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Modular Build Aids [message #97228]

Sat, 25 November 2023 20:14

gofar99
Messages: 1965
Registered: May 2010
Location: Southern Arizona

Illuminati (5th Degree)

If you are like me when you design a project there are several sections that are similar or even the same. I tend to think in a modular fashion during the design process. First what is the device supposed to do and second how to make it happen. The actual device function requires thought and sometimes trial and error often but the second part the power supply is usually straight forward. This is where modular thinking comes into play. I found that with slight variations many projects use rather similar power supplies. To speed up the prototype they do not actually have be part of the initial build. So, what I have done is make about 10 modules that can be used in numerous combinations externally to the new project. Sort of like electronic Legos. This simplifies the design process, reduces the time needed, reduces last minute changes in the "boiler plate" portions and best of all saves components that get damaged or otherwise made unusable during the build. I do grant that on occasion the final layout will force some changes, but about 90% of the time the modules work out well. The various modules are actual power supplies (3), filter and rectifier modules, one for heater lift voltages, one for FET capacitor multiplier filtering and one for use with LR8 regulators for filtering. The number of combinations is quite high and the order of use can be varied to get the best results. I have two bigger "modules". One for a tube phono preamp and one for a solid-state combination linear amplifier and phono preamp. These two modules allow for comparison with new similar builds as they have known properties. /forum/index.php?t=getfile&id=3384&private=0

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Good Listening
Bruce

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Re: Modular Build Aids [message #98124 is a reply to message #97228]

Sat, 14 December 2024 19:18

Leot55
Messages: 236
Registered: June 2017

Master

Nice write-up with a smart idea about creating modular pieces that can act as a plug and play with different projects. I look forward to your posts on here because you take the time to explain your brainstorming process. I'm not much of a natural builder, so it helps me see the big picture.

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Re: Modular Build Aids [message #98126 is a reply to message #98124]

Sat, 14 December 2024 20:09

gofar99
Messages: 1965
Registered: May 2010
Location: Southern Arizona

Illuminati (5th Degree)

Hi, I often find that many projects use the same basic building blocks, so why not build them as separate pieces to use in the design of new projects. I just completed one such project. The active part of the all tube phono preamp is pretty much fixed and unchanging. Two versions only and the layout is the same, just a change in impedance of some sections. As far as I can tell both are so similar that someone listening could not tell the difference. Some subtle measurements only. So the power supply is the one area that I have focused a lot of time on. Way back in the early days I could create a wonderful device that hummed like a bumble bee. S/N at most of 50 dbv. Since then I have experimented with numerous designs. I have a "magic" number in my head of -90dbv. I want all my designs to reach that level. Simple for solid state ones, hard for tube ones. It took a lot of comparative testing on power supply designs to get the phono preamp there. I optimized ones for layout etc I can now get -92dbv. It requires careful tube selection and critical component placement and so on. If just assembled with some care (not excessive like mine) you can get -87 dbv. For those that don't know how dbvs work that is really really quiet. My fridge three rooms away and around two corners is a lot louder. Anyhow I digress. With a test set made up to test and compare all the power supply modules I was able to find what I figure is the very best combination. I was surprised by some things. The what I called "nearly as good" one has a rather simple power supply. I would say it is about 90-95% as good overall as the best one. Adding various additional components (to filter, regulate, chokes and so on) did not matter much. The best one is more complicated and deviates from that one with use of a FET capacitor multiplier, poly filter caps and so forth. A less fanatical user than I am would find it quite excellent. (as most folks know I hate hum and noise...if I can hear it or measure it then it is too much) My preamp now is limited by the internal noise of the tubes. I refuse to use negative feedback on it to cut that down as I feel that part of its magical sound is because there is only class A amplification with no NFB. NFB has its place to be sure but in designs that don't have nearly unlimited gain and bandwidth I believe it subtly alters the sound. IC designs need it and it is fine there. So with the preamp by being able to swap in and out the modules I determined the best combination. What is my next project...don't know yet.