Think I've just blown at least 1 speaker in my GK neo 212 - Advice Needed

[MIJ-VI]

[quote name='Jateca;8650992']Thanks man, I didn't notice any harm on the slip-on connectors but I'll check again this afternoon when I try the FX loop[/quote]

Just to clarify, I believe that B-string was referring to the slip-on connectors not firmly gripping/making contact with each speaker's spade-lug terminals.

This could result in a poor electrical contact leading to arcing/little lightning bolts shooting about in the cab, not to mention an amp which seems to lose volume.

[Jateca]

Well, I've spent the weekend trying to diagnose the problem more thoroughly and it seems I was wrong in concluding that the problem was with the amplifier.

Following B-string's (from talkbass) advice I rechecked my speaker cab with a different head and noticed something that is pretty much indisputable, the lower woofer is moving a LOT more than the upper one.

This would seem to correlate with B-strings point about the speaker connectors. So I would guess that the upper woofer has a poor connection which has increased the overall impedance of the cab. I will try to fix this problem over the next couple of days.

Thanks again to everyone for their advice

[MIJ-VI]

In dealing with loose-fitting slip-on speaker connectors in the past, I found that crimping them slightly with a pair of pliers will result in them fitting more snugly on the speaker's spade terminals.

Applying a small squirt of electrical contact cleaner on the mating surfaces before reconnection is a good idea too.

Caig [url="http://www.stoneaudio.co.uk/"]DeoxIT D5 Contact Cleaner[/url] is often mentioned on TalkBass as being the best contact cleaner to get.

[Jateca]

And finally I hit the root of the problem (for real this time!)

Whilst checking the spade connectors I realised that the upper woofer isn't actually doing anything at all. This was confirmed when I tried running the speakers individually. It seems the air pressure from the working woofer in the cab was making the broken cone move in sympathy, tricking me into thinking it was still working.

There are no signs of the speaker being damaged when examined, the cone moves back and forth easily with traces of why it wouldn't be working, all I know is that it isn't. Used a multimeter to test it too, showed up nothing on the broken speaker and what was expected on the working one.

Seems that the fix is simple, get a new cone. No idea how I could fix this myself without damaging the cone. Bit of a bummer but at least I know at last where my problem is.

[MIJ-VI]

[quote name='Jateca' post='740397' date='Feb 9 2010, 04:44 PM']And finally I hit the root of the problem (for real this time!)

Whilst checking the spade connectors I realised that the upper woofer isn't actually doing anything at all. This was confirmed when I tried running the speakers individually. It seems the air pressure from the working woofer in the cab was making the broken cone move in sympathy, tricking me into thinking it was still working.

There are no signs of the speaker being damaged when examined, the cone moves back and forth easily with traces of why it wouldn't be working, all I know is that it isn't. Used a multimeter to test it too, showed up nothing on the broken speaker and what was expected on the working one.

Seems that the fix is simple, get a new cone. No idea how I could fix this myself without damaging the cone. Bit of a bummer but at least I know at last where my problem is.[/quote]

Right then! You've got it cornered!

1) Perhaps e-mailing G-K re sending you a re-cone kit to be installed by a local repair shop?
2) Have Gallien-Krueger send you a new speaker?

Edited February 9, 2010 by MIJ-VI

[Jateca]

[quote name='MIJ-VI' post='740501' date='Feb 9 2010, 11:51 PM']Right then! You've got it cornered!

1) Perhaps e-mailing G-K re sending you a re-cone kit to be installed by a local repair shop?
2) Have Gallien-Krueger send you a new speaker?[/quote]

Unfortunately, having spoken to the GK contact in the UK, my speaker is out of warranty (I've had it for about 3 years) so they won't replace it and they do not offer a re-cone kit as far as I'm aware.

Do you think there's any way I could remove the dust cap from the cone without causing irreperable damage? The only thing I can think of doing is getting at the wires that go to the voice coil and checking them.

[AlanP2008]

[quote name='Jateca' post='742022' date='Feb 11 2010, 01:05 PM']Unfortunately, having spoken to the GK contact in the UK, my speaker is out of warranty (I've had it for about 3 years) so they won't replace it and they do not offer a re-cone kit as far as I'm aware.

Do you think there's any way I could remove the dust cap from the cone without causing irreperable damage? The only thing I can think of doing is getting at the wires that go to the voice coil and checking them.[/quote]

IIRC (from re-coning experience in a previous life...) the dust-cap is simply glued in at the end of a re-coning operation - it is attached to the cone by a circle of adhesive....

I reckon the only way you could realistically go is to cut the centre out of the dust-cap using a scalpel and/or small pair of scissors, and trim it back as close to the cone as possible. It might or might not be possible to pick or dissolve the glue off the cone, but I would say the chances of damaging the cone are fairly high...

Once the dustcap is gone, you should be able to see the lead wires to the coil - again, I think the chance of the open-circuit being right there is pretty slim, but you don't have too much to loose I think... On the odd chance you do fix something, you could probably get a gash dust-cap from someone like Wembley - as long as it is larger than the original, it should it's job...

Alternatively, if you could get to Wembley (or some other re-coner) there is every chance that they could work out who actually made it, and source a re-cone kit for it. I seriously doubt that GK actually made that speaker themselves, I'm pretty sure the economies of scale are such that it wouldn't be economically feasible.

On another point - don't run that remaining (good) speaker at any volume all by itself in that cab (even if you block up the hole), or else you'll be looking for two replacements...

Alan

[MIJ-VI]

[quote name='Jateca' post='742022' date='Feb 11 2010, 08:05 AM']Unfortunately, having spoken to the GK contact in the UK, my speaker is out of warranty (I've had it for about 3 years) so they won't replace it and they do not offer a re-cone kit as far as I'm aware.

[u]Do you think there's any way I could remove the dust cap from the cone without causing irreperable damage? The only thing I can think of doing is getting at the wires that go to the voice coil and checking them.[/u][/quote]

Perhaps posting this question in the TalkBass thread would help.

Aside from there being plenty of G-K users on TB, rag (Robert A. Gallien) posts there quite often.

[JTUK]

My reservations here are that you will be lucky to get away with just the one speaker being damaged.

I hope that is not the case.

[bumnote]

I cant find the original article but Steve Rabe of SWR wrote an article where he said the best way to check if a speaker is working correctly is to connect a 9 v pp3 across a lead and check that the cone moves.

It is also usefull for checking the speaker are wired in phase

I have never done it so i cant confirm this is correct

[AlanP2008]

[quote name='bumnote' post='742962' date='Feb 12 2010, 12:07 PM']I cant find the original article but Steve Rabe of SWR wrote an article where he said the best way to check if a speaker is working correctly is to connect a 9 v pp3 across a lead and check that the cone moves.

It is also usefull for checking the speaker are wired in phase

I have never done it so i cant confirm this is correct[/quote]

It is totally true... and if both speakers don't move the same direction at the same time, and the same amount, then you have a problem...

[Jateca]

[quote name='JTUK' post='742866' date='Feb 12 2010, 10:13 AM']My reservations here are that you will be lucky to get away with just the one speaker being damaged.

I hope that is not the case.[/quote]

How so?

[AlanP2008]

[quote name='Jateca' post='743111' date='Feb 12 2010, 02:16 PM']How so?[/quote]

The basic problem is that the cab is tuned for two speakers.... With just one speaker, the physical excursion of the cone will be waaaaaay more than normal, and could give rise to physical damage...

[MIJ-VI]

Just in...

[url="http://www.talkbass.com/forum/showpost.php?p=8687860&postcount=28"]http://www.talkbass.com/forum/showpost.php...mp;postcount=28[/url]

[Jateca]

[quote name='MIJ-VI' post='743209' date='Feb 12 2010, 03:44 PM']Just in...

[url="http://www.talkbass.com/forum/showpost.php?p=8687860&postcount=28"]http://www.talkbass.com/forum/showpost.php...mp;postcount=28[/url][/quote]

Thanks for that, seems my only option.

For my own reference, people are mentioning that having one speaker in the cab will damage the remaining speaker. The speaker is 16 ohm and rated for 300 watts. I understand that running it by itself will damage it, but why is that? The amp will be putting out around 300 watts at 16 ohm (at a guess), so is it because the higher impedance will somehow damage the speaker?


Problem is that it had been run by itself fairly intensly before I diagnosed the problem. Hopefully it has escaped harm, but I guess I'll just have to see

[MIJ-VI]

[quote name='Jateca' post='743222' date='Feb 12 2010, 11:00 AM']Thanks for that, seems my only option.

For my own reference, people are mentioning that having one speaker in the cab will damage the remaining speaker. The speaker is 16 ohm and rated for 300 watts. I understand that running it by itself will damage it, but why is that? The amp will be putting out around 300 watts at 16 ohm (at a guess), so is it because the higher impedance will somehow damage the speaker?


Problem is that it had been run by itself fairly intensly before I diagnosed the problem. Hopefully it has escaped harm, but I guess I'll just have to see[/quote]

As I understand it, speaker cabs are ported & tuned to 'load' their diver's cone(s) (air pressure in the cab resists the cone's movement) when it is reproducing low frequencies, especially at high volumes.

With only one speaker, your cab may not provide enough back-pressure to dampen excess cone excursion if it is played at loud volumes/at its mechanical limits.

Just turn the amp down and cut the lows a tad until you get a proper replacement driver.

JFTR. A jerry-rigged re-cone is unlikely to provide the best results.

[JTUK]

Just my experience that if one speaker is damaged the other doesn't tend to get off scot-free. The more plausable reason is as AlanP said but as long as the cab hasn't been caned with only one speaker working then you might be ok.

FWIW, I always double up my cab rating to twice the amp max power but that is probably historical...

[stevie]

[quote name='AlanP2008' post='742085' date='Feb 11 2010, 01:47 PM']Alternatively, if you could get to Wembley (or some other re-coner) there is every chance that they could work out who actually made it, and source a re-cone kit for it. I seriously doubt that GK actually made that speaker themselves, I'm pretty sure the economies of scale are such that it wouldn't be economically feasible.
Alan[/quote]

You actually seem to have ignored the best piece of advice you have been given (by Alan). Call Wembley and ignore those 12-year olds on TalkBass.

Edited February 12, 2010 by stevie

[MIJ-VI]

[quote name='JTUK' post='743321' date='Feb 12 2010, 12:31 PM']Just my experience that if one speaker is damaged the other doesn't tend to get off scot-free. The more plausable reason is as AlanP said but as long as the cab hasn't been caned with only one speaker working then you might be ok.

FWIW, [u]I always double up my cab rating to twice the amp max power[/u] but that is probably historical...[/quote]

+1

There's nothing like a bass rig which can be safely abused like a guitar amp.

Plus any additional cone-age and cab-age moves bigger air for bigger bass tone.

--------

For anyone who is interested, Rick Jones at Acoustic Image wrote an interesting piece:

[url="http://www.acousticimg.com/manuals/The%20purpose%20of%20Power%208.pdf"]The Purpose of Power[/url]

[MIJ-VI]

[quote name='stevie' post='743428' date='Feb 12 2010, 02:44 PM']You actually seem to have ignored the best piece of advice you have been given (by Alan). Call Wembley and ignore those 12-year olds on TalkBass.[/quote]

Some of the folks on TalkBass have [i]more[/i] than 12 years worth of experience.

[MIJ-VI]

Hi Jateca.

[url="http://www.talkbass.com/forum/showpost.php?p=8688358&postcount=32"]http://www.talkbass.com/forum/showpost.php...mp;postcount=32[/url]

[Jateca]

[quote name='stevie' post='743428' date='Feb 12 2010, 07:44 PM']You actually seem to have ignored the best piece of advice you have been given (by Alan). Call Wembley and ignore those 12-year olds on TalkBass.[/quote]

Members of Talkbass have been very helpful to me, both now and in the past, why the hostility?

And I didn't ignore anything. I've contacted Wembley and been looking into speaker repairs and will report here if I find anything that may be useful to other users (like whether it's more economical to get it repaired or replaced.)

[stevie]

[quote name='Jateca' post='743984' date='Feb 13 2010, 01:55 PM']Members of Talkbass have been very helpful to me, both now and in the past, why the hostility?

And I didn't ignore anything. I've contacted Wembley and been looking into speaker repairs and will report here if I find anything that may be useful to other users (like whether it's more economical to get it repaired or replaced.)[/quote]
What hostility? I just have a low opinion of much of what seems to pass for advice on that list. The thread discussing your problem absolutely confirms that. Glad to hear you're looking at the reconing option.

[Jateca]

Just a quick update, I have been quoted approximately £70 for Wembley to sort the speaker (inclusive of VAT and shipping). In the spirit of enquiry (and desire to spend less money) I'll be turning the speaker over to them to see what they can do.

Overall I'm pretty optimistic about how it will all turn out. I'll post a report on how the fixed speaker matches up to the old one, and also how well the remaining driver coped with being caned whilst I was determining the problem.

[MIJ-VI]

[quote name='stevie' post='744313' date='Feb 13 2010, 03:51 PM']What hostility? I just have a low opinion of much of what seems to pass for advice on that list. The thread discussing your problem absolutely confirms that. Glad to hear you're looking at the reconing option.[/quote]

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