Moist conditions.....?

[503Timber]

So I want to put a little system in our bathroom. For now it'll be some "hot rodded" Minimus 7's and a TA-2020 based amp in a cigar box. I'm fairly certain I can clear coat the metal Minimus cabinets and maybe even the woofers a bit to protect them and I think the cigar box will handle the heat and moisture........but what about my board, chip, volume pot, RCA terminals and whatnot? Is there anything I can do, or should try to protect it? The only source input will be via 1/8" to RCA from a smartphone so I don't need to protect a tuner or cd player. Thanks in advance guys/gals

[AndrewT]

fit waterproof ceiling mounted drivers.

Some car types are waterproof. All types for boats are waterproof.
They are available in a wide range of prices. I used some very cheap "skytronic" water resistant speakers (2way 5" 8ohm). The electronics were located in the next along ceiling space which is relatively dry. They perform well enough for soaking in the bath, or relaying the door bell/telephone ring/ring.

[!]

While I'm not 100% certain, I thought the Minimum 7's had a non-ferrous cast metal housing? If so, rust won't be an issue (maybe still oxidation, are they magnesium or aluminum alloy?) but if you want the exterior (painted?) finish to remain intact, I would not clear coat as that seems like it would just come off even easier than the original surface coating. More of a cosmetic issue I suppose but instead I'd wax them.

Use gold plated components when possible. Bathroom moisture can vary from "not much at all" when there is no showering, to some with bathing or showering w/exhaust fan, to lots with showering and no exhaust fan running. If the moisture is bad enough you will want sealed pots and possibly a rubber gasket (or o-ring, etc) over the pot shaft (or a lot of grease in it, or both). If the pot isn't a sealed type you can seal it with various things like epoxy but take care not to get any inside and ruin it).

Heatshrink (with... what's it called? Hot melt glue? lining inside) over open wire/solder joint connections. Spray a conformal coating over the PCB and anything that isn't a mechanical connection (not on jacks, interior of pot, etc).

A cigar box isn't ideal, usually cardboard or wood based which absorbs moisture, BUT if moisture isn't very bad I suppose that would work. Think I'd still spray conformal or other water resistant coating liberally all over the inside and out of anything cardboard or wooden... though if it saturates the hinge area of the box it might become stiff, brittle, or frozen in that position.

If the heat level in your enclosure won't be very high you can avoid the heatshrink tubing and conformal coating by putting it all in a sealed plastic /etc. box, still using gold plated jacks (and sealing the back of the jacks). With TA2020 in a small room I suspect the heat would not be a problem but I'd probably put a heatsink on the chip top with some thermal epoxy just for the heck if it if it's going in a sealed (or nearly so) box. On a DIY build amp project that has a TA2020 in it, and plenty of vent slits in the enclosure, I found a heatsink I had attached still got fairly warm during use although I probably had higher volume levels & heat with it running in a larger area than a bathroom... a little volume goes a long way in a bathroom, especially if there's tile reflecting the sound waves.

On the other hand from what I recall the last time I tore apart my non-waterproof hair clippers which have been in the bathroom with a shower and exhaust fan for years, nothing in it seemed to have suffered any steam damage so all of the above might be overkill if steam isn't too bad... keeping in mind time and cost vs value of the components used, and that water vapor isn't nearly as destructive if it has little to no salt content... EXCEPT if the PCB (or you add) has hygroscopic solder/flux that ought to be scrubbed off with a stiff toothbrush and water or alchol/water solvent. Typical electronic manufacturing today does leave a certain amount of flux residue on a PCB, and common DIY use rosin flux based solder can be hygroscopic. Again it's a matter of how much water vapor is present. At the very least try to leave no bare copper exposed anywhere.

[john blackburn]

Hi 503Timber.

I use a tuner and amp in the next room with the speaker wires through the wall to a pair of the waterproof 5 inch speakers in the bath side panel. I use a battery powered fm transmitter and mp3 player source to give volume control and track skip with no wet hands touching anything electrical.

Better safe than sorry.

John