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John Warren

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John Warren last won the day on October 4 2014

John Warren had the most liked content!

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About John Warren

  • Rank
    "So much for the experts on this board"

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  • Interests
    Engineering-Audio, magnetics, materials for electronic and magnetic applications, engineering models and simulation, SPICE, MATLAB, FORTRAN, acoustics, complex algebra, physics of sound, microphones, vintage audio, loudspeaker design, amplifier design, McIntosh amplifiers, discrete semiconductor devices.....and movies including silents, foreign and indies.
  • My System
    12" Utah Tri-axial drivers mounted in LRE bass "reflex" enclosures.

    Sony Superscope FM only

    Lafayette Solid State Stereophonic Integrated Amp

    16 GA Lamp Wire

    Koss Pro 4AA

    Technics SL-QD33

    CD Player:
    NAD 325i (modified)

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  1. CL-D Bi and Tri-amping (lots of photos and plots)

  2. Capacitance Filter Question

    The RMS voltage isn't the issue, it's the ripple at full power under load measured with a load simulating complex speaker impedance and able to dissipate full amplifier power without catching on fire. Ripple current, if excessive, causes a big, big, BANG!
  3. Capacitance Filter Question

    ROM estimate for FW rectifier/120Hz/100W/8 Ohm the current required is 3.5A so for given reservoir cap size the Vp-p ripple voltage is then: 15,000uF / 1.93Vp-p 30,000uF / 0.97Vp-p 60,000uF / 0.48Vp-p 120,000uF / 0.24Vp-p The 30,000uF recommendation is reasonable. If you plan on amplifying electronic music or your building a sub amp then 60,000uF. Use a grounding wand.
  4. CL-D Bi and Tri-amping (lots of photos and plots)

    Final (through hole and socketed) design shown below. After working with the prototype I revised chassis and circuit ground paths, added RFI/EMI common and differential mode front end filtering, reduced feedback factor to about 2X, added additional filtering to supply rails and re-routed a few of the traces. For this build bandwidth across RL=10kOhm is -3dB @ 80kHz. With headphones, a listen with either an LME49720 or NE5532 evidences nice, quiet background. Buffer/splitter takes balance or unbalanced signal and splits it three-ways for tri-amplifier arrangement. The board shown is two channel board so six splits in total, three/channel. Each split can feed a separate amplifier or active filter. Input impedance is about 18kOhm. Output impedance is about 600Ohm with the LME package and lower with the 5532. Resistors are 1% (lower will improve circuit CMRR, theoretically). The plots are with through hole components and socket mounted packages, power supply is unit described above. Might be a nice kit for builders. The SMD version is much tougher to solder up.
  5. Bought an MC250. Most parts have arrived.

    One across +V rail to GND and the other across -V rail and GND.
  6. Bought an MC250. Most parts have arrived.

    Would suggest bleeders on the 22000uF cans, 1kOhm, 2W.
  7. Class D

    The 3255 is capable of about 100W/ch with reasonably low distortion . The McIntosh MC2100 is a 100W/ch amplifier with about .5% distortion at 100W, 1kHz with 8Ohm resistive load. That amp has great low end thanks to about 40,000uF/50V filter cap for each channel. With 6 channels that would be about 0.25F! That would be one heck of a power supply.
  8. New "Stealth" forum

    My pleasure.
  9. Class D

    The shell at each end is part of the XLR system, the shells act as extensions of the chassis ground. The chassis at the sending end, the shell at the sending end, the cable sheath, the shell at the receiving end and chassis of the receiving end are all attached to respective chassis grounds then to the IEC earth prong. For EMI and RFI immunity, the sheath at the receiving end has RC filter to chassis ground. The whole point is to achieve high level of common mode rejection in the cable run.
  10. Class D

    I'd suggest that this sort of stuff is best done with the test amp being brought up to operating voltage using a Variac with all eyes on an Ammeter. Dial up the slowly and watch the current draw. I've caught myself a few times.
  11. New "Stealth" forum

    I have a webserver and on that server I uploaded a forum. The address isn't published. If you want to join, talk technical issues, etc. this is what you do: First, type this address into the browser http://www.northreadingeng.com then type /Forums/ It's not really moderated but if it gets nasty I'll flush it. Forums are magnets for spambots, robots, maleware, pornware etc. but I like a place to discuss topics I find interesting. I'm also open to making changes, adding topics (audio or solid state electronics related) if anyone offers suggestions. jw
  12. CL-D Bi and Tri-amping (lots of photos and plots)

    It's not a balanced line using the 1/4" RCA adapter shown above.
  13. CL-D Bi and Tri-amping (lots of photos and plots)

    I really like the XLR combo inputs but there a bit of a pain to design around. Phot shows RCA adapter. See AoE, 3rd ed. Fig. 8.127 A for Pin 1 wiring.
  14. CL-D Bi and Tri-amping (lots of photos and plots)

    Distortion/Output Voltage (7VRMS), 20kHz, across 600Ohm load, all outputs loaded. Analyzer as 30KHz low-pass filter engaged, this represent %THD in "audible" spectrum (if your a dog).
  15. CL-D Bi and Tri-amping (lots of photos and plots)

    Power supply transistor temperature after 2h operating all 6 outputs at condition shown above. Well below max of 150C.