Shifted magnet? |
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Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
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Posted: 24 June 2015 at 11:22am |
I went to cut the cone out of a seized driver. After getting down to voice coil gap, it would seem 1/4 side of it is completely jammed and there appears to be no space for movement.. Is it safe to say this is a shifted magnet?
I just got a price back on a new unit (15" neo) and nearly crapped myself..
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3035 |
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Sounds like a shifted magnet/pole piece issue to me.
What driver is it?
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
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Its a Turbosound LS-1519 out of a TFM-450. I forgot how expensive neodymium is! Can you / Do you know anyone around our area that could potentially sort out a shifted magnet? I pulled the driver out of the cupboard for a re-cone then realised it was completely seized. Been sitting there for a couple of years at least
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midas
Old Croc Joined: 27 October 2011 Location: Cumbria Status: Offline Points: 2117 |
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Roy at RMJ Loudspeakers has a method that seems to work.
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In bass no one can hear you scream!
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Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
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Thank you very much! I shall send an email!
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70,s hero
Young Croc Joined: 14 December 2014 Location: bristol Status: Offline Points: 637 |
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If the voice coil heated significantly and brunt off the insulation and distorted when it blew then it may have just corroded causing the stuck voice coil. Aluminium or copper when exposed for a few years in the presence of dissimilar metals and moisture will corrode quite significantly so it may not be a magnet shift.
Best wishes
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Top banana
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ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
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Can you take a picture of the driver please? I have a strange memory that it's a P.Audio WN-15 in that cab. I think the HF is P.Audio too.
Edit. Maybe not the Winner Series but got a feeling it's something along those lines. Been a very long time since I had one apart. Didn't actually like the sound of the cab much but that's another story. Edited by ceharden - 24 June 2015 at 9:04pm |
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Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
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Hi Chris, Yeah ill send you some across when I get back in. The driver seems to have the same chassis shape and size as a PD and the specs are almost identical to the PD.153ER, the only difference being the LS-1519 has a 4" voice coil as apposed to the 3" coil in the 153 and the magnet is neodymium rather than ferrite. Recently replaced the HF diaphragms in a couple and were labelled EV (I pulled the exact same diaphragm out which was labelled Turbosound). Not sure what the comp is though. However since you said it, I had a little look on google and whats quite interesting is I have 4 of these myself, 2 older cabinets with recessed backs for the NL4s and 2 newer units with the NL4 sockets on both sides. I noticed that the actual compression driver was different in the older cabinets and look similar to the P.Audio WN series. Also there were old bolt holes that had been filled in with wood filler that supported what looked like a bigger chassis. After looking at the P.Audio WN15 it has the same profile as a LS-1519 but overall a bigger outer chassis diameter.. Looking on the component map it looks like the components have never changed, so perhaps my older 2 are prototypes or something? Boxes are exactly the same (other than recessed backs) but small differences. Little things like non heat shrinked tabs on the NL4s and different turbo badges designs are different. Grills are the same but the older 2 have extra bolt holes on the front and no badge. I like them. There are 'sweeter' sounding boxes, but they are loud, robust (if you have the NL4s rather than EP6) and you can slam kick and snare through them like nothing else. The one Im currently trying to sort is a work monitor. Must be early production as they have the EP6 connectors rather than my 2 newer NL4 units. Haha im off track now! You're opened up a can of worms!
This could all be speculation on my behalf tbh, I will get some pics Edited by Grubbah - 24 June 2015 at 10:41pm |
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ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
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Funnily enough it's come up on a Facebook thread too. Consensus on there is it's a EV ND6 compression driver, although it must be OEM because the off-the-shelf EV ones are painted black.
15" must be a PD OEM then. I've never used them on monitors but I took a pair out for a small FOH gig once and just couldn't get enough vocal presence. Ended up swapping them for the cabs I had taken as monitors, so I guess I did end up using them on mons! If you look at the specs for the cab, they seem to have a very 'smiley face' response to them and a complete lack of midrange, which would fit with subjectively sounding good but actually being useless as a live FOH box! |
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tlong79
New Member Joined: 06 January 2012 Location: Rugby Status: Offline Points: 4 |
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I have exactly the same problem with an LS1519 gapshifted. I am told it was PD's first attempt at a neodymium 15, there have been 2 other stock units since which used the same basket and only slightly modified magnet assembly. I want to try and save this one but its not certain that I can. I have managed to save different speaker with standard magnet partly luck and part skill. The speaker I saved was an LS1009. I was able to lift each side a little and put thin plastic under the magnet reducing the main magnetic pull so that I was then able to whip the magnet off straight upwards and not disturb the voice coil. The next part was luck. The soft iron baseplate to the magnet assembly was bolted OUTSIDE of the spider so it could be unbolted without touching the spider. Ian McDermot then cleaned up, spaced and reglued the magnet assembly for me. Cone and voice coil assembly still perfectly OK. This isnt often possible as mostly the magnet assembly bolts, are under the spider, which makes it nearly impossible to save the cone kit. In the case of my LS1519, the bolts are from the top so that side of things is OK but the only way to remove the magnet will be to use something like a bearing puller to pull from inside the hole in the polepiece. I'm still looking for the right tool. This may go wrong due to the immense strength of the neo magnets. I did speak to Roy at RMJ about this. He said he tried one and its in the bin ruined. With regard to the Horn The original was an EV ND6-8 but later they fitted a far east made copy which was much cheaper but takes the same diaphragm. The EV was CD209 and the copy is DC213.2.
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tlong79
New Member Joined: 06 January 2012 Location: Rugby Status: Offline Points: 4 |
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The CD213.2 are silver, the ND6-8 are black. I have photos of both. I have 8 TFM450 and have used them as small PA/disco and monitors. Mine were used at the LIVE8 gig and many similar. nearly everyone of note has used them at some point. I dont think they lack mid at all. The horn crosses over at 1K3, with a dip at 1K6, and lifts at 3K5 and 5K, but you can change the ballance of horn to the 15, I do depending on what Im using them for.
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