Specs for building stage monitors with E-120 and 4706 bullet

[mulqueen]

Hi, I am new here, so pardon me if I'm asking in the wrong place, or the wrong way. I have a pair of ancient, not exactly matching stage monitors which contain E-120 drivers with the old 4706 bullet tweeters. I would love to have the box dimensions and porting information to turn them into the great wedges I suspect they can be. They are impressive sounding as they are, but are very bulky and one has a volume control, the other does not, and I'm sure the boxes are home made. I would appreciate any info you may have.

[jcrobso]

http://www.audioheritage.org/vbullet...ad.php?t=23635
Welcome to the forum!
Scroll down to the pictures. If this is what your looking for I can take measurements and send them to you. John

[mulqueen]

Hi John, thanks for your response. I would love the specs for that cabinet.

[Baron030]

Here is a link that might be helpful:

http://www.jblproservice.com/pdf/Cabaret%20Series/4602B.pdf

Unfortunately, the N4602B crossover network uses a tapped coil, which is going to hard to come by if you are trying to build one yourself.
So, unless you have test equipment and coil winding skills, you will need to come up another crossover network circuit.

Surprisingly, JBL Pro Service just might be able to sell you one. Part # 63736-0060 is still listed on page 84.

http://www.jblproservice.com/pdf/Misc.%20Parts%20List/Misc%20Parts%20List%20(by%20part).pdf

Baron030

[mulqueen]

Wow. You people are great. The boxes I have appear to be the same shape and dimensions. I am having the speakers re-coned and the crossover networks checked out by MSR Sound here in Vermont. They have the right kits for both, so maybe I don't need to do anything with the cabinets. The horns are offset in the ones I have. They are located where the ports are on the real ones. Only one of mine has the high frequency roll off. My main concern is that the ports are an oddly shaped cut out, and I wanted to be sure they were the correct volume.
I am doing this project as a favor to a Coffee House music series in Ripton, VT. It's their gear, leftover from the 80's, so I get to decide how much energy to really put into it.
Interesting to read some of the opinions on the sound. In this great sounding little room - 160 people max - on this 8 x 12 stage, people seem to love them.
If anybody has the actual physical measurements, and port volume, I'll check it out again, but otherwise, you are a great, civil, and really helpful community. Thanks.
Mark

[boputnam]

Interesting to read some of the opinions on the sound. In this great sounding little room - 160 people max - on this 8 x 12 stage, people seem to love them.

Cool, but this...

Glad it worked out for you! I used these monitors with a couple of bands back in the 80's...probably one of the worst sounding things JBL ever made, but the bullet and the 12" are nice on their own, they really hate trying to work together in that box!

...has been my experience too.

At spec, that cabinet crosses at 3kHz, so the woof is carrying a lot of the load. Also, know that both those drivers are conical dispersion - there is no rectangular horn, so there is less ability to focus the "spray" of the wedge to minimize feedback and the spill to adjacent artists. The "bullet" is certainly beamy, but the specs on the 075 say it has 90° dispersion = too much. (as an aside, Meyer makes a "somewhat" similar wedge - USM-1P - with 45° conical dispersion, and with crossover at 1kHz).

Those may do fine for low SPL (acoustic?) acts, but with the dispersion characterisitics of those drivers and the high crossover I would expect them to be problematic at higher SPL stage volumes.

I am doing this project as a favor to a Coffee House music series in Ripton, VT. It's their gear, leftover from the 80's, so I get to decide how much energy to really put into it.

Mark, if you're new to SR, there is one thing you'll want to learn very quickly - that is to control your sound dispersion on-stage (and on-to the stage from the mains) and to use mics with good (cardiod) rejection patterns. Those wedges, good as they might seem, could present some real limitations - just have fun and keep that in mind!

[mulqueen]

"At spec, that cabinet crosses at 3kHz, so the woof is carrying a lot of the load. Also, know that both those drivers are conical dispersion - there is no rectangular horn, so there is less ability to focus the "spray" of the wedge to minimize feedback and the spill to adjacent artists. The "bullet" is certainly beamy, but the specs on the 075 say it has 90° dispersion = too much"

I wonder if we're talking about the same horn here. The JBL spec I found : http://www.jblpro.com/pages/pub/components/2402.pdf
says it's a 40 degree dispersion at 10k, which I think is closer to true, as I have had more issues trying to cover too many musicians with just the two of them, as opposed to having them spill over.
It is usually, low SPLs that I deal with in this room. It's a nice, wooden 200 year old meeting hall, and on stage you are hearing as much room as stage, and a really sweet natural reverb comes with it. I'm more curious about these things than anything else.

I am actually a pro sound guy on a tiny Vermont scale. I do almost exclusively acoustic and folk music for festivals and listening room series here in the Champlain Valley. Everything from national singer songwriters and bluegrass groups to the Tuvan throat singers I'll be doing tonight.

I have had very good results from monitors that cross over at 3k, if the woofer is of very high quality. I like the smooth flow through the main vocal range, with the high frequencies coming in to add clarity and presence at the top.

You know how it is - to each his own, and if the guy's rig sounds great, it sounds great, whatever the cost and combination.
Mark