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Author Topic: picked up monster subwoofer few days ago(JBL 4648A theater/pro subwoofer)  (Read 832 times)

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RexAeterna

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past couple months i was looking for a worthy subwoofer to help out sub-bass area with my large altecs. while the 921-8a woofers in my altecs can extend easily down to 30hz no problem i wanted something to argument it from 30hz and below for reinforcing the sub-bass frequencies. i found a local on cl getting rid of a huge jbl 4648a dual 15'' subwoofer on sale. but, i asked the guy if he'll do a trade instead and he agreed. we met at a home dept parking lot,chat for a bit and, both was happy with the trades.

this thing is huge and weighs around good 120-150lbs. it houses two well regarded jbl 2226j drivers wired in parallel. the cabs are beat up but, are strong still and, the drivers are missing the dustcaps and, have some unknown black goo in couple parts of one of the drivers but, are fully functional and the cloth and surrounds are perfect condition. i brought it home and ripped out the drivers. everything looked super duper but, the old ass decaying fiberglass had to go. i ripped it all out and put in fresh r30 9'' thick fiberglass along the walls and floor and filled the rest with whatever left over polyfill/pillow stuffing i had in the box. i also cut pieces of black open cell foam and placed it inside on the ports just to prevent any fiberglass particles from flying out when this sucker is being pushed.

after finishing the cab and replacing the ancient fiberglass inside, i decided to give it a test run. jbl claims 1200w with program material it is capable of handling. i made my own twisted 6ft 14awg speaker cable with speakon connector and wired it +1, +2 to use it for bridge/mono operation. hooked it up to my crown xls 2500 which is rated 1550w@8ohm in mono/bridge operation and put on the lowpass crossover filter to 50hz(lowest point for the active crossover). kicked it on and gave it a test go...holy popper this thing can cause some serious damage. i mean holy crap this thing alone was rattling not only houses next to me but the complexes block away. it was easily knocking things off of walls and shelves 3 floors down. lucky the neighbors weren't home lol.

these can handle some serious power too. i actually was able to hit past the clipping point on my crown and the drivers were not crapping out or showing any signs of it. it just kept going and going and i was easily pushing over 1500w into them. the forced air vent cooling jbl design for these pro drivers seem very effective of keeping these things cooled to the point they keep on going and going and going.

after the one day of causing a neighborhood earthquake and pissing off couple of blocks of people i say these are good to go. i don't push them really anymore since it was just a test run but, i can see why these were used for professional and theater use(they can handle abuse very well). i just use them as normal subs at home with my redone/reworked large altecs and they blend very well. the jbl 2226j drivers are wonderful drivers and i consider them great for home hi-fi use as well. drumkicks and bass guitars comes out very clean on them and sound wonderful. organs come out great on them as well with effortless clean extension. i think these work well and will be keeping these around. can defiantly say my home system is complete finally and very happy with them.

later on in the near future i am gonna pop on new dustcaps and will refinish the cab but, for now since it's perfectly working is all that matters. it might be huge and ugly but, works and sounds great. will post a pic maybe later on from my phone. im now using the library computer writing this and can't do much of course. i just wanted to share this little experience with people here since i know i don't post much on here anymore from being busy and so forth. really like this site since i first joined it and became part of it in the past so, i still enjoy trying to share some things when i can.
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Bass...

What I miss from using headphones...
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RexAeterna

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Here's a couple pics as promised. As mentioned cabs are beat up and dust caps are missing but, can easily be replaced. There is black crap on  the woofers as mentioned too but, doesn't bother much and complete recone can fix that if I really wanted to. I plan on trying to get dust caps in the near future and will touch up the cab a bit but, for now it's fine and perfectly functional.
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LFF

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Very nice!
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So jelly! I'm kinda looking for one too. Darn you guys have more luck.
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RexAeterna

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Thanks guys. I plan on working on these in the near future. It was kinda not surprised that these were beat up a bit since they came from a college hipster guy so, could of already imagine what these went through haha. He was really cool guy though. Were gonna hang out sometime but, other day my phone went retarded and needed to be replace so I lost the dudes number.

The 4648 is originally a bass bin to huge 2-way speaker system with massive sized horns and were used in big theaters/cinemas and still are. The cab has bolts on top for the horn placement but, no horn came with it which is not big deal since I wouldn't know what to do with a single horn. These are the older 2226j 16ohm model woofers which are wired in parallel to make a 8ohm nominal load. The newer h models are 4ohm models. The new ones look very similar to the altec 921-8a woofers cause of all black design with no ridges on the cones anymore.

These woofers are rated for down 30hz each while the bigger 18" 2241 brothers are rated down to 25hz but, with sheer power these 2226 woofers can extend lower then 30hz easily cause the cones/surrounds and, motors are very strong. These be perfect for organs in infinite baffle design.
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RexAeterna

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So jelly! I'm kinda looking for one too. Darn you guys have more luck.

You can ask around at theaters to see if they plan on getting rid of older equipment. You can probably get them at steal prices. My one friend bought pair of large jbl speakes same as mine but with the 4ohm 2226h drivers in the bass bins and came with a massive sized horn and external crossovers for 400 bucks at a local theatre . He was gonna sell them to me in them in the past but, I passed since I already have massive sized altecs and my room only being 20x20 I can only fit so much lol. I picked up the 4648a bass bin cause I knew what was when I saw it and traded up pretty rare and valuable technics sb-7000a for it. Not only it made space to house the 4648a but to me well worth the trade. I loved the technics sb-7000a and is very special speakers in its own right(very under rated to be honest  still nowadays cause I found them extremely exceptional and smooth) but, after getting my large altecs I needed space and im a one speaker set type of guy. Just needed a subwoofer to complete system.

Just be patient. You'll be surprised what some people have and get rid of. Lot of pro gear is not as popular as well with hi-fi buffs/audiophiles as well, which makes it easier too to locate some older professional equipment for steal prices next to nothing.
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gamecube

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RexAeterna

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heck yea. i still play older consoles when i have time. right now playing legend of zelda ocarina of time cause supposedly my g/f never beat it before and she had the game for years lol. i sold all my current systems for dirt cheap to some kid from india visiting his parents bout week ago. i told him to enjoy cause i have no need for them since i don't play much anymore. i still have my old consoles though and still play them once in awhile.

only update is i had the jbl sub about month or over and still feel same as i got it. i use it all the time on with my large altecs and blends very well where it's completely seamless and effortless and does everything from organs,bassdrums/kickdrums to electronic bass very well and easily with such force and extension. it works wonders with movies as well. i was looking at a 21'' cerwin vega sub when i found the dual 15'' jbl 4648a sub and i decided to go jbl instead cause i knew what type of drivers they had in them and i love older professional drivers that use cloth materials/composites. some of my favorite speakers always used some type of cloth material for midranges or woofers.  plan on buying small can of paint soon to touch up the cab so they can be finish aesthetically but, for now i dont mind how they look. not trying to impress anyone and my g/f doesn't care much either and even likes my giant ugly altecs so, my audio weirdness doesn't bother her one bit.   
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''I'm a music lover. Not an audiophile.''

''The World is Study.''

''I have no special talent. I am only passionately curious.''

''Logic will get you from A to B. Imagination will take you everywhere.''