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Graham Slee View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 24 Mar 2019 at 7:33am
OK, if you're here to learn but I once remember during a phone call being asked if I'd like to borrow his son's college books on op-amps. He said it might help me...

I was very polite... I suppose not being an electronics celeb, people might think that way.

I am not into hi-fi snake oil, but will say I used Elna ROD's in the past. Quite effective, but now banned being of an hazardous chemical nature. All components have characteristics, but I'm wise enough to avoid the opportunists.

Why "I would do that"? All I am actually doing is making a particular circuit work as well as can be expected. Making things do the best it could get might mean going to extremes in component value selection: 103.678 pF might theoretically do a better job than 100 pF for example, but all components have parasitics, and there are also manufacturing tolerances. Can the difference be heard? No is the usual answer. Can the difference be measured? Again I think the answer will be no unless it's some precision filter.

High end hi-fi is full of opinions and I know of some who are unstable enough to use violence in forcing their opinions. I think we can do without that? I remember one particular character doing the rounds of the forums telling everybody how bad the Solo headphone amplifier sounded. He later admitted he'd never heard one, but was just supporting his favourite brand.

And as for bypassing C9: I tried to explain what bypassing does in an earlier reply?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 2019 at 12:33am
C9: I will get to try that now I have my "very own" Genera Phono Pre! Took your advice and put the highest voltage-to-size that would fit side-by-side and it exceeded my expectations for something I actually put together. I usually go by "if the ON led lights up - i've done something right!???" It has turned my Phono playing into "something else!" Very nice indeed! So, I got back to some reading and following along and I must be learning something because : http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1965/Transistor%20High%20Quality%20Audio%20Amplifier.pdf has something VERY WRONG in it's explanation. On page 4. he starts to explain the workings of the schematic (Fig. 2) under the sub-heading: Revised Preamplifier. in the second paragraph which starts: "Equilisation is again performed by feedback.." and then makes connections referring to Fig. 2 that don't make sense! How is the "collector of Vt2 going to the emitter of Vt1...???" I even googled the symbol of a transistor to confirm my long held knowledge of some years back! It's things like THIS that "do my head in!" as I am really trying to make sense of all this and some bloke with a * MA after his name spruiks absolute bunk! Maybe I should get out my prototype board and make up his "amplifier" per schematic and see if it actually works..?? That much does look ok!  but I think i'll stick with Graham's explanations, thanks all the same. 
 As far as C9, all I could find [pretty quickly] was "see what you think - after it settles down for a while.." I researched 'By-Passing' but have forgotten [like so much these days] what it was I found out - which tells me it wasn't too profound... 
Anyone else give it a try? 

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 2019 at 9:49am
Follow C5 to the right of VT2 collector via any of the EQ networks selected by S1b to the end of C4 which connects to Vt1 emitter.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 2019 at 11:55am
Yes, I take it back. Didn't consider it could make its way via that route. Embarrassed Unhappy One day... (hopefully!) 
Maybe the Art of Electronics will knock a bit of sense into my head - if I can swing it right...! [pretty heavy!] Clown
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 2019 at 5:00pm
As an old tutor used to say to me, when it gets too heavy, simplify! It got me through a year of mathematical modelling. Another clue he used to give me is "from what we know", but that is dangerous here because I'm guessing you've been reading in the wrong places. In fact I will go as far as saying you have been - this is obvious to me - I'm just trying to help.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2019 at 7:27am
Originally posted by Graham Slee Graham Slee wrote:

In fact I will go as far as saying you have been - this is obvious to me - I'm just trying to help.

Embarrassed ..Is it 'that' obvious? You are helping. ThankYou! for wanting to. I would 'really' love to get my head around "the nitty gritty" of it all. I've been trying to for quite a while and sometimes it does start to make sense when - then it doesn't. Maybe it never will. I do get a lot of enjoyment out of putting things like 'kits' together and getting things in the right places.. and thinking 'why' they get "put there!" I'll continue reading and trying to make sense of it all as listen to my records of Pink Floyd and Jimi Hendrix and Zero 7... that now sound better than I have ever heard them before! 
 Must be doing 'something' right..Shocked 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2019 at 8:03am
Isn't it amazing how a reasonably-well thought out circuit can sound using nothing more than "industrial" components? Wink

Incline toward the engineering and away from the bluster and you won't go far wrong.

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