604 questions

[edharbur]

I've got a pair of 604-8ks in ersatz 612 cabinets that I'm about to fire up for the first time, and I've got a couple of questions.

The bug screens are partially blocked with a white powdery substance of some kind. It looks like oxidation on aluminum screens. How do I remove them? Do I just start removing screws until something happens, or is there a trick? From the front or back? I know a lot of folks prefer not to use the screens - is there any downside, aside from bugs, to just leaving them out?

One of the 604-8k crossovers is missing a plastic knob. It's 1-1/4" dia., with a 1/4" shaft hole with 24 splines, and a chrome ring and hash mark on the face. Are these available easily?

Thanks,

Ed

[bowtie427ss]

You'll have to cut the screens out, and i don't advise it if you plan to sell them anytime soon. Removing screws is likely to take you somewhere that you don't want to go.

What i have done for knobs, both early and late style, is to shop single networks in the off season, rob the knobs, and then flip the knobless networks this time of year. There are a few other pieces of "under the radar gear" that are economical knob sources as well, especially for the earlier bakelite knobs and chckenheads.

I have a lifetime supply of spares, and made a few bucks doing it.

[Old Guy]

Davies Molding - 1110 - Dials and Knobs - Knobs - Allied Electronics

[edharbur]

Thanks, gentlemen! OG- the knobs look great. I'll have the speakers up and running sometime next week, and see if the blockage is noticeable. I'm thinking I attack it with an acid brush and a small vacuum, and do the best I can from the outside.

Ed

[RonSSS]

Be sure you remove the diaphragm before doing the work.

Ron

[cradeldorf]

I agree with Ron, take out the phragms and then use a brush kinda like a toothbrush but with the bristles pointing out the end and try brushing the screen through the horn and sucking it out with a vacuum.

Sorry, somehow that's just what you said, for a minute there I saw a brush with acid on it.