budget 2 chanel amp?????

Discussion in 'Archived Threads 2001-2004' started by Lyden, Dec 6, 2002.

  1. Lyden

    Lyden Stunt Coordinator

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    im looking for a 2 chanel amp with 200watts per chanel at 8ohms, i dont have alot of cash maybe $400 after Xmass so mayber something cheap if at all possible, im going to be useing it on the pre/outs for the mains on my 810s (ive noticed the lack of oomph in the amp [​IMG] ) even if its an amp that goes to 200watts a chanel at 6ohms, is there a way to make my speakers look like a 6ohm load instead of 8ohm to the amp? thanks for help if you eed more info let me know
     
  2. Justin H

    Justin H Stunt Coordinator

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    If you are looking for a 2 channel amp I would suggest checking out www.audiogon.com . Used two channel amps from reputable manufacturers like Rotel, Adcom, Parasound, etc. are frequently available in the
     
  3. Guy Usher

    Guy Usher Supporting Actor

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    Why would you want your speakers to present a 6ohm load to your amp?? Most people would love 8ohm steady state.
    Often you see a 200wpc amp @ 8 ohm rated 400 @ 4ohm, doesnt mean you have more power, even 800 at 2ohm doesnt mean you have more power, sign of a good amp. I am sure there is a electrical person who can explain this better than I can.
    If you want to double the sound pressure level of your speakers thats a 3db increase that requires 10 times the power so if you are using a 200 watt amp that would mean . . .
    I do agree that a 200 watt amp versus a 100 watt amp will give you more "weight" to your sound and your speakers may perform better.
    I would look for a clean Adcom 555 (200x2) you should be able to find one of these monsters for 350-500 dollars, they are great amps that will drive anything from a hair drier to a welder and sound great doing it. Typically used amps either work or they dont not like buying used processors or VCRs etc, even older Adcoms GFA-1 and GFA-1As are out there cheap. You can bridge the 555 for tooo much power cannot bridge the older Adcoms.
     
  4. RussKon

    RussKon Stunt Coordinator

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    ebay is a great source of good deals if you know what you are looking for....now i know carver amps are a debatable item on here...but...a carver M-400 that puts out 200 watts per channel can be had in the $200 to $250 range and is an excellent amp for most speakers...check out the reviews at audioreview.com

    i have a M-400t in my main system and it is amazing. I'm driving a pair of Klipsch KLF-30's and the sound is incredible!

    Russ
     
  5. GeorgeTW

    GeorgeTW Stunt Coordinator

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    It's all about Ohms Law

    Power is = I x V
    200Watts = ? x 120 Volts

    Why 120Volts? 120 V/A/C from outlet.
    Why "?" We don't know how much Current is available from your unit. You can get an idea from the UL listing, but not all of that is given for speaker amplification.

    No matter.

    Since Current is opposed by Resistance, lowering Ohms increases the Current proportionately.
    Using Guy's example.

    200 @ 8 Ohms
    400 @ 4 Ohms
    800 @ 2 Ohms
    1600 @ 0 Ohms (dead short)

    In less expensive amplifier designs, higher Current can only be sustained temporarily. Your unit would put out more power, but probably at the cost of something else (your voicecoils).

    This has little to do with brand name in the consumer market. It has everything to do with Ohm's Law. If you allow lower Resistance, Current goes higher. It's the Law.

    You can see why falling Impedance can lead to dangerous condition, because 0 Resistance = Max Current. (Uncontrolled, maximum electron flow thru the system until something gives, a fuse burns, a breaker pops, etc.)

    Unless your equipment is known to have high current capability (example, Crown amps), you do not want speakers running at lower Impedances.

    Good Luck.
     
  6. mark rush

    mark rush Stunt Coordinator

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    I know it takes 10 times the power to double the spl, but I thought that was a 10 DB increase, not 3 DB. A 3db increase in SPL is like doubling your power from 100 watts to 200 watts? am I right or wrong on this
    Mark
     
  7. DanaA

    DanaA Screenwriter

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    A bit confusing to me too, so somebody please correct me if I'm wrong. I thought doubling the SPL was every 3 Db's, but that it takes about 10 Db's to achieve what the human ear perceives as twice the volume.
     
  8. GeorgeTW

    GeorgeTW Stunt Coordinator

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    It takes a doubling of the watts to achieve a 3 db increase of sound to your ear. Remember that the Volume control is an attenuation, not amplification.
     
  9. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    2x the power gives you roughly 2x the sound pressure (3dB increase). 10x the power gives you a 10dB increase.
    While it's not quite as easy as a 10dB increase is preceived by the human ear as twice the volume, that's a pretty good guide. We preceive sound differently at different frequencies. To make matters even more complicated, men and women are sensitive to these frequencies differently. [​IMG] However, all in all, 10dB is generally considered by many as a reasonably good reference to a 2x perceived volume increase.
     
  10. Guy Usher

    Guy Usher Supporting Actor

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    I may be wrong and probally are as it has been too long since I thought about this stuff.
    I was always told that 3db was percieved as a slight increase in volume to the human ear while in reality 3db was doubling the sound pressure level and to double the SPL took 10X the wattage, since most of the time we are using less than 1 watt for average listening levels a 10X increase is not significant, even a 100X increase or 1000X increase is not much if you are only using a tenth of a watt, what you are saying is that if your speakers are rated at (to make it easy) 100 db 1w1meter then 200 watts should produce 400db spl as it would be 200X. . . This makes my head hurt. . .
    How about one of you DIYers put it in perspective. . .
     
  11. Jeff_Krueger

    Jeff_Krueger Stunt Coordinator

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  12. Guy Usher

    Guy Usher Supporting Actor

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    yes I forget it is not linear. A 3db gain with 1 watt and a 3db gain with 512 watts, still makes my head hurt, think I will just listen and not analize for now. . .
     
  13. Lyden

    Lyden Stunt Coordinator

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    wow thanks for the replys this is good im learning stuff i dident know [​IMG] .... wait so the volume knob doesnt ajust the power thats being out put? its mroe like canceling out some of it or something please explain i dont get that... i allways thought the volume knob would just lower the amout of total power being put to the speakers
     

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