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Old 2nd October 2012, 07:28 PM   #1451
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Originally Posted by dadod View Post
Better?

That's better, interesting. I think you are missing a couple of diodes on the right side of the input stage, this might saturate the cascode.
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Old 2nd October 2012, 07:30 PM   #1452
dadod is offline dadod  Croatia
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Loop Gain.
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Old 2nd October 2012, 07:32 PM   #1453
dadod is offline dadod  Croatia
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Originally Posted by scott wurcer View Post
That's better, interesting. I think you are missing a couple of diodes on the right side of the input stage, this might saturate the cascode.
I used LED instead, that is 1.9 V, more then two diodes.
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Old 2nd October 2012, 07:54 PM   #1454
EUVL is offline EUVL  Europe
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Would you be kindly enough to post your LT Spice files ?
Then we can all play with it.


Many thanks in advance,
Patrick
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Old 2nd October 2012, 08:14 PM   #1455
dadod is offline dadod  Croatia
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Originally Posted by EUVL View Post
Would you be kindly enough to post your LT Spice files ?
Then we can all play with it.


Many thanks in advance,
Patrick
If you meant me here it is.
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Old 2nd October 2012, 08:21 PM   #1456
qusp is offline qusp  Australia
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Originally Posted by bcarso View Post
I compliment those who use "complement".
ha, sorry for the laziness, autocomplete gives me that as I use it more often I guess and I havent trained myself to correct it. it also isnt set in my brain to use complement as a singular noun (by itself), or complementary as a noun at all… I know its correct, it just isnt habit. it seems to get used as a technical adjective, noun, or pronoun interchangeably.

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Old 2nd October 2012, 09:26 PM   #1457
qusp is offline qusp  Australia
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pronoun? lol..no

anyway back on topic, I can see another model of custom jfet SMD heatsink coming on. I guess I better break out the matching rig and go through my j103/k246. would these compound mosfet networks be of any use here? i've been thinking about getting some to play with for a while.

fairly low voltage though

Last edited by qusp; 2nd October 2012 at 09:44 PM.
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Old 2nd October 2012, 10:18 PM   #1458
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Originally Posted by scott wurcer View Post
... Re: post #1380 circuit ..

Q15 just samples a voltage to drive the current sources for the output stage, this saves some devices and keeps all currents set by the input stage. It also provides a slew boost to the output devices, not much benefit here at band limited audio but it makes prettier square wave pictures.

Sorry about the bad JPEG conversion that dropped some 1 pixel wide lines, post #1387 has a schematic that caught this.
Don't the CCSs, J1 & J2 isolate Q6, 7, 8, 9, 11, 35 and hence Q15 from the signal path?

I can see a signal path through Q15 on some of the later 'symmetrical' versions but not on the simple () #1380 circuit.

Or are there some missing tracks on #1380

ricardo
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Old 2nd October 2012, 10:32 PM   #1459
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Excuse, my ignorance but az i kunt reed en rite, I'm only on page 97 in my journey through these guru postings.

I get the impression this is a competition to be judged against Guru Wurcer's offering via LTSpice

From his #1380 post, the constraints are
- -100dB for 2nd, 3rd etc @ 20kHz with 20dB gain into 600R
- 2nV/rtHz noise
- zillion V/us into 10n
- 50R headphones too.

Please correct me if I'm wrong. I'd like to enter with my offering using NOS Mullard EF37As.
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Old 2nd October 2012, 10:47 PM   #1460
fas42 is online now fas42  Australia
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Many thanks to dadod for posting his version, I'm having problems with the output operating point, which is varying all over the show, up to nearly a volt offset. I need to play around with the models a bit more to get a handle on things ...

Frank
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