SPL meter showing 100 db at 1 meter or by measuring the voltage going to the driver, if that's even possible as I don't know for sure.


​


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## longdrive03

Thanks for the info Mike.

Update, got two coats of Kilz roll on primer applied and one coat of spray Rustoleum truck bed coating applied. One more coat tonight. The Kilz really fills in any imperfection and covered the rounded over baltic birch plywood edges nicely. Should be finished with this in two days. Will report after we get it indoors and check it out (if we can pick it up!).


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## longdrive03

Got er finished! Reinstalled everything today including corner guards and four carry handles pluse the 15" raised removable metal grills. 

The removable roller dolly sits inside a 1.5" wooden riser frame. I gotta get this inside for some listening!


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## mwmkravchenko

Lookin nice!


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## caper26

what a beast! How did you go about the grills? I am also building a 24" cabinet with the trio12 & 2 PRs ! cheers!


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## ISLAND1000

Wow! That's a VERY business like piece of auditory analysis experimentation equipment cell.
I'll bet those handles are going to rattle.
Excellent work. Nice design.


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## longdrive03

Thanks guys. So far the handles haven't rattled but I haven't put the power to it. They are spring loaded with a hard rubber grip so may they won't rattle. 

Due to the size of the sub and pr's I went with a 15" metal snap on frame. Given the large xmax of the pr's I decided to elevate the metal ring by using female speaker grill guides turned upside down (with opening against the cabinet) with a hole drilled in the center to allow the 1 5/8" screw to attach to the cabinet. I still don't know if this will allow full excursion on the pr's but he will probably only use the grills when he is traveling to protect against damage. I also thought this might eliminate any rattling since the contact area is limited.

Got the grills from PE for $5.00 each. This is a great price and they are all metal. You could cut out a wood ring to match the frame but that was more work so I just went with the female grill guides. I've got 12,000 o them so that's not problem.


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## longdrive03

Got this in my empty living room (13ft x 13ft with 12" ceiling with a 6" x 9" arch on the opposing wall) and we hooked it up to my friends laptop and Creative Labs DAC using the headphone jack into the Behringer EP2000. We were attempting to hit 99db at 13Hz at 1meter per the graph predictions on this setup in order to get a feel of the gain position where 100watts is produced. I was disappointed. We didn't get close to 99 db at 1 meter in front of the sub. I have the cabinet situation at 45 degree angle in a corner. We could turn the gain up all the way (supposedly 400watts per channel) and not hit 99 db.

Here is link to original post:

http://www.hometheatershack.com/for...8-new-member-needs-help-lab-15-apr15-sub.html

We thought we might have an impedance matching problem. After he left I found an RCA to 1/4" jack converter and hooked this to my cd player with a test cd that plays 20 hz and 40 hz. There didn't seem to be too much difference. 

Any ideas on what to check. at 13 Hz most of the output is from the two PR's. His spectrum analyzer can't read below 20 hz he says. However, according to the raph Mike P sent the output at 20hz is almost exactly the same at 13Hz???? What gives? What am I missing? Specs on the amp ahow input sensitivity (at 8 ohms) of 1.12 v and input impedance of 10K unbalanced and 20 k balanced. is there a mismatch here on the impedances that is limiting the output? I'm open to any and all suggestions questions! 

Please tell me I'm stupid and this has a simple answer. 

My friend kept saying there wasn't much air moving. The sub and PR's were moving quit a bit but I didn't experience the effect I thought I would get.

My question is if we can't HEAR 13 hz (or for me below 19 HZ) then how do we know the db level being produced (without spl to measure that low? 

HELP!!!! THANKS.


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## mwmkravchenko

Move around the room. That is mic location. You will find a sweet spot. Move the sub around to.

If your room is truly a square it is the worst shape for getting any bass. Close the middle of the room offset will most likely be where it starts to shine.

And 13hertz out of a single twelve at any appreciable level is a bit on the lala land side of things. Just not enough air being moved. You need over a gallon of air movement per side to begin to get 13 hertz that loud.

I have installed systems in square rooms and they are the worst. Never find an acceptable placement for the sub. Only beaten by round rooms. I played a concert in a round room and don't think i ever heard myself!


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## Mike P.

Lets try and figure this out. You added 20 washers to each PR? The driver and PR were installed with weather striping tape to ensure no air leaks? You said you didn't get close to 99 db at 1 meter, what SPL meter did you use?

The EP2000 has switches on the back that engage a hi-pass filter (low cut filter) at 30 hz or 50 hz are the switches in the off position?


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## longdrive03

Mike, thanks for the quick response. Your earlier post said 900 grams (20 washers at 45 grams each) on each PR. I have 20 on each instead of 9. I'll change and see what difference that makes.

Yes I did use weatherstripping on all holes and don't detect any air leakage. We only got around 73 db as I recall at 20Hz at 1 meter with the gain at 28 (3oclock). The graph show same db for 13 and 20 hz at 100 watts.

I've hooked a cd player to the amp and can run 20 and 40 hz signals off the disk. I'll remove 11 washers per pr and retry. I don't have my friends laptop and dac now but we will retry tomorrow. I did have the subsonic filter off (except for the 5hz non-defeatable filter). Thanks for your help.


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## Mike P.

I made a mistake in that post, it's supposed to be 20 washers for 900 grams of mass. 

I need to know the make and model number of the SPL meter you used, it probably has a correction file.


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## longdrive03

Thanks Mike, I'm feeling better already. I can't recall the name and number on his meter but I'll get it and post. I just changed the washers and have 9 on each pr now and it has loosened up considerable but I can play below 20 hz now since I don't have his laptop/program. Thanks for your help on this!!!


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## longdrive03

Thanks Mike, I'll go back to 20 washers per side. The sound meter is Phonic PAA2. Is there any chance we aren't hooking up the amp with the proper cables? My friend is going to pick up an RCA to XLR adator to see how that works. At first my friend was having problems with getting output on his signal generator problem through the DAC. He's has a Creative Labs H-Fi Hd dac. Here's a link

http://www.amazon.com/Creative-Sound-Blaster-System-SB1240/dp/B004275EO4

Does it matter whether you use the headphone or mic output jack?

Any suggestions appreciated.


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## Mike P.

Pro audio amps require a higher voltage then consumer grade products. It's possible the H-Fi Hd isn't supplying the amp enough voltage. Do you have a home theater receiver that has a subwoofer output?


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## longdrive03

Yes. Could I also just use a standard preamp/poweramp and run the rca connections from his DAC straight into the preamp. I've got a couple of 150wpc power amps that should get us an idea. How can I connect his laptop and DAC to


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## Mike P.

I don't know enough about the DAC to comment on it. I suggest using a receiver with a sub out with your CD player. Run some test tones through the setup and we'll see what happens.

I'm also wondering on the accuracy of the Phonic PAA2. Most aren't accurate under 30 hz. For example, the Radio Shack models that are popular have correction values. Shown below are the correction values for the Radio Shack digital SPL meter.


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## longdrive03

The PAA2 has "ranges" (between 30-70hz") etc which I didn't understand. I'll try to HT setup tonight and see what happens. Thanks again Mike for all your help.


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## longdrive03

WOWSERS INSPECTOR GADGET!!!!!!!!!!!!!!!!!!!! It's fixed. Mike P I followed your suggestion and ran my cd through a Carver HT amp and out the sub out. My test cd only goes to 20 HZ. Wow, now we have some output! At 14 on gain on amp (9 oclock) this baby is loud and solid at 20HZ. Last night we had it turned all the way to 32 and never got close to this loud. Don't have the spl meter here but I'll be it rocks now. I ran RCA ot of Carver sub out and into a 1/4" connector adaptor and now we have power to spare. Rattling windows you canhere in my yard. I have it in center of same room we use last night. 

Mike P thanks again for your help!!!! I really appreciate it. My friend should really be impressed now since it is night and day from last night.


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## caper26

now I am stoked too !!! can't wait to test mine as well !


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## longdrive03

Great, did you do the modeling to see how many washers and output etc? I think you're gonna like these puppies. I'm glad I used the double layer cabinet because these things create a lot of movement. I think it weighs about 150 lbs.


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## caper26

yes... well, Mike P did for me  My primary goal was LOW END OUTPUT, so I went with the 24" cube vice the 20, and will go with all the washers on the PRs. I went with double layer of MDF on the front only. Right now I have a 12" sealed Monitor Audio sub...pretty nice sub but rolls off below 30 Hz I believe, and the cabinet is rather small too...Anyway, here is the chart:
The orange line is the 24" cube

My amp also has 1 level of EQ on it as well, and I can ask if it is safe to boost the low end a bit...


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## Mike P.

Glad to hear it's up and running, it would seem there is a voltage issue with the DAC. You should download some test tones in the 13 -20 hz range, burn them to a CD and see how it performs. Just don't get carried away, you don't want to burn the coil.


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## caper26

where do you download them from? And do you burn as an Audio CD, I would assume so.


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## Mike P.

Test tones are here:

index.html 
Open the file with your Browser.


​


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## longdrive03

Project completed. My friend pick it up today but we didn' test because he didn't have his laptop. I did run the 20 hz test cd tone through it at 14 on the gain setting and he was impressed. Here's a photo in the back of his vehicle.

He needs a bigger vehicle!


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## caper26

awesome dude! Mine weighed in at 122 lbs !


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## longdrive03

Was yours double thickness - 3/4" mdf and 3/4" Baltic birch ply?


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## caper26

longdrive03 said:


> Was yours double thickness - 3/4" mdf and 3/4" Baltic birch ply?


just double thickness on the front. 2 X 3/4" MDF.


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## longdrive03

Mine has to weigh at least 60 lbs more because of the 3/4" baltic birch. it was a struggle for two of us to get it in his vehicle. Probably need to weigh it just for the sake of knowing.


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## Mike P.

If your friend is going to use a laptop for sending tones to the amp then it's going to need a voltage boost for the amp to work properly.


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## longdrive03

Yeah, we discussed that yesterday when he picked it up. I thought he was bringing his equipment so we could retest (SPL) etc. I don't know if the RCA outs on the DAC will push it versus the headphone/microphone jacks.


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## caper26

You need an external sound card (USB dongle) with optical out. I use it with my laptop with my upstairs system, and use Foobar. I have a Turtle Beach Audio Advantage Micro II. The only problem I have had is that some optical cables don't work with it for some reason, for example, the "premium optical" cables from monoprice (the silver ones) will not work, but the regular cheap ones do... I even have 30 footer (ish) and it works no problem. I think I paid $25 for the Micro II.


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## longdrive03

Thanks Caper. He has a small laptop with the DAC. So will hooking up what you suggest between the DAC and the Behringer EP2000 fix the problem? Thanks.


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## caper26

longdrive03 said:


> Thanks Caper. He has a small laptop with the DAC. So will hooking up what you suggest between the DAC and the Behringer EP2000 fix the problem? Thanks.


Not sure what inputs the EP2000 accepts. The dongle is a USB sound card and outputs both 3.5mm and optical. It works with my Yamaha receiver perfectly via optical.


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## longdrive03

I don't think the EP2000 has optical input only 1/4"jack and XLR.

I think I have a fairly accurate guess at the weight of this thing. I found info on the weight of 3/4" mdf and baltic birch ply (3.75lb sf mdf and 2.3lb ply for the technical people). Best I can cipher is the 3/4"mdf inner shell weighs at least 75lbs. The 3/4"ply outer shell weight 62 lbs. Then you add the weight of the Trio 12" woofer (I can't find weight spec) and the 2 APR12's and the handles bottom riser and screws/nails which i figure to be about 25 lbs more at least and you get 152lbs. it would make a good bench press or dead lift!!


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## caper26

longdrive03 said:


> I don't think the EP2000 has optical input only 1/4"jack and XLR.
> 
> I think I have a fairly accurate guess at the weight of this thing. I found info on the weight of 3/4" mdf and baltic birch ply (3.75lb sf mdf and 2.3lb ply for the technical people). Best I can cipher is the 3/4"mdf inner shell weighs at least 75lbs. The 3/4"ply outer shell weight 62 lbs. Then you add the weight of the Trio 12" woofer (I can't find weight spec) and the 2 APR12's and the handles bottom riser and screws/nails which i figure to be about 25 lbs more at least and you get 152lbs. it would make a good bench press or dead lift!!


Box says 8 KG net weight for the driver; PRs 1.8 KG each. What about the weight of the amp?? which one did you use?


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## longdrive03

So about 24 lbs for the trio 12 and two aprs so its around 155lbs. 

He's using the Behringer EP2000 amp. Only using one of the channels to push this baby. At 9:00 pm (14) on the gain it is loud!!


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