| tabbypurr@gmail.com: Sep 24 01:46AM -0700 On Tuesday, 24 September 2019 06:00:48 UTC+1, Jeff Urban wrote: > I have already had problems due to tape bias on those. Wasn't filtered out well enough. Couldn't hear the bias but you could definitely hear the hum. > Fact is any HF leakage out that class D amp will see a near dead short on the load if it is piezo. The idea was efficiency. Don't got it like that. > Sorry to intrude on your vision of perfection. Piezo drivers are capacitive (albeit with a lot of resonance peaks/troughs), but piezo tweeters generlly include a transformer to raise the voltage, and are usually in series with an external resistance, since some amps don't like C loads. I've never measured one at half a megahertz, but expect it to look largely like a transformer at that f. NT |
| John-Del <ohger1s@gmail.com>: Sep 24 06:51AM -0700 On Monday, September 23, 2019 at 8:37:14 PM UTC-4, Phil Allison wrote: > ** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only. > .... Phil I can promise you that if you saw several of these a month, you would have by now acquired both the equipment (cheap enough) and the skill to do this in your sleep. Although SMD requires a learning curve, it is not difficult if the tech has decent hands and magnification. |
| Fox's Mercantile <jdangus@att.net>: Sep 24 07:00AM -0500 On 9/23/19 10:35 PM, Phil Allison wrote: > https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG > The spinning disk will not move unless both current and > voltage of the same polarity exist at the same time. Back in Manhattan Beach, California, while living with a friend, The house had a single 120 vac feed, not the more common 120/120 240 vac feed. So his 1 KW Heathkit amplifier would draw a LOT of current. I picked up a power company power factor correction capacitor. Heh, when we put that across the line, the watt meter would come to a complete halt. Watt hour meters will read, properly, with an r+j impedance load. They get confused with an r-j impedance. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Phil Allison <pallison49@gmail.com>: Sep 24 05:18AM -0700 Fox's Mercantile wrote: ---------------------- > friend, The house had a single 120 vac feed, not the more > common 120/120 240 vac feed. So his 1 KW Heathkit amplifier > would draw a LOT of current. ** Heathkit ? 1kW ?? FYI, there is ZERO phase angle between the V and I drawn by an amplifier. > meter would come to a complete halt. > Watt hour meters will read, properly, with an r+j impedance > load. They get confused with an r-j impedance. ** Hope that is not some weed induced hallucination form the late 1960s... The only thought I have that connects is the power company, aware such shenanigans sometime went on, fitted a device to PREVENT the watt-hour meter ever going backwards. Easy enough to do, in the reduction gear chain for eg. Piss the hell out of greenish coloured folk nowadays, with their roofs covered in acres of PVs. .... Phil |
| Fox's Mercantile <jdangus@att.net>: Sep 24 07:37AM -0500 On 9/24/19 7:18 AM, Phil Allison wrote: > ** Hope that is not some weed induced hallucination > form the late 1960s... Nope, never did weed or any other drugs. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Sep 24 05:43AM -0700 There are several Heath amps that put very nearly 1 kw on the outlet. The AA1640 comes right to mind, as it, in mono, makes 800 watts into 4 ohms. circuit losses of 200 watts or so does not seem unlikely. My Harman Kardon Citation 16 draws close to 12 amps @ 120 VAC at full load, making 1,440 watts. Not that it has ever been driven to that extreme - but it is just possible. Dynaco 416, Phase Linear 700, Crown CE1000. There are a good many brute-force amps out there, not accounting for quality, just force. Peter Wieck Melrose Park, PA |
| Fox's Mercantile <jdangus@att.net>: Sep 24 08:20AM -0500 > There are several Heath amps that put very nearly 1 kw on the outlet. This was an Amateur Radio RF amplifier. 3.5 to 30 MHz. SB-200 <http://www.n2ckh.com/FORSALE/AMPLIFIERS/SB200/sb-200_front.gif> -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
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