THD and amp specs.......

nooshinjohn
nooshinjohn Posts: 25,893
edited March 2009 in Electronics
I am looking at two amps... A sunfire cinema grand signature7 with 410wpc@ .5THD or a Rotel RMB-1095 with 200wpc@ .03THD:confused:

I know that thd= total harmonic distortion and that the lower the number the better, but I also know there is more to the game than just lower THD... between the two amps, which comes out on top?:confused:
The Gear... Carver "Statement" Mono-blocks, Mcintosh C2800 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson

How many flies need to be buzzing a dead horse before you guys stop beating it?
Post edited by nooshinjohn on
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Comments

  • F1nut
    F1nut Posts: 51,703
    edited March 2009
    One of my amps is rated at 0.007% THD. :p Another is rated at 0.1% THD. Both sound stellar. Don't concern yourself with that spec, you'll never hear anything below 1.0% THD.

    Specs can guide you, but cannot tell you how it will sound.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

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  • Mike21
    Mike21 Posts: 252
    edited March 2009
    Hi nooshinjohn.

    Anything below 1.0% THD is acceptable. But you are right - there's more to comparing amp specs than just THD. But, I'm no expert. Where is cnh when we need him?

    Also, I notice that the Sunfire has over 400wpc and the Rotel "only" 200wpc. Will your speakers take 400w?
    ____________________________________________
    Home Theater 32"LG LCD; Comcast; 7.1 Onkyo 805; Fronts: Polk M50s; Center: Polk CS2; Sides: Polk M40s; Rear: B&W LM1s; Subs: (2) Sony 12" x 100w; Samsung 1500BDP; Toshiba A-2 HD-DVDP.
    PC stereo: Viper custom PC: Windows XP; ASIO4ALL; JRiver Jukebox> Pop Pulse USB to S/PDIF conv> Monarchy DIP > Musiland MD10 DAC > Parasound 2100 pre> Aragon 4004 MKII amp> Dali Ikon6 towers; Sunfire True Sub; PSA Duet, Ultimate outlet and Noise Harvestors.
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  • nooshinjohn
    nooshinjohn Posts: 25,893
    edited March 2009
    My SDA-1c's will thrive on the juice, I am a bit concerned about my cs1 center,tsi100 and monitor 50 surrounds however.....
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2800 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson

    How many flies need to be buzzing a dead horse before you guys stop beating it?
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  • unc2701
    unc2701 Posts: 3,587
    edited March 2009
    If you look at a typical THD graph, it'll hover at a baseline level, then as you approach the true power handling of the amp, it'll start to rise. The THD spec says nothing about the quality of the amp, but it does say something about the marketing department.

    For example, my bryston 9b is marketed as 125wpc. On it's spec sheet, it actually put out 155 watts at the rated THD (0.001%, I think?); but if sony was selling it, they'd crank it till it hit 1% THD and probably call it 200wpc.

    If you wanted to make a watts-for-watts comparison, you'd have to find the THD graph for the Rotel and find where it hits 0.5%... but even then if you've got crap watts against good watts, it's not a real comparison.

    Finally, you don't need to worry about whether your speakers can handle it- with all else equal, a higher wattage amp is LESS likely to blow your speakers.
    Gallo Ref 3.1 : Bryston 4b SST : Musical fidelity CD Pre : VPI HW-19
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