And forgot to mention, my voltages, after the dual bridges and the inductors in the CLC storage is +/- 45 volts DC, less than 0.063 volts ripple.
The toroid is a 2.4 KVA dual primary and secondary with 37 VAC output each winding.
The toroid is a 2.4 KVA dual primary and secondary with 37 VAC output each winding.
As in many cases - what I've done to Papa's iteration is having same functionality, but it's hopelessly more complicated
so, same with Papa's pcbs vs. mine
if you want to populate them as breeze, use Papa's
if you prefer to populate them feeling pain and sorrow, use mine
so, same with Papa's pcbs vs. mine
if you want to populate them as breeze, use Papa's
if you prefer to populate them feeling pain and sorrow, use mine
Looks like good times ahead.. I went with the ZM Bablethingie FE boards because they fit well on top of the new ZM OS boards. Maybe there is a method to the madness. 😉
The PDF files are just print outs of the parts for visuals. I can generate some pdf files with the dimensions if you need them but the DXF files are CAD drawings and when opened in a CAD package you can get dimension there, or use the file on a CNC machine to drill the plates for you. Let me know, it would take an evening to generate dimensioned drawings when I get some time.
No you have done enough, thank you. I will find CAD package and open in that. Has anyone used your gerbers and had boards made yet?
Also looking at your design what is the original amp you are copying? SA1? With 45 vdc rails you are getting max about 32vac rms to speakers? If so your looking at maybe 128W/ch max. Which would be about perfect for my application. Do you know original rail voltages in SA models?
Also looking at your design what is the original amp you are copying? SA1? With 45 vdc rails you are getting max about 32vac rms to speakers? If so your looking at maybe 128W/ch max. Which would be about perfect for my application. Do you know original rail voltages in SA models?
I am not aware of anyone using the gerbers to have boards made. I regularly have other PCBs made from the gerbers I turn so I know they will work. I use Seeed Fusion PCBs in Shenzhen. They haven't had any problems with them.
My originals were SA/1 which I purchased in 1986 and unfortunately had to sell a couple years later but I kept all my service schematics and info, so these are a copy of the SA/1 and the original rail voltages were +/- 47vdc but the inductors between the capacitor banks drops the voltage a bit. So, in the pictures you can see the SA/1 has 1 FE and 2 output boards, each with 20 outputs, for a total of 40. The SA/2 has 1 FE board and two OP boards with 14 output transistors per board so 28 total. SA/1 and SA/2 are monoblocks. The SA/3 is a stereo amp using 2 FE boards and 2 SA/2 OP boards.
The Gerbers are for SA/1 and SA/2 boards but also made a Mini with 10 output transistors per board so take your pick.
You can find DXF viewers online or get a free trail version of TurboCAD. You can also find Gerber viewers online to see the boards.
My originals were SA/1 which I purchased in 1986 and unfortunately had to sell a couple years later but I kept all my service schematics and info, so these are a copy of the SA/1 and the original rail voltages were +/- 47vdc but the inductors between the capacitor banks drops the voltage a bit. So, in the pictures you can see the SA/1 has 1 FE and 2 output boards, each with 20 outputs, for a total of 40. The SA/2 has 1 FE board and two OP boards with 14 output transistors per board so 28 total. SA/1 and SA/2 are monoblocks. The SA/3 is a stereo amp using 2 FE boards and 2 SA/2 OP boards.
The Gerbers are for SA/1 and SA/2 boards but also made a Mini with 10 output transistors per board so take your pick.
You can find DXF viewers online or get a free trail version of TurboCAD. You can also find Gerber viewers online to see the boards.
So am I correct than that the SA1 and 2 are a bridged design. Speaker outputs from 2 channels out of phase?
If you look at post 1106 if will see a much used schematic from my amp repair days. If clearly shows the 4 stasis and 36 current mirror transistors in a paralleled configuration. That way it has an extremely low output impedance and could deliver lots of current to a load. Makes for very controlled low frequencies and "utterly open and clean sound" was how one of the audio mags put it in 1986. I think I still have that article in the Threshold folder, funny it was pages about the design philosophy and specs and one line about the sound.
Ok John thanks. Just want to make sure I understand all this before diving in. The SA1/2 is monoblock. One FE board feeds 2 OS boards in Parallel to the driver transistors(4). The two OS consisting of 2drivers and 18 complimentary pairs for each board are fed to the output connectors in parallel. Is there any issues with keeping the OS balanced to share the load?
You can test the transistors and use them in groups of 40 that test about the same. Or, you can just use any of them in the same amp, the 1 ohm emitter resistors do enough to balance the work. I can see in my amp where reading voltage across the emitter resistor that some are working harder than others but the devices are being used waaaaay under their rated output currents so no problem. With an average of transistors in my amp my DC offset at the output is 9 millivolts so nothing to worry me.
The original selection process simply chose output devices for adequate current gain. There was a small percentage of Motorola production that came up low.
I guess I got lucky. In 1989 I bought 320 of each outputs from a distributor in Santa Clara. Received two different lots, only tested a couple and was satisfied.
Price back then in those quantities was around $1.25 each. And everything was readily available. Good times for experimentation.
Price back then in those quantities was around $1.25 each. And everything was readily available. Good times for experimentation.
Hello everyone, best regards Nelson Pass and Zen Mod.
I am a new user to this forum but not a newbie. Recently I have been doing research on Usher power amplifiers and this is how I found Threshold and then the Stasis topology and Nakamichi power amplifiers. I have read practically the entire topic and would like to build this power amplifier. However, the version of SUSY interested me the most and I would like to ask about it because the topic died at some point. Has anyone put it together and run it at all? Is there anything going on about SUSY? Will it even work? I would love to do something like that.
I plan a 1500VA transformer and 50VDC voltage and a capacity of 180000uF, is it a good choice? Especially when it comes to the supply voltage.
Greetings.
I am a new user to this forum but not a newbie. Recently I have been doing research on Usher power amplifiers and this is how I found Threshold and then the Stasis topology and Nakamichi power amplifiers. I have read practically the entire topic and would like to build this power amplifier. However, the version of SUSY interested me the most and I would like to ask about it because the topic died at some point. Has anyone put it together and run it at all? Is there anything going on about SUSY? Will it even work? I would love to do something like that.
I plan a 1500VA transformer and 50VDC voltage and a capacity of 180000uF, is it a good choice? Especially when it comes to the supply voltage.
Greetings.
I did mention SUSY as possible, but that one needs serious work - first making everything, then put it to work
there are additional problems, regarding general stability and issues of relative offset ( voltage level of both outputs ref. to gnd)
in worst case, it'l need servo circuit, to keep outputs where needed
in short, SUSY absolutely doable, but take proposed schematic of it only as prototype
there are additional problems, regarding general stability and issues of relative offset ( voltage level of both outputs ref. to gnd)
in worst case, it'l need servo circuit, to keep outputs where needed
in short, SUSY absolutely doable, but take proposed schematic of it only as prototype
I think there are a lot of fun options to consider here, before getting into the SUSY.
The diyAudio store has some very convenient building blocks available, starting with the Deluxe 5U Aluminum chassis. This one comes with the mounting holes pre-drilled in the heatsinks, a great time saver for the large number of output transistors used in this design. I would recommend using a pair of 400VA transformers w/ 32V secondaries in this chassis. Then crank the bias current until the heatsinks are the right temperature. The 400mm depth can easily accommodate the dual-mono power supply, whether CLC or CRCRC. You can choose the 6 deep or 8 deep output stages, how you prefer.
The diyAudio store has some very convenient building blocks available, starting with the Deluxe 5U Aluminum chassis. This one comes with the mounting holes pre-drilled in the heatsinks, a great time saver for the large number of output transistors used in this design. I would recommend using a pair of 400VA transformers w/ 32V secondaries in this chassis. Then crank the bias current until the heatsinks are the right temperature. The 400mm depth can easily accommodate the dual-mono power supply, whether CLC or CRCRC. You can choose the 6 deep or 8 deep output stages, how you prefer.
At the moment I have two Kitamura Kiden R-Core transformers but only 320VA each with output voltage 37V. It's a bit too little power for bigger amps projects so I think of selling it, but I still have it for now.
I also have a pair of aleph 2 pcb and the plan was to build it on these transformers, before I found out that they do not have 450VA but only 320VA. Another problem is the huge amount of heat produced, which with my mode of use will not work because the amplifier works for several hours a day, as soon as I come back from work and turn on the computer, I also turn on the amplifier. Another thing is the large size of the heat sinks that are needed to dissipate this heat and a large amount of energy that it will take from the power grid. This is why the single ended pure class A is not for me I think.
I need something like the X150.8 or better X250.8 kind of power amplifier, so the STASIS should be good to me.
I can have 4 pieces of heat sinks with dimensions of 250x200x83mm for the side walls, so I can dissipate a lot of heat but not enough for the Aleph 2.
Tell me what would you recommend, sell these transformers and buy something stronger for STASIS or maybe build on what I have? Or maybe something completely different?
I also have a pair of aleph 2 pcb and the plan was to build it on these transformers, before I found out that they do not have 450VA but only 320VA. Another problem is the huge amount of heat produced, which with my mode of use will not work because the amplifier works for several hours a day, as soon as I come back from work and turn on the computer, I also turn on the amplifier. Another thing is the large size of the heat sinks that are needed to dissipate this heat and a large amount of energy that it will take from the power grid. This is why the single ended pure class A is not for me I think.
I need something like the X150.8 or better X250.8 kind of power amplifier, so the STASIS should be good to me.
I can have 4 pieces of heat sinks with dimensions of 250x200x83mm for the side walls, so I can dissipate a lot of heat but not enough for the Aleph 2.
Tell me what would you recommend, sell these transformers and buy something stronger for STASIS or maybe build on what I have? Or maybe something completely different?