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stereo coffee

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    Chris

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  1. Trouble is it does not fully isolate if we peer into electronics, beyond budgetary constraints , as conventional power diodes when used in DC rectifier circuits exhibit a reverse bias leakage, that causes both heat and inefficiency, and loss. which asks what happens to that reverse bias leakage ? It suggests as being a awkward to explain switching reactance that finds its way back into the supply, which it attaches to. A LT4320 using mosfets has far better efficiency, and sounds a lot better as a result VAC / .707 for a full wave bridge vs VAC / .650 for a LT4320 indicating its rectification is more complete see image. Thyristors too are a far better switch for AC rectification than power diodes. The schottky diode is an improvement though, but has limited voltage and current capability. What @ikhuong might kindly do is repeat the tests , and perhaps show the difference if any shows up with a isotek cable vs a no brand conventional type, which might show the contribution the cable is making.
  2. Hi Rob Yes, I can see the advantages in doing that, being contactless switching switching a contactless switch, as it would be in the process preserving the main board output. I will set about designing a remote control contactless switching board for the kit. @Silent Screamer issue I think is presently best solved with a LDR board which could provide if he wishes, volume control attenuation at the same time in between his oppo unit and the butler unit. He could then use a fixed output from the oppo , rather than degrading audio quality with digital attenuation.
  3. Always best using contact less methods for switching. This might help:
  4. It seems you forgot to link the video. In the mean time here is some nice work done by SNA member @ikhuong using the same brand power leads
  5. As any circuit breaker event will prove, current is ultimately drawn from the power grid itself, but more easily visualised by the switchboard at your house,which stops current via circuit breakers being exceeded. Equipment draws from the circuit breaker to limit current, but before that a meter placed these days inductively, but ultimately your connection to the street transformer and then via Lorentz transformation equations to the grid. As such all AC wiring matters, and is referenced to 50hz at the power station delivering, Why a 2-3 metre extension to hundreds of kilometres before it matters, would need greater explanation IMO , it may as example provide a small AC inductive reactance difference that changes slightly the relationship of voltage and current over that small final section https://www.electronics-tutorials.ws/accircuits/ac-inductance.html It may be too that the manufacturers have studied the atypical toroidal transformer load, and found some very small advantage in pre conditioning the mains delivery, by using the cable as providing a conduit offering better transformer performance. The cable then acting as a filter. https://www.powerelectronics.com/content/article/21858116/power-transformer-attenuates-harmonics Instead of getting fixated alone about cables attaching to transformers or hifi gear, the focus as well IMO should be about far better rectification. the LT4320 presents itself as a ideal product, and IMO rectifiers using diodes are always problematic, a thyristor is a far superior rectifier, which is why I use them https://www.analog.com/en/products/lt4320.html
  6. ... and also even healthier still , noting the respect , when discussion begins asking questions that create the landscape of Why, One of those big questions being that the house wiring before the cable and its contribution, that does not magically disappear with 2 or 3 metres of other type of cable in front of it. If a power cable is contributing then it falls under us requiring a better understanding of series circuits, lets call the circuit, cable A + cable B which invites perhaps knowing more about that particular cables construction when B assesses being different to A
  7. Its good to consider an amplifier as being two units, an attenuator in one case , and a power amp or power amps as mono blocks in another.
  8. Finishing the evening without admiring a ESL57 grille , well its just not on is it, so here is the left channel of my 1961 speaker a bit of dusting needed mind you.
  9. Yes I have it , and regularly refer to it, its a great read, , The essence being to not directly ground the speaker load rather to reference the speaker load with only as much lower potential ( typically plain resistance ) that is is needed for the amplifiers desired output, the residue above, is directed to a sensitive inverting amplifier input, that senses the speaker lack of linearity, compared to the amplifiers input , that then nicely proceeds to correct for it.
  10. Whilst its great to match a power amplifier to a given speaker for good result, this has to also be balanced against the amplifier having suitable input sensitivity, as there are perhaps more losses that can occur earlier, that can end up being of greater concern. A amplifier should have sensitivity of 500mv or less for full output, as seen in the attached graph from a amplifier manufacturer, ( Quad ) who knows what they are doing with 85 years of experience. This is a favourite topic of mine, so regular readers will know what comes next, but can perhaps be seen in similar basis as matching amplifiers to speakers, in that earlier in any audio system the best result occurs when the voltage leaving the source component remains intact. The way this is done is to use only resistance to attenuate for purposes of volume adjustment. Similar to a voltage amplifier driving a reactance component laden speaker and sometimes really struggling to do so , A source components ability can also change irreversibly when faced with reactance. There are exotic very costly ways of designing around reactance, but invariably it is far better to avoid it wherever possible.
  11. Hi David Ah not mine, but I do have 4 of the bronze grill type 57's which look just as good, one pair from 1961 and the other from 1969. The impedance of the 2912's are 4- 20 ohms, which occurs at different frequencies. The habit of solid state amps is to deliver their available power into low impedance, whereas valve amps do the exact opposite, by delivering available power into higher impedance loads. We can see the 2912 is both, which requires if we want the best result to delve a little further into the electronics theory of electrostatic designs and amplifiers that best suit them. Electrostatics represent a capacitive load. capacitance different to resistance has energy storage which returns energy to the circuit when the circuit is then driving later signal, so an amplifier that is used, has to somehow overcome capacitive reactance. Quads own answer to this was to use a voltage amplifier with a regulated supply ( the 303 ) that drove a capacitor itself, in between the electrostatic panels and that capacitor was a transformer with mainly properties of inductance. Electronics theory tells us that capacitors and inductors combine well, so generally speaking we could expect good result by doing the same. Amplifiers after 1975 usually abandoned single ended designs and instead arranged a negative and positive supply that used transistors that used the energy from those supplies but cancelled each other in and about the audio related signal, leaving millivolts (mv) of residue called offset. Predominantly the common speaker was not sadly the electrostatic, but the moving coil design. Many decades later effort was made to suggest current drive for moving coil designs. https://www.edn.com/loudspeaker-operation-the-superiority-of-current-drive-over-voltage-drive/ and this is the real future for amplifier manufacturers to now tackle. This left a question for some amplifier designers to plough on with perfecting amplifiers for electrostatics that were frustratingly voltage drive, knowing current drive would likely provide far better answer. One such amplifier that tries to do both types of speaker is made by Sanders http://sanderssoundsystems.com/
  12. Horn speakers are typically very efficient. a well made model being the Klipsh la scala , you might only need 50 watts a channel to have exceptionally high sound levels.with them. The delicacy and essence of music you need though is earlier in the reproduction chain., needs underlining. My favourites in speakers are acoustic suspension types, ie gale GS401a or early AR models, the lack of distortion in the bass registers has charmed me for over 50 years. Quad ESL57's have the best midrange arguably of any speaker, and require careful consideration with amplification, as do most panel speakers. Worth noting too panel speakers usually have higher impedance. a solid state amp i agree is a very good choice but needs to suit higher impedance, one such power amp is the Quad 303 or Quad 306, or higher power models like the 909. with any such amp look for exceptionally low distortion
  13. Likewise this video which explains a lot of history about Digital audio, and informs what it can, and cannot achieve. Whilst its a brief detour from the exact topic its always good to know the basics, and reflect where concepts originated from IMO , which might assist understanding the audiophile gubbins ( love those new words ) @chopinmagic refers to. The most common form of digital modulation is PCM ( Pulse Code modulation ) invented by Alec Reeves in 1932, and as a concept at that time almost unusable, was assisted greatly by the work of Nyquist and Shannon who proposed the sampling theorem in 1936. There are other types of modulation that in many ways are better still than PCM for audio, one being Delta modulation. As to what is the best connection , it is neither of the two @chopinmagic refers to, rather is likely to be ultrasonic soldering https://en.wikipedia.org/wiki/Ultrasonic_soldering
  14. With some easy decisions, be prepared instead, to enjoy your computer https://www.linuxmint.com/
  15. If you read Rob's equipment list, the model of Neat speaker he uses does not have a ribbon tweeter and further received praise in review with comment "The axial frequency response is tidy, especially in view of the low order network employed." http://neatacoustics.com/wordpress/wp-content/uploads/2017/03/MomentumSX3i_HiFiCritic_-2015.pdf
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