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  1. MWP

    Purpose of driver surround paper/filter?

    Hi all, Audiotechnica AD-900's here, with many years of daily use. I recently fitted Brainwavez sheepskin pads (feel & sound great, but sweaty). I noticed that the white paper/filter material surrounding the driver is pretty gross. If it was porous, it now very much is not. What's its...
  2. MWP

    Post pics of your builds....

    A few years ago i went backpacking OS for 12 months. Not satisfied with my laptop's internal soundcard (no surprise there), i built this.   It has a bit of a nasty power-on surge current which shuts down some USB ports, but with most its ok. The TA6120a is supplied +-12V rails by two DC-DC...
  3. MWP

    Circuit design critique (USB headphone dac+amp)

    Quote: Originally Posted by saab nice work. I take it you soldered the USB cable directly to the board. How does the sound compare to local favorites? (that you may have listened to) Yup, the USB cable is soldered to the board. No real need for a socket and separate USB cable...
  4. MWP

    Circuit design critique (USB headphone dac+amp)

    When i get stuck into a project, it gets done quick Although, i have probably spent ~20hrs on this from design to being built. A good majority of that was on the PCB routing... it was rather difficult. The PCB was made by doing the following: - Print the PCB design onto bubble-jet printer...
  5. MWP

    Circuit design critique (USB headphone dac+amp)

    Ok, photos: During building: Working: Building it into the hammond case atm.
  6. MWP

    Circuit design critique (USB headphone dac+amp)

    Im hindsight, i probably should have built in power control to turn off all the ICs except the USB recv when idle. Although i think i would have run out of PCB space then
  7. MWP

    Circuit design critique (USB headphone dac+amp)

    Yup, gimme 5mins. Just tested power usage... it sucks ~500mA at idle (not playing, no headphones connected), and ~600mA when playing music through 32ohm headphones at a decent (above normal) volume. The laptop's power meter says it uses an extra 2W compared to when playing music into the...
  8. MWP

    Circuit design critique (USB headphone dac+amp)

    Well i just finished building this DAC/AMP and it sounds friggin incredible I made a few changes to the schematic above, but nothing too drastic, mainly around the PCM2707 (wasnt setup correctly) and in some of the power supply. I managed to build it on a double-sided PCB thats 45x75mm...
  9. MWP

    Protel/Altium PCB/footprint software question...

    Hi all, Sorry if this question doesnt belong in this forum... I have drawn a custom footprint for a through-hole component ill be using (3pin power module). The foot print only uses the normal through-hole pads and outline using top overlay lines. The footprint outline is 40x40mm with...
  10. MWP

    Circuit design critique (USB headphone dac+amp)

    Hrm, youre right, it will be close. Well ill build it, see what happens.
  11. MWP

    Circuit design critique (USB headphone dac+amp)

    The switching power "blocks" are from TI (as is just about everything else in this project). I actually have no idea how well suited they will be to audio, but its the only ready made compact +12v and -12v switchers i could find so i thought i would give them a try. Both switch at 800kHz, can...
  12. MWP

    Circuit design critique (USB headphone dac+amp)

    Hi all, Im just about to start desiging the PCB for this USB->DAC->Headphone-AMP design of mine. The aim was to build a decent small headphone USB "soundcard" which is only USB powered (its for laptop use). Any comments/sugestions?
  13. MWP

    OPA627 for headphone drivers?

    Quote: Originally Posted by amb While paralleling more opamps does increase the current output capability, you need to add resistors in series with each opamp's output before summing them together. Typically this is around 22 to 47 ohms. Unfortunately, the resistors limit the current so...
  14. MWP

    OPA627 for headphone drivers?

    Quote: Originally Posted by Jazper I'd want about double that Ok, well i actually have enough OPA627AP's to have 3 per channel. Parallel three would give ~135ma per channel. A rather expensive solution i know, but if it works, ill be happy. Ill put the OPA634's in sockets...
  15. MWP

    OPA627 for headphone drivers?

    Yeh, i know, ive only got one BUF634, and cant get another, so im looking for alternatives. How much o/p current to i need to drive 32ohm phones comfortbly? OPA627's will o/p up to 45mA.
  16. MWP

    OPA627 for headphone drivers?

    Greetings all, Im designing a USB powered DAC to replace the very ****** (pfft, sh1tty isnt that bad) soundcard/amp in my Laptop. Itll be somthing like USB -> PCM2707 -> a DAC (undecided atm, maybe PCM1781) -> OPA627 LPF -> Volume control pot -> Headphone driver amp. Power will be via a...
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