Hi AR2,
Thanks for all the insight and input, especially the pictures. And nice job on the photos too!
The way I see it I am going to need about 65 volt rails to do this with two 3 KVA transformers per amplifier each feeding one rail. That's probably close to 100 pounds of transformers alone. I am undecided on heatsinking and weather to do convection or water cooled. I lean towards water cooled because so few people here attempt it and copper heatsinks with copper tubing silver soldered for heat transfer just seems appealing and efficient. It should also make for a more compact amplifier. Anyway, more thinking to do on this for sure...
Thanks!
Mark
Thanks for all the insight and input, especially the pictures. And nice job on the photos too!
The way I see it I am going to need about 65 volt rails to do this with two 3 KVA transformers per amplifier each feeding one rail. That's probably close to 100 pounds of transformers alone. I am undecided on heatsinking and weather to do convection or water cooled. I lean towards water cooled because so few people here attempt it and copper heatsinks with copper tubing silver soldered for heat transfer just seems appealing and efficient. It should also make for a more compact amplifier. Anyway, more thinking to do on this for sure...
Thanks!
Mark
Mark,
water cooling will work quite fine I agree. I was looking into that but than I found these heat sinks relatively affordable, so I went for it. I think doing water cooling might be really interesting. I am just curious if there is sound coming out of pump? That might be annoying, since you will not listen to this amps at higher levels.
How are you going to use these amps? I really would suggest to try them in real environment at half VA size transformers and than to decide. You might find that you will not need that much of reserve, because you will rarely reach peaks. I have original transformers used in X1000 and X600 and decided not to use them. They are massive and super heavy and packing those is a major undertaking. Nelson was handing those out at our first Burning Amp and not many people were interested in taking them as they really need muscle and real estate. So I ended up with few of those good enough to build X1000. In my case 1500VA per amp works quite fine. If you are building Class A I would say yes, you will need it nut these are Class AB after certain point.
On the pictures I posted I had at the time just that desktop mill but here is the beauty I use now:
water cooling will work quite fine I agree. I was looking into that but than I found these heat sinks relatively affordable, so I went for it. I think doing water cooling might be really interesting. I am just curious if there is sound coming out of pump? That might be annoying, since you will not listen to this amps at higher levels.
How are you going to use these amps? I really would suggest to try them in real environment at half VA size transformers and than to decide. You might find that you will not need that much of reserve, because you will rarely reach peaks. I have original transformers used in X1000 and X600 and decided not to use them. They are massive and super heavy and packing those is a major undertaking. Nelson was handing those out at our first Burning Amp and not many people were interested in taking them as they really need muscle and real estate. So I ended up with few of those good enough to build X1000. In my case 1500VA per amp works quite fine. If you are building Class A I would say yes, you will need it nut these are Class AB after certain point.
On the pictures I posted I had at the time just that desktop mill but here is the beauty I use now:
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AR-2,
I agree on trying a smaller transformer plus it is almost impossible to get 3KVA toroid's off the shelf, you have to have them custom wound. 1500 VA seems to be the largest off shelf toroids available these days and what I would do is make space for two of them in the chassis so a second Toroid could always bs be added and the power supply re-wired as transformer one per rail. However, if Nelson still happens to have a pair of those laying around I would jump on getting them. In fact I'd drive all the way there to get them! But I realize that was some years back and they are likely gone by now.
The pumps we use in digital cinema projectors are relatively small and basically silent. The motor is Hall effect and drives the pump magnetically. In several versions of the NEC projectors the entire water cooling system is modular and removable as a unit for cleaning and repair. The are no-drip quick disconnects between the light engine loop and the pump/heat exchanger unit. The bigger issue is going to be the noise from the cooling fan moving air through the heat exchanger. On the Krell's that I built even though the fans are turning at half speed they are still barely audible and annoying during quiet passages in music. So I may have to consider some sort of central cooling unit that handles the cooling of both amplifiers and has noise reducer duct inside so you can't hear the fan. Experience in designing THX cinema sound systems getting the NC level low enough and working with various HVAC contractors has taught me that if you place several S-turns in the HVAC ductwork the air handler becomes inaudible. This sort of thing may also be possible to do in a small cooling unit.
Mark
I agree on trying a smaller transformer plus it is almost impossible to get 3KVA toroid's off the shelf, you have to have them custom wound. 1500 VA seems to be the largest off shelf toroids available these days and what I would do is make space for two of them in the chassis so a second Toroid could always bs be added and the power supply re-wired as transformer one per rail. However, if Nelson still happens to have a pair of those laying around I would jump on getting them. In fact I'd drive all the way there to get them! But I realize that was some years back and they are likely gone by now.
The pumps we use in digital cinema projectors are relatively small and basically silent. The motor is Hall effect and drives the pump magnetically. In several versions of the NEC projectors the entire water cooling system is modular and removable as a unit for cleaning and repair. The are no-drip quick disconnects between the light engine loop and the pump/heat exchanger unit. The bigger issue is going to be the noise from the cooling fan moving air through the heat exchanger. On the Krell's that I built even though the fans are turning at half speed they are still barely audible and annoying during quiet passages in music. So I may have to consider some sort of central cooling unit that handles the cooling of both amplifiers and has noise reducer duct inside so you can't hear the fan. Experience in designing THX cinema sound systems getting the NC level low enough and working with various HVAC contractors has taught me that if you place several S-turns in the HVAC ductwork the air handler becomes inaudible. This sort of thing may also be possible to do in a small cooling unit.
Mark
Mark,
Look at the F5T article and also at the BA-3, either design will scale to use many, many mosfets and with a bridge front-end driving the outputs balanced, be able to hit essentially whatever power goal you desire.
At some point, however, heat management becomes a much bigger issue than circuit. But you seem to understand that.
Look at the F5T article and also at the BA-3, either design will scale to use many, many mosfets and with a bridge front-end driving the outputs balanced, be able to hit essentially whatever power goal you desire.
At some point, however, heat management becomes a much bigger issue than circuit. But you seem to understand that.
Aluminum Big Amplifier Chassis Enclosure Based on Pass XA160 5 480 260 499mm | eBay
Aluminum Big Amplifier Chassis Enclosure for Pass XA200 High Power Class A Amp | eBay
Above links to Chassis clones, amazing that they can make them for so little.
Best of luck
Peter
Aluminum Big Amplifier Chassis Enclosure for Pass XA200 High Power Class A Amp | eBay
Above links to Chassis clones, amazing that they can make them for so little.
Best of luck
Peter
The Chassis look nice but the few things I have bought from China have all been let downs. Plus I don't believe in supporting their slave labor market. It just isn't right. So I don't buy anything from there any more. I think I can make as good a chassis for half that price anyway... not counting my own time of course.
Looking into Water VS. Static heat sinks... The cost may actually be slightly higher to do water cooled. I need 1/4" heavy copper sheeting to mount the devices on to and then copper tubing and lots of silver solder and copper prices are outrageous right now, then there is the heat exchanger system.
When I built my Aleph 2's back in the early 2000's I spent more on the heat sinks than I did on any other aspect of the amplifiers, about $350.00 back then. They are huge in size for an Aleph 2 and my amps only run warm and are now 12 years old! I could have easily built Aleph 1.2's on them.
Mark
Looking into Water VS. Static heat sinks... The cost may actually be slightly higher to do water cooled. I need 1/4" heavy copper sheeting to mount the devices on to and then copper tubing and lots of silver solder and copper prices are outrageous right now, then there is the heat exchanger system.
When I built my Aleph 2's back in the early 2000's I spent more on the heat sinks than I did on any other aspect of the amplifiers, about $350.00 back then. They are huge in size for an Aleph 2 and my amps only run warm and are now 12 years old! I could have easily built Aleph 1.2's on them.
Mark
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It is funny about Chinese goods. They would make it right and than skip on basics, such as screws in critical places. I bought my first mill - that desktop mill from Grizzly who sells their stuff. Mill is all good, but there are two main screws that are holding mill to the round post. All of the energy is transferred to those two screws. They used unhardened steel for those. Their steel is like a bubble gum, awful.
Although no one can argue about price for that knockoff. $ 600 and $ 300 for shipping is steal, counting for material and time needed for one to do it. $ 600 is maybe just for raw heat sinks. Obviously from a moral perspective, it should be against the law to sell complete knockoff. At least he is not selling electronic parts within, just the Al case.
For someone with mill, there is a great pleasure of making its own case, and the pride of owning it after it is done. It is just the time needed that is the highest price one needs to pay. For hobbyists, that is the biggest obstacle, short of owning machine shop. But pleasure of doing it on your own is unmatched.
Although no one can argue about price for that knockoff. $ 600 and $ 300 for shipping is steal, counting for material and time needed for one to do it. $ 600 is maybe just for raw heat sinks. Obviously from a moral perspective, it should be against the law to sell complete knockoff. At least he is not selling electronic parts within, just the Al case.
For someone with mill, there is a great pleasure of making its own case, and the pride of owning it after it is done. It is just the time needed that is the highest price one needs to pay. For hobbyists, that is the biggest obstacle, short of owning machine shop. But pleasure of doing it on your own is unmatched.
I completely agree on the Chinese goods. I have been there and done that in the past. When I had my shop in Chicago a lot of it was Enco stuff. Their big vert. mills are great, but the average Enco lathe can not hold repeatable tight tolerances. I found this out when I had to machine some flywheels for film sound reproducers. Just could not maintain decent run out so I had to farm them out and what I ended up doing was to have them precision ground between centers. They worked perfectly but that added about 2 grand to the cost of the project. I keep one of these flywheels on my office shelf as a reminder to by a Hardinge lathe the next time!! WHen I moved out west I sold off all the shop tools... kept all my measuring and cutting tools though and have been slowly piecing things back together.
A picture if the infamous flywheel....
Mark
A picture if the infamous flywheel....
Mark
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Cold Plate:
Aavid Thermalloy - 416601U00000G - Fans, Motors & Thermal Management - Heatsinks - Allied Electronics
Price isn't too bad, when stock is available. Mount the mosfets right on the plate (which is 15"x5"). There's an ebayer who occassionaly sells these in lots of 5 pretty cheap. I picked up a bunch for that single chassis 50W SOZ I've been dreaming about.
Aavid Thermalloy - 416601U00000G - Fans, Motors & Thermal Management - Heatsinks - Allied Electronics
Price isn't too bad, when stock is available. Mount the mosfets right on the plate (which is 15"x5"). There's an ebayer who occassionaly sells these in lots of 5 pretty cheap. I picked up a bunch for that single chassis 50W SOZ I've been dreaming about.
Great idea! They even come in 2 Pass, 4 Pass and 6 Pass models. Go figure... I was not able to track any place that has stock on them so I will inquire at Thermalloy. There is also this place that sells by the inch at very reasonable prices, but nothing suitable for this amplifier...
Extruded Aluminum Heatsinks from HeatSinkUSA
Mark
Extruded Aluminum Heatsinks from HeatSinkUSA
Mark
Also found the place I got my Aleph 2 heatsinks from. They were reasonable on price too!!
http://www.alexandriaindustries.com/pdf/heat_sink_catalog.pdf
Mark
http://www.alexandriaindustries.com/pdf/heat_sink_catalog.pdf
Mark
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