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Old 23rd August 2012, 07:00 AM   #61
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by dirkwright View Post
May I ask why 30 ohms? I think opamps are usually spec'd for 600 ohms.
This amplifier will be used for other than driving 600 ohm input Z's. Driving headphone z is a current application for such circuits. About 1/2 of the headphones are below 600 Ohm Z.
30 ohms is not uncommon. For example, two of my headphones (Senn HD800 and HiFiMan HE6) are 300 and 50 Ohms.

Ic are limited in power handling but this is a discrete design and no such limitation need exist. Thx - RNM

Last edited by RNMarsh; 23rd August 2012 at 07:16 AM.
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Old 23rd August 2012, 07:16 AM   #62
PMA is offline PMA  Europe
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You professional guys want for DIY audience to design a "discrete opamp" that you would use in your commercial designs?
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Old 23rd August 2012, 10:04 AM   #63
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I hope we see a design come of this thread that is new or at least has some novelty, tweak or improvement over circuits most of us have seen shown here to death. That includes circuits that some experts believe is new but are available all over the internet and as old as 30 or more years. Possible ???
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Old 23rd August 2012, 11:04 AM   #64
Bonsai is offline Bonsai  Taiwan
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I don't disagree with this, but as always, the devil is in th detail. Probably 80% of those designs have the wrong trade offs and are subsequently sub optimal.

Yes, i also hope we se something novel and with 8 trannies, it's going to have to be.

:-)
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Old 23rd August 2012, 12:14 PM   #65
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Lots of talk, no action. sigh....
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Old 23rd August 2012, 12:16 PM   #66
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True but one designer may optimize for a different reason which may not be obvious to you but important factor to him, so how can one judge that his way is not optimal afterall it is trade offs. For instance J Curl will optimize for wide bandwith but this is not neccesarily good for THD while Edmond will go out of his way to post lowest possible THD. Which one is suboptimal ??

I think the percentage is much smaller than that, probably less than 10 percent when it comes to commercially available equipment.
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Old 23rd August 2012, 12:24 PM   #67
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Quote:
Originally Posted by dirkwright View Post
Lots of talk, no action. sigh....
Patience please, geniuses at work on it.

And then comes the dissapointment of seeing something weve seen years ago.....
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Old 23rd August 2012, 12:26 PM   #68
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So, some schematics a copied off a simple search. So much talk, so little action.
Attached Images
File Type: gif NTP_M100_OPAMP.GIF (34.1 KB, 742 views)
File Type: gif je-990.gif (7.7 KB, 752 views)
File Type: jpeg quad8am10op.jpeg (94.4 KB, 739 views)
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Old 23rd August 2012, 12:27 PM   #69
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Quote:
Originally Posted by homemodder View Post
Patience please, geniuses at work on it.

And then comes the dissapointment of seeing something weve seen years ago.....
It doesn't have to be unique. It just has to meet specs.
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Old 23rd August 2012, 12:43 PM   #70
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A few more for inspiration.
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File Type: png 0129a7fd_Discreteopamp.png (169.4 KB, 740 views)
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File Type: gif disc-oa.gif (8.6 KB, 434 views)
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