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Hans
09-18-2004, 11:50 AM
Please help me! I have (among many other wonderful JBL drivers) a K140. Now I want to build a box for it and use it for electric bass. The problem is that the box can't be too big. Those of you who have experiense of this matter please give me some sugestions.

Hans Kvarnbrant
Sweden

johnaec
09-18-2004, 12:09 PM
Just post the biggest size box you can use and let someone run the numbers for optimum port size. A 4 cu. ft. box tuned to 35hz is fairly flat to 40hz with the K140, (around low E on the bass guitar). A bigger box would perform a little better.

John

Zilch
09-18-2004, 12:24 PM
Originally posted by Hans
The problem is that the box can't be too big. Hans Kvarnbrant
Sweden See Cabaret 4625. 4.5 cu.ft., tuned around 40 hz. It's a very forgiving driver....

See here: http://audioheritage.org/vbulletin/showthread.php?s=&threadid=2731&highlight=Cabaret+Sub1500

Too big?

:rockon1: :bouncy:

boputnam
09-18-2004, 03:22 PM
You might get some ideas from these old JBL Plans, which Don has archived on the Library:

Enclosure Porting Chart - Musical Instrument Loundspeakers:
http://www.lansingheritage.org/images/jbl/plans/1975-kit-plans/page14.jpg

Baffles for 3.75 and 5.75 ft3 enclosures- Musical Instrument Loundspeakers:
http://www.lansingheritage.org/images/jbl/plans/1975-kit-plans/page10.jpg

Enclosures for 3.75 ft3 - Musical Instrument Loundspeakers:
http://www.lansingheritage.org/images/jbl/plans/1975-kit-plans/page12.jpg

There may be some udpated porting solutions, so come back to this Thread for modelling help with that.

Good luck!

Hans
09-19-2004, 06:28 AM
Thanks a lot for your efforts! Of course I made an error. It's not the K140, it's a D140F. Will that make a difference? Around 4 cu ft will be OK, I understand that you can't make the box much smaller and still have a good bassreproduction. Great if someone can help med with the calculations.

Hans K
Sweden

boputnam
09-19-2004, 09:38 AM
The most relevant thread, but maybe not your entire answer:
http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=1315&highlight=d140f

Tom Loizeaux
09-19-2004, 06:45 PM
The JBL D140F was a great bass speaker in the day of 100 watt tube amps. The K140 has a stiffer surround and is a better speaker for electric bass for todays music and amps. (I use multiple K140s in my bass amp setup)
If you build a cabinet for the D140F, be carefull not to tune the cabinet too low and don't overpower the speaker, especially in the lowest and subsonic bands.

Tom

Hans
09-21-2004, 12:41 PM
Thanks for your answers. I think I skip the D140F bass box and instead use 2 boxes that I allready have. They are vented 4 cu ft boxes with K-145's. Do you think that there is a need for tweeters? Many of the new bass cabinets use tweeters!?

Hans

Tom Loizeaux
09-22-2004, 06:41 PM
If you've got a pir of K145s in vented boxes already, I think I'd just go with those! They have respectable low end output and also deliver nice mid/high end as well. (kind-of K130s but more robust!) I don't think you'll need anything else if those K145s are driven properly.
Let us know what you find.

Tom

Alex Lancaster
09-22-2004, 08:36 PM
Im pretty sure the K145 will sound more robust than even a K140, but with less power handling.

boputnam
10-13-2004, 07:09 AM
Originally posted by Hans
It's not the K140, it's a D140F. Will that make a difference? Hey, Hans...

I just found this on the Lansing Heritage site - this was a new addition for me. Our illustrious Webmaster has been busy!!

JBL "F-Series" (http://www.lansingheritage.org/html/jbl/specs/pro-comp/f-series.htm)

Alex Lancaster
10-13-2004, 07:52 AM
Even the "exotic", "special", etc etc hype is great, retro.

I thought the "F" ending meant Fender.

So it is the Ks daddy, I still would not use any of these, or Es for reproduced music, a 2235 is to me the one.

Harvey Gerst
10-16-2004, 07:50 AM
God, what a bunch of crap. I don't know who the hell wrote that - I sure as hell didn't. Sounds like a Tony Lowe flyer, but it also sounds like some outside marketing guy had a hand in it, too.

It refers to a 707 instruction manual, which I assume is an update to the 702 manual I originally wrote for the F series. I'd love to see that, if this is an indication of where they were headed.

boputnam
10-16-2004, 08:52 AM
Hey, Harvey...

I thought the color scheme was pretty indicative! ;)

Hans
10-16-2004, 10:15 AM
Hello to everyone,
and thanks for your answers!! I am doing some tests with different configurations of speakers and boxes for electric bass and will be back with my results.
Have a nice holliday!

Hans