Replacement iMac speakers

[FBz]

Have seen various YouTube videos and references to other replacement speakers for
the iMac G3 400 DV SE (Slot Loader) and was wondering if anyone here has found a
near performance-match for the original 1” Harmon-Kardon bubble mounted speakers?



Just acquired one of these and the H-K speakers are shot. Otherwise, in perfect condition.
Currently running OS 9.0 with the original 13 GB HD and 128 mb of RAM. Intend to add
an Airport card adapter, SSD and max the RAM. Hello 1999 Graphite and Ice!

[Philgood]

Hi.
I bought a replacement once from eBay and I think there are the same but guess what...
I had them lying around some time(maybe 3-4 years) before doing
the exchange and when I reassembled them the foam was already showing signs of rot so I actually would try to re-foam the originals if that is an option. Just search for an adequate new foam ring.

I have now like 8x replacement speakers of another brand called PEERLESS and though I still can't say anything about sound quality as I still haven't done any repair with them, they seem yo be of lesser built quality than the originals but at least they don't suffer from the foam rot as they seem to be from newer production dates.

I guess there are still tons of the original replacement speakers but they run out long ago of production so will eventually have all the foam rot problem at that stage.

Another problem is when you get replacement speakers that they don't come with the whole assembly so if you only get the old out and try to sandwich the new ones into the enclosures they will need some some support from the back to hold them in place (not a big problem) BUT...
The assembly from the original ones includes another metal outer shield and an extra magnet which will get rid of some of the magnetic field which otherwise makes the image of the CRT wobble when you listen to higher volumes.

I just found a new (to me) video which will explain it better than I could probably.

https://youtu.be/OOPhYMb2DL0

[FBz]

Thanks Philgood!

I’ve two different possible speaker candidates here to go back in. One pair is from a Sony SRS equipped monitor and the other, from an early G4 iMac. Both pairs don’t have the foam rubber surround of the originals, which means that hopefully they’ll last a bit longer. I’ve not yet disassembled it and wonder if they’re 4Ω or 8Ω speakers? I may seek out a PEERLESS set too to try as well.

From this video https://www.youtube.com/watch?v=yc8NGDw5aSQ it seems that they might be 4Ω. (The guy uses tape to adjust for the different depth of his replacements in the video.) I do like the use of the old backs in the video link that you provided, to make up for speaker depth / size differences.

Cheers!

[Philgood]

By iMac G4 speakers you mean the Pro Speakers?
These don't fit as there are triple the size. The rubber surroundings surely would give you peace of mind and would be nice as an option but I think they would alter the sound as there are quite heavier.
I'm really suprised by the quality of the original speakers. I think they nailed it there.
I was really disappointed by the Pro Speakers with the rubber surroundings as they didn't seem to reproduce the high frequencies as good as the iMac ones.

I actually had the foam rot happening after buying another used iMac G3 and tried another option.
I used some flexible glue with a brush I put on the teared foam as it was still complete.
Just lay the iMac upside down to help you center the little speakers as much as possible (that will prevent distortions on high volumes) while the glue dries.
This will alter the sound also I'm sure but I was happy enough with the results.
I did get a little distortion when at full volume but it's ok.
I really enjoy listening to music on that iMac. I have it on my Desk in front of me and I'm using an iSub (the 1. Generation USB one). That is really an improvement and the sound just fills the room.

I saw that video you linked to but I made the experience that if you not
provide the old assembly you will get screen wobble on higher volumes.

[FBz]

“Screen wobble” ~ as a result of not using / having that original back metal shroud to shield the monitor?

Turns out that the two other sets of size-comparable speakers here are 16Ω. D-rats!

I checked the Peerless replacements out but found these Dayton CE30P-4 speakers instead that I’d like to try. BUT they’re not currently available in the U.S. until December. Those of you in the U.K. (and possibly elsewhere) can get them from WallofSound.co.uk for £4.99 each (SKU #848791000355). Wall of Sound does not ship to the U.S. - but… any core member (Philgood?) from the U.K care to pick up a pair and ship ‘em over here? I’d PayPal you the costs in advance. (PM me.)

 

Finally got the “bubbles” removed and the speakers. (Wonder which group of brainiacs
designed them and chose the foam-surround speakers… Harmon Kardon or Apple?)
Speakers might have lasted longer if no silicone was used to seal enclosures.



Red dots and arrow denote areas where hot glue will go to re-seal the enclosures. Blue arrow notes plastic “clip” that’s very difficult to disengage for removal of the bubbles from the iMac chassis. I used a very long & thin screwdriver to press this clip / tab down from the mounting to carefully release the bubbles. (Lawrence Welk Show, anyone?)

I do like the overall design of the speaker enclosures - but whoever decided to seal the two halves of the bubbles with silicone, didn’t really do the early iMacs any favors. Silicone (as it cures) “gasses off” releasing acrid fumes that most likely attacked / interacted with and broke down the foam surrounds of the speakers over time… eventually turning the foam surrounds into sticky goo. Especially because the speakers were enclosed in the bubbles and could not vent the fumes via the small sound ports of both speaker enclosures. The gasses likely permeated, attacked & broke down the porous foam speaker surrounds from the inside.



After cleaning all of that goo (and 99% of the silicone from around the bubbles) the small speakers harvested from an early G5 iMac fit perfectly into the bubbles w/o spacers. *Only problem is that these speakers and the Sony SRS speakers are 16Ω - which means that they may be a much-much lower volume installed in a system designed for 4Ω speakers.

I’ll use hot glue to anchor the new speakers in place - AND to seal the bubbles back up. This might make it difficult to ever again replace the speakers… but sans the silicone, might never need replacing for another 20 years? Interesting how Apple later changed from the foam-surround G3 iMac speakers to the butyl rubber surrounds of the G4 & G5 speakers? Wonder why? You can see the surround rot of the original speakers in the above image.

https://imageserv5.team-logic.com/mediaLibrary/99/Outgassing_20of_20Silicone_20Elastomers.pdf
“Ventilation is a necessary part of the post-cure process. Figure 8 compares well ventilated samples to samples sealed in aluminum foil. It is immediately obvious that the sealed samples do not “breathe” and volatiles are trapped within the rubber. (After 15 minutes the ventilated samples have lost more volatiles than 5 hours for the sealed samples.) All of the sealed samples showed evidence of reversion (i.e., rubber degradation). If rubber ‘breathing’ is prevented the post-cure process is ineffective and may lead to excessive service outgassing and ‘smoking’.“

Will now attempt to remove the back metal shroud from the old speakers to possibly use on any new speakers for shielding. Have tried to pry them from the magnet but no luck. Really strong magnets… but I think they’re also glued. Next, I’ll attempt to torch them in order to burn away any glue. Also wondering about the shield-ability of encasing magnet backs with a thick layer of hot glue… which also might fill the gap for any new speaker depth deficiencies in the bubble.

Why all of this bother for an old G3 iMac?
I too remember just how good the originals sounded way-back-when.
Hopefully all of this will eventually produce similar (and longer-lasting) sonic results?
And for now I’ve yet ANOTHER project awaiting parts.

UPDATE: Emailed Wall of Sound (U.K.) late today about other possible alternatives and then discovered that the CE30P-4 speakers are made by Dayton Audio in Springboro Ohio (U.S.). So now I’ll give them a call on Monday. In the meantime, there’s one listed on eBay and one available in the Netherlands.

[Philgood]

Hi.
I love your extended posts.
Always nice to read.
It seems you got it sorted out and won't need any help to get that replacement speakers but if not I'm happy to help though I'm in spain and shipping from the UK is expensive.

I wouldn't try to torch magnets. They would loose their magnetic properties I think? I mostly got them separated by using wooden tools to pry them. They are glued together in my case.

It seems you are spot on with the silicone fumes causing the foam rot. I guess the foam is way lighter so the membrane is more able to move and therefore able to better reproduce higher frequencies than with the rubber surroundings.
I'm no expert so take everything I say with a grain of salt.

[FBz]

Thanks Philgood,

Well… after now nearly a 5-month wait, have finally ordered the Dayton Audio CE30P-4 speakers from Wagner Electronic Services A/ASIA in NSW Australia. Parts Express kept “kicking the can” for restocking them every month (since October 2020) and now says February 19th - 2021 restocking. Paid double ($21.00 U.S.) for what I could’ve gotten them for IF Parts Express had them - but now at least I can possibly get this project wrapped and determine if these speakers are the way to go for the iMac G3 400 DV SE.

Perhaps setting myself up for “antici-pointment” but if these perform as well as I expect, might consider the 8Ω variants for other iMacs and eMacs as well. These speakers use a butyl rubber surround instead of the porous foam (degradeable) surround and their noted frequency response performance is better than the Peerless speakers.

Fingers crossed here.

*Wagner has two left in stock - in case anyone else wants them… until Parts Express might actually restock. https://www.wagneronline.com.au/  Wagner - TheLoudSpeakerKit was very considerate and helpful considering this was such a small order to be shipped overseas. I’ll be checking with them for other items made of unobtainium in the future.

LATER THAT SAME DAY... Parts Express NOW shows that they again have these in stock. Figures.