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Re: I can't help with selection, so amplifier sizing. by Ray of Light 06/20/2010, 4:57am PDT
The Happiness Engine wrote:

that with 93dB at 1W at 1m, a 30W/ch amplifier would give you a maximum volume of 122dB, which is really loud. 12W/ch would yield 105dB, which is pretty loud. This could be affected by your laptop not being able to provide a hot enough input signal.


Right, right. I should have given that more thought. In a physics lecture once, the lecturer used an SPL meter and some math to show that she dissipated about 5 joules in a one hour lecture, or <2mW continuous power.

Your math is bad though, 93dB @1W means 103dB @10W, 113dB @100W, 123dB @1000W. However, I will be listening from distances of more than 1m (consequences unclear -- SPL falls off cubically in the absence of echo, but this will be in a room with smooth walls). However however, I will be listening to two speakers. Let's just assume these cancel each other out.

Using this dB thermometer, I'd guess I want to be around 85-90dB most of the time and would like to be able to get above 100 (but not much, you never get any hearing back!), with some headroom left over for loud passages.


That means something like 15-20Wpc. But I can't expect to just turn the volume to max and get good sound. Putting in a 50-100% safety factor to avoid clipping, I'm about back where I started, 25-50Wpc.

Looking into these kits in more detail revealed they're all based on the same family of chips, the Triforce TA2020 or its smaller variant, the TA2024, popularized by (now-defunct) Sonic Impact and their super-cheap T-Amps. These chips are popular with DIYers and get almost universally good reviews. They are repackaged by HLLY and TrendsAudio, among others.

Some other stuffs I found were Scythe KAMA ($55 but only 10Wpc) and Gainclones from HLLY (nice-looking but pricey).

I ended up buying a Dayton DTA-100 from Parts Express, for about $150 after shipping and currency conversion. 50Wpc into 8ohm, tiny aluminum box, separate phones-level and line-level inputs (but no selector switch, I assume the front panel input mutes the RCAs). It's based on another Triforce chip, the TK2050, and cost about the same as a TAMP-20 from HLLY, except shipped from the US instead of China.
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I would like to buy a small stereo amplifier. by Ray of Light 06/19/2010, 11:34am PDT NEW
    I can't help with selection, so amplifier sizing. by The Happiness Engine 06/19/2010, 6:25pm PDT NEW
        Re: I can't help with selection, so amplifier sizing. by Ray of Light 06/20/2010, 4:57am PDT NEW
            I must defend by faggotry! by The Happiness Engine 06/20/2010, 10:25pm PDT NEW
                Yes in the specs they say THD: .01% to 30W, 3% at 50W by Ray of Light 06/21/2010, 1:47pm PDT NEW
    Re: I would like to buy a small stereo amplifier. by Fullofkittens 06/20/2010, 5:20am PDT NEW
        I considered this! by Ray of Light 06/20/2010, 9:28am PDT NEW
            THEN DON'T EXPECT TO REALLY ***HEAR*** THE MUSIC JERKOFF!!!!!!!!!!!!!!!!!!!!!!!! NT by Jhoh Cause..... 2 06/20/2010, 9:55am PDT NEW
 
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