M_Balou said:
well, i still haven´t finished my cabs yet....
but i think i´m done early next week, just some last tweeks left...
my 2 cents about the infamous foam-surrounds: the surround is the same make as
in the current sigma-series and i havn´t heard about any issues with the surround on
the sigmas.
and it´s not the normal foam, its more lilke foamed-up rubber or so, with only few
and very small air-bubbles. to me it looks quite durable. i think the reason why Fostex
use foam with these surrounds is because they have the funny tangential edges in them,
and that can´t be made with a cloth-surround.
cheerio, Mirko
Mirko, I'm sure that funny little UDR configuration of the surrounds (and in the case of the 138SER, the lower suspension spider as well), is a critical factor in the outstanding midrange performance of the newer Sigma series (and the orphan of the FF series the 85K)
Hopefully, it will trickle down to future generations of non-Sigma FE series.
As to the question of the foam material itself, I thought it'd been years since most manufacturers of more conventional drivers had solved the issues of environment deterioration of early formulations. There exists a substantial market for repair of rotted surrounds to domestic speakers dating back over 30yrs.
The fact that someone has reported issues with foam surrounds in the much more recent F120A design is somewhat of a concern, it would be interesting to try and get an official answer from Fostex on that question. (i.e. not doubt there would be an aftermarket repair kit of appropriate size, but it would be a shame to diminish the performance of a finely tuned design for the F120A or FX120 with a surround yielding different performance parameters)
Depends on how loud they were playing them at the time... 😉
Please don't mention ESigmas for a while guys... it'll depress me as I'm a few hundred quid out of pocket & never did get the drivers I paid for this time last year.
Please don't mention ESigmas for a while guys... it'll depress me as I'm a few hundred quid out of pocket & never did get the drivers I paid for this time last year.
Probably around £700 to complete which really is not too bad considering the drive units came in at about £500 of that.
I was very tempted to just go with a Gabriel and a pair of p10 fettled FE127s which would have worked out around half the price but in the end the 138s just kept calling me
On a separate note - bit OT.
I used birch ply as the base for these and am very happy - however part of the deal from the wife was that they had to be Mahogany, hence the veneer.
I have just noticed that one of the marine timber merchants here in the UK provide marine plies of mahogany and sapele.
Has anyone ever tried one any of these (would have made my veneering much easier)?
Does anyone have any opinions on whether they would be suitable for speakers?
I used birch ply as the base for these and am very happy - however part of the deal from the wife was that they had to be Mahogany, hence the veneer.
I have just noticed that one of the marine timber merchants here in the UK provide marine plies of mahogany and sapele.
Has anyone ever tried one any of these (would have made my veneering much easier)?
Does anyone have any opinions on whether they would be suitable for speakers?
don't know but when i tapped the oak ply and the maple faced ply at lowes and home depot they rang like bells compared to the dull thud of my baltic birch ply.
Not automatically a problem. It depends exactly where they're ringing. If it's above the operating BW of the cabinet, then you'll be fine.
I don't know if the marine ply would be suitable or not, but the stuff at Lowes and H.D. is nothing like the same stuff.
Regards.
Aengus
marine plywood is treated so as to resist rotting in high-moisture environments. of more concern for speaker building is that it's a void free plywood however it doesn't have as many plys as baltic birch. i was told that it can be difficult to work with because it'll gum up saw blades but don't know how true that is.
mp9, thanks for amplifying - perhaps I should have said more. Marine ply is supposed to be void-free, but in my limited experience it depends on the manufacturer. The stuff that meets British Standard 1088 (Joubert, for example) has been good when I've used it. Also, it's not necessarily treated to resist rotting - it may just be made of rot-resistant woods - but it does have soak-proof glue so it won't delaminate under water.
It doesn't seem to be any worse for sawblades than other plywoods.
The hardwood plywoods sold at the home stores are typically just a thin hardwood veneer over a number of cores, including some pretty feeble ones - they should specify what the core is, however. I very much doubt that any of these will be void-free.
[rant] Why is it that when I live on the west coast, where we are always desperate to create forest-related jobs, I have to buy either Baltic birch (from Russia or Finland) or apple-ply (from the eastern US). The plywood made here is truly crap stuff, with voids, split veneers, special delaminating glue, etc. Fir should make pretty decent marine ply - except no-one seems to bother. Aaargh.
And the home stores are now carrying shop-grade birch ply from China for cheaper than the local fir. Aaargh^2. [/rant]
Regards.
Aengus
It doesn't seem to be any worse for sawblades than other plywoods.
The hardwood plywoods sold at the home stores are typically just a thin hardwood veneer over a number of cores, including some pretty feeble ones - they should specify what the core is, however. I very much doubt that any of these will be void-free.
[rant] Why is it that when I live on the west coast, where we are always desperate to create forest-related jobs, I have to buy either Baltic birch (from Russia or Finland) or apple-ply (from the eastern US). The plywood made here is truly crap stuff, with voids, split veneers, special delaminating glue, etc. Fir should make pretty decent marine ply - except no-one seems to bother. Aaargh.
And the home stores are now carrying shop-grade birch ply from China for cheaper than the local fir. Aaargh^2. [/rant]
Regards.
Aengus
I just looked up the standard for BS 1088. It says in part:
Face Veneers
These shall present a solid surface, free from open defects. They shall be free from knots, other than sound pin knots, of which there shall be no more than 6 in any area 30cm square (1ft2), and not more than an average of 2 per 30cm square (1ft2) over the whole area of the board. The veneers shall be reasonably free from irregular grain, due note being taken to the characteristics of the species being used. Isolated pinholes not along the plane of the veneers, and occasional closed splits are permissible. Veneers showing compression failure shall be excluded. Occasional minor discoloration is permissible.
There shall be not more than one edge joint in any 30cm (1ft2) width of the board, and the veneers shall, when jointed, be matched for color. There shall be no end joints.
Core Veneers.
The requirements for core veneers shall be the same as those for face veneers, with the following exceptions. Small splits are permitted, and there is no limitation on the number of pin knots or edge joints. Discoloration is permissible, provided this is free from dote. Veneers need not be matched for color. There shall be no end joints.
Regards.
Aengus
Face Veneers
These shall present a solid surface, free from open defects. They shall be free from knots, other than sound pin knots, of which there shall be no more than 6 in any area 30cm square (1ft2), and not more than an average of 2 per 30cm square (1ft2) over the whole area of the board. The veneers shall be reasonably free from irregular grain, due note being taken to the characteristics of the species being used. Isolated pinholes not along the plane of the veneers, and occasional closed splits are permissible. Veneers showing compression failure shall be excluded. Occasional minor discoloration is permissible.
There shall be not more than one edge joint in any 30cm (1ft2) width of the board, and the veneers shall, when jointed, be matched for color. There shall be no end joints.
Core Veneers.
The requirements for core veneers shall be the same as those for face veneers, with the following exceptions. Small splits are permitted, and there is no limitation on the number of pin knots or edge joints. Discoloration is permissible, provided this is free from dote. Veneers need not be matched for color. There shall be no end joints.
Regards.
Aengus
1)the e-sigma's have been around long enough to have problems.M_Balou said:
2)both foam and rubber rot and breakdown over time.
3)i don't doubt the engineering of the tangential edges and i would guess they're easier to mass produce being most likely formed in a mold.
1) that its used in the spider is of more concern, i can't imagine replacing that too. makes the seas exotic that much more appealing to me (at least i think its a good bet seas will be around for a while for service or replacement surrounds. i think this is the only 5" udr by fostex. d@®&∂† i really like the 5" size of the 138 and the smallish cab's!!!!chrisb said:
2)sounds to me like something a dealer or manufacture would like you to believe and i'm not so sure of that. unless your idea of solved is a 10-15 year shelf life for foam and rubber surrounds, which to some may not be bad when you consider how disposable everything is these days. only contrast 10 -15 to the textile surrounds of my 30 year old drivers which are still good. im not a big fan of built in obsolesce.
3)i have to wonder how old are those F120A's and if fostex sent him replacement surrounds?
http://www.madisound.com/catalog/images/userimages/fe138es-r_side.jpg
It looks like the UDR impressed spider on the FE138ESR is a similar thermo-set/doped fabric material to the more conventional concentrically corrugated spiders found on most other drivers.
As to evils of foam or rubber, I'm just guessing here, but have not the chemical formulations been modified over the years to significantly reduce the problem of environmental deterioration?
I think you could find discussions of vintage doped cloth surrounds having problems of their own (i.e. hardening of the doping materials), and the associated dilemma of trying to find the least harmful remedy.
And to be a bit cynical, it's been my personal observation that for many DIYers and consumers of mainstream audio gear, there exists an inverse relationship between the effective system life span(i.e. how long it actually stays in the system) of almost any component in their system and the unit's cost.
To mix a metaphor, in the never ending search for "a better high", many surfers of the bleeding edge would have moved on to the latest thing long before the surrounds on their drivers rotted out or the coupling caps in their new tube DAC fully broke in.
It looks like the UDR impressed spider on the FE138ESR is a similar thermo-set/doped fabric material to the more conventional concentrically corrugated spiders found on most other drivers.
As to evils of foam or rubber, I'm just guessing here, but have not the chemical formulations been modified over the years to significantly reduce the problem of environmental deterioration?
I think you could find discussions of vintage doped cloth surrounds having problems of their own (i.e. hardening of the doping materials), and the associated dilemma of trying to find the least harmful remedy.
And to be a bit cynical, it's been my personal observation that for many DIYers and consumers of mainstream audio gear, there exists an inverse relationship between the effective system life span(i.e. how long it actually stays in the system) of almost any component in their system and the unit's cost.
To mix a metaphor, in the never ending search for "a better high", many surfers of the bleeding edge would have moved on to the latest thing long before the surrounds on their drivers rotted out or the coupling caps in their new tube DAC fully broke in.
mp9 said:
ok, ok, i stop trying to convince you...
... but remember, all things rot and breakdown over time, you only have wait long enough.
(i´ve seen many holes in many old cloth-surrounds of Fe103´s and others)
don´t get it wrong, the Spider of the es-r has this tangential edges, but of course its
made of cloth.
the Seas has a foam-surround, too. and it´s a 8" with a whizzer, so what´s the deal ...?
have a nice day.... Mirko
....yeah i know that and they're twice as expensive but if seas made a 5" version like the 138...? anyway i misunderstood what was said about the spider, that i'll make it easier on me when i order them.
thanks again guys.
thanks again guys.
Hi Folks,
it is over ! my cabs are done ! yesterday i screwed in the drivers and wired them to
my amp.
and i´m quite pleased with the result. i can´t say much about their sound yet, cause they
seem to be quite critical about placement, and i haven´t find the right spot yet.
but they have enormous potential.
it is over ! my cabs are done ! yesterday i screwed in the drivers and wired them to
my amp.
and i´m quite pleased with the result. i can´t say much about their sound yet, cause they
seem to be quite critical about placement, and i haven´t find the right spot yet.
but they have enormous potential.
Attachments
MisterTwister said:
If snything at all like the aluminum dustcap on the FF85 (and all indications are that it is a highly eveloved version of that), then it is directly attached to the voice-coial and acts as a central dome tweeter and will take frequency responce up past 30k. lighter, stiffer magnesium, will mean a higher dome break-up mode, but i know from some other drivers Fostex makes with metal dustcaps that they try to keep this under control.
dave