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Extremely light pressure fixes Extremely annoying problem... (help?)

0

0r0b0r0s

New Member
Hi, I'm new to re-foaming/fixing speakers, and recently started off with an Ohm C2 I found locally for cheap. The woofer speaker foam was totally rotten but otherwise they were great.

So I did it and one of them would up with a buzz. It's a mechanical buzz on the woofer; if I'm playing music and gently lift the speaker cone away from the magnet the buzz completely goes away. If I push gently, VERY gently, on one side of the front of the speaker cone, the buzz goes away. But if I leave it be there is a bad buzzing and lots of bass is missing.

It's a matter of a few ounces of pressure it's crazy how much difference it makes.

I have not taken off the dust cap/looked at the voice coil stuff, is this something I need to do? Is there an easier fix, does anyone know immediately the problem?

Hopeless and helpless in Upstate NY...
 
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0r0b0r0s said:
Hi, I'm new to re-foaming/fixing speakers, and recently started off with an Ohm C2 I found locally for cheap. The woofer speaker foam was totally rotten but otherwise they were great.

So I did it and one of them would up with a buzz. It's a mechanical buzz on the woofer; if I'm playing music and gently lift the speaker cone away from the magnet the buzz completely goes away. If I push gently, VERY gently, on one side of the front of the speaker cone, the buzz goes away. But if I leave it be there is a bad buzzing and lots of bass is missing.

It's a matter of a few ounces of pressure it's crazy how much difference it makes.

I have not taken off the dust cap/looked at the voice coil stuff, is this something I need to do? Is there an easier fix, does anyone know immediately the problem?

Hopeless and helpless in Upstate NY...
Click to expand...
I did a complete write up with pictures the believe it or not the ohm C2 has Grease packed inside the voice coil on the inside not on the Unseen portion with the wire but the seen portion after you use a hair dryer and a flat blade thin small screwdriver to slowly remove the original OHM dust cap so you can reuse it... You will see the yellow orange Grease here is a picture.. and if you look through my history about 20 or 25 pages into my history, you will find my whole right up. . I am a firm believer in shimming when refoaming even though I've done it without shims before. .. but now that I discovered I can remove original caps with a hair dryer a flat blade screwdriver and lots of patience and Common Sense not to overcook the cone with heat. ..
IMG_20180519_133456671.jpg IMG_20180515_152415021.jpg
The first picture you can see the grease the second picture was taken immediately after I sprayed starting fluid in the center of the voice coil while holding the whole speaker upside down spraying inside as the grease would fall out onto the ground completely cleaning out the grease. .. the grease is 40 years old and has hardened and is impeding the speaker's ability to produce sound so you may get lucky and that is all you need to do.. but if you refoamed already without shimming then your voice coil might be rubbing and you will need to refoam.. and let me tell you it'd be worth every penny because having the original woofer is most desirable and I know from experience
IMG_20180519_132831457.jpg
IMG_20180519_132821961.jpg
 
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Do not use anything but starting fluid to clean and spray out the grease!!!
Everything else is too caustic and will cause the adhesives to dissolve!
 
Wow I definitely came to the right place! Thanks for all the awesome replies and links!

When you showed me what was under that dustcap... it was horrifying. YUCK YUCK YUCK. I def. have to pry up, gently, the dustcap and see what horrors are beneath. I pray that it's just some horrible crusted grease that's causing all the problems not my refoam job but whatever, refoaming is cheap and relatively easy.

Should I also do the same to the other speaker, which seems to sound totally fine but probably has disgusting dried crusty grease within?
 
0r0b0r0s said:
Wow I definitely came to the right place! Thanks for all the awesome replies and links!

When you showed me what was under that dustcap... it was horrifying. YUCK YUCK YUCK. I def. have to pry up, gently, the dustcap and see what horrors are beneath. I pray that it's just some horrible crusted grease that's causing all the problems not my refoam job but whatever, refoaming is cheap and relatively easy.

Should I also do the same to the other speaker, which seems to sound totally fine but probably has disgusting dried crusty grease within?
Click to expand...
I would definitely remove dust caps and get the grease out of both of them....
My hairdryer trick works perfect for saving the original caps just work slow and all will be fine don't pull too hard when it starts to come off so you don't rip the cone or the cap!
You definitely want the grease out of there it's affecting the sound even if you don't realize it.... The RESONANCE of the whole cone assembly is being damponed buy it...
It's old its viscosity has hardened
 
What was the point of that grease, and if it actually does something, shouldn't it be replaced? Although I can't imagine WHAT it would be good for.

Starting fluid, hmm. Heptane mostly, some diethyl ether, and a smidge of ethanol. Petroleum naptha (aka VM&P Naptha) would be a similar, fast evaporating hydrocarbon, just without the ether. Mineral spirits may be a bit heavy and slow to evaporate but also quite benign. I will defer to your experience with these speakers. Solvents are generally not 'caustic' (i.e. alkaline) though. Perhaps a more aggressively polar solvent could cause problems, like ethanol, acetone, lacquer thinner, MEK, MIBK. Those aren't needed to dissolve grease anyhow. Just thinking out loud.
 
Oh, and for the OP, try flipping the woofer 180 degrees so the 'top' is on the bottom. If it's the merest microscopic rubbing of voice coil on magnet, it's possible gravity may help clear it up. After the grease cleanout that is.
 
toxcrusadr said:
What was the point of that grease, and if it actually does something, shouldn't it be replaced? Although I can't imagine WHAT it would be good for.

Starting fluid, hmm. Heptane mostly, some diethyl ether, and a smidge of ethanol. Petroleum naptha (aka VM&P Naptha) would be a similar, fast evaporating hydrocarbon, just without the ether. Mineral spirits may be a bit heavy and slow to evaporate but also quite benign. I will defer to your experience with these speakers. Solvents are generally not 'caustic' (i.e. alkaline) though. Perhaps a more aggressively polar solvent could cause problems, like ethanol, acetone, lacquer thinner, MEK, MIBK. Those aren't needed to dissolve grease anyhow. Just thinking out loud.
Click to expand...
I replaced the grease in my C2'S with a couple of quick shots of White Lithium grease...IMG_20180520_131303441.jpg IMG_20180520_111944555.jpg
If you blow up my second photo and look closely at the Voice Coil you can see how lightly I sprayed it into the Former and Gap. .

I've been told Ohm had thought in place of Ferrofluid they used grease to aid in cooling the inside of the Aluminum Former...
 
OIC. Seems like it would put drag on the voice coil and affect the driver parameters. I suppose that was factored into the design though.

I'm no expert but it does seem like a rather narrow VC gap there too. At least on the inside. Maybe a driver one ought to shim even if you're not typically a shimmer.
 
toxcrusadr said:
OIC. Seems like it would put drag on the voice coil and affect the driver parameters. I suppose that was factored into the design though.

I'm no expert but it does seem like a rather narrow VC gap there too. At least on the inside. Maybe a driver one ought to shim even if you're not typically a shimmer.
Click to expand...
Yep everyone that has done refoam jobs on ohm Acoustics speakers makes the same statement.. .Shimming is the best way
 
I wish I could run across a pair but there was probably not a dealer in my town during that era. I see a fair amount of smaller Infinities and other brands but never a pair of old Ohms lurking in someone's garage.
 
toxcrusadr said:
I wish I could run across a pair but there was probably not a dealer in my town during that era. I see a fair amount of smaller Infinities and other brands but never a pair of old Ohms lurking in someone's garage.
Click to expand...
I just helped the guy here on the boards make the decision to purchase two different sets of ohms.. .The model L and the model C2 he had them shipped from other States to Arizona.. .
He is going to Re-foam them both and they'll be like brand new...
 
I could look harder for gear but I don't because there's quite a bit here in various stages of restoration for either listening or selling. I wouldn't pass em up if I ran across them locally though.
 
Thanks for all the help everyone! I'm nervous about it but I'm "GOING IN" tonight. I'm removing the dustcap with a blowdrier and seeing what nasty is there.
 
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