Introducing myself and seeking sub-woofer advice

[Earwax]

Hi audioholics!

My real name is Ernesto and I'm pleased to join this fine forum of discerning audiophiles. I'm not into home theatre systems or surround sounds and all that fancy stuff. I enjoy my movies at the cinema and I'm more into listening to good music at home.

I have a rather vintage Rotel system from the early 90s coupled to a sub-sat Magnat speaker system, also from that era.

I must be used to the quality of the sound or may be the wax in my ears but the whole system still sounds amazing! However, after all these years the sub-woofer's air suspension surrounds have totally disintegrated and some deep bass has been lost as a consequence.

I may be too optimistic but I reckon new air suspension could be refitted. What do you guys think? Is it worth to try and get them fixed? Is this a DIY job?

I appreciate your advice.

Ernesto

 

[gregz]

Hi Ernesto, and welcome!

Speaker "foam surround" repair kits are sold for super cheap, so there's absolutely no harm in trying. At worst, you'll end up ditching subs you were going to ditch anyways... And at best? You have EVERYTHING to gain!

As far as the odds go, my experience has been that changing the foam surrounds alters the operating characteristics of the sub. If your subs are sealed, then they're more forgiving of alignment changes than a ported system where you can really screw up the tuning.

Do it and let us know how it works out.

 

[bwilkinson]

Actually, I'm not even sure that the worst is trashing the subs. Even if you do try to install the surrounds yourself and fail miserably, you can always send your driver to a professional to recone the speaker. It's typically not that expensive, and there are some really good ones around. I'm not sure where you are located, but even if there isn't one close to you, you can send them out and they will ship it back.

There is one in Grand Rapids, MI (near me, actually it's now in Caledonia - a suburb of G.R.) that has reconed all of my 18" subs for my PA when I did something stupid with them... including setting one on fire! All worked better than new. He has done a whole lot of work, and never had a problem with it at all.

I am sure there are others around the world that have the same expertise as well - it just all depends on who you trust and who you want to send your money to... again, assuming it doesn't work doing it yourself (or you don't feel comfortable doing it).

 

[Earwax]

Thanks!

I've decided to give it a try. I just ordered a standard 8" repair kit from Simply Speakers at $37 including shipping to South Africa (Johannesburg). It will probably take about a month to get here. I'll let you know how it went with photos. It looks simple to do. I hope I won't bugger them up!

Thank you for the advice!

Ernesto

 

[sedwardz]

thank you for the info

 

[Earwax]

Fixed! ... Or is it?

Hi guys!

After a long wait I received my 8" speaker foam surround repair kit from Simply Speakers. I paid more in shipping and import duties to South Africa than what the kit actually costs, but such is life.

It was an easy repair job being the scrapping off the old foam bits a time consuming task. The new foam surround was a perfect fit and the glue worked very well. It took me about 2 hours, including the time needed for the glue to dry. I only fixed the outer speaker since the inner one's foam surround is still ok. I have some photos, but I don't know how to upload them.

So, I immediately started playing my favorite CDs finding no noticeable improvement in sound quality. So I went on and on with all different kinds of music: jazz, classical, house, pop, rock, reggae ... even mariachi. No difference.

And then it happened. When I played the Gotan Project's CD, the Santa Maria del Buen Ayre track. The deep bass sounds horrible! The distortion is very bad. I can't remember exactly how it sounded before the repair, but I'm sure it wasn't like this.

The only thing I can think of is that the cone is not properly centered. I still have the 2nd foam surround that came with the kit, so I'm thinking of redoing the whole thing again more carefully and try to find the sweet spot, perhaps even playing the track while the glue is still settling.

Any ideas?

 

[TLS Guy]

Hi guys!

After a long wait I received my 8" speaker foam surround repair kit from Simply Speakers. I paid more in shipping and import duties to South Africa than what the kit actually costs, but such is life.

It was an easy repair job being the scrapping off the old foam bits a time consuming task. The new foam surround was a perfect fit and the glue worked very well. It took me about 2 hours, including the time needed for the glue to dry. I only fixed the outer speaker since the inner one's foam surround is still ok. I have some photos, but I don't know how to upload them.

So, I immediately started playing my favorite CDs finding no noticeable improvement in sound quality. So I went on and on with all different kinds of music: jazz, classical, house, pop, rock, reggae ... even mariachi. No difference.

And then it happened. When I played the Gotan Project's CD, the Santa Maria del Buen Ayre track. The deep bass sounds horrible! The distortion is very bad. I can't remember exactly how it sounded before the repair, but I'm sure it wasn't like this.

The only thing I can think of is that the cone is not properly centered. I still have the 2nd foam surround that came with the kit, so I'm thinking of redoing the whole thing again more carefully and try to find the sweet spot, perhaps even playing the track while the glue is still settling.

Any ideas?

When refoaming you should cut out the dust cap with a razor blade. Then put shims in the voice coil gap. Remove the shims after the glue has cured and then glue on a new dust cap.

 

[just-some-guy]

i just refoamed my boston hd5's. i also got my new foam from "simply speakers".
the surrounds are of good quality and fit perfect. i DID NOT remove the dust cap. the install was easy, though i did use a little too much glue. my cones aligned just fine, no scraping. if the cone is not aligned correctly, pushing on it will make a scraping noise.

EARWAX. check all of the connections. reverse the speaker wires to see what that does. otherwise i bet the coil is cooked.

to post pics, you need to have more posts. i don't remember just how many, but it isn't a lot.

 

[TLS Guy]

i just refoamed my boston hd5's. i also got my new foam from "simply speakers".
the surrounds are of good quality and fit perfect. i DID NOT remove the dust cap. the install was easy, though i did use a little too much glue. my cones aligned just fine, no scraping. if the cone is not aligned correctly, pushing on it will make a scraping noise.

EARWAX. check all of the connections. reverse the speaker wires to see what that does. otherwise i bet the coil is cooked.

to post pics, you need to have more posts. i don't remember just how many, but it isn't a lot.

I have refaomed quite a few speakers in my time and would NEVER to it without shims. That is just asking for trouble. I bet the OP has cap rub. You can get lucky without shims but the odds are against you. I would bet the rent the VC is not cooked, but he has gap rub due to not using shims.

There is correct practice for everything and refoaming without shimming the voice coil is bad practice and not to be advised.

 

[Earwax]

@Just_some_guy: I actually didn't have to take out the speaker from the sub-woofer encasing, so the connections should be fine. So it must be the alignment. I'll try by reversing the L-R channels.

@TLS_guy: excuse my ignorance but... what are shims?

Thank you both for your advice!

 

[TLS Guy]

@Just_some_guy: I actually didn't have to take out the speaker from the sub-woofer encasing, so the connections should be fine. So it must be the alignment. I'll try by reversing the L-R channels.

@TLS_guy: excuse my ignorance but... what are shims?

Thank you both for your advice!

They are thin strips of cardboard, that are the right thickness to make the gap between the inside of the voice coil and magnet pole correct. If you don't use shims to center the voice coil, then you have a high chance of getting gap rub, which I'm certain is the reason your first attempt has failed.

If the voice coil even touches the pole piece slightly, the sound quality is awful.

 

[ron3033]

They are thin strips of cardboard, that are the right thickness to make the gap between the inside of the voice coil and magnet pole correct. If you don't use shims to center the voice coil, then you have a high chance of getting gap rub, which I'm certain is the reason your first attempt has failed.

If the voice coil even touches the pole piece slightly, the sound quality is awful.

Like holy wow that is some set up in the attched pictures.
Where is a good place to get foam kits? I was thinking Orange County Speakers. And I will heed your info use shims. Is folded up strips of paper okay? And is cutting off the dust cap difficult? I am not sure I have surgeon steady hands.

thanks
ron3033

 

[TLS Guy]

Like holy wow that is some set up in the attched pictures.
Where is a good place to get foam kits? I was thinking Orange County Speakers. And I will heed your info use shims. Is folded up strips of paper okay? And is cutting off the dust cap difficult? I am not sure I have surgeon steady hands.

thanks
ron3033

Yes, Orange county is one good source.

Orange County may have the shims and dust cap for your speaker. If no factory shims are available, then post cards cut in strips are usually the right thickness for most speakers.

Cutting the dust cap is no problem, cut close to the edge of the dust cap, directing the blade away from the voice coil, but to the inside of it.

Glad you liked the pictures!

 

[ron3033]

Yes, Orange county is one good source.

Orange County may have the shims and dust cap for your speaker. If no factory shims are available, then post cards cut in strips are usually the right thickness for most speakers.

Cutting the dust cap is no problem, cut close to the edge of the dust cap, directing the blade away from the voice coil, but to the inside of it.

Glad you liked the pictures!

Thank you for the info I will be ordering a kit.
ron3033

 

[Earwax]

Yes, Orange county is one good source.

Orange County may have the shims and dust cap for your speaker. If no factory shims are available, then post cards cut in strips are usually the right thickness for most speakers.

Cutting the dust cap is no problem, cut close to the edge of the dust cap, directing the blade away from the voice coil, but to the inside of it.

Glad you liked the pictures!

Looks like I'll have to re-foam again following this procedure. Can dust caps be reused if cut off carefully?

Thanks for the advice!

 

[TLS Guy]

Looks like I'll have to re-foam again following this procedure. Can dust caps be reused if cut off carefully?

Thanks for the advice!

A new dust cap is best.

 

[just-some-guy]

when pushing on the cone. do you hear and/or feel any scrapping/scratching ?

 

[ron3033]

when pushing on the cone. do you hear and/or feel any scrapping/scratching ?

Hello
I am guessing that you are thinking that he can cut off the dust cone and use shims to recentre the speaker when he tries the new refoam kit? makes sense to try again.
This is helpful when I go to refoam my Axioms and replace them back in their enclosure. That being I will have to make new enclosure for the replacement speakers I bought.

 

[just-some-guy]

I am guessing that you are thinking that he can cut off the dust cone and use shims to recentre the speaker when he tries the new refoam kit?

no. i am wondering if he did it good in the first place.

 

[TLS Guy]

no. i am wondering if he did it good in the first place.

Obviously not. The speaker sounds lousy. The feeling of roughness is not infallible. You can have gap rub you can not detect by your method. If you detect it however it is there. If it is absent it does not mean there is no gap rub. Sweep tones from a generator is the most reliable way to detect gap rub.