Tube vs. Solid State Preamp
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From: Joerg on 31 Mar 2010 13:58 Tim Williams wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:81fimuFsusU1(a)mid.individual.net... >>> http://www.thevalvepage.com/testeq/tek/545a/545a.htm >> Some of those things could constantly blast half a kilowatt of heat into >> the lab. When I got a 7704 I was thoroughly surprised that it contained a >> very efficient primary-side switcher. Maybe it was designed during the >> energy crisis. > > They weren't afraid to use switchers -- HV supply in those is usually a 6AU5 > or such blocking oscillator (g2 controlled, of course), with a multiplier > hanging off one end for the 2nd anode (~7kV). It's just that the high > voltages and massive waste of heater power kind of drowns out everything > else in terms of wattage. :) > Afraid of switchers, that's a good observation. I find that at times and it takes some convincing along the lines of "It's going to be ok, we won't crash and burn". Then when the design is done, and there is no heat sink, and nothing gets hot, that does the ultimate convincing. That's why I think it is good that you experiment with switchers while still at university. You'll probably have tons of work once you enter the workforce. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 31 Mar 2010 14:00 Michael A. Terrell wrote: > Joerg wrote: >> The German text in there is rather funny. For "low noise" they use the >> expression "niedriges Geraeusch". That words normally describes a noise >> such as the squeal of a bearing that's about to go bad. > > > Or heavy metal. ;-) > If you listen to music from the Scorpions the noise figure does not make one iota of difference :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Tim Williams on 31 Mar 2010 14:37 "Joerg" <invalid(a)invalid.invalid> wrote in message news:81hgqrFltrU3(a)mid.individual.net... > Afraid of switchers, that's a good observation. I find that at times and > it takes some convincing along the lines of "It's going to be ok, we won't > crash and burn". Then when the design is done, and there is no heat sink, > and nothing gets hot, that does the ultimate convincing. > > That's why I think it is good that you experiment with switchers while > still at university. You'll probably have tons of work once you enter the > workforce. Speaking of school, I recently tested part of my final project. http://myweb.msoe.edu/williamstm/Images/EE409_PFC1.jpg Had it making some wirewound resistors nice and toasty, the Fluke 43 (there are some advantages to working in a school lab!) showed 0.99 PF and 450W input. I didn't have a heatsink for the test. The MUR860 got the hottest, because it's the smallest, followed by the FWB and MOSFET. ;-) Now I just need to get rid of that masking tape! ;) Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Joerg on 31 Mar 2010 16:10 Tim Williams wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:81hgqrFltrU3(a)mid.individual.net... >> Afraid of switchers, that's a good observation. I find that at times and >> it takes some convincing along the lines of "It's going to be ok, we won't >> crash and burn". Then when the design is done, and there is no heat sink, >> and nothing gets hot, that does the ultimate convincing. >> >> That's why I think it is good that you experiment with switchers while >> still at university. You'll probably have tons of work once you enter the >> workforce. > > Speaking of school, I recently tested part of my final project. > http://myweb.msoe.edu/williamstm/Images/EE409_PFC1.jpg > Had it making some wirewound resistors nice and toasty, the Fluke 43 (there > are some advantages to working in a school lab!) showed 0.99 PF and 450W > input. I didn't have a heatsink for the test. The MUR860 got the hottest, > because it's the smallest, followed by the FWB and MOSFET. ;-) > UC3842? How did you get PFC and regulation done with just one chip and one inductor? > Now I just need to get rid of that masking tape! ;) > Whoops, did it bake on? -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Adrian Tuddenham on 31 Mar 2010 17:11
�Leo� <leo2100(a)gmail.com> wrote: [...] > This happens so because the transistors are more ideal amplifying > devices than tubes are...so the signal that comes in is the one that > comes out, with as little distortion as possible. Since the tubes are > less ideal, they add different components to the original signal... > this have turned out to be more pleasant to the human ear. I would disagree with this statement. The curvature of the transistor characteristic is much sharper than many valves and the harmonics generated are much nastier-sounding. Valve stages with no feedback are quite common and the distortion they generate with moderate signal voltages is quite tolerable, but transistor stages with no feedback are virtually unusable for audio. Transistor amplifiers can contain more devices in less space for the same price and that allows them to employ much more feedback than valve ones, not just overall but within individual stages; this is what gives the improvement in overall linearity which you have erroneously attributed to the devices themselves. The down side is that when they eventually overload, they do so much more sharply and generate higher harmonics, which sound vile. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |