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About stereo coffee

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    Chris

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  1. Firstly don't assess by touching , as there is risk of electric shock, which can be FATAL Turn the equipment OFF, and disconnect from the power point NOW , and await until fixed by a licensed electrician. https://sound-au.com/articles/mains-safety.htm High on the list of Why is or could be a extension lead wired wrongly, see the article. You need a licensed electrician to inspect , assess and make your power lead and possibly other equipment awaiting diagnoses, equipment safe . https://www.elextrofix.com.au/?keyword=Electrician Near Me&matchtype=p&device=c&msclkid=9d876a095a991f45101e34c2cd10bdba
  2. A few pages on their site are error 404 , also their News section has nothing new since Nov 2019 yes seems strange to not market a australian /Nz connector.
  3. No , if these types are used https://lunainc.com/product/optocouplers/ as the coupling is a variable resistance. There are poor ways of powering and good ways as explained here. Resistance Minimum though is 60 ohms, and suggested would be the two op amp method of powering, explained in the latter part of my article and exampled showing powering a LED . you can then use a conventional switch to switch each anode in turn ON, then in OFF state, the resistance created, forms on the signal side a contact-less switch. There is then above 25 mega ohms, and then when back ON, approx 60- 100 ohms - which is normally of no consequence when transferring audio from one point to the next. Adding a shunt pair with suitable ratio to the series pair which are fully ON to then form a L pad similarly with another 2 op amps, will create total silence when music is not playing. all in in all a great solution, for most ground hum problems we see time and time again - for very minimal expenditure.
  4. Bluetooth relies on pairing one device to another. You need to refer to the yamaha manual for the RX A3080, specifically pages 96, 149, 51 and 182 https://www.hifiengine.com/manual_library/yamaha/rx-a3080.shtml Pairing ensures only one device can work with another. You may though need to reassign the bedroom controller appropriately
  5. Think firstly of avoiding losses associated with contacts when passing audio signals. You can avoid contacts altogether by optical coupling, relying on the specifications provided with part NSL32SR3 https://lunainc.com/product/optocouplers/
  6. Good advice indeed, explained here, is what can happen when polarity is swapped: https://sound-au.com/articles/mains-safety.htm " Connecting Class 2 And Earthed Appliances To Each Other Although prohibited by the rule: 'Class II - do not earth', linking Class II and earthed items of audio and video gear is done routinely via the shielding on signal carrying cables. Though users enjoy a great bonus by eliminating ground loop hum, doing this eliminates all the safety advantages of Class II and allows for a horrific possibility. A potentially lethal hazard occurs if ever an earthed appliance in such a system becomes live on its chassis or internal ground circuit – the fault condition will then pass the full AC supply voltage onto the exposed metalwork of each and every Class II item in the system. As shown in Figure 6, this can happen merely because a miswired but quite functional supply lead (IEC or hard wired) is used with an AC outlet that has the otherwise harmless error of reversed Active and Neutral. While the following may seem unlikely, most service techs will have seen similar scenarios with mains leads that have been 'repaired' by unskilled people. Reversed active and neutral are surprisingly common, especially in older houses and venues, or where unskilled people have performed 'upgrades' to existing wiring. Not everyone is capable of following simple colour codes and/ or identifying which lead is which in an installation (compounded by older wiring using different colour codes). Figure 6 - Correct & Incorrect Wiring (Australian Mains Fittings Shown) The incorrectly wired plug shown will work more-or-less 'normally' in a correctly wired outlet, but it will trip the safety switch - if one is present. Without a safety switch, it's probable that no-one would ever realise that the lead is miswired unless a tester is routinely used to verify that all leads used are wired properly. While this might happen with a touring band, it most certainly will not happen in a private residence, and the fault will go un-noticed until a miswired outlet is used. The combination is then deadly. While I've shown an Australian mains outlet and plug, the same principles apply worldwide. It's nothing to do with the style of the connectors used, only the way they are wired. "
  7. Agreed, but working in tandem too, as one driver moves in the other moves out - they can fit in modest sized cabinets like gales 401, which is heavy at some 56kg each, but domestically fits in well, dare I say reasonably high WAF and very satisfying with audio, as many have found.
  8. No not necessarily proportional to speaker size, when Edgar Villchurs acoustic suspension principle is used, outstanding results can be obtained from modest cabinet size. As shown here 35 Hz +-5db http://0339436.netsolhost.com/WordPress/gs401-speaker/ using 2x 8 inch drivers. As for tweeters 2khz is about the lowest frequency in a two way, and in a 3 way system, 450- 500 hz for midrange and 5 Khz is the recommended crossover point for its tweeter.
  9. Some, certainly desperately want you to believe, and trust them, that the audio spectrum is limited. However we absolutely need audio equipment to have audio spectrum capable of reproducing the actual ability of musical instruments as shown here to 102.4khz : http://www.cco.caltech.edu/~boyk/spectra/spectra.htm http://recordinghacks.com/articles/the-world-beyond-20khz/ As for the other end, its exciting to have ability at the very lowest octaves, as there are many pieces of music containing these frequencies.
  10. The short answer is a simple 2 way passive, where the crossover frequency matches the drivers well, is a recipe for good audio result The long answer, delves into why a active crossover is still though better in a 2 way, which will depend a lot on your own expectation of approaching realism with audio reproduction, at which point you might want to firstly see just how good a simple passive 2 way can be, before taking the active path. Choosing a amplifier would lead to choosing a power amplifier rather a integrated, because the amplifier can then better match to the actual amplifier task of driving a loudspeaker ie more current can be used for the voltage amplification. There is no distraction for the power amplifier manufacturer, its a simple or should be a simple task of getting no deviation in voltage amplification. The better ones though go a bit further and will begin to test their amplifiers with specific needs in mind, ie can the amplifier work with an electrostatic speaker ? and does the amplifier manufacturer actually listen to the audio being produced, or is it like a production line with robotic assembly, with some measurements, but quite alien to our hearing capability. An example of a loudspeaker manufacturer listening is Martin Logan, a inquisitive reviewer found in one of their rooms a pair of Quad ESL 57's There should be with ANY amplifier chosen, adequate sensitivity to a input signal, with 1v for full output, or preferable even lower, you are otherwise narrowing down what form or type of attenuation you can use. Similarly simple is best with attenuation, and the simpler the better. Contact less volume and switching of inputs is a must. As to best types of amplifier, there are certain designs that have automatic appeal, as they incorporate novel distortion cancelling, namely Quad's current dumping. In choosing one amplifier vs another, rather than simply looking at specifications, look more toward the design intention, and what effort any manufacturer has made to provide for outstanding audio result. For instance the use of feedback, the input stage design, and output design, are all factors, that any purchaser should investigate. ------------------------------ The long answer is: The majority of amplifiers you can buy, are specified into a resistor load, and the amplifier itself knows nothing of the loudspeaker, it attaches to. What manufacturers offer is plainly a voltage amplifier. Some amplifiers will have more current capability to deliver said voltage, but are still voltage amplifiers. There are very few current power amplifiers presently made, but they offer exactly what is needed, namely being able to continuously sense the loudspeaker, and to adjust timing and current delivery that matches the source component. Some though do not sense the loudspeaker, rather provide resistance sufficient to have what is called transconductance occurring. The better design of current amplifier would have a percentage of forward current and return current from the speaker being monitored and then used to compare to the input signal. Its a difficult thing to do - but provides the best result: https://www.current-drive.info/ Generally with any electronics providing for audio, the more dedication to each needed task , and the higher degree of retrospection before proceeding, each area has - the better. An active crossover will always be better because it does exactly this, it tailors for the needed frequency without a amplified audio signal to contend with, and without other crossover components interfering, it delivers to the speaker exactly what the speaker expects - its intended frequency range Active crossover is better, but needs for a two way system 2x stereo amplifier, so one channel of each amp is providing for higher frequencies, and the other channels of each amp for lower frequencies. the exact crossover frequency can be chosen. Simply put there is more expenditure in amplifiers but the outcome with active crossover designs, is better. I hope that has been helpful.
  11. In answering your question, you need to qualify if passive crossovers or active crossovers are being used. For instance a 2 way with passive crossover can be very good due to simplicity of the crossover network, in that it is not interfering too much with the amplifier and is relatively easy to drive. A great example of a two way like this is the Acoustic Research AR7, or with a more complex crossover the LS 3/5a , A 3 way with passive crossover needs much attention, to how the passive crossover is designed, and can be successful like http://0339436.netsolhost.com/WordPress/gs401-speaker/ But generally a three way, unless the passive crossover and drivers are carefully chosen, becomes a difficult design effort, you will need to listen to appreciate, and to see if the manufacturer has nailed it, so to speak. All though, including 4 way if you want to go that far, are much better with active crossovers:
  12. Looking at the schematic, its a funny one indeed , the output stage has a zobel at R149 and C113, and I was wrong the output transistors are the ones you are trying to source, whereas Q130 and Q129 are part of a different part of the circuit. I would therefore try and change to have TO3 devices which will be made forever ( well nearly ) and MJ15004 for PNP pair and MJ15003 for NPN might be good choices. it will need a few hardware changes, but nothing too drastic.
  13. Its at hiFi Engine https://www.hifiengine.com/manual_library/audiolab/8000p.shtml
  14. The problem arises mainly because Sanken finished production of the MT 200 package in 2018 , relegated to unobtainum, you might be able to get stock from audiolab or gryphon , of the original parts. As for substitutes, looking at the schematic for the 8000p, the 1216 and 2922 are not the output devices, rather are part of a much lower current pre driver stage. Also audiolab are cagey to say the least as to the voltage rail, which at 100 watts rated output is likely 55 volts on each rail The output transistors are Q130 and Q129 which are not revealed as to their manufacturers part, perhaps MJ15004 and MJ15003 There appears no need for such high current, in this driver stage as it runs into a resistive L pad divider, so BD140 pair for the PNP and BD139 for NPN should be good IMO
  15. make and model of the amp ? will help to advise.
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