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Don Richard

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  1. Don Richard

    PPSL build?

    DJK, RIP, had written about the PPSL design here and on other audio forums. If you search the archives there are several threads about PPSL bass bins, both here and elsewhere.
  2. There were two local guys in the late 60s who made a no holds barred stereo PP class A tube amp that featured regulated DC filament power and regulated B+, two separate channels in one enclosure with a cable connecting the power supplies to the amplifier. The power supply was bigger and heavier than the amplifier by quite a bit. That, and the one you linked are the only ones I've seen like that to date. Any idea what the dynamic headroom is for your amplifier?
  3. What's cool is that distortion is lower at those low power levels, probably lower than any other type of speaker. The clarity of horns in a home setting is truly amazing.👍
  4. Most test results I've seen are for solid state amplifiers, and stiffly regulated supplies with those result in less dynamic headroom. Can you show me a schematic of a very highly regulated supply in a typical tube amp? Mostly I've seen filter circuits with an input cap, a choke and an output cap, but it's been years since I've messed with tube circuits. I have built tube circuits that had regulated bias voltage, but the B+ had no regulators for the most part.
  5. This is correct. FTC standards do not apply to home theater equipment, pro sound, or auto sound. QSC provides FTC numbers for some of their amplifiers, and some home theater products give FTC numbers for 2 channel operation, but that's not commonly done.
  6. Dynamic power is a result of the Federal Trade Commission standards for home stereo equipment. During the FTC method of power rating the amp is run at 1/3 power for an hour before testing, then the power is measured up to a defined distortion level. That is the continuous average power rating, erroneously called "RMS power", of the amp. An amplifier may be able to put out more power than the FTC rating without the preconditioning at 1/3 power, for a shorter period of time, and perhaps at a different distortion level. That is the "dynamic power" of the amp. Unlike the FTC power rating, there are no standards for the dynamic power number. In general, amps with a stiffly regulated power supply will have less dynamic power output than amps with unregulated or less stiffly regulated power supplies. Peak power for a sine wave is 1.4 times average (RMS) power. For non sinusoidal signals the crest factor of the signal is a determining factor in computing peak power.
  7. $62,000 for a pair. A true bargain.😁 97A Monoblock Amplifiers (per pair) $61,995.00
  8. Very nice. Pricey, but nice.
  9. Push pull amps can run Class A, and 12 dB feedback is fine, assuming the amp is designed with that in mind. The danger is using too much negative feedback in order to linearize a poorly designed amp. You seem to have a strange fascination with turds. They have therapies these days that can help with that.😈
  10. Don Richard

    In The Early 70’s

    I had a guy try to pull that stunt on me about 5 years ago. Old school audiophool salesman.
  11. Especially when used in a push-pull circuit. With about 12 dB negative feedback.
  12. Trigger warning for subjectivists - you may not want to read what's in that link. 😀 Edit: Too late. It seems that some have already read the link...
  13. Don Richard

    Poll & Prediction: Autonomous Car Equipment at 5k by 2019

    In cold weather the range is reduced, by as much as 40+%: https://insideevs.com/tesla-model-3-range-drop-cold-weather/
  14. Don Richard

    Alnico Drivers

    He said that alnico was a conductor of electricity and ferrite wasn't. That is an accurate statement.