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Author Topic: EAW JF80 inconsistencies  (Read 12426 times)

Seth Huling

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EAW JF80 inconsistencies
« on: May 30, 2012, 11:44:06 am »

I have been trying to work on making the stock JF80s at my shop consistent.  Unfortunately, EAW seems to change the design of their speakers frequently.  I have multiple "acceptable" LF drivers and multiple crossovers.  I am having a problem with one specific speaker that has a 10db dip around 3k.  I cannot see any damage to the crossover or damage to the drivers, both HF and LF. The only thing I can think of is that there is an old crossover and a new tweeter or vice versa.  Does anyone here have experience repairing JF80s and/or other JF series EAW speakers? Any advice is greatly appreciated.
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Langston Holland

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Re: EAW JF80 inconsistencies
« Reply #1 on: May 30, 2012, 12:01:21 pm »

Hello and welcome:

The first thing to do is go into your account and change your alias to your real name per the posting rules.

---

Your post is quite well written, BTW. Make sure the (2) woofers are in polarity with each other. You can go by wire colors, but I'd suggest placing a 9 volt battery on the input and make sure both drivers move in the same direction.

If they were not in polarity, remeasure and see if that fixed it. If they were in polarity, try reversing polarity of the tweeter leads and see if that fixes it.

Oh yeah, unfortunately I do have experience fixing JF80's...
« Last Edit: May 30, 2012, 12:05:31 pm by Langston Holland »
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God bless you and your precious family - Langston

Seth Huling

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Re: EAW JF80 inconsistencies
« Reply #2 on: May 30, 2012, 02:07:11 pm »

Hello and welcome:

The first thing to do is go into your account and change your alias to your real name per the posting rules.

---

Your post is quite well written, BTW. Make sure the (2) woofers are in polarity with each other. You can go by wire colors, but I'd suggest placing a 9 volt battery on the input and make sure both drivers move in the same direction.

If they were not in polarity, remeasure and see if that fixed it. If they were in polarity, try reversing polarity of the tweeter leads and see if that fixes it.

Oh yeah, unfortunately I do have experience fixing JF80's...

Name all set---

thanks for the input.

I'm fairly certain that the problem i'm experiencing has nothing to do with the polarity of the 2 LF drivers because the crossover point is something like 1.8k and when I put a 3k tone in the LF drivers are completely still.  I changed the HF driver as well as switching it's polarity (with bad results) and still had no success.  As of now the speaker is on a pile of "parts".  UNCLE
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Langston Holland

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Re: EAW JF80 inconsistencies
« Reply #3 on: May 30, 2012, 02:28:30 pm »

Quote from: Seth
UNCLE

Seth! Never let something inorganic beat you! :)

Sounds like it's time to steal a tweeter from one of your functioning JF80's and see if that fixes it.
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God bless you and your precious family - Langston

Seth Huling

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Re: EAW JF80 inconsistencies
« Reply #4 on: May 30, 2012, 04:13:01 pm »


Sounds like it's time to steal a tweeter from one of your functioning JF80's and see if that fixes it.

I tried that and unfortunately it didn't help :-/
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Geri O'Neil

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Re: EAW JF80 inconsistencies
« Reply #5 on: May 30, 2012, 06:09:29 pm »

Seth! Never let something inorganic beat you! :)

Sounds like it's time to steal a crossover from one of your functioning JF80's and see if that fixes it. (Okay, if you haven't already).

Sorry, Lang, you made it sooo easy... ;D

Geri O
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Ricky Lighthall

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Re: EAW JF80 inconsistencies
« Reply #6 on: May 31, 2012, 12:40:02 am »

I have repaired literally scores and scores of these.  They were and still are very popular Broadway boxes when I worked up there.

There are two major possibilities.  Either the electrolytic caps in the xover are dried up and/or  one or more cement resistors has broken loose (if any wiggle- replace them and reglue), or it's time for a new diaphragm.
If you swapped a driver from a good box of the same version it's probably the xover.
You might as well replace all electrolytics and check all resistors while you're in there.
Also, the inductors like to break loose and may need new glue.   
They use some odd values so it's much easier to order parts from EAW or Performance Audio.
I can PM you current part numbers if needed.
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Greg Ruddell

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Re: EAW JF80 inconsistencies
« Reply #7 on: June 10, 2012, 02:14:33 am »

Seth! Never let something inorganic beat you! :)

Sounds like it's time to steal a crossover from one of your functioning JF80's and see if that fixes it. (Okay, if you haven't already).

Sorry, Lang, you made it sooo easy... ;D

Geri O

This is good advice. I recently bought 6 JF80's from a sound company that was downsizing. I bought all 6 for $600.00..So, they all had the original RCF drivers, and the original horn drivers. After evaluating each box I discovered huge inconsistencies. I couldn't even find any two that were similar sounding. However, upon removing all of the crossovers I soon discovered the issue. The 4.7Ohm  resistor on the LF Xover board next to the two elecrolytic caps gets very hot when it's getting a lot of signal. This will partially fail and also cause the caps above it (21MFD, and 15 MFD) to leak or fail. That's pretty much the issue.  But don't ever expect these things to sound exactly the same from box to box over generations. Any change in a vital component can yield a different result somewhat...but not dramatically. The sound of these things regardless of variations is just stunning. 120 db all day long and extremely hi fi. There isn't a box on the planet that can touch that. They are amazing.
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Mac Kerr

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Posting Rules
« Reply #8 on: June 10, 2012, 10:33:45 am »

This is good advice. .

Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules clearly displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
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paul bell

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Re: Posting Rules
« Reply #9 on: June 10, 2012, 11:36:17 am »

Is there a reasonable replacement woofer for these boxes without using the RCF version?
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Re: Posting Rules
« Reply #9 on: June 10, 2012, 11:36:17 am »


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