Whatever happened to DCM's Steve Eberbach? - Page 2

Tracy,
You might want to get two of those resistors in case you need to replace the good bulb in the other speaker, posibly to match. I'll see what I can do to get you a better copy of the scematic. Steve had to fill in some of the missing lines and values on mine. I'm using one 6.5" driver and one new TW7 tweeter. Here are some pictures. The crossover is attached to a removeable rear baffle. When it's finished I will post a picture. The smaller speaker is a normal CX17 for comparison.

Tracy,
I would think that the frequency response should be slightly better at both ends with the TW7 tweeter and increasing the box volume by 10% (any more than that and I would lose the tuning of the box- the CX17 was originally designed to be 10% larger than it is). The CX17 is a good speaker as is. It's a ported transmission line and gets good bass response for it's size. The main goal is for accuracy. The ways that I doing this is to highly dampen the enclosure and more important, to add the delay circuit of the TW7 to the tweeter circuit to make the speaker "time aligned". To my understanding, there were only a few speaker manufacturer's that did this and Steve did it very well. It's one of the things that make the TimeWindows and TimeFrames what they are. To add a woofer, you would have to change the design of the enclosure and to my understanding a horizontal arrangement is normally not desirable (lobing problems?). If I feel a need for more lower end (I haven't so far), I would rather cross it over to the sub or mains, or Steve suggested a small dedicated sub underneath it (doubled as a stand). Power handling and ohm rating should be the same. 100w 8ohm. I'm still waiting on parts for the crossover. When it's done, I'll post some photos

Jamie

Tracy,
Sorry to hear that your still having problems. To really get into the cross over yourself you'll need a LCR meter, one that can read inductance, capacidance and resistance. Look on ebay. I can email you a better copy of the crossover schematic for the correct values. Start checking each piece. How are you testing the tweeters only? Are you using a high freq sine wave? They are wired in series with the inboard 1st, outboard 2nd and rear 3rd. I've attached a photo of the part of the crossover dealing with the tweeter circuit, labeling the components. L4, C16 and R13 are part of the midrange. It starts with C7 as the high pass filter, then the bulb, then a wire going to pot on the spectral balance cup, then back to the circuit board. From there it splits, first to C8 and L6 to ground (this is the dampening circuit), then to the delay circuit shown on the rest of the schematic. The order between C7 and the delay circuit are different then the schematic. As you can see, if you did not get continuity across the blown bulb, you should not have gotten anything to the tweeter. So I'm questioning how you tested them. If you were indeed hearing something, some how the circuit was altered to bypass the bulb. The red caps are mylar, the larger round are bipolar electrolytics, the resistors are non-inductive. The pot is 5ohm 5W, a good replacement would be Digi-Key # is CT2150-ND. I would be suprised if something was wrong with one of the inductors. With those you could just rewind if you need to. Good luck.

Jamie

So what is Steve doing now?

Tracy,
I talked to Steve this afternoon. He is at a lost, as I, on how you were getting anything to the tweeters with the bulb blown. He said to fully diagnose your problem, he would need the complete speaker and his old test equipment which he doesn't have. The tweeter circuit extends to both boards. There are some jumpers between the traces if that is what you are talking about. Like I mentioned before, I would compare the crossovers from both speakers closely side by side for any difference in jumpers and how the driver leads and wires from the three spectral balance pots are plugged into the boards. You may want to get a test CD with different individual frequencys to narrow down the problem. Rives Audio Test CD 2 is one or you can find sine waves on the internet that you can download and burn. The problem may be in one of the drivers. You might have to isolate them to find out. I need to scan the cleaned up schematic so I can send it to you. Try and trace the first part of the tweeter circuit pass the C7 cap. If something was bypassed I would look there first. There are a pair of CX17s and a single CX17 in black on Ebay right now if you are still looking for parts or a center speaker. If you are not up to the task, you may need to search for a speaker repair shop. I think if you invest in a LCR meter and a test CD, you could probably find the problem yourself.

Jamie

I'm guessing a spectral analyzer, calibrated mic and probably some more expensive equipment. Plus, Steve does have any replacement parts. I don't think that he can help you. Sorry. I've e-mailed you a cleaned up copy of the TW7 schematic.

Well for those interested, I finally finished the crossover for my center speaker. I am very satisfied with the results. Here are some photos as promised. The last one is of the speaker assuming it's position between the Sevens.

Jamie

Also I forgot to mention, it weighs in at 45 lbs!

Tracy, The pot is part of the original design. I have not played with it yet and let it in the centered position. Cost is hard to come up with since I already had the black walnut, lead and other material. I suppose if I had to buy everything new, I might have $200-$300 including the CX17 donor. Labor would be another thing, but hey, it's a hobby. Maybe I should start a third business! Just kidding. Steve has not heard it yet. He's been pretty busy with a lot going on. He said that he's looking forward to it. Time to break out some cold beer and Pink Floyd!

The first question is: What do the chalk-marks on the tweeters and woofers mean? I called DCM and asked if it's okay to try to tighten the drivers. They said yes. Would this interfere with the chalk marks? Also, do the original Time-Windows have the right and left designations(and does that mean when you are facing them)? What are the setup parameters for the speakers? I vaguely remember(and so does my brother) that they should be about 3 feet from the back wall. I also remember some stands that were hella shaky that lifted the speakers about a foot off the ground. They seemed to make the Time-Windows more spacious, but destroyed the bass.

From what I remember Steve telling me, the chalk marks are for line up for the best frequency response of the drivers when they were tested. Of the TimeWindow, only the 3's and 7's have the right and left designations. It's been said that the early TimeWindows and the 1a's benefited by putting them on a 9" stand. Six to seven foot separation is recommended and they did like to be off the side and back wall, but like most speakers, the bass will start to drop off. My 1a's benefited with a subwoofer, the Sevens in the middle of the room would put most subs to shame.

I just recently got the Nuforce 8.5's. I have the original DCM's(the three's were recommended to me for my situation, but from what I read here and intuition, it will keep me from the 3's as an update.) These Nuforce's play the bass, even on analog! I want to mention Mapleshade's recommendation of having a tweeter lower than you ears. That might affect the 9-inch stand recommendation.

Hauser, I will try to investigate the 7's. I am interested in tightening the drivers, and I was wondering about the effect-due to the chalk marks. The tweeter seems to have two different tightening mechanisms-an outer one and an inner one. With the bass, I'm less hesitant, although it is curious that they have chalk-marks also.

It's you ears, not your ears?

Since you gave me advice, Hauser, I want to recommend two things. One(and this is from Naim) separate power cables from signal cables. The second(from Mapleshade) says to elevate your cables at least 8 inches from the floor(I used 3-16 inch styrofoam cups from the Dollar Tree.).

Mmakshak, I talked to Steve E. about your tweeters. There is no adjustment. The tweeters were torque to a specific amount but he does no remember the figure. He said to just "snug" them up evenly. He also mentioned before there is another school of thought that recommends that the tweeters be above ear level. I have read many older posts telling how much the original TW and the 1a benefited with the 9" stand.

I'm missing something in your 2nd post "It's you ears, not your ears?"

If you are looking at the Seven's you'll find that they are hard to come by with only 200 sets built. I would definitely look at the Three's. They are a much more refined speaker that the original or the 1a and do come up on Ebay once and a while.

Thanks for the tips.

I have a pair of Time Windows (passed down from my father) that I'm hoping to use in a home theatre set-up. Does anyone have any recommendations for a center speaker I should purchase that will produce the best voice-matching capabilities with these speakers?

I'm looking to spend in the $300-$500 range and would like to get a balanced sound.

Thanks Tracy.

So I'm a bit new to this - DCM CX-17's are bookshelf speakers - can they handle the needs of a center speaker functionality? Would that sound better than buying a brand new center speaker from a different vendor?

Tracy,

I appreciate all the good advice, thanks. I'll let your know on the Tannoy center speaker. I'm still toying with lots of ideas, including buying a new HT speaker set and using the TW1's as a second room stereo option.

Still, the idea of having a vintage HT speaker setup, with TW1's and CX-17s also sounds really cool. Hard choice!

I would like to contact him . Is there any way to email him or call him.? Any help here would be greatly appreciated.

For those interested, I needed to replace the four electrolytic caps that are in my TW3's crossover since they over 10 years old. I decided if they were going to be taken out of service for awhile, I would really trick them out with new end caps to match the TW7s (sevens side and in piano black). There will also be a matching stand that will be 6' tall to raise them to the same level as the sevens. I can post photos as I progress if anyone is interested.

Beardown, if you have a specific problem or question for Steve, I could probably ask next time I talk to him. He stays fairly busy and I wouldn't feel comfortable giving out his number.