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Kahoona360
12-27-2012, 08:05 AM
Hi
I've lurked but now I've joined. Hope I am able to contribute once in a while.You guys are way beyond me though so I don't know.
I am fixing up a pair of 577915779257793's. I suspect one of them spent time in a sunny place but I'm not certain. One of the 2213H woofers is a lot stiffer than the other. It's resistance to motion is at lease 1/3 more than the good one. Travel seems less also. The "goop" had run a little on the bad one only. I cleaned it up. Neither is leaking air through the surround. All parts look nearly perfect. Resistance is the same. I am concerned that that level of difference will effect the sound.
I have tried a few things that I found searching these forums, in this order. I doped both pleated surrounds. I tried using acetone first then MEK (nervously) to loosen up the old goop. I treated the spider with Acetone. That made me nervous also but it was recommended. I exercised the woofer with first a 100hz tone then a 30 and finally a 10 for about an hour. I used enough power to move the cone about a quarter inch which showed as about 10w on the meter but required setting the volume at a number that would normally be closer to 80w. I feel that there was some improvement in the travel but actual measurement does not indicate any significant improvement. I have not tried heat. The spider does not feel stiff to my fingers. The coils seem centered correctly.
What do you guys think I should try? I am poor but I have a small amount of experience working with speakers. I would appreciate any advice you can give.
Thans
Rob

pathfindermwd
12-27-2012, 10:02 AM
Hi
I am concerned that that level of difference will effect the sound.

What do you guys think I should try?
Thans
Rob

Hi Rob, welcome to the forum!

I don't personally have any experience to give about this type of woofer. But to clarify, do you think they are the same vintage? How do they sound, does the output sound louder on one than on the other? If they test fine, I would play them for awhile and see. Without some extraordinary measures, I don't know how you can bring them to the same level of wear, short of doing what you have done and then working them out on some music for a few weeks. If you do, rotate them 180 degrees in the cab to help fight the effects of gravity on the spider/surround.

Kahoona360
12-27-2012, 10:59 AM
Hi Rob, welcome to the forum!

I don't personally have any experience to give about this type of woofer. But to clarify, do you think they are the same vintage? How do they sound, does the output sound louder on one than on the other? If they test fine, I would play them for awhile and see. Without some extraordinary measures, I don't know how you can bring them to the same level of wear, short of doing what you have done and then working them out on some music for a few weeks. If you do, rotate them 180 degrees in the cab to help fight the effects of gravity on the spider/surround.

Hi
Thanks. I will do that then. They are from the same pair of speakers and their serial #s are within 100 of each other so they should be identical. I'll let you know what happens.
Rob

Kahoona360
12-31-2012, 10:14 AM
Hi Rob, welcome to the forum!

I don't personally have any experience to give about this type of woofer. But to clarify, do you think they are the same vintage? How do they sound, does the output sound louder on one than on the other? If they test fine, I would play them for awhile and see. Without some extraordinary measures, I don't know how you can bring them to the same level of wear, short of doing what you have done and then working them out on some music for a few weeks. If you do, rotate them 180 degrees in the cab to help fight the effects of gravity on the spider/surround.

Thanks for that advice. I have done just that and I am finding that the stiffer one is relaxing just fine. It also seems that neither speaker uses more than about 10% of the available excursion anyway and there is a glorious amount of low frequency from both of them anyway. Later I will take sound level measurements from each with a tone generator and a meter just to check but I think they will be fine. Thanks!

pathfindermwd
12-31-2012, 10:50 AM
Thanks for that advice. I have done just that and I am finding that the stiffer one is relaxing just fine. It also seems that neither speaker uses more than about 10% of the available excursion anyway and there is a glorious amount of low frequency from both of them anyway. Later I will take sound level measurements from each with a tone generator and a meter just to check but I think they will be fine. Thanks!

Good to hear they are working out and making some music for you!

Kahoona360
01-08-2013, 08:27 AM
Last word on the woofers. After using them for over a week they really sound the same. I played a test tone at 35kz through both of them and measured the DB level at 8" distance and they were 58db and 62db. Strange but the stiff one has the higher output. I am guessing that the system balance could be off that much and I am inclined to call them good. What do you think? I have not switched sides to see if the louder one changes or stays the same. Should I?

Earl K
01-08-2013, 02:23 PM
What do you see if you shine a flash-light down that center vent ( in the magnet ) ?

Do that for both woofers & report back .

:)

PS ; read this post (http://www.audiokarma.org/forums/showpost.php?p=6105114&postcount=34) from this thread (http://www.audiokarma.org/forums/showthread.php?t=472139&page=1) ( to see where I'm going with this exploration ) .

Kahoona360
01-09-2013, 02:45 PM
What do you see if you shine a flash-light down that center vent ( in the magnet ) ?

Do that for both woofers & report back .

:)

PS ; read this post (http://www.audiokarma.org/forums/showpost.php?p=6105114&postcount=34) from this thread (http://www.audiokarma.org/forums/showthread.php?t=472139&page=1) ( to see where I'm going with this exploration ) .

Hi
Thanks for posting that. That is interesting. I read the threads all the way through. I actually searched AK for info on these but over there our search system has its quirks so I did not see this. I did just that with the stiffer one in the beginning and what I saw (after I poked out the disintegrating remains if the rear dust cover) was the front dust cap and nothing else. I was tempted to get out the MEK and pop the front dust cap off to get a closer look though. I did not want to try removing the spider unless things were really bad and I sure was nervous about removing those paper surrounds! I have to pull them both out of the cases anyway to replace those dust caps (I use a disc of green 3M scrubby pad instead) and I will look closed then and let you know. Nothing is rubbing though. I have been feeding them low sine waves down it 10k and watching the cones and the excursion is the same on both as far as I can tell. I suspect that those big magnets control the voice coils so tightly that the stiffness does not matter. I am also beginning to think that the stiff ones may have had the surrounds replaced at some point and that they are normal and the loose ones are loose from age. What do you think? I wish I had a way to measure suspension compliance and compare with factory standard. That is what I really have to know. They do work great though but that difference still bugs me.
Rob

Earl K
01-09-2013, 04:50 PM
What I think is that you should test each woofer for it's Fs figure ( you need some reference points here ) .

Doped linen surrounds are not usually replaced as an individual part ( like a foam surround ) .

GordonW is still the man to ask about problems such as you are seeing ( he may also speculate that there may be disintegrated "goop in the gap" ) .

:)

Sorry , don't have much more to offer .

Kahoona360
01-10-2013, 06:14 AM
What I think is that you should test each woofer for it's Fs figure ( you need some reference points here ) .

Doped linen surrounds are not usually replaced as an individual part ( like a foam surround ) .

GordonW is still the man to ask about problems such as you are seeing ( he may also speculate that there may be disintegrated "goop in the gap" ) .

:)

Sorry , don't have much more to offer .

This is good. Thanks. What is an F figure, how is it tested and where do I find Gordon? I did some searching looking for "f figure" but found nothing I could use. It sounds like what I need to know about though.

Earl K
01-10-2013, 06:29 AM
"Fs" = Free Air Resonance

- The simplest way ( not the cheapest ) to measure Fs is to buy a ( computer based ) program/hardware package that does it for you . Such as this Woofer Tester 2 (http://www.woofertester.com/wt2product.htm)

- Alternately, one can use a tone generator & a multimeter to make ones own determination ( as described here ) (http://sound.westhost.com/tsp.htm)!

- GordonW can ( typically ) be contacted through the Private Message ( PM ) service residing either here at LHF or AK .

:)

Predrag Dukic
01-10-2013, 05:00 PM
"Fs" = Free Air Resonance

- The simplest way ( not the cheapest ) to measure Fs is to buy a ( computer based ) program/hardware package that does it for you . Such as this Woofer Tester 2 (http://www.woofertester.com/wt2product.htm)

- Alternately, one can use a tone generator & a multimeter to make ones own determination ( as described here ) (http://sound.westhost.com/tsp.htm)!

- GordonW can ( typically ) be contacted through the Private Message ( PM ) service residing either here at LHF or AK .

:)

Download ARTA program from

http://www.artalabs.hr/download.htm

It is a fully functional, sufficient, and free loudspeaker measurement program.

Earl K
01-11-2013, 02:22 AM
Download ARTA program from

http://www.artalabs.hr/download.htm

It is a fully functional, sufficient, and free loudspeaker measurement program.

Thanks, but I don't need the free version of ARTA , I own the licensed version .

:)

Kahoona360
01-12-2013, 08:43 AM
Download ARTA program from

http://www.artalabs.hr/download.htm

It is a fully functional, sufficient, and free loudspeaker measurement program.

Very interesting. Thanks. It looks like all I need is a calibrated mike to use this. Right now I have all of my money "invested" in audio stuff from CL:bouncy:. Might be a whilee before I can buy one. Can I use a cheap twenty dollar mike if all I want to do is see if two woofers are similar?