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Posts by wakibaki

Here's a simple TH layout.     This file has the gerbers:       Or for SMT, I'd modify the schematic a bit to make it easier to route:     Giving us this:       ... which would be more convenient if, for example, you wanted to panel mount it, as the side facing has only the display and a few SMT res. on it. The display would need to be surface mounted, but this is not a big problem as it has long legs, I've...
  Ah, right. Chances are the line inputs are already buffered.   You can do this, as long as the PSU voltages do not exceed +/- 18V       ...but why not just connect the speaker outs from the gainclone to the speaker ins?   w
The sensitivity (gain) of the subwoofer may not match the sensitivity of the gainclone. You really want another preset pot in there to allow you to do a one-time adjustment of the sub volume. You could use a simple opamp buffer after the volume control but before the preset, to make sure that the feed from the volume pot to the gainclone will be unaffected to all intents and purposes..   Of course you may find that the sub is too quiet, relative to the GC. A way...
Nice big transformer there, don't bin that...   w
Assembly language, assemblers and compilers.   While, as I have said, it is possible to look up opcodes in a table and program a computer by entering them as numbers, this is a tedious process.   In order to lessen the effort, a system was devised where each opcode was assigned an easily remembered alias, called a mnemonic.   It then became possible to write a program as a series of lines of text (often stored in a PC 'file'), each line containing a mnemonic,...
What does a microcontroller or microprocessor do?   A microcontroller is obviously intended to do something. But what?   When first switched on, a microcontroller outputs a specified address on its address bus and reads (fetches) the contents of the memory at that address. (This can be external to the device or entirely internal, depending on the exact design). The specific memory location is hardware programmed into the processor's gate logic. It could be...
A repair might be possible if you get good advice, particularly if you can find somebody who recognizes this particular bit of kit.   Very often the best thing to do is a salvage operation, where chunks of the original are kept, such as the power supply.   Do you have a multimeter and know how to use it?   If not, the learning curve will be very steep for you, it might be better to give the whole thing to somebody else, either to fix, or as a gift.   w
OK, from re-reading your original post, the DA and AD in each unit share the same PSU, is that correct?   That would mean that the PSRR of the DA is poorer than that of the AD, if the cause is ripple on the PSU.   So you have to wonder why that would be the case... and take a look at the schematic and the PCB to see if there's anything that might provide an explanation, or that might be down on performance (electrolytic cap?) that you might reasonably replace in...
Here's the circuit for the meter:-     ...you shouldn't have any difficulty making out the detail at this scale. This is jumping ahead a bit, but I'll review a lot of the design decisions later. In the meantime you have the circuit to refer to and think about.   The circuit is simple.   Only the vaguest nod is given to signal conditioning in the form of C2, which will smooth the input a bit, but this thread is not about signal conditioning. Most any...
  98 dB down is quite a long way down. Below the noise floor of a CD long way down.   It's rare in a domestic environment that there isn't a certain amount of mains hum picked up from the surrounding wiring by most any piece of equipment. Depending on the exact nature of your surroundings and installation you may not get an improvement by changing your power supply. It's not absolutely clear exactly how it's getting into the system, you'd have to cross test or take...
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