click on the image to see full resolution.So here we are at the beginning stages of the layout and by that I mean wiring layout... Internal parts layout.
This is by far the hardest part of the amp design... because you are not only considering the voltage paths of everything and the associated magnetic fields, but how easily can it be copied, how easily can it be repaired aka a part be replaced, and how well can it handle 90G impacts during shipping.
As you can see, the layout is symmetrical from the left channel to the right channel. At this stage we are just wiring all the transformer wires to get them out of the way so we can focus on building the amp.
Over the years what you are looking at is what has become my preferred build style. I use nylon stand-offs with internal threading (4-40) to receive plated copper eyelets. This is a bomb-proof design that never comes loose, bends, or caves to the 90G shipping impacts. It costs a bit more, each white stand-off is almost a buck.
The reason for tonights photo is that it occurred to me as I was soldering this that the ground buss is a factor in the design of all dual mono Decware amplifiers that might be worth chatting about.
There is a 6 inch solid copper 12 AWG wire running down the exact center of the amplifier -- this is the audio ground buss. The steel chassis will be the shield. A 10Ohm 5 watt ceramic resistor and a capacitor in parallel will bond the audio ground to the earth ground that is directly connected to the steel chassis.
This ground buss will become the center of a star ground for the entire amplifier, or should I say amplifier(s). The TORII MK5, MK4, MK3, MK2, MK1 have all been dual mono, so that means that it is two complete and separate amplifiers sharing the same chassis.
Naturally the question becomes how is this different than two separate mono blocks? The answer is the ground, and power cord.
Frankly the only thing two power cords can do is offer an opportunity for the resistance between the two to vary. That creates to ground busses that have a small potential between them. That's a recipe for noise and hum and some other nasties.
And in part because of the power cords, the tension of the IEC connectors, the recepticals, and the lengths of each side, and what it runs next to all plays a part in the sound of the amp. Besides noise, it can effect imaging.
Having a single 6 inch copper audio ground buss for both amplifiers, centered between the amplifiers with exactly the same length of wires between each channel relative to that buss and everything else sets up a potential for much tighter imaging focus and blacker backgrounds.
Our Zen TORII MK1~MK5 as well as the ZMA are all built this way, with a very deliberately symmetrical and exactly balanced audio ground buss that floats slightly above earth ground helping it to reject noise and at the same liberate it from earth just enough to create a bit of flex that adds some life to the dynamics of the amplifier.
So while in this picture it looks like almost nothing has been done yet, it reality almost everything has been done. Now it's just the details.
The NC wires you see on each channel are the various voltage taps for the world voltage power transformers... that way the amplifier can be easily re-wired for 100 volts, 115 volts, 120 volts, 220, 230, 240 volts 50/60 HZ. Many of our customers live oversees for several years and then move back home for their job. This makes it possible to have the amp wired for any voltage.
The switches you see, are all DPDT silver contact switches, the best Mountain brand for over 20 years. These are always used in Decware amps and wired with both halves of the switches in parallel so that there is never less than two separate contacts on every switch. We don't have any SPST switches like this in the building.
So as you study this image, and see the transformers both fully wired except for one wire on each side, it is time to study the schematic, (there isn't one) and each and every part (resistors/capacitors) and exactly how it's going to be placed in 3D space.
The wires you see bundled together are alternating current of different voltages. By wrapping them the field interaction smears the phase angles and helps homogenize the ripple. Rectified and filtered DC lines will be clear of these AC wires with nothing but air and space around each feed in 3D space.
3D Space is about magnetic fields around each wire, part lead, and part. On a circuit board the board combines with each part to add capacitance and the fields follow the flat traces creating a fairly 2D interaction on those fields. It is able to be calculated whereas 3D space is not, only in the mind of the guy who lays the parts out in the working bench sample, which is what you are watching develop here.
I will be leaving these images at their 5 Megabyte size so that when you click on them you can see details that simply don't live in the 800 pixel images in this post.
Steve