That doesn't seem to be true. I just test ordered 10 of them and the website said August 10th ship date, which means they will build them for me.
This is a short term situation. Vapour pressure will equalize itself over time. You can fight but you cannot conquer.
No such thing as impermeable for all intents and purposes. All materials including those in a loudspeaker driver and enclosure will have a perm rating. I cannot give you an estimate as to how long before equalization occurs as these are outside normal vapour retarding materials but I think it will be faster than you imagine. Even through the walls of the enclosure, sealed or not.
Do you recall the price on the diaphragms?
Wrt keeping the humidity lowered, that is why I plan to use the CRL desiccant which is meant to remove most the of internal RH as water vapor leaks in. Eventually it will become saturated and would need to be replaced - I would like to make that interval as long as possible. It's crossed my mind that a cheap RH meter at the back of the speaker might be of use🙂
Wrt keeping the humidity lowered, that is why I plan to use the CRL desiccant which is meant to remove most the of internal RH as water vapor leaks in. Eventually it will become saturated and would need to be replaced - I would like to make that interval as long as possible. It's crossed my mind that a cheap RH meter at the back of the speaker might be of use🙂
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I think a RH meter would be a good idea.
I would be interested in knowing about the different materials and how well your ideas work. Unfortunately, there's little way of telling which have been the culprit when the vapour levels equalize as thickness doesn't necessarily translate to retarding ability.
I would be interested in knowing about the different materials and how well your ideas work. Unfortunately, there's little way of telling which have been the culprit when the vapour levels equalize as thickness doesn't necessarily translate to retarding ability.
I see that there is a company that makes color indicating molecular sieve desiccant beads that may be suitable. They are shipped blue as fully activated and will turn pink as they become saturated. With a see-thru exit cover, this might be a possible indicator of RH. However, they are more expensive than the CRL molecular sieve that I have. However, a cheaper way might be using relative humidity cards which are supposed to be able to be used over several humidity change cycles. I see one that indicates 10% ranges from 10% to 60% RH.
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Perhaps this suggestion is a bit out of left field, but have you investigated whether or not a dehumidifer can be had in a compact size? The benefit would be that you won't have to be changing out &/or recharging your dessicant.
Just a thought.
Doug
Just a thought.
Doug
The traditional method to keep humidity out of things is to install a small heater inside the box. In the US south there is a common household appliance called a crisper. Just a heated box for keeping crackers, breakfast cereal etc from getting mushy.
Attached is a page from a scientific paper "Sorption of Water Vapor by Active Charcoals" by M. M. Dubinin and E. V. Zaverina where they demonstrate that water vapor can be adsorbed or desorbed by activated charcoal reversibly at room temperature and for the most part the two curves are superimposed as a function of external RH.
This would suggest that even without a secondary desiccant to keep internal cabinet RHs very low that this compliance enhancement approach will still work to a certain extent at normal indoor conditions when the relative humidity is reasonable but that its performance would improve if the in cabinet RH is less than 20%.
I've seen in some writing about activated charcoal from China that it is usable for RH control in living environments - just keep it in a low RH area of the dwelling until it needs to be moved to a high RH area for humidity control, or even vice versa. So lugging sacks of activated charcoal around could perhaps reduce ones' air conditioning or humidifier bills🙂
This would suggest that even without a secondary desiccant to keep internal cabinet RHs very low that this compliance enhancement approach will still work to a certain extent at normal indoor conditions when the relative humidity is reasonable but that its performance would improve if the in cabinet RH is less than 20%.
I've seen in some writing about activated charcoal from China that it is usable for RH control in living environments - just keep it in a low RH area of the dwelling until it needs to be moved to a high RH area for humidity control, or even vice versa. So lugging sacks of activated charcoal around could perhaps reduce ones' air conditioning or humidifier bills🙂
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A suitable micro dehumidifier sounds like potentially a pretty good suggestion. The idea of having to regularly change out a desiccant that is likely to spill all over the place is not the best, although it still isn't as tedious as swapping used up tubes in power amplifiers.
The 'crisper' approach could definitely help also, perhaps reducing the need for vapor barriers and is technologically simpler.
The 'crisper' approach could definitely help also, perhaps reducing the need for vapor barriers and is technologically simpler.
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Besides any claimed sonic benefits, I use it as we can have very high humidity here and makes dust removal on a paper cone much easier (even with a damp rag which usually starts to lift paper fibres). It does place a very fine elastic membrane over the cone surface.
I did a quick check on some 80gsm copy paper by painting on a small section of LTS 50 and allowed it to dry for a couple of hours. After spraying on water and leaving for a few minutes, the water had soaked through the paper on the non coated areas but the coated area was fine on the underside. Even with water, the coating did not dissolve, even with rubbing over it with a finger.
It's water based but have no idea of it's formulation.
OK. I just rechecked, I had only checked the E145 recones.
The E145 does show as discontinued and unavailable, as is the K145-4
The K145-8 shows as obsolete, but is presumably still available.
K145 owners should probably stock up.
Best wishes
David
If you need any JBL shows me the 8 ohm E145 is available at just under $220.00 each retail.
I suspect it is not too hard to determine how much heat is require to keep a given size enclosure at say 10% RH in a room that may go to 30% RH.
On needs to look up the temperature differential required to do increase the moisture capability and then do a heat loss calculation.
A few 10 Watt square white ceramic resistors and a wall wart would be all it takes.
Now depending on where you live wood tends to hold a certain moisture content range, so some places might not even need to worry.
Also, it appears that if the activated carbon is surrounded by an (acoustic & thermal) insulator such as fiberglass mesh, only it would need to be heated, reducing the power required.
For a total surface area of 25ft squared which would be ballpark or a little higher than needed perhaps for 100 liters of activated coconut charcoal, with 1.75" of fiberglass mesh on all sides (R Value ~ 6.5), a 10 degree F average temperature increase could be maintained in the charcoal with the following power:
(25 * 10)/(6.5 * 3.41) = 11.27 = Power in Watts
1 W = 3.41 Btu/hr
With a full 3.5" of fiberglass insulaton (R = 13), the power would be half, or for the same power, a 20F rise would result. Of course, keeping the insulation from compressing due to the charcoal weight would be a factor in both cases.
So, this definitely appears to be a possibility, with say a 20W or two 10 W or higher rated resistors. One thing about the insulated approach is that it would not need a sealed box to be practical. Of course, an approach with heating will require some time for the temperature difference to stabilize for greatest effectiveness unless it is started ahead of time, or with a 'fast' startup at a higher power which is then dropped off to the average required.
For a total surface area of 25ft squared which would be ballpark or a little higher than needed perhaps for 100 liters of activated coconut charcoal, with 1.75" of fiberglass mesh on all sides (R Value ~ 6.5), a 10 degree F average temperature increase could be maintained in the charcoal with the following power:
(25 * 10)/(6.5 * 3.41) = 11.27 = Power in Watts
1 W = 3.41 Btu/hr
With a full 3.5" of fiberglass insulaton (R = 13), the power would be half, or for the same power, a 20F rise would result. Of course, keeping the insulation from compressing due to the charcoal weight would be a factor in both cases.
So, this definitely appears to be a possibility, with say a 20W or two 10 W or higher rated resistors. One thing about the insulated approach is that it would not need a sealed box to be practical. Of course, an approach with heating will require some time for the temperature difference to stabilize for greatest effectiveness unless it is started ahead of time, or with a 'fast' startup at a higher power which is then dropped off to the average required.
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Is this worse than from a non-time-aligned multi-way speaker, in terms of audible group delay? From a well-designed box, I think not.
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