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Thread: Hobby: building audio systems

  1. #1
    Senior Member foton's Avatar
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    Hobby: building audio systems

    Hello,
    Is there here anyone interested in electronics for audio? Any DIYer intersted in building its own audio systems; amplifiers, pre-amps, speakers?
    Or any electric engineer interested in vacuum tube, transistor technology willing to answer questions.

  2. #2
    I use to be into electronics before my injury, but it was limited to wiring in cars, homes and audio equipment. But that was 22 years ago and now I'd need a refresher course to screw in a light bulb. lol
    What are you working on?

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    foton,
    Hi, I'm an electrical engineer, who took a couple of audio engineering classes in college and had a hobby of building audio gear, especially loudspeakers. My SCI, two years ago, has stopped that for now. I would be happy to try and answers questions that you have.
    C1/C2 walking quad, SCI from 4/2010

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    Senior Member foton's Avatar
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    Hello,
    By trade I am a geophysicist with specialty of oil exploration under the sea bed. I have never worked in the field, though. My SCI forced me to work in IT. Electronics was my hobby back in elementary school. Since I am 50 years old, my electronics time was in transition period between tubes and transistors. Another hobby is music and in my house you can hear everything, but..... disco.
    I love sound of single-drive speakers (no crossovers) and single-ended tube and MOSFET transistor amps. Both in Class A. Not a green technology, but sound is amazing. I am a frequent guest in DIY Audio website. My problem is with limited electronic knowledge. Especially, when I have to find replacement transistors. To be honest, I am not into circuit design stage. I like to build and listen. So, there are many circuits available, but they are old and some parts are not available. Newer transistors offer better performance, but the problem which I have is with tunning the circuit for this matter. Currently, I prepare myself to build HIRAGA amplifier ( 20 Watts version ) and Nelson Pass designed FET preamp. With preamp I do not have any issues, but HIRAGA is a little bit tricky.

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    Senior Member foton's Avatar
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    This is link to Nelson Pass jfet pre;
    http://www.diyaudio.com/forums/pass-...-jfet-boz.html

    In my plans there is also MOSFET Follower amp from here:
    http://sound.westhost.com/project83.htm and Germanium transistor based amp.

    Since is midnight here I will explain my issue tomorrow. The question I have is about transistor replacement for HIRAGA and JLH amp by Mr. Hood.

  6. #6
    Senior Member foton's Avatar
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    Cajun,
    My first question would be related to transistor replacement. Do you understand all parameters of transistors to be able to tell it is good replacement and tune the circuit if it is necessary?
    I did try to read about it, but it looks the knowledge needs to be supported by experience.

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    foton, I got a minor in geophysics in grad school and briefly worked for Shell in seismic prospecting in Mississippi. My favorite audio projects were active-crossover loudspeakers. They largely eliminate the problems with the crossover. I could not get the Pass preamp to open because they require an account. I did look at the follower design. I don't see a provision for tuning in it, but I believe that it needs one to make the quiescent current accurate. To do this one would replace the 3.3V zener with an adjustable VBE multiplier circuit. I will find an explanation of this and send it in another post. I do have a good understanding of transistors and would help pick replacements.
    C1/C2 walking quad, SCI from 4/2010

  8. #8
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    foton, Here is an explanation of a VBE multiplier: http://www.ece.drexel.edu/courses/EC...ClassABAmp.pdf.
    C1/C2 walking quad, SCI from 4/2010

  9. #9
    Senior Member foton's Avatar
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    My diploma's subject was an electric method. After graduation I started to work in the geophysical lab to work on new type of geophone research for seismic method. After couple of years I changed firms and started to work in computer center to process data and plot maps of geological profiles. That was done by main-frame computers.
    Thank you very much for the link. Interesting. This is url to Hiraga "Le Monstre" amplifier. It shows older output transformers, which I still being made (TIP 3055/2955). I refer to 2nd schematic on the page:
    http://www.kk-pcb.com/hiraga.html

    I want to use much better transistors from Sanken: 2SA1216 and 2SC2922. Some recommend On Semi MJ series, but Sankens have very good reputation. One more thing, the schematic from KK-pcb site is scaled down Hiraga. I have just realized it. I need to find the orginal one. Still the idea of the amp is there.
    Last edited by foton; 03-25-2012 at 11:04 PM.

  10. #10
    Senior Member foton's Avatar
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    This is link to TIP transistor;
    http://www.datasheetcatalog.org/data...heohtr1pfy.pdf

    Sanken:
    http://www.datasheetcatalog.org/data...7/73327_DS.pdf
    http://pdf1.alldatasheet.com/datashe...N/2SC2922.html

    I tried to understand parameters, but it is beyond my knowledge. My question is about using them in that circuit. Can we use them without changes in schematic or we need tune it for these parts.

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