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Want to build an amp

Discussion in 'Electronic Repair' started by [email protected], Oct 13, 2007.

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  1. Guest

    Not just any amp. I know how to do it and it is not only time to prove
    myself, my Sansui fried

    So I need an amp. Going in, I want to protect my speakers, and my
    design will never distort. The gain stage that accomplishes that is
    shut down until it is needed, and there are other factors as well. If
    I pour myself into it, I will use this certain power trnasformer. This
    thing is bad to the one. It maintainms + and - sixty something volts
    even under a four ohm load on both sides. Cranking this thing up could
    blow a breaker in the main box, and did so. I think this is about one
    of the best I have ever seen. Highest power output.

    Thing is I have these speakers that I really like that can't handle
    all that juice, so I intend to put in a limiting system. I have given
    some thought to this.

    Since it has to work into low impedance I am thinking really hefty
    trasnsistors, three pairs of them per channel. And regulators,
    switchmode regulators.

    I intend to make ananalog algorithim. I want to make it whaere you can
    select the maximum power output, and it will regulate the rails down,
    but still provide a bit of instantaneous power. I intend to do this
    all in analog.

    The maximum power of this amp will be about 263 watts per channel into
    eight ohms, What I want to do is to protect my speakers. So I intrend
    to build in regulatiors. I am wrestling with the algorithm now. Do I
    detect current or voltage ?

    The deal is this, there will be three pairs of outputs in each
    channel. There will also be three swictmode FET regulators feeding
    each bank of them. This is to limit power. This is to save the
    speakers I like.

    Now the idea here is to give it alot of oomph. I want to deytect when
    the woofers are in over-excursion, and limit it to that. That user
    will have power levels to choose from, and that is the max, but then a
    lower average power is selected and the amp couold have as much as
    +12Db dynamic headroom.

    To do this, The regulators will have to operate at at least 100Khz.
    Maybe higher. I need top keep ahead of the demand. I want the impact
    my subwoofers can deliver, but I do not want to destroy my tweeters.
    This is a tall task in the analog domain, but I think I can do it.

    Now to provide the dynamic headroom, heretofore unseen on Earth, I
    will have to build a time constant into it. I will have to tkae into
    account what my speakers can tak as wel as the ouput devices, actually

    It is time, I am getting to the pimt where I really want to do this. I
    know I can. I have a very different bias cicuit that is tolerant of
    supply rail changes, I did find a wat to compensate. I know how to use
    commutator switches and efven analog commutators, but thet is not the
    direction I want to take. I want to give my amp alot of headtroom so
    it never distorts. Impossible you say ? I have already designed it.

    Even some generic 829 can do it, the trick to keep the distortion down
    is to keep the gain stage out of the loop untill and unless it is
    needed. In other words the 829 just shuts up until it is time. It will
    add a bit of residual noise but that is all.

    But this is more advanced, I want the power supply to tradck the
    audio, and provide a PREDETERMINED amount of extra power for a very
    short time.

    Don't get me wrong, set this thing to max and you got over 500 watts a
    channel into four ohms. It would be 600 into my speakers but it will
    never see that level unless I go spend money on something else.

    My speakers are good enough that I wnt to keep them, and they are good
    enough to land me in jail. How much more power do I need ? But I would
    consider this a personal achievement, to build this.

    We are talking twelve really good bipolars, twelve high speed FETs and
    four coils alomg with a few high performance lower capacity filters.

    I mean I want to detect when a woofer cone goes out of the magnetic
    field via current monitoring. I have never seen an amp do this right.
    I mean in a real time way with no digital. And this is only for the
    bass. I got plans for the rest of the audio spectrum as well.

  2. Lynn

    Lynn Guest

    Why don't you learn how to use Google, Jerk.
  3. James Sweet

    James Sweet Guest

    How about one of these?

    I built one a few years ago and have been happy with it. It's all the power
    I could ever need.
  4. Arfa Daily

    Arfa Daily Guest

    Aiwa did something similar to this years back, when they had the supply
    rails to the output stages switched 'on the fly' by FETs, according to the
    demands of power. There was then a very sophisticated protection circuit,
    which monitored many things, including output current.

  5. And it it's not a repair issue, the post doesn't belong here.

    This is, not something else.

    Read Mark Zenier's guide to the sci.electronics.* hierarchy
    and post in the proper place instead of adding to the decline
    of this newsgroup.

  6. Arfa Daily

    Arfa Daily Guest

    Apart from the obvious spam posts, which almost all groups suffer from, and
    is by no means the fault of the posters here, I see nothing that constitutes
    the spiralling decline that you are always bleating on about as occuring to
    this group. I have been active on it for some years now, and it seems to me
    that little has changed. Most questions still get answered in a polite and
    gentlemanly way. Most posters' problems are resolved by the regular posters,
    much as on other groups. I don't see anything in the guide that you have
    linked to, which seems to cover any kind of 'decline' that you perceive. You
    have a real bee in your bonnet about what you consider to be off-topic
    posting. As I have said to you before, sometimes people wander on here by
    accident with a question which, whilst being electronically related, is not
    necessarily to do with repair, but never-the-less is still an interesting
    discussion point. Sometimes, regular posters, who regularly help out with
    other people's problems, (such as ZZ who started this thread) have a general
    electronics issue that they wish to discuss with other engineers who are
    their 'net friends'. Should they go off to some other group where they don't
    know anyone, just to please you ? Sometimes, real engineers just want to
    'chat amongst themselves' about things in which they have a mutual interest,
    which may not be directly repair related. Provided that this takes place
    generally within existing threads, I don't see that it impacts on the
    validity of the group as being one primarily for repair topics, at all.

    Just as a matter of interest, other than playing at usenet policeman, just
    what exactly do you consider your function on here to be ? I don't recall
    ever having seen you make a constructive repair reply to any poster. Do you
    even have an electronics repair background ? Your normal input is just to
    tell people that their post is unwelcome, and to clear off to a different
    group ...

  7. jakdedert

    jakdedert Guest

    Bingo! This is the heart of the matter. Nobody named 'Michael' has
    ever, TTBOMK, contributed anything of value to this forum. I myself
    have contributed damn little beyond anecdotal advice; but I have learned
    much from the masters here. That would not include Michael, whomever he is.

    I suggest to him, that he get a life and quit trying to run others'.....

  8. hr(bob)

    hr(bob) Guest

    If you check Michael's profile, he has posted more than 14,000 times
    in the past couple of years to every single usenet group. The
    internet is his life, poor soul.

    The original Poster did post a strange sort of message, but that's
    still no excuse for the kind of reply he received from Michael.

    H. R;l (Bob) Hofmann
  9. Meat Plow

    Meat Plow Guest

    Your reply is not a repair issue. By your own logic it does not belong
    here either. Practice what you preach Netcop-Wannabe.
  10. Paul Feaker

    Paul Feaker Guest

    I don't recall a time when you told somebody how to fix their tv or
    whatever every time I read a post from you you're bitching about
    somebody's else's posts because you're too much of a retard to actually
    input some useful information.

    Go start your own newsgroup you fucking faggot.
  11. Guest

    "Why don't you learn how to use Google, Jerk."

    You know what, I'll show you what kind of jerk I am. My IQ is around
    200 what the **** is your's ? I can do the math to build an amp like
    this in my head, can you ?

    All you know is fucking Google for this and Google for that. You know
    nothing, you depend on outside sources, while I find my own, and have
    all my life.

    Don't bring that fucked up brain to a battle of wits with me. While I
    admit I had a buzz on when I posted this, the idea is clear. And it is
    really strange that using Google is what gets me here. What's more I
    doubt you comprehend search engines better than me, I had a four word
    string that came up with ONE result. The four words are available to
    those in my good favor.

    Get off your high horse and uncall me a jerk. Then we can talk.

    Just your one statement gave me your whole life. I know how you are
    and I know how to hurt you. Am I still a jerk or not ?

    I will get to the rest of the responses ASAP.

    For the rest of you, I really don't like to get like this with people,
    but this is usenet, and you never know where someone is. I can incite
    this guy to want to kill me, I can simply tell him where I live. I
    even have help to get rid of the body.

    I do not know how to use Google ? for what ? A circuit design ? Hell
    no. Mine is better, it autocompensates for varying supply voltages,
    and there is not a single capacitor in the circuit. So the supply
    voltage can change fast, and that is what I want.

    OK, I will start another reply here, this guy got his, now I go read
    the rest.

    And Lynn, you are obviously young, I have no doubt. Learn. You have
    not the power to embarrass me,I am secure in my achievements and my

    When you call off work and tell them straight out you took off
    because you did a bunch of coke the other night you might be able to
    tell me who has skills.

    I do not want anyoine else's design, I want MINE.

    I settle for no less. And I can Google with the best of them. Do not
    **** with me again Lynn.


    Be Back Soon.
  12. I didn't think that I had never contributed anything... I don't think I have
    contributed a lot since I'm not an electronics engineer, but every now and
    then I help answer easy questions that passer byes ask like whats wrong with
    my LCD monitor. :)

  13. Guest

    Lookit, if we can't play nice, well I dunno.

    I have met some good people here Bill Jr and Leonard come to mind.
    They both have helped me out, as have others. I try to help people
    when I can. If this bullshit does not stop all the good people will
    leave, leave the morons to their own means, which amounts to nothing.

    let me tell all the motherfuckers around here about just who I am . I
    am also JURB6006. I have been published all over the web, and even
    though they caught it in this newsgroup doesn't mean credit goes to
    this newsgroup. I have been to pay sites at work and seen my own
    posts. As such I don't have to take shit from anyone.

    I decided to post a post about the amp I am going to build, you got a
    fucking problem with it, answer one fucking question; do you own
    usenet ? Do you even own ? Can you even type
    that ? I just did.

    And amma fuckin tellya one more thing, people who fix electronics know
    alot more about certain aspects of it. And that is why the post is
    here. If anyone doesn't like it I have a fucking perfect solution for
    you, when your mouse pointer is over a thread you don't like, DO NOT
    CLICK IT ! It is treally that fucking simple.

    My next post is going to deal with the specifics of the analog
    algorithms used in the power limiting system. The fucking peanut
    gallery will shut up. Ideally I would like to get it to set itself,
    detect the peak in current that is always precedent to a woofer

    Anyone who wants to flame me can go to work for eight bucks an hour.
    This is higher reasoning and I put it here for good reason. My reason.
    AND this is not

    Boil it all down, anybody who says I shouldn't post this here can go
    **** themselves, I have every right to be here and I have helped many.
    If you think that bullshit and you think you are some kind of police
    or something I will give you my home address, and when you get here
    you will leave with a 327 Chey V8 camshaft up your ass, guaranteed,
    and if you think you might like that, we can use your throat instead.
    Just ask.

    Just ask.

    I won't bother to sign this, you knoiw who it is from.
  14. Guest

    Now that we got that out of the way......

    I have been thinking about this algorithm, this is a bit new to me,
    but I do want to persue it.

    OK this is a bit of a complicated situation, but the engineering can
    be of great benefit. My speakers are Boston Acoustic A150s with the
    addition of four ohm subwoofers on each side. I have no desire to
    biamp them, and I wouldn't mind having a really great amp.

    I can't let those 65 volt rails near my speakers, but....

    First of all I would like to have the dynamic range reproduced
    transparently until and unless the unit is cranked, and the does mean
    significant power of course, and it also means a smooth transisition
    from real to managed dynamic range when the power linits are

    But do they have to be set or can they be detected ? I am sure it can
    be done with woofers, but what about the mids and tweets ? I like
    bass, but not to the exclusion of the rest of the sound.

    Those who know, in an amp you have the main feedback resistors, a
    divider network that sets the gain. at the point where the cap goes to
    ground, is my circuit. It is a short circuit until needed, then it can
    reduce the voltage gain of the whole stage.

    For one it will always be triggered by clipping, and that comes either
    at 200 something a channel or some lower limit set. Then it also
    monitors abrupt increases in current in the bass regions. Now if it is
    running in cranked mode, it also handles the dynamic range. The power
    regultors will allow short bursts, even of full power if the impedance
    of the speaker does not drop like rock. When that happens, it charges
    a capacitor, which limits further incursion into the power range that
    can kill the speakers. It doesn't lowr the average power setting that
    the user determined, just the allowed headroom.

    I think I need these regulators to operate at least at 150Khz or so,
    and designing that part is no joke.The thing is what to do with it. I
    mean how do you determine how much power is too much ?

    While I think dynamic midranges and tweeters can be detected the same
    way, and intend to implement multiband detection, I do not want
    multiband control. If any speaker is in danger I want the gain cut.
    All of it, I do not want to affect the frequency response.

    More later.

  15. Well bozo, I've been reading this newsgroup since 1995. I can remember
    when it was loaded with posts about repair.

    I read it to learn, and posted when I had something to contribute.

    I've had enough posts here, and hey, there's even a snippet of
    one of mine in the FAQ.

    But like so many other newsgroups, it's turning into a hangout for
    people who can't be bothered finding the right newsgroup.

    The "proof" of someone's value to a newsgroup is not how many posts
    they make. Because some people with too much time on their hands
    decide they'll hang out in a newsgroup, and post all kinds of off-topic
    junk. They rack up massive posting history in that newsgroup (and
    too often don't post anywhere else), but they often don't have that
    much to say on topic.

    The newsgroup becomes their hangout, and they don't care what
    the original intent of the newsgroup was.

    The lack of on topic messages makes people tune out, the
    "regulars" don't notice, because they are too busy hanging out.
    Indeed, those "regulars" are likely shorter time posters than
    the people who leave.

    And the fewer people who read a newsgroup means the fewer people
    who are around to reply when someone needs something. The pool
    of people who can answer is diminished. Just because a handful
    are oh so quick to respond to every post at any hour of the
    day does not mean they are the best people to answer all questions.

    Someone who traced the linear/power supply board in the Mac Plus
    years ago won't be of much value when someone asks about it if
    they are no longer reading the newsgroup.

    Some specific bit of knowledge may come up rarely, but the
    moment someone asks about that area, you'd better hope they
    are still reading the newsgroup.

    If the hotshot "regulars" so badly want to answer every single
    post, then let them find the proper newsgroup.

    When so much of the posting is off-topic, it's not really a surprise
    that I have nothing "worth" posting about.

    While ironically, there is nothing much to post about in the proper
    place either, because they aren't getting the on-topic posts either.

    I can remember when sci.electronics was split. "Too much traffic"
    some complaind about. It was rather brisk, but then I was using
    a 2400 baud modem and had no more than an hour a day access
    to the BBS where I was reading the newsgroups.

    But what we have now is lots of newsgroups, and half the time
    people don't even post in the right place. I don't read .design
    any more because it became a hangout, the swaggering of the "regulars"
    who took over the newsgroup, who "decided" it was acceptable to
    post all kinds of junk. The fact that there is a lot of political
    junk in there is both a cause and effect, because they decided
    it was acceptable and then hey, one thing people fight about
    is politics. But then all kinds of beginners post there because
    "this has the most traffic".

    Meanwhile, there is a perfectly good newsgroup for .basic posts,
    and it's pretty empty because nobody much is using it for its
    intended purpose. There's one about .components and it's underused,
    and so on. There area load and loads of newsgroups to discuss
    computers, and places to discuss vacuum tubes.

    We might as well all fold into One Big Newsgroup if people can't
    be bothered to use the proper ones.

    ANd hey, when idiots post in the wrong newsgroup, they hurt
    themselves. Any beginner who posts in .design is likely to
    get an answer that isn't useful to them. Someone who posts
    here about a computer problem is relying on someone incidentally
    having knowledge that can solve it. Find the right place,
    and you increase your chances of getting a useful answer.

    Most of the newsgroups I read, I've read daily for over a decade.
    I've added some, a handful I've tuned into for a relatively short
    time, but most of the newsgroups I read today I was reading a decade
    ago. But increasingly I am tuning out. Not because of spam, not
    even because of the too often massive cross-posting. I don't tune
    out because there's no traffic (some get a handful of posts
    every few months).

    No, I tune out when it becomes a hangout. People more interested
    in arguing among themselves than talking to each other. People
    bored with the purpose of the newsgroup, who still stick around
    instead of finding the proper place, so they post about the weather
    and politics and their computer problems and everything else.

    And in each of those newsgroups, I have a "big enough" posting
    history. I also have a long enough reading history. But hey, it's
    dwarfed by the people who rack up thousands of messages in a few years, but
    much of which isn't on topic.

    If I wanted to read general purpose newsgroups, I'd read the local
    newsgroup (which ironically I do, but it's not being used much).

    Most people don't realize how a newsgroup declines, because they
    aren't paying attention. And by the time it is noticeable by many,
    it's too late.

  16. Lynn

    Lynn Guest

    I got an even bette idea. How about you go **** yourself?

    the original poster has posted here several times and is well

    What have you posted here besides your bitching?
  17. Fleetie

    Fleetie Guest

    [... etc.]

    Well said, Arfa!
  18. John Todd

    John Todd Guest

    audio, and provide a PREDETERMINED amount of extra power for a very
    short time.

    Power supply tracking audio, implemented in analog--in its
    simplest form, this is a description of an audio amp! How will you
    prevent the introduction of distortion?
  19. Meat Plow

    Meat Plow Guest

    You're a real fuckhead. You don't own the group and if you don't like
    reading it then unsubscribe now and save those that like to hang out here
    the trouble of reading your petty fucking bitching.
  20. Arfa Daily

    Arfa Daily Guest

    You know, if you had a valid point with respect to this particular group, I
    might be persuaded to go along with you, but over the years that I have
    'hung out' on here as you so quaintly put it, I have seen no signs of any
    kind of general decline. In fact, I would go as far as to say that this
    newsgroup is a shining example of one that continues to exist for its
    primary purpose of helping people with their repair problems, and is
    absolutely the right place for anyone with a repair-related question. The
    vast majority of posts to this group - and there are a good number most
    days - are absolutely 'on-topic' by your very limited criteria, and get
    dealt with by one or many of the very good people who 'hang out' on here,
    and have a huge raft of both specialist and general electronic knowledge
    gained by a lifetime either as a professional or serious hobbyist.

    I, and I'm sure many others who 'hang out' on here, resent your implication
    that we are internet saddos who live to jump on every post, and collect as
    many posting statistics as possible. I come on here, as part of my
    professional life, because I feel that 35 years of experience in the repair
    business, is worth offering to amateurs, hobbyists and less or differently
    experienced professional service engineers. I genuinely enjoy helping
    others, and I'm pretty sure that most of the other regulars on here, do as
    well. I also come here to continue to learn from others differently
    experienced from myself, as I'm certain many of the other regulars do.

    If you are active in a useful way on all of the newsgroups that you claim,
    and you honestly believe that this one is in terminal decline, then perhaps
    you should just leave, as you keep threatening to do. Perhaps you should
    also stop and consider the old phrase "If things don't change, they'll stay
    as they are ..." Nothing in this world stands still. Everything evolves,
    and not always for what we might all consider to be the better. Usenet is no
    exception. There is now a much wider spectrum of people who know that Usenet
    exists, and have found out how to get access to it. That in itself changes
    the nature of the beast. Accept it. Get over it. Move with the times.

    And if you can't, then really do consider departing to a group where there
    *are* problems, and your dissenting voice might be better heard and received

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