DCM Home Invasion

[RJolly87]

This is the more promised to come here: http://audiokarma.org/forums/index.php?threads/dcm-speaker-id-please.694215/

The situation: I have just acquired 4 CX-17's, 1 CX-Center, and 2 TimeFrame TF-600 speakers

The plan: I will go through these speaker by speaker, take photos for the DCM aficionados, and address any concerns that should be addressed for longevity's sake. I would like to use this setup to give my parents a 5.1 surround sound setup (this thread will not address the subwoofer). If I end up with a pair of CX-17's for myself, that's even better. Aesthetics are not a major concern, however my father has been known to push limits on equipment, especially in the heat of the moment, so I do not want the speakers to be the weakest link.

Given DCM's reputation revolving around tweeters, I would like to do anything possible to keep the working tweeters alive and kicking for years to come.

Any thoughts, feedback, and general knowledge is welcome in this journey, and thank you for sharing anything you can. I have found some information on them already, including the basics on their configuration.

 

[RJolly87]

Opening round goes to the CX Center channel. I pulled the plate with the interconnects, and looked around to get a lay of the land. The forward half of the box seems to be foam stuffed, and no ports on this enclosure. I haven't become too intimate with all that is going on here, but I am suspecting that the bass getting to the woofers is limited here. I hit it with some full range music (not too much of course) and it seems as though the behavior of the woofers would agree with this guesstimation. I was unimpressed by this, and was unable to hear the magical things spoken of in posts of many others. I fired up a vocal discussion and that seemed to fair better. This may be a right tool for a specific job instead of a jack of all trades kind of scenario, but that remains to be seen.

The photos:




I can't really tell what the woofer surround material is. Maybe a smoother foam variant? Also, I think I am looking at 3 electrolytic capacitors, which I am thinking probably should be addressed on this pass. I welcome feedback on that however. It's my understanding that this whole loadout of speakers is in the 20 year old territory.

 

[RJolly87]

Round 2 goes to CX-17 1 of 4

The photos:



Admittedly, I wasn't expecting to see the lil' blinky bulb in here, and this is the only 'black label' unit in the lot. I see another 2 electrolytics in here however. I am not sure if the thin wire on one side of the bulb is intended to act as a fuse-able link however, and I am curious about that, from a future service perspective, and if it should be kept if I do encounter a failure on one of these units.

 

[RJolly87]

Round 3 goes to CX-17 2 of 4

The pics:



Seems like standard fare in here too. 2 eletrolytics, a lil' blinky light, and all the hot glue you can eat. The DCM logo in this case is hanging on with weak double stick tape, so no surprise that the logo has been moved.

 

[RJolly87]

I have tested the first pair of CX-17's, and all the drivers are in working order. At first, I was a bit concerned because it didn't seem like they were reaching frequencies as high as I thought they should have. Once I settled down and moved away from them, I then understood what all the talk was about, and I completely agree. I was completely blown away.The sound coming out of these things was better than anything I have heard coming out of anything else in my house! I only tried some rock and vocal/orchestral, but WOW! The speakers disappeared, and there was only a wall full of soundstage in front of me. I had to cut the tour short because I kept getting some popping and distortion on one side, but I think the amp is to blame, and not the speaker. If this is just the small bookshelf unit, I can't imagine what the Timeframes can do. I'm hooked, and I hope my parents are as impressed by them as I am.

 

[krlill]

That's a great deal you got there! I have a pair of CX-17's and like them very much. My version has the fuse in the crossover much like the speaker in your round 3 set of pics. About that popping sound... I have a pair of small ADS L310's and one of them started making popping sounds. I opened it up and found that the woofer magnet came loose. It's fixable. I just have to go buy some JB Weld.
Here is a thread about CX-17 magnets coming loose: http://www.audiokarma.org/forums/in...now-what-is-up-with-these-dcm-woofers.645550/

 

[hjames]

a pair a TF600s - how cool.
even when I sold the rest of the Timeframes I had collected, I kept them because they really opened up the part of the room I put them in. Using mine for Rear surrounds these days!

 

[leesonic]

I wouldn't expect the center channel speaker to put out much bass, that's the job of either a subwoofer or the left and right speakers.

I have used caps from Erse Audio in the past on my DCM speakers, in fact, I have a pair of TF-350s still to do. See if you can figure out what caps go to the tweeter and/or are otherwise in the signal path. Use the yellow film caps for these, and their excellent electrolytics elsewhere.

Lee.

 

[mtlmn1971]

I second what "krlill" said, check the magnet. I have a pair of TF600's and when testing them I missed the rattle I heard when I got them home. Maybe it happened in transit. Found a loose magnet. Great speakers. You have a very nice setup.

 

[RJolly87]

That's a great deal you got there! I have a pair of CX-17's and like them very much. My version has the fuse in the crossover much like the speaker in your round 3 set of pics. About that popping sound... I have a pair of small ADS L310's and one of them started making popping sounds. I opened it up and found that the woofer magnet came loose. It's fixable. I just have to go buy some JB Weld.
Here is a thread about CX-17 magnets coming loose: http://www.audiokarma.org/forums/in...now-what-is-up-with-these-dcm-woofers.645550/

This is great info, thank you. I haven't actually diagnosed the source of the issue, but I suspect the speaker may not be to blame. I still need to track down the issue however.

That is a valid point about the magnets moving around. Is this something that should be addressed preemptively, or just repaired if it's broken? Given the chunks of particle board on the back side of that speaker, it's looking like the drivers are glued in, in which case I would take the "if it's not broke, don't fix it" approach, because the fix seems relatively straight forward, and risk associated with a failure seems relatively low, provided I don't run these through a cycle in the tumble dryer.

 

[RJolly87]

In the words of Jeremy Clarkson, "I went on the internet, and I found this:"

http://www.audiokarma.org/forums/in...-have-a-dcm-cx-17-crossover-schematic.585186/

Please forgive my ignorance, but looking at the schematic for the crossover, I am not quite sure what I am looking at. I can understand C2, and recognize it is directly in the tweeter path, and should probably get switched out. But what is C3 doing? I recall mention of someone servicing this crossover with one upgraded cap (foil?) and one electrolytic, but I am not sure why now. Is this essentially scrubbing off frequencies that are higher than what the tweeter should get? If I replace both caps with upgraded units, would I gain anything over replacing this one with another electrolytic, whether it be longevity, sound quality, etc?

 

[RJolly87]

And the beat goes on....

Round 4, CX-17 3 of 4

The pics:





This one did give me a bit of trouble. Not only does it smell funny (like it may have been sprayed by a cat) but it sounds like there is something up with it. I believe the tweeter is working, but sounds dull and muddy, and doesn't reach high in to the frequency spectrum. Something's up with this one, and it's likely to stay with me so that I can get a better look at it when I have more time.

 

[RJolly87]

Round 5, CX-17 4 of 4






Status quo here. Both drivers working, both sounding great!

 

[RJolly87]

Now the fun stuff, the "Main Attraction" if you will...

Round 6, TF-600 1 of 2 (Right side)



The lower left corner of the rear plate is cracked, and it looks like it may have been used by the cat as a scratching post. It seems like there are 2 layers of material going around these, and it has definitely seen better days. But, all of the drivers work, and they all work great, all 3 tweeters, and both 6" drivers. It's also interesting how much of a kick you have to give them (power wise) to really get them going. I think the shiny blue cap is somewhat interesting looking though, and not in pattern with everything else I have seen so far. Looks like a 16uf 100v electrolytic in here, but doesn't look consistent with the capacitors in the other units so far.

 

[RJolly87]

Round 7, TF-600 2 of 2 (Left side)



This speaker is another case of all drivers working great, but looks like it's seen better days, thanks to the cats. There is some funny business going on in the crossover however. First, the same bottom left corner of the plate is completely gone. Next, the electrolytic capacitor is 15uf 50v. The brand is consistant with the previous units, but I was expecting a 100v unit in here, and it's also different than the 16uf capacitor in the first TF-600. I don't know if this is by design, or if something has been replaced. Finally, the interconnects are scary right here. The ground connector is leaning against a live power connector. That is an amp failure waiting to happen if I ever saw one. I poked at it and the tweeters dropped out. That is sickening, and I can't believe someone who knows what they are doing would let this happen.

 

[RJolly87]

Opening round thoughts:

Winner winner, chicken dinner! At one point I had one of the CX-17's on the bench, and I took it for a pretty good spin, and I can't imagine what it takes for the protection bulbs to start burning. It makes me wonder what they are doing in this vid:

(volume warning) although, if I am honest, I am not sure I want to know.

Time to continue digging around for details and things.

 

[RJolly87]

I did some interweb digging, and found this schematic for the TF-600:

http://forum.polkaudio.com/discussion/165106/dcm-tf600-crossover-question

If I am reading this correctly, the cap should be a 15uf unit, and the 16uf unit may be a replacement. It is out of the tweeter signal path however.

I still wish I knew if there would be any gains switching to poly caps in all electrolytic applications, even if it is JUST for longevity sake.

 

[KentFJ]

Howdy RJolly

I just pulled out some tf600 crossover out of the closet that I had bought on here I believe. serial # in the 15000's one had 16uf the other 15uf
So I then went and pulled crossovers out of active pair ( bought from a doctor unmolested/damn nice) serial# in 39000s
I am sure no one but me has opened it . left side I could not read value the right was 15uf both side same brand as your last picture.

By the way I believe speaker post are wired wrong in last picture ,
Black/ground should be in the hole in the board and Red on post outside of board .

betting that had an effect on the sound unless some one reversed the posts red outside black inside .

Have fun they are definitely worth restoring, Head liner material and speaker clothe at JoAnn's here in California.


Do me a favor listen to them without materiel on them before you glue on headliner material then after and let us know if you hear a difference.
I didn't on a pair of 350s i redid.

I have all the parts to make another pair of 600's but thinking using veneered MDF no liner or cloth

 

[RJolly87]

Howdy RJolly

I just pulled out some tf600 crossover out of the closet that I had bought on here I believe. serial # in the 15000's one had 16uf the other 15uf
So I then went and pulled crossovers out of active pair ( bought from a doctor unmolested/damn nice) serial# in 39000s
I am sure no one but me has opened it . left side I could not read value the right was 15uf both side same brand as your last picture.

By the way I believe speaker post are wired wrong in last picture ,
Black/ground should be in the hole in the board and Red on post outside of board .

betting that had an effect on the sound unless some one reversed the posts red outside black inside .

Have fun they are definitely worth restoring, Head liner material and speaker clothe at JoAnn's here in California.


Do me a favor listen to them without materiel on them before you glue on headliner material then after and let us know if you hear a difference.
I didn't on a pair of 350s i redid.

I have all the parts to make another pair of 600's but thinking using veneered MDF no liner or cloth

Thanks for the info. I was planning on running them looking the way they are at the moment, but that's not to say it won't happen down the line. Polarity is consistent on everything, but I think the terminals on the last ones have been replaced, and they were just reversed when the new ones were put in.

The thought did cross my mind to get them smoothed and painted black, and make wire speaker grilles for the front, and for the rear tweeters. Right now the primary focus is function over form.

 

[RJolly87]

I will go ahead and throw this in here too. I haven't been able to find a schematic on the CX-Center crossover, nor do I plan to map one out, however I will add that there are 2 3.3uf electrolytics, and 1 10uf electrolytic, all 50v units.