niknik wrote:
With a modded SB the max level into the amp is 1.1 volts. This should
not usually cause any speaker to blow -as far as I have heard.
So I'm not so scared of running directly to my amp. Especially when
it's a modded SB..
If you are not scared, just try it. But this is an engineering issue,
not voodoo or theater.
The actual problem that seems to get lost in all the hype
has nothing to do with the SB being bone stock or modded. It has to do
with the maximum output voltage, and what your amp will do with it.
The key idea that keeps getting lost is not that you need a preamp, but
that you need to be sure that if the SB drives a signal at its loudest
possible level, that your amp and speakers can handle it.
The amp part is important because if you overdrive the input, your amp
may clip. And any amp that is clipping it putting out ugly waveforms.
That is the definition of clipping. Putting such a waveform into a
speaker is very bad, and at high volumes, it can destroy a speaker in
seconds.
If the amp can drive your speaker load without clipping, then you have
to be concerned that the speakers can handle the power.
If your amp and speaker are clean when fed the output of a SB when it is
set to zero attenuation (aka 11, or 40 depending on the firmware/web
skin) than all you have to care about is your hearing. If it is under
110 dBa (120 for some folks) then you are done.
If it is too loud, then you need to use physical attenuators to make
sure that no matter what the SqueezeBox does, you don't over drive the
amp. This can be a preamp, or it can be some in-line attenuators.
The attenuators that Sean posted a while back cost about $40, and even
if you have to use two in series, it is much cheaper than a preamp.
It is hard to test with music, you are better off with a pure sine wave
at 200 hz, and another at 5000 kz or so. Or even a signal with a few
clean sine waves, something like 200, 400, 800, 1600, and 3200 hz
If you can do that without blowing a speaker, you are done. If not,
don't blame me. YMMV, etc.
--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html
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