I have 2 K8060 kits to build and want to construct a stereo amplifier. At page 16 of the (English) assembly manual there is a NOTE that warns "Never attempt to run two amplifiers from a single transformer. Can someone tell me if this warning only relates to using the recommended transformer -TR8040 - or ALL transformers? I had planned to use a 2X30VAC, 5 amp transformer to power 2 kits. Why would there be a problem?
What if I use my transformer, 1 separate bridge rectifier (remove the 4 rectifiers from each board) and a pair of 10,000 mfd /75 volt caps to power both boards?
What if I keep the boards as originally designed (rectifiers on board w/board mounted supply capacitors) - but use my single transformer to power both boards?
We DO NOT recommend to run two kits from a single transformer (ANY transformer). Doing so will result in serious hum problems due to ground loops !
Don’t be offended, but unless you are an expert, which you are obviously not as you ask this question, do NOT attempt to modify the amps so that they can run from a single transformer. Use two transformers and go for a ‘dual-mono’ approach. It will save you a lot of hassle and frustration!
I do appreciate your prompt reply. However, I would like this exchange to be educational - to help me understand why running 2 - K8060 modules from ONE transformer creates a problem. I am aware of concept of “ground loops”; however, in as much as the vast majority of amplifiers on the market do indeed operation with ONE transformer powering 2 channels, there must be something about the circuit layout or wiring scheme for the K8060 that results in a ground loop - when using only a single transformer. I would simply like to understand what that characteristic is - and then I’ll move on!
If indeed, there is no way to make both channels operate from a single transformer - without ground loop problems, would it do damage to ONE K8060 module if I operate only that ONE module from my 2/30vac, 5 amp transformer??
We are sorry, but supplying theory would take us too far and is beyond the goals of this forum. Limited time and resources forces us to stick to the main purpose of this forum.
From my previous post, it should be clear that you can run two units from a single transformer. However, we do not have the means to make a test setup and send you a ‘grandma-proof’ diagram of how to do it. If you are not able to do it yourself and solve the problems you encounter along the way, then you should not attempt to perform this modification.
It was just a figure of speech, I did not mean to offend anyone…
What I mean is: we do not have the means to supply a diagram, which if followed to the letter, will result in 100% satisfaction and no problems whatsoever. If you insist on running two amps from a single transformer, you will have to remove the bridge diodes from both units and use a single bridge. The smoothing caps can remain on the board. Make sure to use a ‘star’-topology for the ground wiring. Be warned: it is very likely that you will encounter hum problems caused by the layout of the ground wiring. At that point, you will have to solve them yourself by experimenting, as we cannot solve such items without actually having the assembly on our testbench.
