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stereo coffee

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  1. Yes ...shirley, the bolt needs to be isolated, so as not to form a shorted turn through the transformer https://toroid.com/general-isolation-transformers/ " If you choose to apply your own mounting solution, remember that it is important that our transformer be mounted in such a way that the mounting screw and the metal chassis will not form a closed loop through the center and thereby create a shorted turn on the transformer."
  2. Toroidals exhibit highest flux at their core, hence the central bolt needs isolation from chassis, as well as mentioned by @rockeater rubber gaskets either side of the transformer.
  3. Money is not necessarily related, for instance we are in a era where CD integrated circuits to a large degree dictate what is heard. many choices we used to have and really enjoy, sadly are no longer there, and features of use rather than sound quality gather attention. We have sadly passed the baton of sound quality to those who may, or may not not necessarily concern themselves with sound quality. Rather if we step back in time when the multi bit players were ( and still are ) the best sounding, we then approach a CD player purchase differently. the era of multi bit players saw specialist analog output stages, it saw attention to oversampling, and how digital to analog conversion occurred. each area received individual attention, much to the delight of audiophiles. Indeed some modern players have adapted well from the golden era , but others less so. Widening your choices can only be of benefit, to what you then hear.
  4. If the topic could instead ask, "Best sounding CD player" Features are no doubt important, but sound quality more so I think.
  5. The important specification of any power amp is its sensitivity for full output, in the case of the marantz https://www.hifiengine.com/manual_library/marantz/mm9000.shtml its specification is outstanding, at 0.1v for full output. Sadly though it makes level adjustable via a small trim on its rear panel A two channel power amp, with suitable sensitivity below 500mv for full output, might be the better choice, if your needs are stereo vs AV
  6. With transformer step up, unfortunately L (inductance) from my experience is not conducive to transparent audio at all ( TVC ) , rather what you end up with is a awkward inserted reactance circuit with phase issues. Keeping audio signal with just ideal resistance properties in its simple and pure form as a L pad, is by far preferable. Better to always arrange the sensitivity of power amps to always perfectly match the output of your source component, and use appropriate resistive attenuation in between. Or arrange the sensitivity of your speakers, assisted by power amplifier wattage, to compensate.
  7. The heatsink is under the circuit board, with transistors between. it is a technique of assembly often seen in Radio frequency amplifiers.
  8. Yes LM4562, or opa2107 https://www.ti.com/lit/ds/symlink/opa2107.pdf
  9. A pleasure . Some interesting reading is the attempts at reducing AM radio transmission mast dimensions, with a design called the Crossed field antenna which were published in Electronics World and caused many heated discussions. https://en.wikipedia.org/wiki/Crossed_field_antenna The design made a number of claims http://customers.hbci.com/~wenonah/cfa/cfa.htm but other than antenna's installed in the designers home country, there have been no successful attempts thus far, to reduce the very awkward engineering and enormous cost with the dimensions AM antenna's require.
  10. Popping noise can be what is called positive feedback, which gets the cute name of motor- boating https://en.wikipedia.org/wiki/Motorboating_(electronics) Is it showing green as charged, and are you using the recommended charger ?
  11. If your replica Pass Aleph 5 follows the original schematic, and you use sensible levels, then you can avoid some of the circuit paranoia that the Aleph deploys. A study of the schematic shows the original has arrangement for balanced input as well as single ended, and arranges 9.1v zener diodes to clip the audio signal should level go that high. I am unsure if you are using balanced or single ended cabling? The downside of using zener diodes, at audio inputs like the Aleph uses, is dark current noise, a unwanted attribute of diodes, whilst some might argue the diodes are not conducting until their avalanche characteristic is reached, this paper finds better characteristics from such diodes when exposed to light and at higher temperatures. https://www.vishay.com/docs/85966/thenoiseofavalanchebreakdown.pdf or better not to use such diodes at all - which then just requires use of sensible levels. I have often pointed to understanding actual levels that are in audio systems, which bears repeating here. Namely a CD player, and audio codec files playing commercially available CD's or streamed content restricts its actual output to below 350mv RMS, this is because there is no higher level on the CD, or file itself. The image shows Swiss band Sonars track Tranceportation. Accordingly it makes very good sense not to artificially increase level, by adding coloration and distortion, beyond the source, rather to preserve the source audio, and simply use appropriate attenuation, and have power amps rated with sensitivity to precisely this same level namely lets say 375mv. But addressing your requirements, there are two approaches, namely using the Aleph 5 exactly as it presently is, the schematic shows the use of a L pad at each type of input, there is also very slight imbalance in the circuit values, namely the shunt 100k has no equivalent at the cold input., which requires a 100k resistor. Or to change the divider relationship which appears not to be critical by arranging each of the shunt resistances as 22k I hope that assists
  12. Yes one to label AM the other to Gnd , however the loop antenna design , needs comparison to a outside mounted and lightning protected with gaseous , type, or on the cheap a auto spark plug. You may find the actual earth grounding outside of such an antenna superior to the Gnd facility on your tuner. Also metal window frames might prove useful using a clip to fasten , to work as your antenna - if your antenna has to stay inside. As for length of the receiving element, go absolutely nuts, as you won't even get close to what is really required, if you can find a water pipe to attach to that might save cost in cabling. If we briefly look at how AM is transmitted we see what are called earth mats and usually deep rods into the ground, and the mast often top fed, meaning coax cable to reduce loss, goes right to the top of the transmitter mast, then the transmitting element is below that vertical structure. https://en.wikipedia.org/wiki/Mast_radiator
  13. Reading the manual for you, it appears to be supplied with a universal adapter, however just needs a USA to Australian mains plug adaper which are readily available. See page 5 https://downloads.monoprice.com/files/manuals/33305_Manual_190219.pdf
  14. Yes quite correct, it can be done with one full wave bridge, but is a bit lazy, as it involves the transformer centretap being grounded, and the full wave bridge snapping each polarity on in turn. Better is a full wave bridge for each rail, and as you say derived from two secondaries. From there the amplifier actual load should be in the grounding, vs ground potential. For interest the AR classic amplifier schematic at hifi engine shows how DC loads should be wired, but never invariably are.
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