Clearing debris from doping goop of Altec 755A?

Hello,

First post here - not sure if this the right section to post in, but I thought I'd go ahead.

I just picked up a (somewhat) discounted 755A due to the cone condition from the Bay. DCR reads ok, and it seems there's no vc rub. However, the seller tied a cardboard cutout to the front of the driver while shipping. I very gingerly removed it, but some small remnants have gotten stuck in the goop on the surround.

I'm sure it won't affect performance, but I still wanted to ask if anyone has tips on how (or even whether...?) to remove it.

And more generally - how do you all store fragile vintage speakers? Especially ones with high amounts of doping material around the edges. Just lying the speaker directly onto bubble wrap etc.?
 

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gable

Senior Member
Hello,

First post here - not sure if this the right section to post in, but I thought I'd go ahead.

I just picked up a (somewhat) discounted 755A due to the cone condition from the Bay. DCR reads ok, and it seems there's no vc rub. However, the seller tied a cardboard cutout to the front of the driver while shipping. I very gingerly removed it, but some small remnants have gotten stuck in the goop on the surround.

I'm sure it won't affect performance, but I still wanted to ask if anyone has tips on how (or even whether...?) to remove it.

And more generally - how do you all store fragile vintage speakers? Especially ones with high amounts of doping material around the edges. Just lying the speaker directly onto bubble wrap etc.?

I would probably try to _very_ gently remove some of the cardboard that's stuck with some tweezers. Get whatever you need to see up close, in sharp detail, lots of light, and possibly even something to lay one of your hands on to keep it steady. It looks like there isn't much stuck on the driver, thankfully.
 

gable

Senior Member
Congratulations and welcome to HFH!

I'd be scared to do any cleaning...but that's just me. :)
You definitely don't want to damage it, but I bet you can get some of it off. If there's really not much on there, I would probably leave it as well.
 
Thank you both for the advice - I tried very gently for half an hour, got a few tiny strands off. I think it's best to leave well alone! I'll focus on getting the cabinet built first. Later, maybe, I can try again - if my nerves can handle it. But there not all that much there, so I'm hoping it'll be okay.

And thanks for the warm welcome! - I've read several of the Altec threads here with great interest, and have been impressed by the general helpfulness and camaraderie from all involved. It helped kickstart my journey in putting together a 414/802/32 mono setup (for a tiny studio apartment in LA). Only the 802 + cabinet left to source...

@je2a3 Out of interest, for your Silbatone/Bae box, did you drill/mount binding posts through the rear of the cabinet? I couldn't see from the photos on your blog how you hooked up the wiring to the amp.

Thanks again, and apologies in advance for (m)any basic questions that I lob into the forum. I'm just stepping off into the deep end of high efficiency speakers/low powered tube amps as my first real speaker system.
 

Audionut

Next Round Is On Me
Welcome to the Haven and congrat’s on the 755’s, hope to try a set soon.
With a steady hand tons of patience you can probably get some of it off. Might do more bad than good. Curious if GPA offers rehabbing on these as I’ve seen aftermarket cones.
Can’t wait to hear about the rest of your gear.
 
I stored my drivers on wax paper/baking paper on top of plywood bolted to the speaker, worked a treat until i took it all apart and left for a month or two and they got quite dusty.

I used painters tape to remove the dust on the doped edges however they are not 755s so that might not work, the dope on mine is much less sticky than the accordian edge type.

When researching cleaning doped surrounds several people reccomended a stiff artists brush and acetate/nail polish remover after removing larger debris with tweezers.

Good luck, im sure paitence and a stedy hand are key.
 
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je2a3

Junior Member
It helped kickstart my journey in putting together a 414/802/32 mono setup (for a tiny studio apartment in LA). Only the 802 + cabinet left to source...

@je2a3 Out of interest, for your Silbatone/Bae box, did you drill/mount binding posts through the rear of the cabinet? I couldn't see from the photos on your blog how you hooked up the wiring to the amp.
Was listening to half my Altec 753C during lockdown for an upcoming blog post! The WE753C was designed during the mono era, so why not?

Here you go:

SBback.jpg


Curious if GPA offers rehabbing on these as I’ve seen aftermarket cones.
Just want to share my experience with re-coned 755s in the mid 90s>early 2000s. I heard a pair of re-coned 755As and they sounded worse than a 755C or 755E. The cones looked similar to those fitted to 755Es. Even then original 755A cones AND voice coils were almost impossible to find. However, my encounter with 755C re-cones supposedly done by Bill H. sounded indistinguishable to my original 755Cs. But Bill quickly ran out of original 755C cones and voice coils.
 

Redboy

Knobophobe
That cone looks pretty good to me! And that teensy bit of whatsit stuck on there? Ppffffffftt, I wouldn't worry about it! Heck, I've seen 'em with big chunks of chipboard hanging off the front and they still seem to sell just fine...

Looks like you did pretty well on the cost, too. They're certainly not getting any cheaper.

...and welcome!
 
Welcome to the Haven and congrat’s on the 755’s, hope to try a set soon.

Can’t wait to hear about the rest of your gear.
Thanks - hope you you do! I might give an update in a few months - I'm just trying to get a few things together, and the only fully assembled setup right now is a modest headphone rig. I'm sure people here can relate!

I stored my drivers on wax paper/baking paper on top of plywood bolted to the speaker, worked a treat until i took it all apart and left for a month or two and they got quite dusty.
I'll use that tip for storing drivers, thanks!

Was listening to half my Altec 753C during lockdown for an upcoming blog post! The WE753C was designed during the mono era, so why not?
Look forward to seeing it - as well as the 757A clone at some point I hope! And I definitely agree about mono, so many great albums/films pre-stereo, I don't think I'll miss the second speaker. I'm curious about the difference between mono coming from 2 speakers vs. true mono as well. That early Sound Practices article (issue 1?) got me thinking about it, especially for vintage speakers. I'm looking forward to seeing how it goes!

And thanks for the photo, that's really helpful. I'm guessing any binding terminal from most sources should work fine? - Partsexpress etc.

That cone looks pretty good to me! And that teensy bit of whatsit stuck on there? Ppffffffftt, I wouldn't worry about it! Heck, I've seen 'em with big chunks of chipboard hanging off the front and they still seem to sell just fine...

Looks like you did pretty well on the cost, too. They're certainly not getting any cheaper.

...and welcome!
That sets my mind at ease, I'll quit worrying about it then! More mental space for getting an EICO HF-12 restored, and sorting out cabinets..

I had that thought regarding cost, too. Definitely didn't want to be priced out, and regret it.. And I picked up a local 755E recently, so I'm hoping it'll be enlightening comparing the two.
 

Drugolf

Senior Member
I'm probably dumb to throw this out there, but a little heat might be used to soften the goop. I got a set of home made speakers with 4 414's that were rear mounted. They needed to come out but the goop had settled at the bottom and stuck to the edge of the cut out.
I didn't want the extreme heat of my heat gun so I used the wife's hair dryer. (Shh) worked great! There was some hair and such in the goop to and that allowed me to pick it out.
Unfortunately the accordion surrounds were shot on all of them anyway.
BTW, I am about done restoring a pair of HF-12. All recap and new power transformers from Hayboer. One of them is done, other just needs the transformer installed.
 

gable

Senior Member
I'm probably dumb to throw this out there, but a little heat might be used to soften the goop. I got a set of home made speakers with 4 414's that were rear mounted. They needed to come out but the goop had settled at the bottom and stuck to the edge of the cut out.
I didn't want the extreme heat of my heat gun so I used the wife's hair dryer. (Shh) worked great! There was some hair and such in the goop to and that allowed me to pick it out.
Unfortunately the accordion surrounds were shot on all of them anyway.
BTW, I am about done restoring a pair of HF-12. All recap and new power transformers from Hayboer. One of them is done, other just needs the transformer installed.
I would love to see your restoration work on the HF-12's... do you have a thread somewhere?
 
I'm probably dumb to throw this out there, but a little heat might be used to soften the goop. I got a set of home made speakers with 4 414's that were rear mounted. They needed to come out but the goop had settled at the bottom and stuck to the edge of the cut out.
I didn't want the extreme heat of my heat gun so I used the wife's hair dryer. (Shh) worked great! There was some hair and such in the goop to and that allowed me to pick it out.
Unfortunately the accordion surrounds were shot on all of them anyway.
BTW, I am about done restoring a pair of HF-12. All recap and new power transformers from Hayboer. One of them is done, other just needs the transformer installed.
Thanks for the suggestion - I'd be only too happy to give it a try if the cones were replaceable. Same goes for Joe83's suggestion above (forgot to quote earlier). But going by Je2a3's comments on aftermarket cones, and reading J-Rob's comments elsewhere on the 755A cone stock being only from the original WE batch, I think I'll lay this to rest. If only GPA or someone else had a bona-fide replacement cone..

And I second @gable 's comment on the HF-12 thread. I'd be really interested to see that. Trying to figure out which cap/resistor choices to make without going overboard.

Finally, (and I don't know if this is totally off-topic, and if it necessitates a separate thread?) does anyone take precautions on types of music played when using fragile/old/difficult to replace speakers? I only say this as I play fair amounts of music with substantial bass. Dub, Reggae, Acid House, Detroit Techno, Breakbeat stuff etc. etc. I've seen various opinions floating around, and thought here might be a good place to sound out!
 
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Drugolf

Senior Member
i have not done a dedicated thread for the Eicos so I will put one up on them. I think I may have posted a few things on others over on AK in the Eico Place section.
 
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