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  1. What is being shown on the right is the relationship of signal ground to LDR cathode, at exactly the same ground potential, worded as "Fixed No Contact" Rather,in a good LDR circuit the signal ground and the "cathode" (- conventional current leaves a polarized electrical device ) , are always separated by a potential difference.
  2. Yes the LT4320 is very impressive in audio circuit power supplies. Here is a short video explaining its ability to provide higher efficiency and less heat Conventional bridge rectifiers rely heavily on capacitors to smooth the partial rectification they can only achieve. Other band aid solutions with conventional bridges include snubber networks to try to control the rate of switching. The conventional bridge rectifier is a useful circuit but is not the ideal answer for audio products. The LT4320 also requires a output capacitor but offers smooth switching without noise spikes, as phase is as I understand, timed with zero crossing As usual the proof is in the pudding - suggest you try one. The 3, that I built were very successful I used TO220 N channel mosfets part IRF 540N It is quite a challenge to build an equivalent DC rectifier from active semiconductor parts. If you attempt this using mosfets you need to slow the mosfets down by controlling each gate appropriately.
  3. Observe the top waveform which is incoming mains which has zero fluctuation in this robust demonstration of the capability of the LT4320 , https://www.analog.com/en/technical-articles/the-dreaded-file-test-on-an-lt4320-ideal-diode-bridge-controller.html
  4. The product information reveals two important graphs in the attached document for the F-81 We can see impedance at lower frequencies is a whopping 512 ohms and not too bad at high frequencies ( compared to other ESL brands ) dipping to 4 ohms at 20k This explains their recommendation of a higher powered amplifier ie above 100 watts, but lower than 300 watts. as the very high impedance of the speaker in the normal listening range is the major contributing factor to end sound pressure levels. It says to me conventional amplifiers are not up to the task. But not to say a purpose amplifier cannot be designed. Entering into this as well is for the amplifier to have low distortion - as electrostatics reveal all. I will keep on looking for you. staxELS.pdf
  5. However in caring, if for a moment that is possible I am really hoping so, it would help you to sort through external influences to a electricity grid which has some merit to know is there, and can be addressed to a degree by filters. vs not having to unnecessarily worry about harmonics that are impossible for the national grid to produce itself. Beginning to know vs presently not caring will help you pin point how these external aberrations can be solved. If you want some visual evidence of stability of the electricity supplies adherence to 50hz where you live, simply purchase a multimeter from the usual retail outlets that can read frequency and measure the output of a isolated fused 12v AC transformer - as I outlined in a earlier post. The better approach though for audio equipment is to design and use a better rectifier than the ubiquitous arrangement of diodes and capacitors we ponderously accept. Hands up how many of us have bothered to connect one of these in a audio system https://www.analog.com/media/en/technical-documentation/data-sheets/4320fb.pdf I raise my hand. Secondly optocouplers can help enormously to solve the majority of audio related noise and grounding issues. I also raise my hand.
  6. Regarding Valve amps vs SS , this is a good read http://education.lenardaudio.com/en/14_valve_amps_7.html I think we need to know more about the Stax and its specifications - have you any reference links ? Generally Yes a valve amp will have more power delivery into a higher impedance load - like an electrostatic. This too makes a fascinating read https://www.diyaudio.com/forums/pass-labs/273239-mosfets-direct-drive-esls.html , But noting there are many good valve designs and at the same time mediocre valve designs. And noting at high frequencies Electrostatics dip to a very low impedance. My thoughts are care needs to be taken with Zobel networks at the very least to enable the typical voltage valve or SS driving amp to behave. See Posts 17 and 20 https://www.diyaudio.com/forums/multi-way/190300-zobel-network-2.html also here the speaker side of the speaker cable Zobel https://theartofsound.net/forum/showthread.php?48715-Cyril-Bateman-speaker-side-Zobel-network&highlight=speaker+side+zobel
  7. You are referring I think to external influences on a national grid, not the grid itself which cannot create harmonics of its own generated frequency.( Read that again if needed ) You should find the national grid is sufficiently stiff with that frequency and current capability to not be influenced in the slightest, by domestic consumers. Which is not to say someone welding or using a motor nearby cannot create momentary added noise in some poorer distribution wiring situations. A good example of this is in parts of rural Australia where the old two wire systems delivery remain. But you will or should find with your own investigations, that the cyclic frequency of power delivery is amazingly stable.
  8. Electrostatics create certain demands on a amplifier, namely ability to drive a wider impedance and different electrical load than conventional loudspeakers. Not that voltage drive amps have any particular knowledge presently of the speaker they attach to. So its not so much outright power that is needed, rather ability to a drive wide impedance. Usually low or medium powered amps are used, that sometimes have been designed specifically for electrostatics. Like this great combination: http://www.audiomisc.co.uk/57and303/interact.html Here is a guide that applies to (perhaps the most famous electrostatic ) the Quad 57 , that could IMO be useful in choosing a suitable amplifier for the Stax electrostatics. http://www.quadesl.org/index.php/hard-core/amplifiers/christian-steingruber You will notice valve amps are good with electrostatics as their nominal impedance is typically above 15 ohms, which is not to say a SS amp is not applicable. A SS amps power delivery nicely in this case is less when driving a higher impedance, but more when driving a low impedance. You can start to see the electrostatic loudspeaker creates specific requirements of an amplifier.
  9. To measure frequency stability where you are can be done quite safely by measuring NOT the mains directly but the secondary ie low voltage side of a 12v AC transformer. Caution NEVER measure mains voltage or frequency directly using a oscilloscope or measuring frequency a conventional multimeter , rather if doing this ALWAYS USE - a fuse protected lower voltage isolating transformer. You could either use a oscilloscope which will easily handle 12v AC, or indeed a multimeter that has frequency measurement to measure 12v AC frequency stability. I did this a few nights ago with a multimeter and the frequency measuring the output of a 12v AC transformer was maintaining precisely between 49.9 and 50 hz I observed this over a ten minute period. This should by all accounts also be a rigid 50 hz where you live. Mains frequency generation to repeat is NOT subject to harmonics occurring. This is because of the total inability of the generation equipment to create any harmonic. Frequency of mains rather can alter slightly from its nominal value but is constantly monitored and adjusted accordingly typically during peak demands. https://en.wikipedia.org/wiki/Utility_frequency
  10. Yes agreed,as mains frequency stability which is extremely concise, is not subject to any harmonics occurring. higher in frequency. THD is indeed the wrong term to use with mains currents and voltages. As an aside the use of the term THD for audio frequencies is not telling you a lot, rather any harmonic distortion should be properly stated in terms of the actual frequency harmonic it occurs at, not as a lumped figure that gives little indication of the spectra the distortion may or may not reside in.
  11. Some good general ideas for using panel speakers are here, whilst Rob's are ER audio 505's there are similarities, each being panel types. Hope you sort it out.
  12. I would approach a recording studio in Adelaide. and ask if your requirements can be met. Generally they may seek to offer you noise reduction when transferring to digital - which for the cassette medium is very worthwhile, however get one digital copy with and one without said noise reduction, so you can assess which is best. There are quite a few to choose from like https://www.jrrecordingstudios.com/services https://www.wundenbergs.com
  13. Disturbing to read Kef have not considered the ever growing Linux community with this speakers software. A manufacturer of their reputation should be considering all users, and not be dictating customers toward restrictive proprietary bound software.
  14. A Quad 306 is 64mm high - other dimensions being 321mm wide by 207mm deep
  15. Actually no, from my experience it is the attenuation and power amplification which comes first, followed by the source component and finally the speakers. The layman's terms reasons are akin to building a house, the bricks being the source component, the straightness of the walls, foundations and structure being the attenuation and the amplification, and the furniture inside, being the speakers.
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