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Author Topic: Passive x-over in Turbo TXD 252's?  (Read 5907 times)

chuck clark

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Passive x-over in Turbo TXD 252's?
« on: March 11, 2011, 05:44:30 pm »

Ok, I got into my Turbo TXD 252. Someone had shot a little touch-up paint along the edge of the grill and there was some cussing before I finally got it to come loose but finally ..victory!  The good news is the drivers all test good. Whew! My problem is the passive x-over is not passing audio. Doesn't look like it ever overheated,..no discoloration, no visible burn marks, no broken leads on coils or caps. A row of what looks like ceramic resistors still firmly in place. ??? A small green box with 2 1/4" wires sticking out of it got my attention. Tried shorting across it- still nothing. No hi's to the horn, no mids or lows to either 15...nothing.  Double checked test signal  in other spkr. -worked dandy!  Any suggestions?  Thanks for your help!
Chuck
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Chris Davis

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Re: Passive x-over in Turbo TXD 252's?
« Reply #1 on: March 11, 2011, 06:15:45 pm »

Ok, I got into my Turbo TXD 252. Someone had shot a little touch-up paint along the edge of the grill and there was some cussing before I finally got it to come loose but finally ..victory!  The good news is the drivers all test good. Whew! My problem is the passive x-over is not passing audio. Doesn't look like it ever overheated,..no discoloration, no visible burn marks, no broken leads on coils or caps. A row of what looks like ceramic resistors still firmly in place. ??? A small green box with 2 1/4" wires sticking out of it got my attention. Tried shorting across it- still nothing. No hi's to the horn, no mids or lows to either 15...nothing.  Double checked test signal  in other spkr. -worked dandy!  Any suggestions?  Thanks for your help!
Chuck


Could the speakon connector be rewired to 2+/- or something along those lines?
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chuck clark

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Re: Passive x-over in Turbo TXD 252's?
« Reply #2 on: March 11, 2011, 07:01:42 pm »

I already tried that, no difference. It has 2  NL-4 input connectors wired in parrallel with hot lead to pin1+ and neg. to pin 1-  standard stuff.
I even tried applying signal straight onto the input solder connects on the board, thus bypassing the nl-4 input connectors and the lead wire from those nl-4's to the crossover itself.
Interestingly, the whole wiring harness appears to route thru a 3rd NL-4 (NL-8? naw, it's the same size. ?? It looks like an Nl-4 but it has a circuit card fastened to the back of it w/ 8 leads!? ) This 3rd NL-4 is used as a Bi-amp input.
Hmm, so much for simple. Dang! where's that easy button?
Hopefully someone with in depth knowledge of these things will see this and throw us a clue!
Chuck
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Gus Housen

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Re: Passive x-over in Turbo TXD 252's?
« Reply #3 on: March 11, 2011, 07:18:27 pm »

Is there a biamp switch? or some kind of internal jumper that fell off?
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chuck clark

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Re: Passive x-over in Turbo TXD 252's?
« Reply #4 on: March 11, 2011, 08:56:18 pm »

No bi-amp switch. Just that 3rd Nl-4 connector for an input if your bi-amping. I'm tempted to try bi-amping  at this point to see if that works. It's a sure way around the passive x-over I guess. That's the wierd part though. The 3rd bi-amp NL-4 has a wiring harness that connects to the passive crossover. ??? Wow.
What the...?
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Geoff Doane

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Re: Passive x-over in Turbo TXD 252's?
« Reply #5 on: March 11, 2011, 09:35:16 pm »

No bi-amp switch. Just that 3rd Nl-4 connector for an input if your bi-amping. I'm tempted to try bi-amping  at this point to see if that works. It's a sure way around the passive x-over I guess. That's the wierd part though. The 3rd bi-amp NL-4 has a wiring harness that connects to the passive crossover. ??? Wow.
What the...?

There has to be something that does the switching, whether it's a set of jumpers, or a plug that moves from one position to another, or something else.  I'm pretty sure there aren't any Speakons with switching contacts.  Since it's a 3-way cabinet, even in bi-amp mode, part of the passive crossover will still be used.  It's probably a lot of work to get it apart, but carefully inspecting the working cabinet may give you the answer to the puzzle.  And be careful about applying full range signal to the "bi-amp" input.  If part of the crossover is bypassed, you can do some damage, even with moderate levels.

GTD
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John Neil

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Re: Passive x-over in Turbo TXD 252's?
« Reply #6 on: March 12, 2011, 12:54:21 am »

If the "third" jack looks homebrew, perhaps it was used as some type of biamp or passive mode selector.

I know of some boxes that had NL4s wired directly to the drivers for biamp mode.  Then, to run passive, you inserted a NL4 frontshell into a jack.  The frontshell had each pair of pins shorted...i.e., pin 1+ to pin 1-.  By inserting this shell, you effectively connected the crossover outputs to the drivers, allowing the crossover (fed by unique inputs) to drive the box rather than the biamp inputs.

You said you had a pair of boxes, one working, right?  Comparison time?
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chris kmiec

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Re: Passive x-over in Turbo TXD 252's?
« Reply #7 on: March 12, 2011, 05:34:19 pm »

If the "third" jack looks homebrew, perhaps it was used as some type of biamp or passive mode selector.

I know of some boxes that had NL4s wired directly to the drivers for biamp mode.  Then, to run passive, you inserted a NL4 frontshell into a jack.  The frontshell had each pair of pins shorted...i.e., pin 1+ to pin 1-.  By inserting this shell, you effectively connected the crossover outputs to the drivers, allowing the crossover (fed by unique inputs) to drive the box rather than the biamp inputs.

You said you had a pair of boxes, one working, right?  Comparison time?

Hi John,

I couldn't see an email address in your profile, but drop me an email at techsupport@turbosound.com and I'll send you a diagram of how this should look.

Chris
Turbosound
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John Neil

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Re: Passive x-over in Turbo TXD 252's?
« Reply #8 on: March 12, 2011, 07:02:55 pm »

Hi John,

I couldn't see an email address in your profile, but drop me an email at techsupport@turbosound.com and I'll send you a diagram of how this should look.

Chris
Turbosound

Chris,

Thanks for browsing around on the PSW.  The box I mentioned wasn't a Turbo, but an example of having an oddly wired NL8 was used as a mode switch.  Hopefully Chuck will take you up on your offer soon.

jn 
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chuck clark

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Re: Passive x-over in Turbo TXD 252's?
« Reply #9 on: March 12, 2011, 10:09:29 pm »

Thanks Chris! I'm only on here for a short bit, gotta run to a show. I'll be e-mailing you shortly.
I should mention it's a beautiful piece and appears to be very robust w/ large coils and 250V caps!  Looks like it would easily handle serious big watts, I'm really curious what could be the issue here!???
Chuck
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Mark Walter

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Re: Passive x-over in Turbo TXD 252's?
« Reply #10 on: March 14, 2011, 03:29:33 pm »

Hi John,

I couldn't see an email address in your profile, but drop me an email at techsupport@turbosound.com and I'll send you a diagram of how this should look.

Chris
Turbosound

I dealt with Chris on my Turbo gear and he was extremely helpful.
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ProSoundWeb Community

Re: Passive x-over in Turbo TXD 252's?
« Reply #10 on: March 14, 2011, 03:29:33 pm »


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