A 416 dilemma. What to do?

[GM]

That's the prevailing wisdom ( that all Alnico magnets will benefit from a recharge ).
ie ; Not just Altec woofers, but any transducer using an Alnico magnet can benefit from a recharge .

If you haven't read the complete thread , then I'd suggest that you do it sooner than later .

Ferrite magnets rarely demag .

This is true for the various prosound apps, but not for HIFI/HT unless you're stone deaf since they will never be heated up enough to lose an audible amount of motor strength.

Yeah, for a variety of reasons I'm way out of sync, so trying to play catch-up now that I've had my memory refreshed.

Actually, it depends on the type. It seems reasonable to me that Altec and other major prosound drivers would use the hardest grades which need periodic re-zapping for peak performance and if overheated too much won't take a full charge again, so buying 'beater' ferrite prosound drivers is a crapshoot at best IMO. Again though, for HIFI/HT this is moot when using relatively H.E. low power rated drivers, though some of these mega-power band-pass sub systems loaded with super high power/Xmax rated drivers may get hot enough if a lot of movies with massive LFE are experienced at reference (or higher) SPLs.

GM

[GM]

Is magnet strength testing after a recharge but before a re-cone a standard practice?

The two re-coners I used did an impedance trace to confirm Fs/relative motor strength, but don't know if it was a universal standard. In retrospect, they re-coned them after draining, charging them after assembly, but don't recall ever knowing/caring whether they checked them before though. What few I had done came back close enough to mix n' match in the same dual driver cabs, but then I requested they meet specific specs rather than just telling them to fix them.

Later on, when I'd buy new drivers the distributor measured/matched them 'close enough' and gave me a HP computer speaker program printout of the T/S specs and several suggested cab alignments, so considering the low cost of a woofer tester and how quickly drivers can be measured, I feel GPA should be providing this to ensure good quality control and customer service.

GM

[GM]

It is always possible that it's wrong..........

Maybe it's time to search for a near by speaker repair shop that can zap them.

I don't see how, I mean your measured response in a 24 ft^3? cab showed it to be too small (under-damped) when it should have required significant series resistance for it to 'fill' the cab if its specs had been remotely near published.

Still working on it, apparently re-zapping AlNiCo drivers has become ~ a lost art except among manufacturers that still market products with it and a few big/long time re-coners and of course GPA.

GM

[GM]

What is important, is GPA is the only supplier of the stuff this forum depends on for it's existance. Let me underline this before the fight starts; FOR THE MOST PART.

...........and a lot of opinions from a lot of folks about slot cars motors for one thing, and mostly just a lot of CONGECTURE about GPA being incompetent.

All this without some form of defence from Bill or the Captain, or Todd, who is after all the marketing director of the operation.

So, awhile back I asked, how long does alnico remain at usable strength after re-charge? No answer.

Bill H is not the devil.

All the more reason to get stuff like this out in the open and try to figure out all the 'whys and wherefores' and how both the consumer and GPA can avoid them as much as practical in the future.

Well, until somebody proves otherwise, I consider all AlNiCo 5 magnets as one and the same WRT magnetic properties regardless of application and nowhere (so far) have I read any 'conjecture' that GPA is incompetent, only that it has some customer service and possibly some QA issues that at least a few of us believe needs addressing.

Once Bill officially closed the work order by telling Mike to "Just listen to them", how GPA handled it became open for debate same as if you'd paid to have a car repaired and it didn't perform up to spec with no explanation why.

See my earlier responses or better yet, do your own research to ensure there's no 'conjecture'.

One more time, I don't see where anyone has implied anything about Bill's lack of character or that he runs any sort of a 'sleazy' operation, just maybe a bit too casual where at least customer service is concerned, which in no way implies any incompetency. The quality of new driver construction/performance and successful driver restorations are ample proof to the contrary.

GM

[GM]

I agree ( good suggestion ), it would be quite helpful if Todd W. would look into what is the SOP over at GPA ( for recones in a case like Panos ) and then post that info here .

<> cheers

ps ; I think everyone knows that Bill H. is a very personable/approachable guy .

Agreed.

I don't know it as fact, though assume it of everyone until proven otherwise, but GPA is a business and needs to be run like one, so was glad to see Todd get involved recently as I've read/heard of way too many folks being unable for whatever reason to communicate with them. Frankly, after hearing Mike's plight awhile back, I've been wondering how committed it is to the N.A. consumers and its DIYers in particular, what with so much of Altec's products now being in the Far East. Does GPA do any advertising here?

GM

[Todd W. White]

I'm working on this issue, as I think I mentioned, and plan to get a complete answer out shortly.

Thanks for your patience.

[Panomaniac]

Thanks Todd.

Just back from Lone Star Audio Fest in Dallas where I had a lovely pair of 605A drivers that were reconed and recharged by GPA. More on that tomorrow.

This thread has bifurcated into "what to do with them?" and "why didn't this work?"
The second is actually more interesting. Who knows how many folks actually test their drivers after rework? So we have no idea how common - or not - this problem may be.

[Altec Best]

Welcome Back Pano, Please tell me you have some pictures Like to hear all about the fest. :thankU: Regards ~ AB

[Todd W. White]

OK - I talked with Jerry Hubbard, who was Head of Acoustic Research at Altec for over ten years, and here's what he says:

He says we first need to find out if the magnet is charged with the proper polarity. It is possible that it could have been charged in reverse. This happened, he said, at Altec all the time. There were instances when they had to go back and remagnetize entire production runs because they were charged with the wrong polarity.

The type of magnet recharger that Altec used (and Bill has) has the ability to reverse the polarity of the charge given to the magnet. When recharging an Alnico magnet, Jerry says, you set the remagnetizer one way, and you REVERSE it for Ceramic speakers. This is done because of the difference in the magnetic structures between Alnico and Ceramic. When you're done, the performance will be the same, but the procedure for getting there is different.

That said, he suggests you perform a simple test to see if the magnet is charged with the proper polarity:

1. Take the offending speaker and place it face up on a table.

2. Take a 9-volt (or 1.5-volt - whatever you have) battery, and touch the negative terminal of the battery to the negative terminal on the woofer, and the positive terminal on the battery to the positive terminal on the speaker for just an instant.

3. Observe the movement of the cone. Tell us which way it moves.

Once we know this, we can proceed.

[Panomaniac]

Great info Todd. Thanks.

I tested. Both mine appeared reversed.
(positive voltage on red post = diaphragm moving toward rear of driver)