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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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Old 23rd August 2012, 12:43 PM   #71
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Four of those already dont qualify, over 8 transistors.

No CFB types ???
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Old 23rd August 2012, 12:50 PM   #72
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Originally Posted by homemodder View Post
Four of those already dont qualify, over 8 transistors.

No CFB types ???
current sources are not counted. But, even so, if you like it and it has more than 8, then since you're a genius you can fix it, right?

I saw some CFB types, but they had way more than 8 transistors. Do you have any examples you'd like to share or are you just going to talk talk talk???
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Old 23rd August 2012, 01:40 PM   #73
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Anything less complex than a Jensen 990 is a joke, and not worthy of consideration. We are looking for EXCELLENT circuits that we would use in the best audio equipment available today.
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Old 23rd August 2012, 01:55 PM   #74
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> Anything less complex than a Jensen 990 is a joke

That's the strangest statement .........
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Old 23rd August 2012, 01:55 PM   #75
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Originally Posted by john curl View Post
Anything less complex than a Jensen 990 is a joke, and not worthy of consideration. We are looking for EXCELLENT circuits that we would use in the best audio equipment available today.
I thought you already did that? You're asking US to design something for you?

That would be like Luke Skywalker teaching Yoda how to use The Force.
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Old 23rd August 2012, 02:08 PM   #76
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Originally Posted by abraxalito View Post
Digikey is listing both the J76 and K213 series as obsolete. So that looks like a dead end then.

Toshiba has some high-gm FETs (even better on paper than Renesas) but they're rather low voltage and have higher thresholds than the laterals. Along with negative Vgs threshold temp coeff.
Hitachi FET To-220ab 200v .5A 30W GSD *SS | HITACHI *SS | Distributed By MCM
Hitachi Hitachi FET To-220ab N-ch 15V .5A 30W GDS *SS | 2SK215 | Hitachi
Hitachi FET To-220ab P-channel 180v 5MA 30W GSD *SS | HITACHI *SS | Distributed By MCM
Hitachi FET To-220ab P-channel 160v 5MA 30W GSD *SS | HITACHI *SS | Distributed By MCM
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Old 23rd August 2012, 02:08 PM   #77
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Sorry guys EVUL started this so fast I was caught off guard. I hope to put up a couple of ideas later today. I don't think complexity is a goal in itself, performance is. I also don't think a design contest with an 8 transistor limit should be a prime goal.
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Old 23rd August 2012, 02:10 PM   #78
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Originally Posted by dirkwright View Post
So, some schematics a copied off a simple search. So much talk, so little action.
Number two (from post 68) is not too bad. Whose is it? It looks like something that really works.
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Old 23rd August 2012, 02:16 PM   #79
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Agreed.
Nice to have, not must have (less than 8 active devices).

The same applies to extendability to a fully balanced configuration, a la OPA1632.




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Old 23rd August 2012, 02:18 PM   #80
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Sorry guys EVUL started this so fast I was caught off guard. I hope to put up a couple of ideas later today. I don't think complexity is a goal in itself, performance is. I also don't think a design contest with an 8 transistor limit should be a prime goal.
Eight transistors is RM's idea, although he's already relaxed things a bit by suggesting he might accept cascodes as counting as a single device, and might likewise allow current sources.

I was thinking yesterday of days of yore when transistors were dear, and PNP silicon ones were just becoming available. Some active filter papers were showing a three transistor opamp (they called it a VCVS, voltage-controlled voltage-source, as it was used for that function and typically at very low closed-loop gains). They were quite pleased at the performance attained Sort of the early Western Electric tube stuff in solid-state, and I don't doubt there are a few out there who believe that the simplicity somehow confers some sort of sonic excellence.
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