yes. Open loop. I assumed the circuit idea (trim) would be applied to a completed amp circuit. Do you have simple trim technique for reducing distortion.... ac and dc balance... open loop?
THx-RNMarsh
Thanks, John. Yes I did miss the AA party. However, this year I have promised myself that I will be at the Burning Amp. I have never been, and look forward to going.
Cheers,
Bob
If one is crazy enough, one can build a full complementary JFET cascomp to reduce the odd-order distortion, but it eats JFETs like M&Ms at a movie. Even though the JFET is not a translinear device like a BJT, the cascomp arrangement still works for JFETs.
Cheers,
Bob
Simple is good, BTW the active feedback principle (nulling two diff-pairs against each other) works too.
Pat Quinn, not Barrie Gilbert. His patent is attached at the bottom of this post (PDF warning).
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Hum? It gets around! The average living room will have a dozen or more radio sources in it these days, not to mention cheap light dimmers and square mains waveforms. As having good CMRR doesn't cost much seems churlish not to have a belt and braces approach and cheaper than a custom mains filter for each unit!
The standard RCA cables, are susceptible to common mode signals, but high and low frequency.
The rest of the circuitry is "inside the box" and is up to the component engineer to manage. Typically, not an audible problem.
Cool, CA is kinda out of the ways, no? Probably a lot less EMI hanging around than say, me living in an urban part of San Diego, where you look cross eyed and see 60Hz. (Pun intended, given that our "refresh rate" is pretty well pinned to the same number)
Any/all designs I work on from here forward will focus more on CMRR and PSRR than the last n'th in THD+N (the +N part is pretty easy when you get the global gain low enough for home consumption).
Pat Quinn, not Barrie Gilbert. His patent is attached at the bottom of this post (PDF warning).
_
Except it far predates 1977, best to let the precedence arguments rest.
B-bbb-but, that would mean that the US Patent and Trademark Office issued an invalid Patent, because the US Patent and Trademark Office ignored crucial Prior Art. This is unthinkable. This is a travesty. This cannot be so.
No Barrie was at Tek just before I met him in 1974, apparently the idea floated around for a while. Just like the Forsell pre-amp, Bob Demrow presented the basic idea in 1968 as Walt Jung has documented. Maybe you would like to see the story of the guy who "patented" the current feedback amp in 1998 and retroactively sued the entire IC industry. Much to my chagrin he got $250K or more nuisance payoff. It's my favorite patent abuse story, the guy was bonkers and claimed he couldn't pay his maintenance fees because he feared leaving his trailer and the PTO (it might have been the Texas courts) re-instituted his claims. He also sold headgear to protect the user from cell phone radiation.
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Hi John,
An N-channel JFET cascomp is shown in Figure 25.13 in my book. A BJT full complementary cascomp is shown in Figure 25.12.
Pat Quinn was a good friend of mine at Bell Labs Holmdel before he left and went to Tek. Barrie Gilbert mentored him.
Cheers,
Bob
Reverse engineered and done my own version for fun, cant PM attachment's though.....
Ooooch a bit below the belt, next week for my next session!!!!! Biopsy 3 and the major one....
Not so much of a joke as a bit of a gotcha on another thread by Mr Simon winding me up and me falling for it... So I have reversed engineered his design and done my own layout, total time 2 hours
Not so much of a joke as a bit of a gotcha on another thread by Mr Simon winding me up and me falling for it... So I have reversed engineered his design and done my own layout, total time 2 hours
One of the most famous people in audio who pursued that approach for fun and profit was Bob Carver who for a number of years was suing subwoofer manufacturers, from small to large, for royalties related to his "invention" of the subwoofer.
Of course the smaller manufacturers caved and paid because fighting the suit would cost more. Carver's progress was allegedly halted when he progressed to some of the larger manufacturers, which resulted in this filing among others:
http://ipmall.info/hosted_resources/Markman/pdfFiles/2002.06.14_CARVER_v._VELODYNE_ACOUSTICS.pdf
Reminds me of a certain IC 'design house' that held a string of patents using CFL backlighting technology for computers and TV during the 90's and up until LED's took over for back lighting. I remember going through the patents - they were all b.s. and full of prior art. We had customers all over Asia that would not look at anything but this companies parts because they were petrified of getting sued. Then LED's came along, so we screwed them good and proper.
IP protection is needed and its vitally important. But oh my, I do wish the courts - and especially those in the US - would cut through the crap and throw bs claims out. There are too many jackasses out there making money out of this nonsense. In fact there should be legislation - you bring a bogus claim, you get 5 years in the brig and court costs.
IP protection is needed and its vitally important. But oh my, I do wish the courts - and especially those in the US - would cut through the crap and throw bs claims out. There are too many jackasses out there making money out of this nonsense. In fact there should be legislation - you bring a bogus claim, you get 5 years in the brig and court costs.
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