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quindecima
04-28-2016, 07:15 PM
Can a 2405 test O.K. with an Ohm meter but still be bad? I'm not getting any sound from my 2405's

BMWCCA
04-28-2016, 07:27 PM
Can a 2405 test O.K. with an Ohm meter but still be bad? I'm not getting any sound from my 2405's
Let me suggest the obvious: Have you checked the L-pad on the crossover, or swapped the 2405 from one cabinet to the other?

quindecima
04-28-2016, 07:31 PM
After I posted that thought immediately came to me. Something is haywire because both are not working and the L pad adjustment is not effective.

script56
04-28-2016, 08:01 PM
If you can remove it from cabinet and test directly. I had similar issue. It was fixed after I re flowed all solder points on crossover. It was Jbl L65.

quindecima
04-28-2016, 08:17 PM
I checked the wiring on the L pad and the speaker to the Crossover and all is good. I checked all wiring connections for continuity, I have nothing and the drivers ohm out good. I haven't swapped them because there is nothing out of either.

speakerdave
04-29-2016, 12:08 AM
What is the genesis of this event? Did they both stop working at the same time? Are you firing them up for the first time? Did you check the operation of your crossovers before installing them? Have you checked to see if you are getting signal at the driver terminals? Have tested the tweeters with another signal source? Has something untoward happened? Did your little brother have a party?

mech986
04-29-2016, 03:02 AM
I checked the wiring on the L pad and the speaker to the Crossover and all is good. I checked all wiring connections for continuity, I have nothing and the drivers ohm out good. I haven't swapped them because there is nothing out of either.

If you have nothing out of each, then you must remove them from the speaker and test individually with known good signal. If you have it, hook up the driver to a low powered amp, turn down all bass and mid tone controls or put a capacitor in series with the driver (3 to 3.3uf) cap for an 8 ohm driver, 2uf for a 16 ohm driver. That will filter out all the frequencies below about 7000hz.

Then play a low level known music signal with some high frequency content like cymbals, female voice, etc. If you get music, then you know the problem is in the wiring or crossover. If not, then ohm out the drivers again out of the cabinet to confirm if they are ok or open (blown).

And yes, important to know if there was any incident with your system before the drivers stopped working.

Assume nothing and troubleshoot.

script56
04-29-2016, 09:09 AM
If it is 4333 or system with bi amp switch on back under terminals you can work that knob back and forth to clean it. The knob you use a screwdriver to switch from internal to external crossover. Work it back and forth about 20 times. That will clean pot.

quindecima
04-29-2016, 04:01 PM
I pulled a LE-5 from my L100's and replaced a 2405, no joy. I took one of the 2405 drivers and hooked it up in the LE-5 spot, turned it up until I got sound from it and re-ohmed them they are good and the silver seals are still unbroken. I rechecked ALL wiring and continuity between ALL connections, checked to make sure ALL connections were correct and then rechecked them ALL again. I am starting to think my hearing is so bad I can't hear any UHF.

mech986
04-29-2016, 07:02 PM
Quin, I've not been following your posts in the recent past - what type of speaker and crossover is in question, and what mods have been done to it? If the ohm'ed drivers measure ok, then its the crossover. Can you provide the schematic and pictures of your crossover?

If there is a series element like a resistor or cap in front of the 2405, then one of them is open. Either that, or if there is an element like a resistor, inductor, cap or L-pad across both terminals, they could be shorted.
'

quindecima
04-29-2016, 07:24 PM
I'm looking for a short somewhere but in both speakers and the same driver? My head is hurting thinking about it. I'm close to pulling a crossover out and giving it a close look.

mech986
04-29-2016, 08:48 PM
As I said before, assume nothing and troubleshoot, as you have been. The mystery of the no sound tweeters!

Reminds me of the Sherlock Holmes quote:

When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.

4313B
04-30-2016, 08:00 AM
I'm close to pulling a crossover out and giving it a close look.That's what I would do next.

Just before I shipped them they had passed all voltage drive tests so it will be very interesting to find out why both UHF circuits have failed.

quindecima
04-30-2016, 08:17 AM
O.K. 4313B, That's the next move, I have to work today (unfortunately) but when I get home I will take one out and put it on my bench and carefully see if I can see anything. I peered all over it while it is mounted but I need to get it out to get a good look.

4313B
04-30-2016, 08:41 AM
I'll try to get you another pair of networks by the end of May.

And that concludes my days on this forum.

toddalin
04-30-2016, 01:57 PM
If the ohm'ed drivers measure ok, then its the crossover.

When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.

Sherlock Holmes





What of the "possibility" that the voice coil is "jambed" in the gap? It could freeze the movement and kill the sound without affecting the resistance of the coil when measured on an ohm meter.

Considering the impossible and improbable is all fine and dandy, but we must also look to the likely suspects.

Me ;)

mech986
04-30-2016, 03:12 PM
What of the "possibility" that the voice coil is "jambed" in the gap? It could freeze the movement and kill the sound without affecting the resistance of the coil when measured on an ohm meter.

Considering the impossible and improbable is all fine and dandy, but we must also look to the likely suspects.

Me ;)

With any driver or speaker that has had stress, dropped, or hard hit (shipment or fall), that would always be a concern. vintage drives with vintage glues would also be suspect, even without force applied. Pulling the driver, in this case the 2405, and examining the diaphragms and gap, and checking for debris and consistent symmetrical gap, plus good diaphragm which hasn't bubbled, burned, or become non-concentric would be important.

JeffW
04-30-2016, 04:05 PM
I think I'd try hitting it with a little signal directly into the driver before risking disassembly, spin the phase plug taking it apart or putting it back together and you're out a couple C notes.

quindecima
05-06-2016, 08:04 PM
I don't think there is anything wrong with those darn drivers. I put Streisand on and it played very well thank you and if they weren't operating correctly I darn sure would have noticed it on this album.

mech986
05-07-2016, 12:12 AM
my go to song for sibilance checking is Mas Que Nada by Sergio Mendes and Brasil 66. Otherwise, a well recorded Buddy Rich album with a lot of cymbal work also is useful.

Did you also check your ears for any wax? That affects HF perception a lot!

BMWCCA
05-07-2016, 05:03 AM
I don't think there is anything wrong with those darn drivers. I put Streisand on and it played very well thank you and if they weren't operating correctly I darn sure would have noticed it on this album.
On the UHF drivers sometimes it helps to use the tube from the center of a roll of paper towels held up to your ear and the driver to help isolate the sound. It can be a limited frequency range that's hard to hear, especially if your hearing isn't what it used to be! :dont-know:

quindecima
05-07-2016, 04:05 PM
On the UHF drivers sometimes it helps to use the tube from the center of a roll of paper towels held up to your ear and the driver to help isolate the sound. It can be a limited frequency range that's hard to hear, especially if your hearing isn't what it used to be! :dont-know:

Things have definitely changed for the better since I replaced that 2245H and had a bottle of Pinot noir, I stuck the empty bottle up to the UHF and darn if it didn't sound a heck of a lot better.

quindecima
05-07-2016, 06:48 PM
To convince myself even further that my UHF is working properly in put on a CD of "the Red Violin" sound track, holy s--t if you want to give your speakers a work out listen to that at high levels man those 4345's came ALIVE.

4313B
05-10-2016, 11:46 AM
To convince myself even further that my UHF is working properlySo they are now working?

quindecima
05-10-2016, 06:43 PM
So pretty darn well if I do say so myself. This was an interesting foray into the working of a loudspeaker.
when I read the post from BMWCCA I realized that the crux of the problem was me and not the speakers themselves and listening to some of my recordings that entailed a lot of UHF further cemented my belief that work into that speaker system was not for naught, they are working fine and I am already collecting drivers for the next pair.