John Curl's Blowtorch preamplifier part II

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scott wurcer

scott wurcer

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Joined 2004
PMA said:
Based on Scott Wurcer's idea, I have built a new link stage, several month ago. With the best SOTA AD IC's. Let me attach a basic schematics, some parts are missing and values are not declared.
It is the most transparent preamp I've ever heard.
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Thank you PMA, it is a good example of using discrete plus IC to get the best of both and still have something that at least has some claim to simpicity and accessibility to any DIY'er. Two schematics today, back on track?
 
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dvv

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Joined 2004
Kindhornman said:
dvv,
Sometimes I find it better to be somewhat diplomatic in my use of words. Reasonable was one of those words. I don't want to disparage all the designers out there of low cost speakers, they do have to meet a specific price point for the designs they do. Even a few cents is a major factor if you are making millions of small devices.
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Understood and accepted.

My point was that until I saw those speakers, I could not even imagine such junk being produced in this day and age. And I have imagination for export, trust me on that.

Also, I'd like to remind you that I too am a manufacturer (small time, of course), so I am well aware of the economic factor in play.

To end this subthread, in all honesty, the new car I purchased, this time by the new owner GM (Daewoo was originally part owned by GM and used GM's mechanicals throughout, now GM ownes them lock, stock and barrel, and it's no longer Daewoo but GM Korea), in form of a Chevrolet Cruze, has a surprisingly good quality audio system factory built in. With some twiddling, I got exactly where I want it and there's no need for any changes. Uncompressed WAV via the built in USB port is better than I'd expect from it.
 
Kindhornman

Kindhornman

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Joined 2012
Pavel,
Do you have any intentions of sharing the design of your new line level design with those who would be interested in such a design? I can see the logic of a design using both discrete and integrated circuits, it seems to make much sense and that is what I was asking Scott about earlier. I see you included some of those 8 legged spiders in your design!
 
PMA

PMA

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Joined 2002
pmacura.cz/audiopage.html
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Steve,

thank you for your interest in the circuit. The idea is completely Scott's. With balanced output added. I have overlooked it, for some time, but then I suddenly understood the point. I do not think I am posting a complete schematics with values now.

The IC's are those with lowest noise available, yes AD and yes both the legendary one and a new one (Jonathan), together with a best JFET opamp by former BB. JFETs are 2SK170BL.

Output stage is capable to give some 50mA.

Regards,
Pavel
 
apassgear

apassgear

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Joined 2002
fas42 said:
Until people get over this "hangup", :p, the industry will always have a problem, methinks. What one has there is a quite decent midrange unit, which loses only on the top and bottom, it's actually covering, say, 95% of the sound that counts - and it's how well that is reproduced, for all the reasons I've mentioned many times, that's important.
...
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Frank,
After hearing many times of your experience with PC speakers I decided to give my sennheiser cans a rest and brought out a set of Pleomax S2-300B PC speakers (Samsung) and after a week of warming them they still didn’t sound good so decided to look inside the “plate” amp. It looks generally well done with all cable connections welded and the only thing it occur to me was adding a good Pana FC 100uf to the main filter and after a couple of weeks it’s sounding quite decent, albeit not to the level you describe. In fact I’ve just played the Oosten "Organ Symphony No 6" Widor you mentioned and did a credible rendition at a moderate level but no window shattering of course… but quite pleased up to this point.

I’m wondering what to do next, maybe changing all other caps for better ones? Better decoupling for the audio chip? Which would be your suggestion?

Antonio
 
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dvv

Member
Joined 2004
Kindhornman said:
dvv,
Agree on what you are saying. I have been a manufacturer for a long time and understand cost constraints. As for your car glad you are happy with the sound, now if they would just stop putting the speakers at knee level I would be a much happier camper in most cars!
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Agreed.

It doesn't bother me much because I believe a car to the wrong place to dedicate oneself to music, and it's only then that I start paying serious attention to what's reproducing the music. I am usually too busy trying to avoid some kamikaze driver, or some idiot with earplugs on who doesn't give a hoot about the red light for him.

So, as you say "reasonable" is good enough for me in the car, and in truth, I got better than just reasonable, so I'm quite happy.
 
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gpapag

gpapag

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Joined 2002
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dvv said:
So far, I have been able to read books by Douglas Self, Bob Cordell and Ben Duncan. I have had an opportunity to read all sorts of comments by fans prclaiming the to the Word of God, no less, and all others to be False Prophets.
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If you are interested in the evolution of audio circuits, there is also John Linsley Hood with his two books.
No 'prophet' and no fanatic 'followers'.
:)

George
 
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