Is my woofer toast?

[merkin]

On one of my surround Forte II's I get a rattle like distortion when it goes to the lower frequencys on the Avia tester during the subwoofer set up. I don't notice it much during regular play. (probably since it doesn't go through the frequency) My crossover is at 100 hz since that is only what the receiver allows. I also took off the grill and if I just touch the outside edge of the woofer the rattling increases. Doesn't happen on any of my other three forte II's. I checked with parts at klipsch and the K-25k is no longer made. The replacement is the K28E about 127 bucks. If I replace it will there be any noticeable sound difference. Do I just bite the bullet and get the K 28E and stop whining.

[colterphoto1]

Rattling indicates the voice coil is shot. WIthout power applied, spread your fingers wide and gently press the woofer in, do you hear a scraping sound? If so, you've burnt it!

If it's still listenable to you, be my guest. From what I've heard, recone jobs are about as expensive as buying a new unit, but I'd check around to see if a local PA or electronics repair shop could recone your K25 if a direct exact replacement is not available. You might also check out Orange County Speakers. They do rebuilds also, but you'd have shipping involved.

If Klipsch says the K28 is a replacement for the K25, I'd believe them. Just buy it and stop whining. If you're not in a hurry, you might find one on eBay, but I don't see many Forte II's broken down for parts, mostly Heresy.

Good luck and don't do that again!

Michael

[DrWho]

Sounds like a sagging spider or a speaker lead that has gotten too close to the woofer....

Before buying a new woofer you should take this woofer out of the

cabinet and do some inspecting. Behind the driver you should notice two

springy like wires that go between the woofer connections and the

diaphragm towards the middle of the speaker (behind the dustcap).

Sometimes these wires get shaped in such a way that they vibrate up

against the diaphragm at large excursions...if this is the case you

will be able to see it when you play that Avia tester. To fix it, just

bend the wire []

If this isn't the case then balance your speaker facing up (magnet on

the floor). Try pushing down on the diaphragm (as evenly as possible)

and see if you notice any grinding. You're basically checking to see if

the woofer suspension is keeping the voice coil aligned in the gap.

There's a possibility that simply rotating your speaker 180 degrees

will start the woofer sag to occur in the other direction, perhaps

getting rid of that buzz.

And lastly, one other source of buzz can occur from the surround or

spider flapping up against the side of the frame. Check to make sure

your spider is flush against the "ledge" that it's glued to and check

the speaker surround to see if there are any loose parts coming up. If

there are any loose segments then I would suggest you carefully peel

the surround off (using a very sharp knife and go SLOW). Then get

yourself some epoxy and glue the crap out of it. You'll essentially be

performing part of a speaker recone without adding new parts (something

I do all the time). It took me about 8 hours to do this on my first try

with two 12" drivers, but I've got it down to about an hour now

(provided I get it right on the first try).

Oops, one more thing....check to make sure the dustcap is still securely fastened.

Btw, the buzzing sound does come from the diaphgram itself right?

Sometimes speaker cabinets and grill frames can buzz too...just

something to keep in mind. You might try swapping drivers between

cabinets to see if the problem follows the driver or the cabinet.

Oh, and one more thing....a "burnt" voicecoil actually won't make any

sound at all. Or if it does, it will be minimal at most. When a voice

coil burns, it means the wires have melted through the shielding and

are creating a short inside the speaker, or more typically the wires

melt to a point where the connection is broken (so no current flows at

all). Both happen and the first one usually fries the amp with it.

Becuse the speaker can still play low sounds pretty well I would say

it's an alignment problem rather than a burnt voicecoil. But alignment

problems are dangerous because eventually the shielding on the voice

coil will rub away and then create a short....thus really burning the

driver and blowing an amp in the process. I don't mean to scare you,

but it is definetly something that needs to be taken care of.

[merkin]

I tried your test, if I push the woofer in very evenly it doesn't make a scraping sound, If i take my index finger and gently push on the ring on the edge of the cone there is a sound like paper scraping paper. This is only from 4:00 o'clock on the speaker face to 11 o'clock on the face. If I do this from the 11:00 position to four position it doesn't make any sound.

Also I can't think of anything that I would have done to the speaker. Maybe Master and Commander but only at 89 to 90 db. (The cannon balls sound pretty cool going front to back.)

Thanks for your response

[merkin]

Thanks Dr. Who I'll give it a try. See what it looks like in there anyway. Then I'll try switching to the other cabinet before I buy a new driver.

Hey I'll be in your neck of Illinois this weekend. My daughter has a swim meet there I think in Waubonsie Valley. Then she has a marching band competition at Lincoln -way. I guess I'll have to look to see where these places are.

Thanks for your help

[DrWho]

Ok, that indicates a slightly mis-aligned voice coil....and it's

probably only rearing its ugly head when you really crank the volume

and get the woofer into a nonlinear region. Did rotating the woofer in

the cabinet alleviate the results when doing the avia test?

[DrWho]

Oh wow, I went to waubonsie and was even on the swim team too! It's

October...would then be the pentathalon meet or whatever they call it?

(that lasts for mega hours).

Sadly I'm down at UIUC and all my audio equipment is down here

otherwise I would totally invite you over to check some things out

(like my system is even worth bragging about if you got forte's in the

rear) []

So whereabouts are you from? I would love to hear the Forte II and

perhaps we could do some Forte II versus Chorus II comparison listening

sometime.

[johnyholiday]

Nice mustang in your avatar ,i think DocWho meant voice coil,instead of

crossover maybe not? the replacement driver's spec's from Klipsch

would be correct ,you might have a new ashtray or can display the woofer

as an example of the drivers in your forte,chicks dig it, a

conversation piece, sometimes drivers just let go, an CSI Klipsch can not find the perpetration

[merkin]

I just got done rotating it 180 degrees. Sounds a lot better now. Didn't get any rattle with the warble mode of the Avia. Thanks again

[DrWho]

nice mustang in your avatar ,i think DocWho meant voice coil,instead of

crossover,i would think the replacement driver's spec from Klipsch

would be correct ,you might have a new ashtray or can display the woofer

as an example of the drivers in your forte,chicks dig it, a

conversation piece

oops, ya I meant voicecoil, lol...I edited the message

[merkin]

I'm from Rock Island. On the Mississippi. About 2 hrs from Aurora. Just down I 88.

Johnny Thanks for the complement. That is the car I got when I was 16. I totaled it out twice and then spent 3 times what it is worth restoring it. I only drive it a little now. They are noisey and hot. Black on Black.

If you are every over here Dr. Who you would be welcome to come hear the system. Nothing great just 4 fortes and academy and a SVS 12/2 ultra. (the sub rocks for an old man)

[johnyholiday]

I just got done rotating it 180 degrees.

Sounds a lot better now. Didn't get any rattle with the warble

mode of the Avia. Thanks again

good

sometimes cantilevering-rotating the driver works, your a lucky man

[DrWho]

I just got done rotating it 180 degrees.

Sounds a lot better now. Didn't get any rattle with the warble

mode of the Avia. Thanks again

good

sometimes cantilevering-rotating the driver works, your a lucky man

To be honest, I've never seen it work before either []

[johnyholiday]

<spit> []oh sheesh

[colterphoto1]

Nice detective work Doc, just as a matter of course, whenever I'm inside a cabinet for rebuilding and have the woofers out, I give the woofer a 180 rotation just for the heck of it. Might save one, you never know. Plus it allows the ageing process of fading to be more even.

Michael

[merkin]

Dr. Who

Was that your pictures as the all american swimmer and state and national champion that was plastered all over the hall ways in Wabonsie?

[DrWho]

Was that your pictures as the all american swimmer

and state and national champion that was plastered all over the hall

ways in Wabonsie?

I wish [] Waubonsie is supposedly the fastest pool in the state set

by Greg Busse (probably who you saw) who went straight to the masters

and the trials for the american olympic team (but alas he was only a

backup). He swam something like a 17 or 18 second 50 yard freestyle!

Our coach, Tom Musch (such a name, lol), played water polo with the

Australian olympic team...I can remember one day the team was

complaining about the sets and so he got in and raced our fastest

swimmer to see if we could go home early....the old, fat, out of shape

man busted out a 22 second 50 without a warmup, goggles, or a proper

swim suit (he just grabbed a pair of trunks out of the lost and found).

My fastest 50 was a 27, so I was nowhere near the level of everyone

else.

I do have a few pictures up on the walls though. I was one of the

academic all american athletes or something like that (an award to

recognize a varsity athlete who also excelled in school). I was also on

the state water polo team so there are a few pics from that as well...I

was the kid with rec specs (the smaller kid with rec specs, lol...there

was two of us, Dan weist who was like 6'6" and me at 5'8").