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Scored JBL 4648a-8's today

Jcricket

Jcricket

not someday, but today
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Hey Folks, I have been away for awhile. I have been dealing with health issues.
Anyway, I was at a pawn shop today and found five of the JBL 4648a-8's. I got them for pretty cheap, just over a Benny each, right at $600 out the door. I am not surge that is a steal, but I thought it was a pretty good deal. I read the JBL literature. It states a usable range from 35-800. 35 is -10db though. So these are good bass cabs, but not subwoofers. Since I have five cabs and ten drivers, I was thinking I would try to convert a pair of these cabs to subs. I'll have to do some research to see if I can find some suitable 15" subwoofers.

For the top of these cabinets I am running some Renkus heinz cbh500 horns with JBl 2446j drivers. I have a couple of pair of eminence 2-way xovers hanging around here. One pair at 500hz and the other at 800hz. I think I will run the 4648 2446 drivers with this xover and a tube amp.

Then come how to deal with the subwoofer section. I have a really nice yamaha 275wpc rms amp I could use for the subs. I also have a two channel three way dbx active crossover. Sorry for the rambling, just thinking out loud.
 
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Jcricket said:
Hey Folks, I have been away for awhile. I have been dealing with health issues.
Anyway, I was at a pawn shop today and found five of the JBL 4648a-8's. I got them for pretty cheap, just over a Benny each, right at $600 out the door. I am not surge that is a steal, but I thought it was a pretty good deal. I read the JBL literature. It states a usable range from 35-800. 35 is -10db though. So these are good bass cabs, but not subwoofers. Since I have five cabs and ten drivers, I was thinking I would try to convert a pair of these cabs to subs. I'll have to do some research to see if I can find some suitable 15" subwoofers.

For the top of these cabinets I am running some Renkus heinz cbh500 horns with JBl 2446j drivers. I have a couple of pair of eminence 2-way xovers hanging around here. One pair at 500hz and the other at 800hz. I think I will run the 4648 2446 drivers with this xover and a tube amp.

Then come how to deal with the subwoofer section. I have a really nice yamaha 275wpc rms amp I could use for the subs. I also have a two channel three way dbx active crossover. Sorry for the rambling, just thinking out loud.
Click to expand...
Here is a pic
SegDs1Uh.jpg
 
The 4648s, though vented, will handle EQ with composure and can be used as subs. I used a pair to augment Altec A5s below 100hz. I gave them 6db of boost at 30hz and, with wall placement, they measured flat down to about 25hz and dynamically tracked the A5s with no sign of distress.

6F3B6A86-C31A-459A-BEFD-87D1AA5EA8BF.jpeg
 
Well cool. So it seems using them as part of a two way system, xovered at 500 or 800 would work well. I saw the jbl literature listed the compression driver I have is good from 500hz to 20k . I'll try and get some boxes and l-padspads built for the xovers in the next few days and give them a go. I'll report on them then.

any other thoughts or gotchas to watch out for.
 
I tested these last night. :eek2::eek2::eek2::eek2::eek2::banana::banana::)

These are the best sounding speakers I have ever owned. Also, some of the best speakers I have ever heard.

I hooked these up with an eminence 2nd order 500hz xover and an 16ohm l-pad
They are being driven with a Yamaha P-2200 amp
 
I answered a CL ad for an empty 4648 last year and found a place to put a pair of 2234H's I had on the shelf. I found a flared port tube that fit through the ports at Parts Express. A 3-piece, flared both ends type. I cut to length and glued them together in situ. I did have to relieve one brace on each side for the inner flare. I also added a plywood ring behind the woofer cutout to hold the tee nuts from falling inside, which they did at first.
 
Jcricket said:
I tested these last night. :eek2::eek2::eek2::eek2::eek2::banana::banana::)

These are the best sounding speakers I have ever owned. Also, some of the best speakers I have ever heard.

I hooked these up with an eminence 2nd order 500hz xover and an 16ohm l-pad
They are being driven with a Yamaha P-2200 amp
Click to expand...
Well, it's only fair that you shoot a video and post it in the video thread so the rest of us can get a listen!
 
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