HI there.
I have been a KEF fan for over 40 years starting with Calindas. After a few years of KEF 104/2 ( I also happen to be moderator on the KEF 104/2 Owner group on FB) and missing a few deals on 107/2s, I finally ended buying a good set of 107/2 this summer. After 16 hours of undoing what previous tech did to the speakers (including finding shims stuck on the voice-coil after a refoam job), they are now finally clean. Sadly, they didn't come with the KUBE 107/2, and when I found them for sale, they are at outrageous prices. High prices driven by way more demand than offer, plus a little KEF fetichism, I suppose. So, I decided to make clones. It started with a conversation with SpeakerGuru at www.hifiloudspeakers.info/speakertalk, ex KEF engineer, and I ended up with a prototype KUBE 200 that KEF engineers used for testing a new Sub and satellite system in the US around 1991. That KUBE 200 was a left over from when KEF got bought out by the Chinese group. Many good equipment found their way into the trash bin. Sometimes salvaged like this KUBE... That KUBE is no longer a 200 as the BEC (Bass Extension Curve) and input and output gain stages have been modified 33 years ago. But that's a good start to study and make clones. And it works quite good on my 107/2, and better fits them than the KUBE 104/2.
I have put my hand on brand new KUBE 200 PCBs, revision 2, and I am making a 100% clone of the KUBE 200 for myself, as well as a hybrid version of the KUBE 107/2. The later will have the BEC of the 107/2, but the tonal correction of the KUBE 200. I also have all the white papers and data for both devices sourced from SpeakerGuru. Not the limited pdf stuff that can be found on Hifi Engine.
Fascia will be CNC machined. But the box will be 3D printed since purchasing a minimum order of 20ft of 2"x6"x1/8" extruded aluminium won't work for me at that stage of the project. 18 gauge stainless steel for front and rear framework. I have modified RCA quad connectors so that the R channels get the Red plug (bought 100 of them ;-) ). That explains why on original KUBEs, the connector is red plastic. That RCA connecting block is flipped upside down. I also found 12 and 18-pin ALPS latching push button switches. Supposedly "imported from Japan". But I doubt that. Most likely knock-offs.
I don't intend to offer complete units. But will most likely sell bare boards with mechanical components, fascias and front/rear stainless steel framework. 3D print your own casing or make it out of 1/8" precious wood. DIY enthusiasts can then populate the boards with the electronics of their choice. And experts will be able to experiment. Which is why I am using sockets for the OpAmps. Some will stick to the original ones, others will feel the urge to upgrade to newer ones and recalibrate the circuits if needed. Pretty sure that tech savy members will offer to assemble complete boards for others.
I am posting a few pictures here to show progress. Any question or comment? Don't be shy.
I have been a KEF fan for over 40 years starting with Calindas. After a few years of KEF 104/2 ( I also happen to be moderator on the KEF 104/2 Owner group on FB) and missing a few deals on 107/2s, I finally ended buying a good set of 107/2 this summer. After 16 hours of undoing what previous tech did to the speakers (including finding shims stuck on the voice-coil after a refoam job), they are now finally clean. Sadly, they didn't come with the KUBE 107/2, and when I found them for sale, they are at outrageous prices. High prices driven by way more demand than offer, plus a little KEF fetichism, I suppose. So, I decided to make clones. It started with a conversation with SpeakerGuru at www.hifiloudspeakers.info/speakertalk, ex KEF engineer, and I ended up with a prototype KUBE 200 that KEF engineers used for testing a new Sub and satellite system in the US around 1991. That KUBE 200 was a left over from when KEF got bought out by the Chinese group. Many good equipment found their way into the trash bin. Sometimes salvaged like this KUBE... That KUBE is no longer a 200 as the BEC (Bass Extension Curve) and input and output gain stages have been modified 33 years ago. But that's a good start to study and make clones. And it works quite good on my 107/2, and better fits them than the KUBE 104/2.
I have put my hand on brand new KUBE 200 PCBs, revision 2, and I am making a 100% clone of the KUBE 200 for myself, as well as a hybrid version of the KUBE 107/2. The later will have the BEC of the 107/2, but the tonal correction of the KUBE 200. I also have all the white papers and data for both devices sourced from SpeakerGuru. Not the limited pdf stuff that can be found on Hifi Engine.
Fascia will be CNC machined. But the box will be 3D printed since purchasing a minimum order of 20ft of 2"x6"x1/8" extruded aluminium won't work for me at that stage of the project. 18 gauge stainless steel for front and rear framework. I have modified RCA quad connectors so that the R channels get the Red plug (bought 100 of them ;-) ). That explains why on original KUBEs, the connector is red plastic. That RCA connecting block is flipped upside down. I also found 12 and 18-pin ALPS latching push button switches. Supposedly "imported from Japan". But I doubt that. Most likely knock-offs.
I don't intend to offer complete units. But will most likely sell bare boards with mechanical components, fascias and front/rear stainless steel framework. 3D print your own casing or make it out of 1/8" precious wood. DIY enthusiasts can then populate the boards with the electronics of their choice. And experts will be able to experiment. Which is why I am using sockets for the OpAmps. Some will stick to the original ones, others will feel the urge to upgrade to newer ones and recalibrate the circuits if needed. Pretty sure that tech savy members will offer to assemble complete boards for others.
I am posting a few pictures here to show progress. Any question or comment? Don't be shy.
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Sounds cool.
Wondering if you happen to have the detailed specs for the Cube for the 104/2? I am the original owner of a pair, obviously purchased a LONG time ago and never purchased the corresponding Cube. I might tinker with building my own if I had the specs/schematic for it. You're right about what happened to the prices afterwards ...
mlloyd1
Wondering if you happen to have the detailed specs for the Cube for the 104/2? I am the original owner of a pair, obviously purchased a LONG time ago and never purchased the corresponding Cube. I might tinker with building my own if I had the specs/schematic for it. You're right about what happened to the prices afterwards ...
mlloyd1
Hi. I don't have the white papers for the KUBE 104/2. I did make a graph a few months ago showing the different correction curves between KUBEs. Different speakers with different needs. The KUBE 104/2 does show up from times to times and at a much cheaper price than KUBE 200 or 107/2. I have seen 4 being offered in the past 6 months on the FB group. But you are right, it does require time and patience to find one.
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Insane. 32 hours to 3D print a 2"x6"x 7-7/8" box with 1/8" walls.
That will do until I can find a source for cheap aluminum extrusion, in small quantities. Not yet willing to purchase 21ft of it... ;-)
That will do until I can find a source for cheap aluminum extrusion, in small quantities. Not yet willing to purchase 21ft of it... ;-)
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New poster here. I'm running 105/3's and have wanted to get a Kube just because I can't imagine these sounding any better but want to find out!
Your project looks amazing. But for those of us who are still working on soldering something finer than a copper pipe, I'd love to see you offer complete units.
Your project looks amazing. But for those of us who are still working on soldering something finer than a copper pipe, I'd love to see you offer complete units.
I understand the need for some people to have complete units. Which is why I will most likely ask some tech savior members of this group if they want to do the assembly for others. Unless I can find locally a Indian or Chinese techie working for a lower wage than the usual snobie audiophile rate ;-)
BTW I 3D printed a fascia to test fitment and it is perfect. I even improved over the original design so that the fascia lines up perfectly on both X and Y axis by integrating a lip.
Final casing and fascia shall be CNC machined aluminum if I can manage to group a production for at least 20 kits. But I am not there yet.
I will assemble two prototypes for myself and teste them before publicizing any production.
BTW I 3D printed a fascia to test fitment and it is perfect. I even improved over the original design so that the fascia lines up perfectly on both X and Y axis by integrating a lip.
Final casing and fascia shall be CNC machined aluminum if I can manage to group a production for at least 20 kits. But I am not there yet.
I will assemble two prototypes for myself and teste them before publicizing any production.
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I don't intend to perform any modifications to the KUBE. The technical involvement is beyond my capacities. KEF designed a Pro KUBE 30 years ago with balanced XLRs, but I don't think it was commercially produced. You'd have to have an expert tech modify the circuitry. Not to mention that the rear panel is already cramped. You'd have to give up the TAPE inputs and outputs to make room for XLR connectors. Mods to the circuitry to accomodate a higher output too.
But as I intend to offer the components as a kit, then that's perhaps the perfect opportunity to redesign it.
If you can fit 2 male XLRs and 2 female XLRs in a 70mm x 40mm area, then it is physically possible.
But as I intend to offer the components as a kit, then that's perhaps the perfect opportunity to redesign it.
If you can fit 2 male XLRs and 2 female XLRs in a 70mm x 40mm area, then it is physically possible.
Ya I wouldn't care for anything more than kef on and off with no care for tape. I have a 107/2 kube but, I want to utilize xlr
Each square connector requires 27 width x37mm height. That means you'd use the whole height of the rear panel (37mm out of nthe 40mm available) and line up 4x 27mm wide connectors. That will take almost the whole 140mm width of the rear panel, and will require to move the 5-pin DIN power inlet to the end of the panel. So, no TAPE or Auxiliary outputs.
Unless you make a remote connecting panel. But that's much less elegant. ;-)
Unless you make a remote connecting panel. But that's much less elegant. ;-)
Speaker Guru, ex KEF engineer, told me they indeed designed and prototyped a «PRO KUBE with balanced XLR in and out, used NE5532s throughout and ran with a higher headroom +/-20V supplies. They were built in a 1U 19" cases. They were never really launched or promoted and so never took off».
BTW He has leftover components from those PRO KUBE but no schematics. You can contact him directly about that.
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«Can you post schematics please»
I sure will, as soon as I have made the two first clones to ensure everything checks out ;-)
I sure will, as soon as I have made the two first clones to ensure everything checks out ;-)
Contact him... Maybe he can work something out for you.
He has left over parts from the project. Maybe that'S your chance to put your hand on some extra rare parts and finish the project.
He has left over parts from the project. Maybe that'S your chance to put your hand on some extra rare parts and finish the project.
I'm doing the grocery list before ordering the componants to populate the PCBs. I have found most of them, as close as original as possible.
I have already identified the 10nF 63v blue capacitors from the KEMET inventory
But those pesky 100nF black square ones, no result
Anyone has an idea?
I have already identified the 10nF 63v blue capacitors from the KEMET inventory
But those pesky 100nF black square ones, no result
Anyone has an idea?
I did do some looking around for your black 100nf polystyrenes, and couldn't find anything.
One enclosure manufacturer that was used for a dynalo mini group buy was http://www.enclosuresandcasesinc.com/desk-top---specs.html. A completely machined (face/back plates, and top and bottom driilled pattern) and anodized case ran around $60 in lots of 10 IIRC, cut to a specific length. Just a thought.
One enclosure manufacturer that was used for a dynalo mini group buy was http://www.enclosuresandcasesinc.com/desk-top---specs.html. A completely machined (face/back plates, and top and bottom driilled pattern) and anodized case ran around $60 in lots of 10 IIRC, cut to a specific length. Just a thought.
Indeed, those 100nf polystyrene capacitors are nowhere to be found. I guess I'll have to source something of a different material. SpeakerGuru told me that the blue 10nF caps were the higher capacitance they could find with polypropylene. "PP has the lowest loss and least charge retention"
Interestingly, I purchased an early KUBE 200 with Issue 1 PCB, and those 10nF caps are totally different. Looks like the KEF engineers may have increased quality/performance over the span of production. Also a few more differences on that Issue 1 PCB. Blue 1-nF polypropylene caps are nowhere to be found. Solders are all original. So not a repair work.
Thanks for the link.
Interestingly, I purchased an early KUBE 200 with Issue 1 PCB, and those 10nF caps are totally different. Looks like the KEF engineers may have increased quality/performance over the span of production. Also a few more differences on that Issue 1 PCB. Blue 1-nF polypropylene caps are nowhere to be found. Solders are all original. So not a repair work.
Thanks for the link.
The list of components is done. Couldn't find 100µF 63v Polystyrene caps, so for now, will go with Polypropylene. All components available from the same source at Digikey. Original Phillips 10µF 16v Tantal caps are no longer available. Will replace with Vishay.
PSU 1000µF 63v caps shall be Panasonic, maybe Nichicon. People will be free to get any other they want. ;-)
PSU 1000µF 63v caps shall be Panasonic, maybe Nichicon. People will be free to get any other they want. ;-)