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  1. paulb

    MiniVol - Simple DIY PGA2320 Volume Control

    Thanks, I had a look, very impressive. Wish I had the time to take on something like that. My ambitions are more like that of the originator of this thread: simple. I'm going to build a separate analog board and use a prototype microcontroller board of some sort to test it with. I'll probably...
  2. paulb

    MiniVol - Simple DIY PGA2320 Volume Control

    Quote: Nice. Great display. Do you post schematics at all? Did you do anything special with the pga2320?
  3. paulb

    MiniVol - Simple DIY PGA2320 Volume Control

    Dredging up an old thread...hoping error401 is still monitoring... Keenan, How did this all end up? Are you happy with the sound? Did anyone else build it? I'm thinking of making a 6-channel version. Saw your source code, seems quite sophisticated (event queue!) but thanks for making it...
  4. paulb

    EZDAC is officially working!!!

    ezkcdude has started a thread on diyaudio to check how many would be interested in buying boards: diyAudio Forums - ezDAC Group Buy Interest? - Page 2 He's waiting for 25 and up to about 17 so far.
  5. paulb

    Backwards vol pot?

    At full volume, no difference. At minimum, the input is a dead short (which could be really bad and cause damage). Everything between these two extremes depends on the characteristics of the circuitry around it - the output impedance of the source, the input impedance of what it's driving.
  6. paulb

    Notice anything wrong with this design?

    Keep in mind the intended context of this circuit. It is for applications like a high quality Walkman. It probably provides better performance than the standard sludgey circuits. Agreed us DIY types can do much better than this. But for quantities of hundreds of thousands, where every resistor...
  7. paulb

    PSU inquiry

    Yes, either a dual secondary (15-18V would be enough) or a single secondary would work. The dual secondary is more flexible (because you can connect the windings in series to get a single secondary) and you would not need a BUF634. However, using a BUF634, actively driving the ground, may...
  8. paulb

    PSU inquiry

    reaction, Could you clarify what you're looking for? Do you mean +/-15: a +15V supply and a -15V supply? Or do you mean a split 15V supply, of +/- 7.5V? Either way, you can't get a regulated supply unless you use a switching power supply of some type, or unless you can put up with a lower...
  9. paulb

    Help me to choose a DIY amp!

    I believe Tomo's changes are on the Addendum page of the Szekeres article at headwize: http://headwize.com/projects/szeke1a_prj.htm
  10. paulb

    Results of hooking a Cmoy amp to a function generator+oscope

    Amps are supposed to output a larger version of whatever they are fed with. Tube amps may sound 'warmer' because they introduce more even harmonic distortion. With a good tube or op-amp based amplifier, you should not be able to see the difference on your scope once you correct for gain.
  11. paulb

    Confused about opamps on commercial CD player

    Sometimes two opamps, or both channels of a dual opamp, are connected together to get more current. Look at Apheared's #47: http://headwize.com/projects/apheared_prj.htm
  12. paulb

    new website

    Man, this hobby's addictive. I'm thinking about the project after the project after the next project already. Thanks, Rick.
  13. paulb

    new website

    Indeed, I did mention that in Headwize land, he was using a Szekeres. I still want to use his Son Of Zen (modified) to drive headphones, future project. Need to cut my cord to drive the phones in bridge mode. But really, what could be better than using a small range of a FET in Class A than to...
  14. paulb

    Real Pain In The Amp!!

    "Goes away after a few minutes", without considering the other symptoms, sounds like a heat-related problem. Maybe this is secondary to an original problem like oscillation. Anything in the circuit getting warm / hot? Can you put a scope on the output?
  15. paulb

    same op amp, different maker?

    Actually the original was made by Signetics. Philips might be the same company. I think TI buys the dies from Philips or whomever and puts them in their own package. Look at the data sheet carefully, I think the NE5534 may not be stable at unity gain, and even with a small gain you might have...
  16. paulb

    Next amp?

    Never did see a schematic from Apheared on his Variant 42 amp. Are you out there, Michael? Could you maybe add it to your Project Scrapbook at Headwize?
  17. paulb

    In praise of Teflon tape

    TT = DIY version of duct tape? Sounds good.
  18. paulb

    First Amp Ideas

    You might try posting on headwize, or just poke around the site a bit. Hey, half the fun is gathering parts. Usually you end up with enough to build a second one that looks a lot nicer.
  19. paulb

    Volume pot replacement

    Your approach comes highly recommended: http://sound.westhost.com/project01.htm
  20. paulb

    Distortion in Apheared 47 amp.

    I wonder if the power supply voltage is too high. With low impedance phones, you need less voltage and more current, so more voltage gets dropped across the IC. Although you did say they don't get warm. Have you got access to higher-impedance headphones, or a way to reduce the supply voltage to...
  21. paulb

    What is a Driver?

    Tomo's comments should be regarded; this circuit is not critical so substitutions are easy but this is not the case in general. Steven, you'll drop some voltage across the transistor, especially if you use the Darlington arrangement Rod has. Darlingtons multiply the gain at the expense of more...
  22. paulb

    What is a Driver?

    Hey, Steve, I'm building the same thing you are including the capacitance multiplier. A TIP3055 is a plastic version of the classic 2N3055 power transistor. Another version is the MJE3055. You can use a single "Darlington" transistor instead of the BD139/TIP3055 combination; I'm using...
  23. paulb

    Controlling digital pot without microprocessor

    I'm afraid I've been two-timing a bit, my post on the PGA2310 came from the diyaudio site, where there's a new thread on the topic. I posted something here because I remembered there had been some discussion on it. I'm thinking of building something like that, but I won't get to it for a bit...
  24. paulb

    Controlling digital pot without microprocessor

    No, the scheme shown will only work with the MAX5160 because it has Increment and Up/Down inputs, while the PGA has a synchronous serial interface that could be done in hardware with more effort. The DS1802 mentioned in the other thread would work without a micro. But I don't know if either of...
  25. paulb

    Stepped Attenuator

    Here's info on a new device from Burr-Brown. It looks pretty good but you need a micro to run it. http://focus.ti.com/docs/prod/produc...Number=PGA2310
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