I am not a fan of gluing surrounds down, it’s not a consistent method for a good solid contact, it is not allowed in high performance parts and applications because of this reason. Using a metal gasket to clamp the surround is a nice method and also helps when it needs to be reconed.
You can make a surround by yourself if you’re handy with a router and know a little about foam and rubber chemistry.
You can make a surround by yourself if you’re handy with a router and know a little about foam and rubber chemistry.
I don't know of one factory that DOESN'T glue their surrounds down. Glue is about the best way to get a consistent attachment, as a good bead of a quality glue provides even tension on the product. I'd like to know which build house/company eschews glue for surrounds...Paradise_Ice said:
Dan Wiggins
Adire Audio
Although interestingly, they also use foam surrounds:dnsey said:
Lowther, for one
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I had this conversation a long time ago with a Hotpoint engineer and then again with a Boeing engineer, I said the same thing, glue is a good effective way to bond a material,,,,, but I was told consistency is the problem, glue can have tiny air pockets and all it takes is poor workmanship to have in consistency which leads to premature failure, now they are talking about very high performance parts which have very tight tolerances, this should apply to audio IMHO.
Also if not enough pressure applied to the glue, it can have variable height around a surround, a small variations of 0.5mm will affect linear excursion, flexible glues add there own modulation, a well bolted down steel gasket will have a lower leakage and a higher pressure rating, this is the same for magnets, bolting is better than gluing IMHO.
I used to add silicon to head gaskets just to help seal them better I though, it does not help, the surface should be as true and clean as possible.
Crystal Audio is a company that do not glue there surround down, Tannoy bolt there dampers down as well, I don’t glue 2 models I make and I ask ATC not to glue down my SCM50 bass units, they supplied them with the standard plastic gasket and I had stainless steel gasket cut and anodized black to hold the surround down.
Foam surrounds have a very nice quality and if when they are bolted down with steel gaskets, replacing them is a lot easier over scraping glue off the chassis,
Also if not enough pressure applied to the glue, it can have variable height around a surround, a small variations of 0.5mm will affect linear excursion, flexible glues add there own modulation, a well bolted down steel gasket will have a lower leakage and a higher pressure rating, this is the same for magnets, bolting is better than gluing IMHO.
I used to add silicon to head gaskets just to help seal them better I though, it does not help, the surface should be as true and clean as possible.
Crystal Audio is a company that do not glue there surround down, Tannoy bolt there dampers down as well, I don’t glue 2 models I make and I ask ATC not to glue down my SCM50 bass units, they supplied them with the standard plastic gasket and I had stainless steel gasket cut and anodized black to hold the surround down.
Foam surrounds have a very nice quality and if when they are bolted down with steel gaskets, replacing them is a lot easier over scraping glue off the chassis,
One of the benefits of being in the Seattle area is we're located in the heart of Boeing country. In fact, the husband of my CFO is a Boeing engineer working on the new 787. That thing is nearly entirely glued together - it's all composites. Glues are used for just about everything in airplanes anymore because of the high reliability, resistance to fatigue, and ease of assembly (easier to assemble means lower error rates).Paradise_Ice said:
I'd say that 99.99% of all speakers out there are glued down, including most (all?) of your tweeters. Height changes in the glue joint would be much more critical for a tweeter (and it's tighter gap) than a woofer, yet they're all glued down to their alignment jig?
The key is proper glue selection. Rubberized CAs with low viscosity are what you need.
I think that's more an issue of the gasket with or without silicone being able to handle the pressures inside the combustion chamber. You use silicone for most low pressure gaskets in a car. A speaker box is low pressure - rarely will you even reach a few tenths of a PSI (a few hundredths of an atmosphere), whereas an engine will see hundreds of PSI (10+ atmospheres).
Crystal uses a LOT of glue to hold down their surrounds - it's a tacky brown Hernon blend. I know, I've worked with their drivers! Tannoy also uses glues on many of their drivers; all, I cannot say, but I have seen lots of glue beads around the surrounds.
You don't need to use glue - that is true. You can use a clamping ring. But don't fool yourself that the clamping ring is better. Properly used, glues are faster, more reliable, more consistent, and will provide a MUCH more even distribution of attachment pressure than a ring.
You bet! You see some car SPL drivers that are all bolt-in because it's easier to swap out burnt/destroyed moving assemblies. But it's not because a glue joint wouldn't hold as good - it's because a glue joint holds too good and makes a swap much more difficult/lengthy to do.
Dan Wiggins
Adire Audio
I would like to add my experiences with foam surrounds to this thread if I may. I bought a pair of N.O.S (about 4 years old) Scan Speak 18W8542 woofers from a local dealer. I found the surrounds to both woofers to be rotten when I installed them in the boxes. Luckily the dealer was prepared to swop them for a pair of 8543's (with rubber surounds) and I was back in business. Scan Speak does treat the foam surounds in the factory, and yet they deteriorated to an unuseable state in only 4-5 years of no exposure to light. It does seem that heat has a very negative effect on the longevity of the foam as our summers are pretty hot and humid. My opinion is that anyone that lives in a hot and humid climate should stay away from foam!
Dirk
Dirk
I think gluing is cheaper and faster, it is way more cost effective over making steel clamping gaskets, there is no one way is the right way to be honest, I like clamps as anybody could assemble it perfectly, when glue takes a little more noodle to work with glue. i take your point about parts being glued on modern planes as its cheaper and faster than rivets that can pop out and need to be checked on wings and all sorts of places, saying that, i saw in London Heathrow a jet engine intake that had duct tape on it! easier to assemble means faster and cheaper as well as lower error rates as production time is a big factor in the cost in the aero industry.
I think humidity is a issus for foam surrounds more than heat, Mumbai and Sri Lanka for instant in the monsoon season, foam surrounds get damp and soggy even if you coat the surround in a varnish the dampness creeps in from the edge of the foam.
The old drive units from Tannoy use lots of bolts and gaskets over glue, I recone and remagnetize the older Tannoy drivers as the factory charge silly money and the Scottish dealers send them to me, the older units like the Berkeley have bolted down motors when they could have used glue, the same fo ATC and Focal and a few others, i like to apply this to the surround as well.
Its not to everybody taste but it sounds good to me
I think humidity is a issus for foam surrounds more than heat, Mumbai and Sri Lanka for instant in the monsoon season, foam surrounds get damp and soggy even if you coat the surround in a varnish the dampness creeps in from the edge of the foam.
The old drive units from Tannoy use lots of bolts and gaskets over glue, I recone and remagnetize the older Tannoy drivers as the factory charge silly money and the Scottish dealers send them to me, the older units like the Berkeley have bolted down motors when they could have used glue, the same fo ATC and Focal and a few others, i like to apply this to the surround as well.
Its not to everybody taste but it sounds good to me
DanWiggins said:
What is rubberized CA?
I thought the usual speaker glue such as the "speaker repair glue" sold by Parts Express was a form of PVA (polyvinyl alcohol, not to be confused with polyvinyl acetate, which is a 2 component resin). Plain white wood glue is PVA can be thinned with water while uncured but will only soften when exposed to water. Plain PVA gets too hard and brittle for speaker use, and also does not stick to smooth surfaces. So they seem to add something to keep speaker glue flexible and slightly tacky. A cheaper alternative to PE's speaker repair glue seems to be "gem tac".
The reason I am asking is that I have been disassembling drivers. I found that newer Seas and Peerless drivers use this clear speaker PVA stuff on most glue joints. Soaking in water will turn the glue from clear to white, and the joins come apart with some careful prying. The residual glue can be pulled off carefully after prolonged soaking in water, detergent and a little ethanol.
There seems to be another variety of glue used especially on older Vifa drivers that is opaque and rubbery and turns yellow-bronish with age. This stuff also turns whitish after soaking and comes apart more easily after this treatment. However, it comes off at the interface to the basket, and I have yet to find a way to get the glue off the spider and surround afterwards.
I thought it was probably some kind of latex emulsion, but maybe this is CA?
By the way, I have seen Magnat speaker build in the mid 90s with polymer basket woofers bearing the Magnat logo on the sticker the foam surround of which is falling apart. I also have pair of T+A speakers with Vifa M21 woofers build in the late 80s and which were sitting with their backs directly facing a southward facing window for 10 years, the foam surrounds of which are still perfect.
Thanks Dan, learned something new today! I knew there were different viscosity grades of superglue but never realized there was a permanently soft variety.
This may actually be what was used on the magnet / pole plate joint of some Vifa M25WO47 I own. There were those characteristic fume marks on the magnet, but the texture didn't feel like regular superglue.
But I don't think it is what was used to glue the surround and spider of those older Vifas TC14 to the basket.
This may actually be what was used on the magnet / pole plate joint of some Vifa M25WO47 I own. There were those characteristic fume marks on the magnet, but the texture didn't feel like regular superglue.
But I don't think it is what was used to glue the surround and spider of those older Vifas TC14 to the basket.
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