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  • #16
    <font face="Verdana, Arial" size="2">Originally posted by HTRN:
    In terms of Digital, go with Legacy Monoblocs...

    .....

    They're also the only amp I know of that will actually go to DC for an output signal

    HTRN
    </font>
    And who's ears are that good? Fact is even the best ears around can not hear under 20 or 15 Hertz. OK, perhaps you can feel it in your skin. But what the hey? Is that really necessairy?

    Likewise, most ears can not hear anything above 20K Hertz. A lot nothing above 10K.

    If I was looking for a better amp I would be looking at other things like signal to noise ratio, crosstalk, harmonic distortion, peak and average power output, power response (most frequency response ratings are for voltage out, not power out. It's a cheat in the way specs are written.)

    Digital in an amplifier is a farce. The output stage is still an analog power amplifier. Digital just adds the possibility of adding digital noise to the mix. Yes, you need it for a digital system but it is not an automatic increase in quality and it is definitely not a way of providing power to drive speakers.

    Paul A.
    Paul A.
    SE Texas

    Make it fit.
    You can't win and there IS a penalty for trying!

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    • #17
      Having been in the repair end of things for 30 plus years, I'm saddened by the turn of events in amp manufacture. The way they're built now is nearly as throw-away junk, even though they can sound good when working properly. Typical these days is one large pc board with several smaller pc boards stiching up out of it. There's often no bottom to remove to get at things, and if it needs repairs, it can be an expensive nightmare. Makes me sick. Give me one of the older good quality amps, and with some maintenance it'll be good for many years yet, and it can be fixed when and if it breaks down. It is true though that if it's loaded with features, there will be more circuitry inside, with more signal pathways, so the potential for signal interruption is higher. Sometimes the switches don't respond to cleaning, and often enough these days, the part is not easily available, if at all. A general guide to whether it's worth fixing or not, is if the switches aren't easily accessible, it won't be worth fixing.
      A lot of amps are suffering these days because a cassette deck is hooked up into them, and a switch in the deck will cause a high frequency oscillation which can play havoc with an amp. If the amp can respond to a high frequency signal, it will be trying to amplify it, and can overload and cook. The contacts in the deck's switch go bad, and that essentially couples the input signal to the output signal, causing an electronic feedback loop to occur. When it cooks the amp, the most common thing is to get the amp repaired, but to ignore the reason why it cooked in the first place. Chances are it will cook again, because the root of the problem didn't get resolved. The deck doesn't even need to be powered on for this to occur, it just needs to have both sets of patch cords connected to the amp (or preamp, if that's a separate piece). Most people don't accept this as a possibility, since it seems far-fetched, but it's very real. I've seen it at least a hundred times, probably more.
      A really good recommendation for those with oldie but goody stereo systems is if you don't use your cassette deck anymore, then disconnect it (not just the power) and avoid this problem. Remove the patch cords from the amp or pre-amp. The older the deck gets, the more likely it is that it will cause the amp a problem.
      By the way, if one or more of your tweeters have cooked, this is probably the reason why.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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      • #18
        ahem, I was referring to frequency response.

        Yes, I know that most people can't hear below 20hz or much above 10K(that's how they piggyback DSL on the phone, phones don't go above a certain frequency)

        As for the Legacy Monobloc, I first discovered them when doing research for an ubersubwoofer(lemme put it this way, ever heard of a Velodyne F-1800? This was going to be MUCH louder) and was reaaallly impressed by the specs... Most amps really peter out below 100hz...

        review
        manufacturers website


        HTRN


        ------------------
        This Old Shed
        EGO partum , proinde EGO sum

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        • #19
          Here you go:

          http://rotel.com/products/specs/ra1070.htm

          Most Integrated Amp for the money I'm aware of.

          Their stuff is good enough that I still recommend it even though they fired us six months ago!

          John

          ------------------
          Pursue Excellence and the rest will follow.
          Pursue Excellence and the rest will follow.

          Comment


          • #20
            I agree with Darryl, Only buy a new amp if you want home theater. The really good amps were made 20 years ago. They can be repaired forever and are readily available for fair prices on EBAY. All the new stuff is made to be disposable with computerized front panels that are non-repairable. Also be real careful of the fine print on new amps concerning the output impedance. They generally can't handle any speakers in parallel.

            Greg

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            • #21
              Greg's comment is pertinent. Most new amps aimed at the home theatre crowd are not rated to drive a load less than 8 ohms. When you consider that an 8 ohm load can vary from less than 4 ohms to more than 20 ohms, depending on many factors, then two pairs of 8 ohm speakers can sometimes appear to the amp as a 2 ohm load (per channel). I won't get into the math, but suffice to say that these flashy, feature rich multi-channel components aren't tough or reliable, and they're not up to the task. If what you're looking for is a good solid amp that can deliver real power for considerable periods of time, then you won't find it in that kind of junk. Power ratings are extremely misleading and have virtually nothing to do with quality. And as Greg mentioned, if something goes wrong with the brain, which is usually the front panel, yer hooped.

              As far as dc response goes, the protection network that virtually every amp has will disconnect the speakers if there's a dangerous level of dc on the output. This could come from the system somewhere, usually the pre-amp, or it could come from a failure within the amplifier. Either way it won't matter as long as the protection circuit operates properly, which it almost invariably does. Personally, if I had the choice of amps to have, and one was rated as flat to dc, I would use that one instead of one rolled off at some number below 20 hz. I know that it would be eliminating one potential source of distortion by not having a coupling cap in the signal path, however the difference would seldom be noticable. Used as a sub amp, the lack of phase shift at the low frequencies would result in a lower distortion of the original sound, but here something ironic happens anyway. Some distortion helps the audio to sound 'powerful', and most people like that and would say that it's 'better' sound.
              At any rate, I wouldn't worry about a dc capable amp destroying your speakers, as pretty much any amp is capable of doing that, if a couple of certain faults develop at the same time. The biggest reason to not run the amp in dc mode is to protect against a bumped turntable sending a huge spike down the line to the speakers. If you're still running a turntable, this might be the deciding factor when considering which way to set the dc/capacitor coupled switch on the back of the amp.
              What JRouche says about an underpowered amp clipping, and being more dangerous than a higher powered amp, is also true. If you run the amp to clipping, you're generating large amounts of high frequency conponents, which the crossover network will deliver straight to the tweeter and overpower it. Any good amp will clip cleanly though, minimizing these unwanted artifacts. Some amps, even some purportedly good ones, will freak out when driven to clipping, and anything can happen. Sometimes it'll go into low frequency voltage swings which then makes your woofers vulnerable. If you see this unusual 'flopping' going on with your woofers, that's an amp to get rid of.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

              Comment


              • #22
                <font face="Verdana, Arial" size="2">Originally posted by Paul Alciatore:

                Digital in an amplifier is a farce.

                The output stage is still an analog power amplifier. Digital just adds the possibility of adding digital noise to the mix.
                </font>
                False....falser than false....I ought to know, I design them.

                Output stage is "digital" in that it has two states. Some have two states plus an "off" state, somewhat like a logic circuit.

                <font face="Verdana, Arial" size="2">
                Yes, you need it for a digital system but it is not an automatic increase in quality and it is definitely not a way of providing power to drive speakers.

                </font>
                Again false. You DON't need it for a "digital system", but it very much IS a way of providing power to drive speakers.

                Most people call it digital, but it is generally actually PWM (class-D), or a derivative of that ("class-T" from the tripath folks, etc, etc).

                VERY good performance available, from the top types such as Spectron, and others. But, yes, the audiophile varieties will charge you several thousand per channel.

                Frankly, it isn't justified, good quality Class-D is actually far cheaper than analog.

                1601

                Keep eye on ball.
                Hashim Khan

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