I am a newbie, novice, neophyte to building speakers. I have thought of starting with a simple build like a Voight pipe or an open baffle project.
Lately I have been pondering my old DCM Timeframe 700's that I have had since new. I bought them because at the time I liked the sound(imaging etc.) and style of planar speakers for my budget!
The DCM's speakers had the look of the planar and a sound(fast transients and imaging) that my previous speakers Cerwin Vega HED 15's did not.
Now I am wondering since they have been mothballed for a few years (I currently use Totems) that before I try a speaker build from scratch, I should try a rebuild 1st as I still enjoy the styling of the cabinets.
So here is the challenge. Who has ideas as to how to get the most out the cabinets? What mods,(drivers/wiring/crossovers) would be best for this cabinet and really be a real sonic upgrade from the originals? project
Lately I have been pondering my old DCM Timeframe 700's that I have had since new. I bought them because at the time I liked the sound(imaging etc.) and style of planar speakers for my budget!
The DCM's speakers had the look of the planar and a sound(fast transients and imaging) that my previous speakers Cerwin Vega HED 15's did not.
Now I am wondering since they have been mothballed for a few years (I currently use Totems) that before I try a speaker build from scratch, I should try a rebuild 1st as I still enjoy the styling of the cabinets.
So here is the challenge. Who has ideas as to how to get the most out the cabinets? What mods,(drivers/wiring/crossovers) would be best for this cabinet and really be a real sonic upgrade from the originals? project
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Why would it have to be? It could have a protruding center baffle of say an additional 3-4" thickness and slope out the the edge as is. Make use of the baffle width. That would be good for a variety of reasons.
I would start by getting them up to spec- replace any foam surrounds that aren't holding up, and any electrolytic caps in the crossover, preferably with decent (not necc expensive) polys, or charge-coupled inexpensive polys.
The Timeframes are known to be a very solid design, you might consider just swapping between them and the totems occasionally, to keep things "fresh". Old isn't bad inherently, there are plenty of good older designs, I'd say these fall in that bracket.
If you've got the builder's itch, I recommend talc.... or speaker kits, or a proven diy extant design, like those at Zaph|Audio
The Timeframes are known to be a very solid design, you might consider just swapping between them and the totems occasionally, to keep things "fresh". Old isn't bad inherently, there are plenty of good older designs, I'd say these fall in that bracket.
If you've got the builder's itch, I recommend talc.... or speaker kits, or a proven diy extant design, like those at Zaph|Audio
The offset drivers use this to an advantage. Mirror image pairs, serial numbered.
Friend had 4 Time Windows and a Marantz quad receiver (remember them beasts) Many happy nights, 30 odd years ago
Is the DCM Timeframe 700 a sealed system? How is the bass response of that speaker? From the photo, it appears that there would be a relatively small interior volume and thus would lack much bass response.
My assumption is that a planar driver is the same as a cone driver in terms of interior volume increasing the resonance frequency of the woofer. -That really is an assumption, as I know next to nothing about planar drivers.
If the above is the case, my idea would be to increase the interior volume to improve bass response, perhaps by an extension behind the cabinet adding to the interior volume and also improving stability of the speaker.
As they are now, how do you avoid them being easily knocked over?
Regards,
cT
My assumption is that a planar driver is the same as a cone driver in terms of interior volume increasing the resonance frequency of the woofer. -That really is an assumption, as I know next to nothing about planar drivers.
If the above is the case, my idea would be to increase the interior volume to improve bass response, perhaps by an extension behind the cabinet adding to the interior volume and also improving stability of the speaker.
As they are now, how do you avoid them being easily knocked over?
Regards,
cT
Well, you might find this interesting
DCM TimeFrame Tf-700 refurb - Hifi Hangar
Looking at the pictures, could you give more info about the port? It does not look optimal somehow.
To REALLY refurb, you would need to get some kind of measurement system or borrow one or have a fellow neighbor come by with one. Then you could measure each driver and rework the crossover.* But that would be a big project.
On the simpler side, if you could get a signal generator or even a test-tone disc, or an online generator or app, you could generate an impedance curve. That could tell you a lot:
- Tuning frequency of the port, from whence we could discuss if the port is really useful.
- Some resonances of the cabinet
- Some resonances of the port itself.
Have you opened these up? Most commercial designs don't have maximum bracing inside, nor stuffing and/or coatings for acoustic and vibration absorption. If you can show us what is inside, maybe this area could be improved.
If you could open them and accurately calculate the internal dimensions, it might be possible to change out the drivers and crossover for a new design.*
*Speaker design has progressed a lot, but then again the DCM stuff was well regarded. I would work to fix the surrounds if loose first of all. Then I would improve the bracing, coating, and stuffing if not already done from the factory-this can make a HUGE difference, really shocking. Then I would try to measure the impedance to see about the porting.
DCM TimeFrame Tf-700 refurb - Hifi Hangar
Looking at the pictures, could you give more info about the port? It does not look optimal somehow.
To REALLY refurb, you would need to get some kind of measurement system or borrow one or have a fellow neighbor come by with one. Then you could measure each driver and rework the crossover.* But that would be a big project.
On the simpler side, if you could get a signal generator or even a test-tone disc, or an online generator or app, you could generate an impedance curve. That could tell you a lot:
- Tuning frequency of the port, from whence we could discuss if the port is really useful.
- Some resonances of the cabinet
- Some resonances of the port itself.
Have you opened these up? Most commercial designs don't have maximum bracing inside, nor stuffing and/or coatings for acoustic and vibration absorption. If you can show us what is inside, maybe this area could be improved.
If you could open them and accurately calculate the internal dimensions, it might be possible to change out the drivers and crossover for a new design.*
*Speaker design has progressed a lot, but then again the DCM stuff was well regarded. I would work to fix the surrounds if loose first of all. Then I would improve the bracing, coating, and stuffing if not already done from the factory-this can make a HUGE difference, really shocking. Then I would try to measure the impedance to see about the porting.
folkie13:
I'm also rebuilding a pair of DCM TF-700s, and am having a very hard time getting a crossover schematic for these
did you ever get one, or by any chance can you post a photo of your crossover? (unmodified if possible)...
I'm especially interested in resistor R1: whether yours had this part included, and if so, what was the resistance value? (possibly 15 or 47 ohms)
I've attached a schematic for the TF-1000, which *apparently* uses the same crossover, except that RA is 47 ohms (not 100 ohms)... it shows an R1 with value 15 ohms
thanks!
I'm also rebuilding a pair of DCM TF-700s, and am having a very hard time getting a crossover schematic for these
did you ever get one, or by any chance can you post a photo of your crossover? (unmodified if possible)...
I'm especially interested in resistor R1: whether yours had this part included, and if so, what was the resistance value? (possibly 15 or 47 ohms)
I've attached a schematic for the TF-1000, which *apparently* uses the same crossover, except that RA is 47 ohms (not 100 ohms)... it shows an R1 with value 15 ohms
thanks!
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