Page 2 of 8 FirstFirst 1234 ... LastLast
Results 16 to 30 of 109

Thread: The purpose of JBL E145

  1. #16
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193

    Re: Jacked Up Numbers

    Originally posted by Earl K
    Hi RobG
    You and I went through this a couple of forums ago. What TS numbers were/are wrong. I remember you reporting that JBL said to measure it yourself,,, etc. The numbers I use seem to give the appropriate curves for this class of speaker. Here's a pdf of a 2 cu' , 50 Hz tuning I did quite a while ago ( ignore the date stamp ) . How does this curve compare to what you see with your tuning-prediction software?

    regards <. Earl K
    Well for one thing...

    Given a value for Fs of 35 Hz, Mms of 0.055 kilograms, and Sd of 0.090 square meters, Vas SHOULD be ~427.7 liters instead of 274.7.

    This is given by:
    Vas = (2 * pi * Fs)^2*Mms)^-1 * p0 * c^2 * Sd^2 * 10^3
    Where Vas is in liters
    Mms is in kilograms
    p0 is 1.18 kilogram/cubic meter (mean density of air)
    c is 345 meters/second (speed of sound)
    Sd is in square meters

    Dyslexia perhaps?
    I think using 427.7 instead of 274.7 jacks up the reference efficiency though... I'd have to work through it...

  2. #17
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193
    Anyway, back to:

    "I was talking with a man here in sweden who liked
    the e-145 more than the 2235 up to ca 600hz, more
    attack he said.."


    Looking at the TS parameters both drivers have the same Qts, the 2235H has a bit better mechanical control with it's lower Qms and the E145 has a bit better electrical control with it's lower Qes.

    The 2235H clearly has a "better" Bl factor but...

    155 grams / (20.5 Newton/Amperes * (1/6.0) Amperes) = 45.4 grams/Newton

    55 grams / (16.1 Newton/Amperes * (1/5.7) Amperes) = 19.5 grams/Newton

    Wow! If my math is correct, I guess we can see why the E145 has such a nice attack
    Attached Images Attached Images  

  3. #18
    Senior Seņor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142

    Dyslexia and typos...

    I've noticed some myself - in the 1982 Pro brochure, p5 JBL appears to have swapped the Enclosure Volume figures for the 4345 and 4355...
    bo

    "Indeed, not!!"

  4. #19
    Niklas Nord
    Guest
    Great, this thread has become wery interesting.
    Is the e-145 a rare object in the USA?

    Are there one alnico version and one ferrite version ?

  5. #20
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193
    No the E145 isn't rare.

    Note that it's the same transducer as the 150-4H (Everest).

    http://www.audioheritage.org/html/pr...bl/everest.htm

    The K-series are alnico, the E-series are ferrite. JBL increased the flux densities in the E-series though...

    Note that these TS parameters haven't been checked yet so some might be "wrong"

    ***********
    K120, K151, E120, E145 look suspect
    Attached Images Attached Images  
    Last edited by 4313B; 06-22-2003 at 05:33 AM.

  6. #21
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193

    Question E145 Effective Piston Diameter

    Hello,

    If someone has an E145, I need to know the effective piston diameter, preferably in millimeters. I already have "published" notes, I need the "real deal".

    Thanks

  7. #22
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    8,170
    Well I can measure my 801C cone. It's different cone kit than the 145. Don't know if it because of the central spider or if the cones/surround are different.

    Rob

  8. #23
    JBL Dog
    Guest

    Re: E145 Effective Piston Diameter

    Originally posted by Giskard
    Hello,

    If someone has an E145, I need to know the effective piston diameter, preferably in millimeters. I already have "published" notes, I need the "real deal".

    Thanks
    Giskard

    I have three E145's. One NOS, two that are reconed with what appears to be a generic kit ("10455" stamped on cone.... looks exactly like the JBL kit, but slightly heavier).

    Let me know how to measure the "piston diameter" and I will get you a number. Sorry, I'm pretty much a novice when it comes to the technical stuff


    This message comes from JBL Dog

  9. #24
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193

    Re: E145 Effective Piston Diameter

    Hi JBL Dog,

    Measure from the middle of the surround Thanks!
    Attached Images Attached Images  
    Last edited by 4313B; 06-22-2003 at 03:31 PM.

  10. #25
    JBL Dog
    Guest
    Giskard:

    I measured it to be exactly 13.25 inches. A conversion to millimeters is 336.55. Hope this helps.

    This message comes from JBL Dog

  11. #26
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193
    Great! Thanks a bunch

    So that means the Vas of the E145 is 427.7 liters instead of the published 274.7 liters. It makes sense since JBL likes to put this driver in a 4.0 cubic foot volume tuned to 40 Hz.
    Last edited by 4313B; 06-22-2003 at 07:06 PM.

  12. #27
    sa660
    Guest

    E145 and 801C

    Originally posted by Robh3606
    I would love to get my hands on a pair of them to drop in my mains. My 801C is based on it and it is one really nice sounding driver.
    Rob
    ROB,
    I have 2 E145 that need recone and I am wondering about getting them done.
    Can you describe the frame of the 801C?
    The E145 has a thicker frame about 3/4 " thick to allow for a deeper cone that usual JBL chassis. Is the 801C the same?

    Do you have characteristic of the vents and volume of the box for the 801C.

    Regards,

  13. #28
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    12,193

  14. #29
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    8,170
    The 801C uses the same frame as the E-145. The diference between the volumes would be the volume taken by the 2425S hanging off the back. Take a look at the attached photo. There is a recess in the UREI cabinet the frame is thicker than it looks in the photo. If you talk to JBL they told me to use the T/S for the E-145. I have always wondered about that though looking at the -3db for the 811C monitor. I think they have the box tunned tight for maximum transient response.

    Rob
    Attached Images Attached Images  
    Last edited by Robh3606; 06-23-2003 at 07:33 PM.

  15. #30
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    8,170
    Some decent pictures
    Attached Images Attached Images  

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. L100 and 43XX Monitor Legacy
    By Don McRitchie in forum Lansing Product General Information
    Replies: 8
    Last Post: 05-22-2012, 08:09 AM
  2. Mobile JBL almost ready...
    By johnaec in forum General Audio Discussion
    Replies: 5
    Last Post: 08-01-2004, 11:21 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •