DCM Time Window Overhaul

Faustin

Picked up a pair of early DCM Time WIndows a few months ago. Back in the late 70's I had wanted a pair, but went the Polk Monitor 10 route. Decided to bring them back to life. Refinish the end caps, rebuild the crossovers, and new "socks". Biggest challenge is that these were built with no regard to ever taking them apart or working on them. Spent a lot of time formulating a plan and put in lots of labor. But they are done and burning in. I will add some of the steps I went through in the next week or so, so if there are others that want to dig into a pair of TW's they will have a little info. Also will be burning in the c/o's and will report on that. Right now they have a nice wide sound stage compared to the Monitor 7's but the upper end is not as good as the 7's. Here are a couple of pics.

Clipdat

Nice job on those endcaps. Any pics of the crossovers? Did you upgrade the components?

I like the name of these speakers "Time Window(s)". It's up there with Totem's "Rainmaker(s)" in the great speaker name category.

Tony M

Nice job for sure.

I've owned 2 or 3 prs. of the Time Windows and hated selling each pair not knowing if I will ever get another pair.

I LOVE their sound and THAT BASS and sound-field too.

I always elevated them on flat 4 or 5 inch risers. It helped with those highs you say are a little less than the Polk 7's.

mhardy6647

Wonderful loudspeakers but, yes, not really designed for the 40 year rehab

Faustin

So, I was not really sure what to do with these. The "socks" are a 1/4" foam that wraps around the cabinet and is glued to 2 wood strips that are then nailed to the cabinet. The socks were easy to remove. The cabinet is glued and stapled together, Particle board and the back curved portion is a heavy duty cardboard type material. Kind of like a concrete form. The end caps were attached with construction type adhesive, 3 wood screws and a half dozen staples. The 4 drivers were not screwed into place, but were glued in with what is referred to as "Black Death". Kind of a caulk, tar adhesive. What were they thinking! Not knowing how the end caps were attached I decided to carefully tap up on the top one with a hammer and a piece of wood. It eventually came off and I could see how it had been attached. Next I tackled a 6 1/2" driver. I carefully used a putty knife to work around the edge of the driver and bent the metal edge in a bit so I could get a pair of needle nose pliers on it to try to pull it loose. Using a heat gun and the pliers it finally came out. I could now see into the cabinet; crossover attached to the top, dampening material etc. I tried to get the c/o off but it was not budging. I had to figure out my next steps.

mhardy6647

The back half of the enclosure is indeed "Sonitube"
It was a clever design trope, later mimicked (e.g.) by Nelson Pass's epochal El Pipe-O subwoofers.

Msabot1

A friend of mine redid a first production run of those DCM's a year ago or so..quickly found out that they were put together with no take apart in mind..went through quite a few hair pulling out sessions and count to ten moments...got through it though with a bit of help..and boy oh so worth it..Those are fine!!...Glad to see that you got through it too...Enjoy em..They are gems...

DSkip

Excellent job!

westmassguy

Those came out really nice Bruce.

voltz

loved your RTA12's and now these Good work!

Faustin

Thanks folks!

Faustin

Once the top end cap was removed I needed to figure out how to get into the cabinet. I decided to take an old knife and cut a slit through the seam between the top and sides. I was then able to get a jigsaw between the top and sides and cut along the seams. Went through several blades cutting through all of the staples and glue, but I was in!





Next I pried the crossover off the top of the cabinet. They used so much adhesive the board was pretty much ruined. No worries, as I was going to use new boards and components and completely rebuild them.

Next step was to get the rest of the drivers out. Took some doing with a heat gun, needle nose pliers, putty knives etc and a bit of elbow grease. Once they were all removed I was able to pull the dampening material out and reach down to the wood screws that held the bottom end cap in place. Once the screws were out I was able to tap the end cap off off the bottom of the cabinet. The bottom was cut off using the jigsaw. There was a lot of time spent cleaning the Black Death off of the drivers and the cabinet. I also had to patch the driver openings a little here and there where they were damaged removing the drivers. After the cleanup was completed I spray painted outside of the cabinet with flat black paint.








Next up was to rebuild the crossover.

Faustin

I cut new mounting boards for the c/o's and decided due to cost, to go with Dayton 1% caps for them. Per some research and input from Dave (Westmassguy) I arranged the orientation of the inductors differently. I also replaced the internal wiring and installed new gold plated copper binding posts. Next decision was how and where to mount the c/o. I wanted it to be accessible and with the way the inductors were now mounted, if I put it on the top of the cabinet where it was before they would be in very close proximity to the 6 1/2 " driver magnets. Per the recommendations of several Polkies, they should be as far away from the magnets as possible. The location I chose was just below the tweeters on the front of the cabinet. I used hurricane nuts donated by Voltz (thanks again) and machine screws. Once that was installed I reattached the bottom of the cabinet with Power Grab and finish nails. I could now reach down to the bottom of the cabinet and screw the end cap back in place.













Next up, getting the top back together and re-installing the drivers.

Mike Reeter

A VERY ambitious project, good work!!!

pitdogg2

Very nice work. Labor of love and it shows

mhardy6647

Wow. Just wow.

ThomasD

Great Project. I was just looking at a CL ad for a pair of DCM TimeFrame speaks. Was trying to find out some information on them. Certainly a very unique looking series of speakers. Were you able to find the specs for these speakers?

mhardy6647

Tonnes of info on Timeframes at audiokarma, FWIW.

Dawgfish

Very nice work! I have a set of near mint Time Window 3s that I love! Next to my SDAs these are one of my favorite speakers I've ever had.

Faustin

Thanks all for the kind words. I have not found much info on the Time Windows such as specs etc. I get the impression they kind of winged it in the early days. Used components that were in stock to keep production going etc. Like Mr Hardy said, there is lots of info on the Time Frames. I have never heard any of the TF models. People say the later models (TF 1000) are supposed to be very good.

Tony M

The TF1000's are huge. I've seen but not heard them.

I own the TF350's now and I re-foamed the surrounds myself. Easy to do once you figure how to remove the top board. I read to bang it off. Well, it didn't move up to the point I figured I need to feel under it. Sure enough, lag bolts holding it on.

But anyway, I also have owned the TF400's.

Both are superb sounding speakers!

They aren't up to the Time Windows but then again, they don't cost as much either. You get half the speaker but 5/8 of the sound. Those TF1000's are something else. here is one guys' opinion.
https://www.stereophile.com/content/dcm-time-frame-tf1000-loudspeaker

The TF600's are pretty powerful I've read. But they are directional.

Can't go wrong with any of them. Maybe the TF250 might be a starter pair.

mdaudioguy

Nice work! Looks like it was a labor of love. Enjoy!

Faustin

Getting close to getting this first TW completed. Before I put the top back together I decided to drill pilot holes and will use wood screws to re-install the drivers. No caulk, adhesive or Black Death going to be used here! I had a bunch of screws laying around from several pairs of Polks that I had installed hurricane nuts and machine screws, but I could not find them. I must of tossed them. Reached out and to the Polk community for some wood screws for the project and pitdogg2 and F1nut were kind enough to send me some that they had laying around. I put the sound dampening back in place and used Power Grab and finishing nails to attach the top of the cabinet. An extra set of hands (my tolerant wife) made the installation much easier. I was then able to reach through one of the driver openings to make sure things were sealed up and re-attach the top end cap. I used foam with adhesive backing as gasket material for the drivers before they were screwed in. Almost done!!






For the new socks I bought some 1/4 foam. It is not jet black, more of a dark charcoal but it works. I used a continuous strip of velcro instead of nails to attach the sock. It will be much easier to remove if need be.



Side note: After dismantling both speakers I discovered there was a dead 6 1/2" driver in each cabinet. I would be hard pressed to find those octagon drivers so I had them rebuilt.

Second TW overhaul went much quicker. They continue to burn in and I will report back after 200 - 300 hours of burn-in.