JP2.0 Project Part IV : How to blow up a ribbon and scare the life out of your cat - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th April 2005, 06:15 PM   #1
diyAudio Member
 
Join Date: May 2004
Location: Dallas, TX
Default JP2.0 Project Part IV : How to blow up a ribbon and scare the life out of your cat

I finally received the final components needed to wire up the JP2.0s and PR170s in my test baffle. I managed to mount and wire the entire left Mid/Tweeter panel. I had the JP2.0 wired with a series 20uF capactor directly to one set of binding posts and the PR170 wired directly to the other set. I connected each speaker to its own channel of my amplifier. I setup the DCX2496 with a 48db/oct LR crossover at 2.5 Khz. Everything was going fine, the speakers sounded better than I had hoped.

Then I did something really, really, really stupid. I decied I wanted to move some the wiring on the back of the speakers so I went to shut down my system. I turned of the DCX without shutting down the amp

There was a !!LOUD!! pop and I saw a blue arc in the JP2.0 Tweeter, I could see the PR170 move way beyond its limit, probably close to 5mm. The ribbon in the tweeter is destroyed. Its pushed way back out of the gap and looks like it's been stretched alot. There is also a deposit of metal where the ribbon either hit the magnet or where a spark jumped. There doesn't appear to be any physical damage to the PR170s cone or surround but I haven't had a chance to listen to it since this happened. I talked to madisound and they can replace the ribbon but they think I might have damaged the transformer as well



I know that this is a "learning hobby" but this SUCKS! I need help from the experts out there:

Anyone have a similar problem with a DCX, I hope I'm not the first bonehead to do something like this. If the DCX always pops when it turns off what happens if there is a poweroutage? Does it just blow up your speakers everytime?

I thought the 20uF cap would have protected the ribbon since its a highpass filter, I thought that was the purpose of putting it there even with digital X-overs.

What are the chances I didn't destroy the PR170? How do I check to see if it is still ok?

--Chris
  Reply With Quote
Old 12th April 2005, 06:25 PM   #2
gary f is offline gary f  Canada
diyAudio Member
 
gary f's Avatar
 
Join Date: Aug 2003
Location: Quebec city
Sorry to hear that. The ribbon is gone! But I doubt you did any harm to the PR170. These things are tough to kill.
F

Good Luck
  Reply With Quote
Old 12th April 2005, 06:31 PM   #3
diyAudio Member
 
ShinOBIWAN's Avatar
 
Join Date: Feb 2004
Location: UK
Ouch, sorry to hear about that.

Hope you get it sorted double quick and with minimal cost.

I had problems with a Behringer DSP1124 parametric EQ aka a BFD. It was wired to a sub and whilst it the noise was unpleasant, subs can take far more punishment than a treble unit. Having said that I only let it do it once and afterwards I always ensured I turned the components on and off in the correct order to avoid it happening again.

I guess you were unlucky.
  Reply With Quote
Old 12th April 2005, 07:39 PM   #4
diyAudio Member
 
Join Date: May 2004
Location: Dallas, TX
Quote:
Originally posted by gary f
Sorry to hear that. The ribbon is gone! But I doubt you did any harm to the PR170. These things are tough to kill.
F

Good Luck
I hope that you're right! The amp is rated at 120 watts per channel and I fear for the worst I'll hook up just the PR170 and see if it sounds ok when I get home from work tonight.. Any suggestions how to test if it was damaged other than to listen for strange noises, distortion, compare how it sounds to the other one I bought?

Quote:
Originally posted by ShinOBIWAN
Ouch, sorry to hear about that.

Hope you get it sorted double quick and with minimal cost.

I had problems with a Behringer DSP1124 parametric EQ aka a BFD. It was wired to a sub and whilst it the noise was unpleasant, subs can take far more punishment than a treble unit. Having said that I only let it do it once and afterwards I always ensured I turned the components on and off in the correct order to avoid it happening again.

I guess you were unlucky.
Yeah I should have known better than to power things up at 1:30 AM... Never thinking clearly that late at night. If its only the ribbon element it will cost $28 plus shipping according to the guys at madisound. If the transformer is blown I'll probably have to buy a new one..

What really bites is that you buy them in matched sets. Now I'll have one original and one repaired one

I'll let you guys know what I find out and try to take some pictures of the blown ribbon to post here.

--Chris
  Reply With Quote
Old 12th April 2005, 07:46 PM   #5
simon5 is offline simon5  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Québec, Québec
Where's the cat part?
__________________
DIYaudio for President !
  Reply With Quote
Old 12th April 2005, 07:57 PM   #6
diyAudio Member
 
Join Date: Jul 2004
Location: Columbus, OH
I'm using the same DCX2496 and JP-2.0 as you are. No offense, but I'm glad you made the mistake before I did. Now I'll be sure to power the Behringer off last!

As far as the 48/db LR you're using, why did you choose this over the Butterworth? I'm using my Fountek in a line array with (10) Vifa TC14 5" woofers and am not sure which filters to use. I will probably see which one sounds the best, but if we have 8th orders at our disposal, why not use them, right? Or am I wrong?

Again, sorry about your luck but thanks for posting this and helping me out.
  Reply With Quote
Old 13th April 2005, 03:16 AM   #7
diyAudio Member
 
ShinOBIWAN's Avatar
 
Join Date: Feb 2004
Location: UK
Quote:
Originally posted by simon5
Where's the cat part?
The cat was probably laid ontop of the speaker when the ribbon blew
  Reply With Quote
Old 13th April 2005, 08:31 AM   #8
simon5 is offline simon5  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Québec, Québec
I think maybe the capacitor discharged itself instantly when you powered off the DCX.

Maybe the DCX does a short-circuit in between the speaker terminals when powering off, causing the capacitor to discharge itself in the speaker in a fraction of a second and killing the tweeter easily.
__________________
DIYaudio for President !
  Reply With Quote
Old 13th April 2005, 12:39 PM   #9
diyAudio Member
 
Join Date: Oct 2000
Location: The People's Republic of Maryland
The big cap mainly protects the transformer from any DC voltage that might hit it from the amp. 20uF would provide a too low frequency of filtering to have saved the ribbon.
If you have an ohmeter, you could measure the DC resistance across the terminals. If it's the same value as the other tweeter, then the xfrmr may still be OK.
  Reply With Quote
Old 13th April 2005, 01:37 PM   #10
diyAudio Member
 
wigginjs's Avatar
 
Join Date: Dec 2003
Location: Columbia, SC
Is this a problem with active crossovers in general or specifically with Behringer products? I would think there should be no reason why you should not be able to turn the crossover off before the amplifier. What causes this large spike of power? Is the crossover outputting a DC signal and then the amplifiers are amplifying it? I'm building an active crossed speaker right now and while I'm going to be using a computer as my crossover I'm still concerned for the health of my drivers.
__________________
The Four Chairs
DIY Home Theater
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
NAD fuses, slow blow or fast blow? AllCaster Solid State 3 25th October 2009 06:11 PM
diy ribbon tweeter project paulfk Full Range 1 24th October 2008 02:51 PM
Help with ribbon project bizza Planars & Exotics 7 19th October 2007 05:07 PM
dead project, new life? yosh Tubes / Valves 4 24th March 2005 05:24 PM
Blow up once, Blow up twice and Blow up somemore S.C Chip Amps 14 6th March 2005 12:09 AM


New To Site? Need Help?

All times are GMT. The time now is 12:18 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2