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Author
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Topic: Transistor Is 50 Today
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 06-10-2003 11:43 PM
If you take two diodes and connect them "head to head" or "tail to tail" and put electricity through two of the inputs, one of the diodes will start to work backwards! It's such a fiendishly clever concept! Who would have thought that up?
Okay, it's not all like that. The discovery was a semi-accident. And, No, the transistor isn't simply two diodes crammed together but it's functionally true.
It took me years to fully understand how a transistor works until somebody told me to look at it that way. Vacuum tubes were easy. Electrons are either blocked or passed based on the voltage on the screen. The idea that you actually WANT a diode to "avalanche" and make that property work for you was just beyond me.
I didn't put 2 and 2 together until I was asked, "Do you know what a Zener diode does?" I said, "Yes, it blocks electrons unless they are at or above the Zener voltage." His reply was, "What if you could vary the Zener voltage by varying the voltage on a third input?... TRANS-resISTOR... TRANSISTOR... Get it?" "Oooh! I GET it! Cool!!"
Okay, that's a REALLY basic description but I wonder if Bardeen and Shockley said, "Oooh! I GET it! Cool!!"
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Mark Gulbrandsen
Resident Trollmaster
Posts: 16657
From: Music City
Registered: Jun 99
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posted 06-11-2003 09:08 AM
Bruce, I agree partially. I enjoy restoring old tube equipment alot, but solid state amplifiers have definately surpassed tube amplifiers by a large margin in the sound department. It is possible to have a tube amplifier with the characteristics of the mids and highs of a tube amplifier, and the low end of a solid state quite easily....in fact you can even build your own if ya want to. This is something tubophiles have been wanting for many years. I've had alot of tube amps over the years, Atmosphere OTL, BAT, VTL, Western Electric, McIntosh, etc, and have never been really happy with any of them when hooked to a really good pair of speakers. There are limitations either caused by the coupling capacitors, or the output transformers, or other issues, however, power is not an issue with tubes at all....200 watt tube amps are quite common. The only problem is that the very best tube amplifiers do have limited power output and efficient speakers are required to reproduce realistic levels......efficient speakers can be very good but for the most part, medium and low efficiency speakers generally have sound advanyages that efficient speakers don't.
So far the best amplifiers I've owned is a pair of Pass Labs solid state clones that I built last year. There isn't a tube amp on the planet that even comes close to their performance. I've often felt that they are actually better at conveying the real music than can a tube amp. These amps are class A, single ended, all MOSFET, and have only three transistors in the signal path. There are no coupling caps in the circuit unless you use it in balanced mode, and then there is only one. Mine produce 115 watts at clipping into 8 ohms and around 165 watts into 4 ohms. Talk about having your cake and eating it too....this is it and building your own allows you to go way beyond the original design if you want to......for instance mine have power transformers that are 30% larger, also triple the heatsinking of the original factory built units and I have the bias maxed out. A tube amp capable of this much single ended power would be as large as a semi and be perhaps 15 to 25% efficient! These are 50% effiicient and are still class A. Perhaps the only better ampliflers out there are Nelson Pass's later designs that some are now starting to build. Check it all out on these links and enjoy! Mark @ CLACO
www.diyaudio.com
www.passdiy.com
www.passlabs.com
http://www.diyaudio.com/forums/showthread.php?s=11cc1c2ceb08e2f81ea419de2695b513&threadid=9159
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