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greyhound
06-10-2007, 01:45 PM
in the dutch audio forum (where im active) the discussion started , if it makes sense to turn your woofer (for instance clockwise) because of material fatique. the weight of the woofer may have an impact on the coil.
so turning it every year may stabilise the quality on the woofer in the long run.
ive had some pretty old woofers and none of them had any coil problems.
no scraping sounds or anything like that.
you guys are facing the vintage stuff reguarly does it sound familiar. ther is some logic in it i think.
the discussion started when someone picked up some old Kef's and transported them on their side in staed of on the back and his coil was damaged. The speakers were old (22years). he didnt know for sure that the damage was already done before transport.

moldyoldy
06-10-2007, 04:34 PM
I have no idea when woofer rotation started, but I've seen several 50's cabinets with penciled rotation logs on the backs or inside. The degree of merit for the practice would depend entirely on the properties of the individual suspension. I've been able to get a few more miles out of an old woofer or two that were beginning to rub by 180 rotation, but whether regular rotation can extend the overall life is pretty iffy, and again, depends on the speaker.

Suspensions treated with non-hardening dope sometimes need turned to keep excess dope from puddling or migrating, but simply removing the excess dope is a better fix, after all...it is excess...

I've seen some amazing damage to speakers from shipping, but find it hard to imagine a voice coil getting hurt if nothing else was damaged, like the pole or magnet shifting. It takes more than the coil simply touching the pole a few times to cause any real damage.

There is an exception. Foam surround woofers with disintegrating or no remaining foam could easily sustain coil damage, and are actually pretty likely to, even with decent handling. When the cone weight hangs only by the spider, every bounce will force the coil against the pole plate. Speakers in this condition should use some non-destructive way to ensure the cone is centered and can't move in shipping, or the recipient may need to do a recone instead of the foam job he'd planned on.

For gear that gets roaded, you can reduce concerns by connecting a short across the terminals. When the cone bounces and moves, it creates a small voltage, and the short provides a braking force just like a low output impedance amp. Some Pro cabs use a switched jack that provides this shorting when the plug is removed.

greyhound
06-10-2007, 11:53 PM
well that makes sense. so turning your drivers is something they advised in the old days. The materials the woofers were made from are not heavier than the stuff they use today (i think) exceptions for brands like Kef and tannoy. the older woofers i have seen from them were quite heavy. the spider most have alot of strain on it and will create problems in the long run. Do you think later developments have illiminated this "problem"

i had trouble understanding the last bit of the story.
are you saying that supplying a battery (like 1.5 volt) to the terminals before transport is a smart thing to do?
ore just short circuit them

moldyoldy
06-11-2007, 01:06 AM
Do you think later developments have illiminated this "problem"

i had trouble understanding the last bit of the story.
are you saying that supplying a battery (like 1.5 volt) to the terminals before transport is a smart thing to do?
ore just short circuit them

Improved materials extend performance life, but eventual sag is inevitable as long as we use suspension materials that weaken with time and use. Somebody needs to invent a linear, mag-lev, variable-compliance suspension. ;)

No, DON'T hook a battery to the speaker, merely attach a short wire across both terminals for transit. We think of speakers turning voltage into cone motion, but they can do the reverse as well, movement of the coil will produce a small, but measureable voltage, called 'back EMF'. Shorting this voltage out with a jumper wire for shipping "damps" the cone motion, though it doesn't prevent it entirely. It's also something most people never do. If you're a worrier, it's an easy task that might let you rest easier.

greyhound
06-11-2007, 01:30 AM
Improved materials extend performance life, but eventual sag is inevitable as long as we use suspension materials that weaken with time and use. Somebody needs to invent a linear, mag-lev, variable-compliance suspension. ;)

No, DON'T hook a battery to the speaker, merely attach a short wire across both terminals for transit. We think of speakers turning voltage into cone motion, but they can do the reverse as well, movement of the coil will produce a small, but measureable voltage, called 'back EMF'. Shorting this voltage out with a jumper wire for shipping "damps" the cone motion, though it doesn't prevent it entirely. It's also something most people never do. If you're a worrier, it's an easy task that might let you rest easier.

never gave it any notion but it 's true. moving the woofer wil create energie. well thats a good tip so thank you for that.

and i think its better for me not to get involved in creating new kinds of supsension. i can barely get my tweeter reconed.
So the sagging woofer story is a fact. any idea how this is wilth \jbl drivers. because their quite big but very light weight pulp.

moldyoldy
06-11-2007, 01:36 AM
They're all different. Long-throw subs are likely the worst, but I'm speculating now.

greyhound
06-11-2007, 04:55 AM
They're all different. Long-throw subs are likely the worst, but I'm speculating now.

the cone is heavy but the way their build is pretty robust. I think its better to look at material than size.
ore does size matter?;)

Mike Caldwell
06-12-2007, 01:55 PM
Some of the JBL Cabaret series speakers used 1/4 normalling jacks that would apply a short to the speaker when the plug was removed. I can't think of any pro speaker today that puts a short on the cabinet when it is unplugged. Most high power cabinets today use Speakon connectors and there is no real to do that with them anyway.

I have heard of the cones sagging on some horn loaded designs where speaker is mounted in a face down kind of position.

Mike Caldwell

RKLee
06-12-2007, 04:53 PM
Personally, I would think the fact of removing and re-fastening the mounting screws presents the possiblity of damaging the speaker cone, you know like, "oops." I personally it is not work the risk and I would forgo this process.

greyhound
06-13-2007, 11:03 AM
Personally, I would think the fact of removing and re-fastening the mounting screws presents the possiblity of damaging the speaker cone, you know like, "oops." I personally it is not work the risk and I would forgo this process.


i can agree. also a lot of screwing and unscrewing would eventely damage the screw hole. the wood would crumble i think so the screw loses its grip.

Zilch
06-13-2007, 11:20 AM
T-nuts, typically.

RKLee
06-13-2007, 09:05 PM
i can agree. also a lot of screwing and unscrewing would eventely damage the screw hole. the wood would crumble i think so the screw loses its grip.Not that, just that if your screw driver slips or something falls on the woofer cone and ruptures it, etc etc you're pretty much SOL. Woofer cones aren't cheap.

I used T-nuts on when I built my speakers using 2 Altec 414-8Bs. T-nuts are like little cleats with a nut. You put them in from behind the sound board.

greyhound
06-14-2007, 11:20 AM
Not that, just that if your screw driver slips or something falls on the woofer cone and ruptures it, etc etc you're pretty much SOL. Woofer cones aren't cheap.

I used T-nuts on when I built my speakers using 2 Altec 414-8Bs. T-nuts are like little cleats with a nut. You put them in from behind the sound board.

oh im sorry
i totally understood what you were telling me. i just added a possible problem.

Gary L
06-14-2007, 05:17 PM
MOLDYOLDY,

For gear that gets roaded, you can reduce concerns by connecting a short across the terminals. When the cone bounces and moves, it creates a small voltage, and the short provides a braking force just like a low output impedance amp. Some Pro cabs use a switched jack that provides this shorting when the plug is removed.

I always wondered about this! When I purchased 2 sets of Model 19s new, each came with a U shaped paperclip grounding black to red. There was a tag by the connectors that said "Remove and discard before attaching wires from the power amp". Every time I ever transported them I put the jumpers back on figuring they knew what they were doing and there must have been some reason!

Gary

moldyoldy
06-14-2007, 06:28 PM
Hi, Gary,

If you still have the clips and tags, I'll bet you could pay for several months' satellite access for what some "minty original extremely rare Altec Model 19 motional dampers with instructions" would bring on eBay...;)

Gary L
06-14-2007, 07:11 PM
Hi, Gary,

If you still have the clips and tags, I'll bet you could pay for several months' satellite access for what some "minty original extremely rare Altec Model 19 motional dampers with instructions" would bring on eBay...;)

Thats pretty funny Moldy but probably accurate. I think I still do have at least one set of them around here somewhere. Wife would be the first to tell you I don't throw anything away!

I will be sure to post a pic if I ever remember which one of those boxes they might be in.

Gary

Gary L
06-16-2007, 10:38 PM
I found this interesting as well as a bit upsetting!

I was notified of a response to this thread yet it is not here!

Here is a copy/paste of John's response.

Dear Gary L,

John has just replied to a thread you have subscribed to entitled - turning your woofer - in the Lansing Product Technical Help forum of Lansing Heritage Forums.

This thread is located at:
http://www.audioheritage.org/vbulletin/showthread.php?t=17073&goto=newpost (http://www.audioheritage.org/vbulletin/showthread.php?t=17073&goto=newpost)

Here is the message that has just been posted:
***************

---Quote (Originally by moldyoldy)---
Hi, Gary,

If you still have the clips and tags, I'll bet you could pay for several months' satellite access for what some "minty original extremely rare Altec Model 19 motional dampers with instructions" would bring on eBay...;)
---End Quote---



I am sure those are exactly what was mentioned, paper clips. Altec never shipped there product with shorting clips. That is home brew stuff.
***************


There may also be other replies, but you will not receive any more notifications until you visit the forum again.

All the best,
Lansing Heritage Forums

Too bad your post is not here JOHN because I beg to differ with you.
I bought two pairs of 19s in 1977 that arrived from Anehiem at the Stereo Shop in Middletown, NY which was owned by Jack Cohen. Actually, 10 pairs arrived on that same truck and all were in factory cardboard boxes.

Please refrain from telling any of us here what Altec did or never did with "There Product". THEIR products might have been made at a number of different vendors and may well have been shipped a number of different ways. Some 19s came with a cloth covering the fiberglass visible through the port while others came with the fiberglass spray painted black. 19s were made for quite a while and we have heard a number of stories right here about one in a set having a 416-8B-16" woofer while the other had a 416-8A 16".
Another fellow right here told us about his factory Valencia's that he bought new having one gold horn and one green horn.
Very few here would make any such claim that Altec "Never" did something simply because Altec did what they had to do to get speakers out the door. If they ran short on green or black horns then I am pretty sure they would use a gold one meant to go into a Seeburgh cabinet in a cabinet that had a permanent Lattice grill.

I don't have the time nor the desire to search through many boxes right now but when I do I will gladly post a photo of the grounding straps that came on my 19s that also had a red label stating "Remove and discard before connecting to power amp".
There are some fellows here and over at the Hostboard Altec site that can tell all sorts of stories about things they saw.

Gary

John
06-18-2007, 11:55 AM
I found this interesting as well as a bit upsetting!

I was notified of a response to this thread yet it is not here!

Too bad your post is not here JOHN because I beg to differ with you.
I bought two pairs of 19s in 1977 that arrived from Anehiem at the Stereo Shop in Middletown, NY which was owned by Jack Cohen. Actually, 10 pairs arrived on that same truck and all were in factory cardboard boxes.

Please refrain from telling any of us here what Altec did or never did with "There Product".

I don't have the time nor the desire to search through many boxes right now but when I do I will gladly post a photo of the grounding straps that came on my 19s that also had a red label stating "Remove and discard before connecting to power amp".


Gary

Dude Get A Life.:p

It's only Altec. ;)

I will mention that I have spoken with several origanal owners of model 19,s over the years that were selling them that had all the paperwork incuding bill of sale with their name on it,as well as any old diaphragms that were replaced, and no one has ever mentioned shorting clips were installed when unpacked from the shipping carton. The reason I pulled my post was that I re-read your post that you found them when you were unpacking your's which you claim you bought new right from the truck!!!
I figured hey maybe they were installed on your's??? So after re-reading your post I pulled mine. Why on earth you would find this upsetting is beyond me. You also mention you do not have the time or desire to find and post pic,s of the item you speak of, but you do have time and desire to respond to a thread that was deleted.

Now I find that upsetting:barf:

Gary L
06-18-2007, 03:01 PM
You also mention you do not have the time or desire to find and post pic,s of the item you speak of, but you do have time and desire to respond to a thread that was deleted.



Big difference from spending 5 minutes to type a response to going through 40 years of audio related boxes to locate something I don't really need to! After all, it is a simple piece of wire bent like a horse shoe with a little red tag. A paper clip will work just as well.

Upsetting is something that occurs when others here seem to think that because their speakers had or did not have something that this is the way that particular model came. We all know that Altec had numerous vendors making cabinets and other components so what was standard for one may well not be standard for another even though they are supposedly the same model. It all comes under that thing they say in many owners manuals, "Specifications subject to change without notice".

You said the grounding strap was "Home brewed" and "Altec NEVER used them" while I said I opened the sealed cartons as they came from the factory and they were there and are still here!

I say, never say never where Altec is concerned because they did some funny stuff just like most other manufacturers.

Gary

greyhound
06-20-2007, 02:29 PM
so... do you guys turn your woofers;)

Gary L
06-20-2007, 02:39 PM
I turn mine every way but inside out!:D

Mostly with the Altec woofers I use that have the black goo on the edges I find turning them once a year is fine if they have an excessive ammount of goo. Some may never need rotation for this but I guess it never hurts to change orientation so the sagg effect is never a problem.

Mostly I just turn them UP!

Gary

pocketchange
06-23-2007, 08:10 AM
Nope and don't plan on it. Having more than a few woofers
and respecting the time, possible damage etc., etc., I'd be more concerned with fresh peanut butter on my sandwich. :blink:
There would be nothing left of my cabinets if I was turning the
woofers however often over decades of ownership.

Plug-in Miles and enjoy.. :applaud:

sourceoneaudio
06-24-2007, 08:38 AM
The 846A's I just did the resto on, the woofers needed turning. So on the re-assemble I did, because the goo was heavy at 6:00, it was very evident.

I think it could have a lot to do with where you live. I think in colder climates it would not be such a needed to do thing. But as we know it does tend to get a little hot here in AZ. Supposed to hit 115 this weekend.

Storm
06-24-2007, 08:42 AM
I turned the woofers in my 846Bs that I just sold. I even added the date that I did it and my full name. Wonder if the new owner will ever know.

;)

-Storm.


The 846A's I just did the resto on, the woofers needed turning. So on the re-assemble I did, because the goo was heavy at 6:00, it was very evident.

I think it could have a lot to do with where you live. I think in colder climates it would not be such a needed to do thing. But as we know it does tend to get a little hot here in AZ. Supposed to hit 115 this weekend.

greyhound
06-24-2007, 10:49 AM
I turned the woofers in my 846Bs that I just sold. I even added the date that I did it and my full name. Wonder if the new owner will ever know.

;)

-Storm.


"storm was here":applaud:

wheater could have an influence on the fysiek of a woofer. but also how much they play . as long as there a current through the driver gravety will have less of an impact i think.

Gary L
06-24-2007, 03:12 PM
More often then not the goo drips are caused by direct sun exposure or being too close to a heat register.

None of my speakers ever got the drips but I have bought a few that had them or were close to it.

If you ever see a speakers with the drips, look close and you will probably find some sun fading as well on the wood or grilles.

Most Altecs have T Nuts behind the woofer holes so there is no worry about destroying the screw hole wood.

If your speakers don't and instead have wood screws then before you thread the screw back in go reverse to try to seat the threads in the old groves and not cut new grooves. This is also a good practice when working with plastic parts.

Gary