Recent content by lowredmoon

  1. lowredmoon

    Magnetic resistor end caps - do they really matter at audio frequencies?

    That's my goal -- use as much objective data as possible to make decisions. I'm now at a point where I have a foothold in understanding parts data and material properties and how it is relevant in a circuit, and want to use what I've learned to build. It's a start, at least, and I'll learn more...
  2. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    I tried the moving coil input today. The sound is very good, despite the fact that the input impedance is stated as 50 ohms, and the impedance of my Denon DL-301 MkII is 33 ohms. Maybe there is some loss, but the sound is very enjoyable! I played Suzanne Vega's "Tom's Diner" (a cappella), and...
  3. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    This is the second one I've worked on. Twice, the issue was failed resistors - the small, flat, brown ones. I'm almost inclined to change them all, but I don't know whether Vishay RN/CMF resistors have adequate current noise specs to match the originals. I've paged through dozens of datasheets...
  4. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    The problem was with a resistor (again). I didn't suspect them this time because the previous resistor failure (1.2K's in the tone amp) was easily provoked by gently tapping each resistor. That wasn't the case this time. In fact, I couldn't get them to fail out of circuit, either with heat or...
  5. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    A few of those resistors went intermittently open in the tone control section a couple years ago. I should probably make a list and order some RN/CMF to replace them. Probably as "low noise" as it gets without a second mortgage for metal foil resistors. I'll check the blue caps. Thank you
  6. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    The issue is only in the phono section, and I narrowed it down to this spot. It happens regardless of cartridge or turntable I use.
  7. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    I failed to mention that this is the phono equalizer section. Source: moving magnet cartridges for testing but I might use the MC head amp when it"s back up and running - depending on how I like it. I'm using a Denon DP-45F with a Grado Blue for testing, but that's moot.
  8. lowredmoon

    Tonight's project: Yamaha C-2a and more tough love (with voltages and diagram)

    EDIT: This is the phono eq. amp in my C-2a. This is what I'm working on tonight. I might solve it tonight, I might not. This preamp sure makes OTHER audio equipment easy to work on (personal perspective). Fault mode kicks in after being turned ON for a couple minutes. It then goes back to...
  9. lowredmoon

    Magnetic resistor end caps - do they really matter at audio frequencies?

    Given that just about every metal film resistor has magnetic end caps, it must be of little issue...at audio frequencies or beyond. Otherwise, there would be many non magnetic resistors to choose from. I mean, it's not a high-technology process to use non-magnetic metals in a component. I'm...
  10. lowredmoon

    Magnetic resistor end caps - do they really matter at audio frequencies?

    Thank you for the value added reply. I'm not sure what alloy they use for the end caps, but it has been reported that many values are attracted to a magnet. I haven't had luck in locating what the material is, or how much of it is present in the resistor. Kind regards, Adam
  11. lowredmoon

    Magnetic resistor end caps - do they really matter at audio frequencies?

    I'm building a moving coil head amp. These days, it's hard to find non-magnetic 1/4 watt resistors. Vishay/Dale RN and CMF used to be non-magnetic, but they now use magnetic end caps, except in the CMF line that ends in "143," which no one seems to stock (Mouser has maybe 4 values). Takman REY...
  12. lowredmoon

    Jensen MC SUTs -- anyone tried them?

    That's a pretty provocative approach. So -- the cartridge (33 - 40 ohms for my Denon DL-301 MkII, DL-300, and DL-103) immediately "sees" a 47K load?
  13. lowredmoon

    Jensen MC SUTs -- anyone tried them?

    Thank you for the interesting links! You bring up a point I've ignored -- the quality of the preamp the transformer is connected to. I've been using my receivers' built-in preamps to keep things simple. While the Denon PMA-737 has a better phono section than most built-in preamps I've heard...
  14. lowredmoon

    Jensen MC SUTs -- anyone tried them?

    So it looks like individual flavor is a large part of it when you get into quality transformers, much like cartridges.
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