Amplifiers....size and weight question.

Discussion in 'Archived Threads 2001-2004' started by Geoff McD, Jul 7, 2002.

  1. Geoff McD

    Geoff McD Extra

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    This is probably a stupid question, but I'm just trying to understand the basics behind the hardware of some home theater equipment.

    Amplifiers (specifically...spereate units...not the amps in receivers) very greatly in size and weight. A first thought would be that it depends on the amount of watts...but everyone knows thats not the case. That being said, what exactly causes a amp to weigh so much versus one that doesn't. Or an amp to be the size of a house versus a slim amp.

    Take into comparison Krell 300cx and the Samson S1000. I know these are in totally different leagues...but I'm just trying to understand the technicals differences in the hardware. Both are two channel amps. While the Krell is mainly for normal 2 channel full range speakers, and the Samson is normally paired with SVS subwoofers...isn't it all the same when it comes to the hardware within? Obviously not though!!! So what exactly makes the two amps sooooo different while still providing relatively same amounts of power?

    Wattage (8 ohm):
    Krell - 300 Watts
    Samson - 340 Watts

    Wattage (4 ohm):
    Krell - 600 watts
    Samson - 545 watts

    Height:
    Krell - 19 inches
    Samson - 3.5 inches

    Weight:
    Krell - 90 pounds
    Samson - 36 pounds

    Now...please don't think that I am slamming the samson..I'm not! I'm sure it does just fine powering those SVS subs. I'm just curious (as is my nature) what kind of extra or extreemly beefed up gadgets are thrown into the Krell that make it THAT much bigger & THAT much heavier?? Power supply? probably...but it that can't be it right? There must be something else taking up all that room, and weighing so much (although power supplies do weigh a bunch)!

    A move to seperates will be eventual for me. While I wouldn't ever buy the Samson to power my speakers, I'm just trying to figure out what causes all the differences in amplifier size and weight when they seem to be knocking out the same amount of watts (probably different quality of watts though).

    Anyhow, any technical guru's out there?
     
  2. John Royster

    John Royster Screenwriter

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    Really good question.
    I'm not great with amplifier design but my background in EE might be able to help. I'd guess most of the weight from the krell comes from the power supply and heat sinks. The electronics in either amp are fairly simple, BUT...the heat produced from the krell or any other class A amplifier is quite significant. that heat means you need a good way to get rid of it. large surface area heat sinks do the job here.
    I know the samson and other pro-audio gear use a totally different design. I'm curious how that different design applies here?
    I've seen 2U rack units speced to 2000 watts. What's the difference???
    ps - that and I think krell adds some lead to make them weigh more. [​IMG]
     
  3. Justin Doring

    Justin Doring Screenwriter

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    Size and weight matters. Period.

    There's a reason a 150 wpc monoblock amplifier from Mark Levinson weighs 220 lbs. while a 125 wpc monoblock amplifier from Marantz weighs 14 lbs. Guess which one performs better and costs more?
     
  4. Geoff McD

    Geoff McD Extra

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    Thats what I had been thinking too, John. heat sinks...and depending on the size difference of those, and metals used...they could provide a good bit of weight difference too. I was pretty sure they weren't using freaky transistors that weighed 10 pounds by themselves!
    I agree on the Lead bit as well, I would be suprised that if one were to crack one of those open, they would find the transmission of a VW bug in there! I wonder how good at heat disipation those are! [​IMG]
    Class A amp versus whatever the Samson is...what is different about the different classes? just the design? I assume they are using different quality components that drive this "class". Otherwise, the costs should be different at all! I don't really understand the "class" aspect of amps, other than I think they are rating the quality of the power produced.
    Also, I mis-stated the height spec of the Krell, its actually only 10.3 inches high. The Krell is also 17 inches deep compared to the Samson's 9.75 inches of depth.
     
  5. Geoff McD

    Geoff McD Extra

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    Wow!!!

    Justin, those specs are insane!!! 225 pounds for a single channel of 150 watts!!! thats crazy!!! There may be a V8 LS6 engine tucked into the casing of that amp!

    All along, I had been figuring that weight difference is relevant to price difference, and is probably also relevant to performance difference.

    Just curious what the heck is in one of these chunky boxes that these lighter amps left out? Is it just the heat sinks and power supplies? If so, what is it about the design of the two that requires it for one, and not for the other I wonder? Maybe this has everything to do with the "class" of an amp.

    This has no relevant meaning really...I'm just one of those people that likes to know whats inside...and what its doing.
     
  6. Arthur S

    Arthur S Cinematographer

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    Geoff

    A lot of light weight amps are "switching" amps. They are capable of putting out great power without a really huge power supply. Carver and Sunfire are switching amps. HTa is why the Sunfire Cinema Grand can put out well over 200 watts per channel with all 5 channels driven simultaneously, have no heat vents on the cabinet and you can drive them till your ears bleed and the amp won't even get warm. From what I understand they only generate power when it is called on, so a lot of energy is not wasted keeping the engine running.

    On the other hand, they must use "brick wall filters" at about 22KHz to filter out high frequency distortion.

    Switching amps are fine for subwoofers, and many Carver amp owners love their amps.

    Oh yeah, top notch amps that run in class AB or A need huge power transformers huge power caps, and huge heat sinks to dissapate all the heat they generate. Some of the big Krell Class A amps make fine room heaters.
    Artie
     
  7. Justin Doring

    Justin Doring Screenwriter

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    To give you an idea of what goes into a good amp and accounts for much of the weight, check out the No. 33 and No. 33H Monaural Power Amplifiers page. The "Additional Photos" page is enlightening, and the specs are pretty impressive too!
    http://www.madrigal.com/ml2001/poweramplifiers_fr.htm
     
  8. ling_w

    ling_w Second Unit

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    These Krell/Levinson amps have power supplies that are rated for sustained Class-A operation down to very low impedence. And they could run with minimal voltage drop across ultra low impedences. They usually are capable of running at full rated power down to sub 1 ohm load.
    My 80wpc Krell has been tested to produce over 4000 watts into a 0.15ohm load. That is almost doubling the power with half the impedence almost 6x over from its nominal 8ohm load (4,2667 watts into 0.15ohm load would be perfectly linear).
    Pro amps usually bulid amps for the pro environment. Running cool in tight space and noise rejection in dirty environment. That is about it. Audio amps tries to emphasize sound quality. If that means Class-A to full rated power, fully balanced from input to output or regulated power supply for the output transistors, then so be it.
    I've seen the internals of the FPB-600, and it is very packed with components. 2 boards probably 22x10 in size, each one with a daughter board probably 16x12. All boards fully packed.
    Here is 2 channels worth of Krell MRA and an exploded view of the amp to show the internals:


    If you want to see how they build those amps and what goes in there, you could see the factory tour here:
    http://www.wssh.net/~wattsup/krell/
     
  9. Geoff McD

    Geoff McD Extra

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    Thanks for the link Justin, it was very informative. Ling, thanks for the pics, those are some great shots of the Krell’s. I’ll have to do that factory tour thing on their web page, I’m sure that is interesting as well!
     
  10. AjayM

    AjayM Screenwriter

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    As others mentioned you are seeing the difference between Class A or A/B and Class D (I believe the Samson is Class-D).
    Also the pictures of the Krell above are the Master Reference monoblocks. 700lbs each, they recommend/require at least a 220v 40amp circuit for each amp (so you need 2 for a stereo setup), and it will basically double power for every halving of the Ohm load up to something crazy like 16,000 watts.
    Another fun bit of info, Stereophile ran their usual tests on some lower end Krell monoblocks (350W each), and this is what happened when doing the power test;
    Formally defining clipping as the 1% THD+noise figure gave maximum power delivery of a monstrous 475W into 8 ohms (26.8dBW), way above the specified power. 850W was available into 4 ohms (26.3dBW) and while I measured 1060W into 2 ohms (24.2 dBW) rather than the specified 1400W, the AC line in our Santa Fe office was sagging significantly for this measurement.
    Andrew
     
  11. Joe Tilley

    Joe Tilley Supporting Actor

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    [​IMG] Damn I would love to get a pair of those bad boys.
    Those have got to be the biggest amps I have ever seen before. Hay Ling if that is you standing beside them,next time you get a chance slip them into your pocket & run over to my place[​IMG]
     

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