"A thing of beauty is a joy forever..."
---–John Keats
Splendid work! Well done.
"A thing of beauty is a joy forever..."
---–John Keats
Splendid work! Well done.
Out.
Dr.dB - You've built one of the nicest JBL interpretations I've seen so far. It's just beautiful, with an appropriate nod to the old school guys who placed so much emphasis on producing a speaker that sounded marvelous to the ear, and looked great to the eye! I love your attention to detail in the crossover builds, too.
May I suggest one finishing touch? One hundred years from now somebody - maybe one of your grand children - will develop an interest is audio, but will be unable to find the story behind your fine speakers. I'd suggest writing a one-page summary of the speakers, what they are built from, and the fine components contained inside. Along with a graph or two. And, of course, a short devotion to the builder - you. Glue the paper inside the cabinet with contact cement and you will have done somebody a great service downline.
Can't wait to see your next project!
@gdmoore28:
Thanks a lot for the honor!!
It sounds like a very nice idea, I will do so
@rusty jefferson:
Subwoofers will follow, but I think I won´t have time for that until 2018....
So how do they sound? I imagine that they are very dynamic
Describing sound is allways subjective, but I´ll try
To my ears they sound very detailed and controlled. The sound is very dynamic, but the midrange horn tames it a little bit. I would say other JBL horns are more straight forward e.g. right in your face.
The 2397 e.g. westlake horn sounds a bit softer, more hifi-like...
I think this mates very well with the 2405 slot driver, as this sounds softer than the 2402 bullet for example...
I´ve owned many horns and driver and allways liked the 2402 and big radial horns for a short thrill. But in the long term, the 2397 and 2405 are a little less dynamic but sound much more realistic.
The low-mid and lows are really transparent I have to say! Listening to a contrabass is a pleashure and it is easy to distinguish the different sounds. The punch has endless energy, but the low end is still weak in these big enclosures.
I would say it looses gradually efficiency below 100hz and sounds a bit thin. Yet it does reproduce 35-40hz nicely.
I´ve had these enclosure in my living room for a couple of weeks now.
As some may have noticed in my other thread (musically sub), I´m not satisfied with the low end.
I hoped the E-145 would reach down low in these huge enclosures, but unfortunatelly they have rather lost efficiency in the low end.
My idea would be, to reduce the internal volume from 8ft³ to 5-6ft³ and change the ports from 38hz tuning to aprox. 50hz. This smaller enclosure should gain 2-3db between 50-100hz and give me the punch I´m looking for.
Below 50hz I would use a dedicated sub.
What do you guys think of this idea
I think the only way to reduce the internal volume of this enclosure would be to put some bags filled with pebbles inside...
1/2 of a 2" thk 4x8' dow building insulation sheet (blue styrofoam) ?
it'd be a lot lighter than 3ft3 of pebbles
Does the styrofoam really hinder the sound waves from penetrating it ?
I would think it is some kind of foam and wouldn´t really take away any volume, as sound waves would penetrate it....
Not styrofoam like a coffee cup or cheap cooler.
the blue DOW extruded sheets are very rigid and
incompressible... I understand you're disbelief though
just an idea.
Try to get acquainted with the Thiele papers. Start with table i.
The natural alignment for your speaker would be alignment #3. That would give you a horrible f3.
Alignment #5 is tempting. That would give you a pretty f3 and would be compatible with your box size. But your Qt is too small. Look at equation 70 how to make Qt larger. Use reasonable cables and reasonable inductors and Qt will get larger. You need to play around a bit with your pocket calculator.
Your box is still too large? Make the port cross section larger, this is good anyways. It requires you to increase the port length. You can have a port with a small cross section and a small length, or one with a large cross section and a large length (for the same result, box resonant frequency). Eat up the excess volume with a bigger port.
The resulting alignment can be plotted and optimized by some friendly forum members.
First calculate, then build a prototype from chipboard, then modify your beauties.
Ruediger
Have you simulated the box internal geometry yet?
Would you consider adding a sub?
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