If I don't have a test CD handy, I just take the Telarc recording of Michael Murray on organ with the Atlanta Symphony, of the Poulenc Organ Concerto in G minor, and put it on repeat. 16 Hz pedal tones do the trick!! Just be careful to set the gain at the LOUD part before you walk away!!(oops, there went the cone flying thru the air...)
Regards,
Gordon.
Gordon:
You beat me to it, I was going to suggest the same but with the TELARC 1812, more range, set the volume just so it clips occassionally.
Alex.
Come by an get my old heathkit tube sine generator...... I could listen to it for hours.....Originally posted by JBL Dog
How can I generate a 20hz signal? I don't have any test equipment or a signal generator, etc.
Can I, maybe, uh.... play some rap music laced with profanity for an hour or so and get the same result?
This message comes from JBL Dog
I'll be there in 15 minutes!Originally posted by Audiobeer
Come by an get my old heathkit tube sine generator...... I could listen to it for hours.....
This message comes from JBL Dog
G'Day,
I have just received my 2 x 2225's reconed as one each of 2234 and 2235 from the JBL agents.
The burn in procedure works fine for the 2234 but the 2235 makes a scuffing noise above 7.5V @ 20Hz.
Is 7 V the limit for a 2235H @ 20Hz?
Regards Scott
One would need to know the amplifier gain before an answer could be formulated.But according to the specs 10 volts are used sweeping the freqs from 20-1200 for a dynamic test.Oldmics
G'Day,
Sorry, I should be more specific.
The speaker is suspended on two bits of 6" x 2" and the voltage is measured across the speaker terminals.
After a bit more listening the sound is more like something is hitting internally... like a soft (dull) click...
Regards Scott
Jtgyn.. hate to be the purveyor of bad news, but to me, it sounds like there may be a fault in that 2235. I would be surprised, that if 7.5V (only about 7 watts at 8 ohms) at 20 Hz would be able to make a normally-operating 2235 flinch at all!
My guess, is that someone didn't quite get the voice coil aligned in the gap properly... either an insufficient shimming of the voice coil during assembly, or a premature removal of said shims, before everything had set up and cured thoroughly.Either way, it'll probably be a replacement of the cone kit, unless someone gets REALLY lucky and is simply able to strip off and replace just the foam surround and re-align the cone in the process of gluing the new foam surround in...
Regards,
Gordon.
mass ring
It just might be a problem with a loose mass ring,but hey just take it back to the reconer and tell them to get there shit togeather.
YEP!Originally posted by GordonW
My guess, is that someone didn't quite get the voice coil aligned in the gap properly... either an insufficient shimming of the voice coil during assembly, or a premature removal of said shims, before everything had set up and cured thoroughly.
Regards,
Gordon.
Right, I had the same problem and still wonder why this so called "experts" are unable to align a voice coil. IMO it's just sloppy work.
Since this happened to me I do recones myself. The first recone I did was even better then "their" work.
Sorry
Bingo! Except JBL Pro has made it impossible to get their kits, so do what I do - get to know your reconer, and try and hang around their shop when they're shimming...Originally posted by Guido
Since this happened to me I do recones myself.
bo
"Indeed, not!!"
Bo,Originally posted by boputnam
Bingo! Except JBL Pro has made it impossible to get their kits, so do what I do - get to know your reconer, and try and hang around their shop when they're shimming...
what is thing that you do no longer get JBL Kit's?
Does this mean that it is forbidden for reconers to sell you kit's? I mean if the door direct from JBL is closed, can't you use backdoors?
G'Day,
I was starting to get a bit cross that the re-cone was a dud and I thought I should just check everything again before taking it back.
Well.... I think I have found the problem.
Comparing the two drivers I noticed the voice coil braid on the 2235 driver was much longer than the 2234 and almost touching the spider without any voltage applied.
When I drove the 2234 to 10V @ 20Hz the braid was just missing the spider but the 2235 was hitting the spider at 7.5V.
The 2234 braid hits the spider at 12V @ 20Hz.
Hmmm, I checked the cone displacement and at 10V @ 20Hz it is approx .4" (Xmax) so my guess is than 10V is all it is going to take. (@ its resonant frequency in free air anyway)
So... does anyone have a copy of the JBL re-cone guide that will tell me the correct way to set the braid length?
B.T.W. the Fs for the drivers seem low... 2235H ~17Hz and the 2234H ~ 19.5Hz... is this normal?
Regards Scott
Fs on 2235
The Fs on the 4x2235,s that i have come in at 18.4 - 19.0
"B.T.W. the Fs for the drivers seem low... 2235H ~17Hz and the 2234H ~ 19.5Hz... is this normal?"
Did you measure the Fs before or after breaking them in?
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