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  1. rothwellaudio

    Hum from speakers when amp is plugged into a particular outlet.

    Why would an amp need an earth connection, other than for safety? By what mechanism would hum be created if it wasn't earthed? Since the OP hasn't responded since day one, we may never know what the problem is.
  2. rothwellaudio

    Is high power a waste at low to medium volume?

    The position of the volume control tells you nothing about how much power an amp is putting out, or how much is still in reserve.
  3. rothwellaudio

    Is high power a waste at low to medium volume?

    The "more power is always better, whether you use it or not" school of though is in my opinion fallacious. My experience has been that there's very little correlation between sound quality and power. If there was a clear correlation there would be no market at all for all those valve amps of...
  4. rothwellaudio

    Hum from speakers when amp is plugged into a particular outlet.

    Having a socket tester isn't a bad idea, but I doubt there's anything wrong with the mains wiring. A ground loop will be formed (or more accurately, could be formed) when using two different outlets simultaneously. The OP has already said that he gets no hum when everything is plugged into one...
  5. rothwellaudio

    Hum from speakers when amp is plugged into a particular outlet.

    If the outlet wasn't grounded it wouldn't create a ground loop. It wouldn't be safe, but it wouldn't create a ground loop. The OP should try the experiment I suggested. That would prove definitively if the problem was a ground loop or not.
  6. rothwellaudio

    Floors get rugs, walls get treatments... What about all the ceiling reflections??

    Yes, sucks out some energy - the energy that's unwanted. Which is a good thing.
  7. rothwellaudio

    AR-1500A Phono Circuit Background Noise

    Yes. Bear in mind that the phono input has about 40dB more gain than the other inputs. That's a factor of 100. Also, the noise with the inputs open circuit will be higher than with the inputs shorted or with the inputs in use with an MM cartridge. Don't mess with anything - it ain't broke.
  8. rothwellaudio

    Step Up Transformer with Moving Iron Cartridge????

    No, treat it like an MM cartridge.
  9. rothwellaudio

    L O N G speaker wires versus L O N G RCA cable from pre-amp to amp Pros and cons

    Interesting read, thanks. However, I think you may have misinterpreted it. It doesn't say that double braiding's purpose is to reduce resistance, or that lower resistance produces better hum rejection. It says that there's a correlation between resistance and performance, although in fact the...
  10. rothwellaudio

    Floors get rugs, walls get treatments... What about all the ceiling reflections??

    Well, energy is being absorbed in that spectral range (it's turned into heat) so it doesn't seem unreasonable to say "it sucks out the energy". Anyway, the OP's claim that nobody applies acoustic treatment to the ceiling seems to have been well and truly shot down.
  11. rothwellaudio

    Just read this on speaker series wiring

    Ah, I see what you were saying now.
  12. rothwellaudio

    Just read this on speaker series wiring

    Yes, the output of a solid-state amp is usually so low as to be virtually a short circuit, but it doesn't "cancel out back EMF". It's the back EMF which creates the non-flat impedance curve around resonance. The impedance curve is non-flat even when driven by a virtual short circuit.
  13. rothwellaudio

    L O N G speaker wires versus L O N G RCA cable from pre-amp to amp Pros and cons

    It would have to be seriously bad cable (think wet string) for the resistance of the shield to be so high as to be a problem.
  14. rothwellaudio

    Hum from speakers when amp is plugged into a particular outlet.

    There's probably nothing wrong with the mains outlet. If you had some gear plugged into one outlet and some gear plugged into another you probably created a ground loop. You could verify that by plugging everything into one outlet, then plugging everything into the other outlet. If both...
  15. rothwellaudio

    Heads up Rhodium, it showing up in many types of connectors and terminators.

    Probably made of clay. Very dry clay. :rflmao:
  16. rothwellaudio

    Tube Mono Block Ground Loop

    Connect a wire (any old bit of wire, doesn't have to be an interconnect) between the outer connect of any phono socket on one amp to the outer contact of any phono socket on the other amp. Don't have the turntable connected for this test. Does that create a hum? If so, it's because the two...
  17. rothwellaudio

    Speakers not working when I plug additional pair in pre-out.

    I wouldn't advise that. The only control you would have over the volume would be the tiny little preset pot on the back of the Genelecs.
  18. rothwellaudio

    L O N G speaker wires versus L O N G RCA cable from pre-amp to amp Pros and cons

    That's a very big sledgehammer to crack a very small nut.
  19. rothwellaudio

    L O N G speaker wires versus L O N G RCA cable from pre-amp to amp Pros and cons

    Often signal zero volts and the chassis and mains earth are all tied together in unbalanced (ie RCA) equipment, but they don't have to be and often aren't. It's better if they're not. Anyway, the OP's gear isn't balanced, talking about the benefits of balanced connections is academic.
  20. rothwellaudio

    AR Turntable (My first turntable - help!)

    VM? What's that?
  21. rothwellaudio

    Question about driving multiple pairs of speakers - mismatched ohms

    No, that isn't strictly correct. The volume you get out of any speaker is determined by the speaker's efficiency. Some speakers are highly efficient and produce more volume than inefficient speakers regardless of impedance. However, a given voltage across a 4 ohm load will dissipate twice the...
  22. rothwellaudio

    Question about driving multiple pairs of speakers - mismatched ohms

    Transistor amps will play happily into high impedance loads but will fail into a short circuit, ie zero ohms. The closer you get to zero ohms, the more chance of something going horribly wrong. Pretty much all transistor amps will cope with 8 ohms, and most modern ones will cope with 4 ohms...
  23. rothwellaudio

    Shorter cable and other ideas for more output

    No, it won't make a scrap of difference. There's no reason why the turntable should be at exactly the same level as other sources. It's quite usual for the turntable to be a bit lower. No, the internal phonostage's input sensitivity is 3mV and the cartridge's output is 4mV. If everything is...
  24. rothwellaudio

    Rewiring DAT machine XLR socket

    Just buy the right 5-pin XLR connector, the right 3-pin XLR connector and the length of cable you want. Then wire it up yourself. That way you know exactly what you're getting. I doubt you'll find an off-the-shelf cable to do what you want because what you want is quite unusual. I think...
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