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DCM Home Invasion

RJolly87 said:
In the words of Jeremy Clarkson, "I went on the internet, and I found this:"
ab7f5944_vbattach213769.jpeg

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


C1 is a bypass cap, C2 is your frequency filter. C3 helps determine the slope of the cutoff, along with L2.

You should replace all three. The only one which might be iffy to replace is the bypass cap. I would recommend a good quality Mundorf e-lytic cap for these speakers.

As for the difference between a 15uF and a 16uF cap, it's negligible. You'll never heard the difference and the designers may have made on-the-fly changes to the crossover depending on what parts were available to them during assembly. Remember, DCM were hand made speakers in a small factory. A lot of liberties were taken.
 
Also I would not spend any more time than necessary on the CX Center unless you plan to run it.
 
RJolly87 said:
I did some interweb digging, and found this schematic for the TF-600:

http://forum.polkaudio.com/discussion/165106/dcm-tf600-crossover-question
l8ja0tpj2i8n.jpeg


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.
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Here it looks like C3 and C4 are summed before the bulb protection as the frequency cutoff for all there tweeters. Again, I would replace these with nice quality e-lytics like a Mundorf. The rear tweeters roll off at a 6 dB slope.

The front tweeter has the more complex circuit. I don't know the specifics, but from what I have seen dissecting other DCM speakers is that C5 and L3 are your slope. C7, L4, L5, C6 and C8 are all connected to the time alignment magic that Steve Eberbach invented for DCM. Replacing all of these caps is probably a good practice.

All three tweeters have a 1.8 ohm pad in front of them. The woofers each have a choke, at different frequencies, and nothing else. They run to their full low-end potential, respectively.
 
As for cosmetics, I have a thread on here on the TF1000s that I redid about a year ago. The headliner fabric can be bought at a fabric store. The speaker fabric I like the best is from Madisound or Parts Express. Get a lot. Note that the "socks" are tapered, so when you sew new socks, you have to make sure the bottom is a little fatter than the top or they won't fit right. Remember what I said about getting a lot of fabric? Mistakes happen.

I would also recommend getting a truck bedlinen spray paint, or automotive undercarriage sound deadening paint, and painting as much of the inside of the cabs as possible to deaden the cabinets.
 
baco99 said:
C1 is a bypass cap, C2 is your frequency filter. C3 helps determine the slope of the cutoff, along with L2.

You should replace all three. The only one which might be iffy to replace is the bypass cap. I would recommend a good quality Mundorf e-lytic cap for these speakers.

As for the difference between a 15uF and a 16uF cap, it's negligible. You'll never heard the difference and the designers may have made on-the-fly changes to the crossover depending on what parts were available to them during assembly. Remember, DCM were hand made speakers in a small factory. A lot of liberties were taken.
Click to expand...

In this case, C1 is a Mylar cap according to the schematics, and most say to leave those in. Are you still in disagreement with this? If so, why?

C2 I was planning to upgrade to Dayton Audio Polypropylene units (decently priced on Parts Express). Is there a reason I should stick to electrolytic in this application?

C3 I was also contemplating the upgrade to Dayton Polypropylene as well, however looking at the schematics again with the info shared, I gather that there will really be no benefit to moving away from electrolytic, aside from a longevity gain (if any).
 
baco99 said:
Also I would not spend any more time than necessary on the CX Center unless you plan to run it.
Click to expand...
I do plan to put this to use actually, because the other option is to break up a pair of CX-17's, and I am not too keen on orphans right now. Admittedly it may be a weak point in the system, but it's worlds ahead of what it will be replacing.
 
baco99 said:
Here it looks like C3 and C4 are summed before the bulb protection as the frequency cutoff for all there tweeters. Again, I would replace these with nice quality e-lytics like a Mundorf. The rear tweeters roll off at a 6 dB slope.

The front tweeter has the more complex circuit. I don't know the specifics, but from what I have seen dissecting other DCM speakers is that C5 and L3 are your slope. C7, L4, L5, C6 and C8 are all connected to the time alignment magic that Steve Eberbach invented for DCM. Replacing all of these caps is probably a good practice.

All three tweeters have a 1.8 ohm pad in front of them. The woofers each have a choke, at different frequencies, and nothing else. They run to their full low-end potential, respectively.
Click to expand...

Same story here, all appear to be Mylar caps with the exception of c5, which is electrolytic, which I plan to replace. Same question here, Dayton polypropylene? Stick with electrolytic?
 
I find it unusual that your 600 crossover uses the lamp/fuse and the other crossovers I have seen, including mine, have a self resetting circuit breaker.
 
KingBubba said:
I find it unusual that your 600 crossover uses the lamp/fuse and the other crossovers I have seen, including mine, have a self resetting circuit breaker.
Click to expand...

I have gathered that this is a special bunch. Both the CX-17 bookshelf units and The TF-600's have both self resetting breakers on the main, and the lamp/fuse protection on the tweeter.
 
The Mylar caps are good. If you have an LCR meter on your multimeter to check the values. they are probably fine on the mylars.

You don't have that many caps on those boards.

I personally like Solen or Axon poly caps. But if you do elytic, Mundorf.

My personal preference.
 
RJolly87 said:
Sounds like the +/- 5% of polypropylene will be a step up in this regard too, correct?
Click to expand...

The Daytons will probably actually be within 1-2% they are pretty tight. Be sure to measure everything and check the dimensions of the new parts so you have a game plan on how to get everything mounted. Daytons can get long in the higher values.

The J, K or M % window can be confusing. It really depends if they took the time to hand match the parts. I've seen several cases with speakers where 10% and 20% parts were actually right on the money because they took the time to select the parts and discard ones that where outside their personal QA window. I'm not sure if DCM took the time to do that or not.
 
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The capacitor order just went in last night, and should be here next week.

I did hook up the timeframes however and take them for a quick spin, and what I discovered was rather interesting.

The room I did this in, I could only set them 3-4 feet apart, and I couldn't get more than a few feet away from them. They make all the right noises, and none of the bad ones it seems like, but the back wall was over 2 feet away, and they never did take control of the room. I also kept catching glimpses of bass, I felt a fair amount in the floor, but it never seemed to develop in the room either. I kept catching glimpses of it on occasion, but I never could "touch the sun" so to speak.

It was my fear that if I set up these speakers, and gave them a listen, I would never wan't to let them go, but all that I heard confirmed everything that I needed to hear, there is no place for them in my house, no place for them to shine. It just makes me that much more excited for my parents, because they do have a good space for them, complete with a backing wall.
 
I wanted to give a brief update on this.

The Center (round 1), and the 2 sequentially numbered CX-17's were recapped (round 3 and 4, one of which was the problem child). The TimeFrames are being ran as is, mainly because they still sound great and the replacement poly cap that was ordered was prohibitively huge. I can now see why others go for another electrolytic in this application, however I plan to address this down the line, as these speakers deserve the refinishing they are in need of. I am not sure if the problem child is completely fixed because of the recap, because I haven't had a chance to do any extensive testing. They were pretty much recapped, verified that both drivers were still working, and plopped in rear speaker mounts.

For setup, everything is being driven by a Sony STR-DE597 receiver (90WPCx6, Surround center unused), and being backed by a Sony SA-WM40 powered sub (12", 120watt). The cutoff on the receiver was set to 80hz based on internet research. For music, the system is incredible, but we are running in to one issue, bass, or namely, too much of it in all the wrong frequencies. I likely need to readdress the cutoff frequency and subwoofer approach. I wasn't able to get to deep in to this because my mother returned home soon after initial setup, with a migraine, and NO tolerance for the noises that were being made in her living room.

So far, it sounds like some great noises are being made, it's all a matter of tuning from here.
 
It has come to my attention that I never gave a final update on this thread, so I should probably correct that.

The receiver was later switched out with a Sony STR-DG920, which not only opened up HDMI options, but also provided a substantial sound improvement and opened up more configuration options.

The cutoff was then lowered to 40hz on the Timeframes and CX-17's, just to keep them from taking abuse from frequencies lower than what they are capable of reproducing, and to take a load off the amp. The bass issues mentioned previously were corrected by moving the rear ported subwoofer an inch further away from the wall. Also the automatic setup offered by the receiver goes a long way equalizing the system.

To this day, my father still raves about this system, and he frequently discovers something new about it, whether it be the way it plays old favorites, or plays new songs. I love this system too, but as mentioned before, room placement is EVERYTHING with these Timeframes, and I am perfectly content leaving them where they are.

Admittedly, the 1 CX-17 with the funky tweeter still has issues, but it doesn't seem to bother him, so I haven't really pursued it any further.
 
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