Am I really listening to my F5 at 0.22 watt? - Page 2 - diyAudio
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Old 15th September 2012, 04:59 PM   #11
tsiros is offline tsiros  Greece
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missed a dot?

to answer the OP's question: of course. 1/4 W is quite enough to produce clear music.

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Old 15th September 2012, 05:06 PM   #12
Pano is offline Pano  United States
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For his speakers in his room, yes it is. On average it's much lower.
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Old 15th September 2012, 05:43 PM   #13
willamp is offline willamp  United States
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Quote:
Originally Posted by Pano View Post
The answer to your question "Am I really listening to my F5 at 0.22 watt?" would be "No". You are listing to it at 0.01 watt average, 0.5 watts peak (per channel).
Wow, what a revelation.

I've already began parts collection for the F4 and I'm guessing I won't 'need' a pre-amp gain stage but who knows maybe I'll try one someday.
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Old 15th September 2012, 06:34 PM   #14
tsiros is offline tsiros  Greece
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i'm gonna figure a way to measure the instantaneous power used in an amplifier over the course of a very high dynamic range piece and graph it vs. time

listening to a favourite song of mine, "Enter the Dog of Pavlov" (by Soilwork), at a loudness i find almost loud enough (i'd like quite a bit more but it is 10pm now) the oscilloscope says 0.5Vrms (edit: at one speaker)

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Old 15th September 2012, 07:12 PM   #15
Pano is offline Pano  United States
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Quote:
Originally Posted by willamp View Post
I'm guessing I won't 'need' a pre-amp gain stage but who knows maybe I'll try one someday.
Seems that you will not need any voltage gain. But you may need some current gain, depending on how hard the F4 is to drive. I'm sure someone here knows.
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Old 15th September 2012, 07:50 PM   #16
willamp is offline willamp  United States
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Quote:
Originally Posted by Pano View Post
Seems that you will not need any voltage gain. But you may need some current gain, depending on how hard the F4 is to drive. I'm sure someone here knows.
F5 is 100k input impedence. F4 is 47.5k as spec'd in the store's schematic. I think either is fine for my sources.

The 47.5k comes from an input load resistor to provide a path to ground when there is no signal attached, I believe. It might be possible to increase it's R value. I could check into that if necessary.
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Old 15th September 2012, 08:29 PM   #17
willamp is offline willamp  United States
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I just got approval from the F4 thread....100k input load resistor is fine. Schematic updated.
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Old 15th September 2012, 08:45 PM   #18
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Should be no problem to drive as long as input capacitance is normal. It should be. Just remember, you won't be able to turn it up much more than you already run.
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Old 15th September 2012, 09:01 PM   #19
willamp is offline willamp  United States
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Yes, I agree but I listen to my system a lot and I've never wanted to crank it past the -20 point. Usually I'm a few dB below that. If I find myself wanting more someday I have no problem building a pre-amp. There's plenty of room inside my current passive-pre to add a gain stage.

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Old 15th September 2012, 09:55 PM   #20
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I usually keep an oscilloscope around, and with my 92 dB drivers I find
that I can stay within the "4 watt window" which is where the top of the
screen is +8V and the bottom is -8V, corresponding to the range of an
amplifier that delivers 4 watts rms - peaks of 8 watts.

With music, the average figure will be less than half a watt, and this is
pretty loud.

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