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  1. cotdt

    How to 'brush' aluminum?

    Quote: Originally Posted by Uncle Erik Really? I didn't know phosphoric acid did that to aluminum. I am absolutely going to give it a try. Do you use Naval Jelly, or do you order it from a chemical supply place? How long do you leave it on/in and how do you neutralize it afterward? That...
  2. cotdt

    How to 'brush' aluminum?

    Quote: Originally Posted by fishski13 cotdt, does the acid just brighten it? the acid does the opposite, it gives it a matte finish. useful for heatsinks, as a matte finish radiates heat better than a polished finish.
  3. cotdt

    y1 gamma-1 DAC

    if anyone lives in the san diego area and needs help assembling their Gamma1 just let me know.
  4. cotdt

    41Hz Amp3 vs. GainClone, which one sounds better?

    My modded Amp5 sounds better than the Gainclones in every aspect.
  5. cotdt

    noisy Dynahi PSU

    just use an S22 instead. troubleshooting these things tend to be a big headache, and every hour you use up there is an opportunity cost.
  6. cotdt

    Nikon Film SLR suggestions

    get a classic, like the Nikon FE!
  7. cotdt

    Why hasn't SMD caught up for DIY amp designs?

    not true, even switching amps operating at very high frequencies do just fine with thru-hole components. i've builty many such things and they sound great.
  8. cotdt

    Thermal coupling the 2SK170/2SJ74 matched pairs

    Saw a thread about it on diyaudio.com. Worth doing? diyAudio Forums - The next best thing to 2SK389 / 2SJ109 ? - Page 1
  9. cotdt

    Balanced headphone questions...

    Quote: Originally Posted by ArmAndHammer Ok, but not a standard 1/4" plug? And if one were to recable, is there any advantage to running two cables, one from each driver all the way to the plug keeping them separate all the way until they meet at the plug? Just wondering because I have...
  10. cotdt

    Headphoneus Supremus forum?

    I can confirm that it does exist
  11. cotdt

    Can audiophiles agree on something please? for me?

    I'm pretty sure all audiophiles can agree that an amp is always desirable. Efficient IEMs can be powered by the source's internal buffer but even here an amp is beneficial.
  12. cotdt

    Wet Shaving

    Nothing beats the straight razor IMHO but you usually have to sharpen them as they are never sharp fresh out of the factory. I had to use a 12,000 grit water stone to get it super sharp, then strop it on leather. Straight razors don't seem hard to use as people say. It's no different from how...
  13. cotdt

    Aussie DIY builder for a balanced β22

    Heh heh there's not really an amb house sound. The mini^3 sounds completely different from the Beta22 as far as amps go.
  14. cotdt

    Another Balanced Solid State Amplifier

    I wish they would simply use a single 4-pin XLR for balanced headphones.
  15. cotdt

    Roll Call: Who's building, built, or thinking of building a beta22?

    You have a ground loop problem. How is everything connected? Pics?
  16. cotdt

    Can someone explain what OTL means?

    Quote: Originally Posted by tintin47 Also, what are amps that have output transformers called? are they called OT amps or something along those lines? Just wondering for reading of specs and the such. Tube amps with output transformers are called OPT in most circles. So it's OPT...
  17. cotdt

    Roll Call: Who's building, built, or thinking of building a beta22?

    Are you confusing the inputs and outputs? That tends to create the sound-out-of-tunnel effect.
  18. cotdt

    Medium Format Camera suggestion...

    I really like my Mamiya 645, there are some fast f/1.9 lenses for it that are razor sharp wide open.
  19. cotdt

    Balanced headphones.

    Yeah good points wavoman, I guess it all comes down to semantics.
  20. cotdt

    Balanced headphones.

    A lot of misinformation here. There's no such thing as balanced headphones. Dual mono headphones are required for balanced amplifiers. Balanced amplifiers have theoretical, measurable, and audible advantages over unbalanced. I remember there were some threads that went into a lot of detail on...
  21. cotdt

    Attenuator talk

    Quote: Originally Posted by luvdunhill did you read his post? you're saying the exact opposite of what he was arguing... I just reread his post and not sure what you mean. We're both saying that 23 steps is enough. He argues for basically using 1dB steps in the region where you...
  22. cotdt

    Attenuator talk

    My experience is the same as dsavitsk, 23 steps is more than enough if the gain is set properly. Most headphones, and even speakers, need pretty similar voltage gain. Actually for the majority of headphones you don't need voltage amplification at all. If 23 steps really isn't enough, you...
  23. cotdt

    PCB bottom to metal, how close is too close?

    Quote: Originally Posted by Navyblue But how much do I throttle so that it remain well in class A operation? Headphones don't require much current so you can cut the bias current dramatically and still be in Class A. However, the transistors are more linear when biased at its...
  24. cotdt

    The β22 is done! Pictures on page 5

    Quote: Originally Posted by compuryan So it doesn't seem like it'd cost me over $1000 at all, am I missing something? It will cost over $1000 once you finish the amp to find out that it hums badly, and that the power supply needs a separate enclosure with special connectors and...
  25. cotdt

    Mosfet output

    Quote: Originally Posted by TzeYang cotdt, due to the lack of negative feedback, those transistors might make a difference to your ears. but what is the sonic difference, can you describe? maybe i should try swapping transistors in my CKKIII and see for myself...
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