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Old 23rd September 2013, 01:19 PM   #11
12B4A is offline 12B4A  United States
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The gain change is not going to make a meaningful difference. If you feel it doesn't have enough volume as is then you're going to want an amp with 2 to 10 times more power.
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Old 23rd September 2013, 01:27 PM   #12
flg is offline flg  United States
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I'm not even sure where I got that from but, I think it was a real figure people were getting some time in the past
"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
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Old 23rd September 2013, 01:30 PM   #13
AndrewT is offline AndrewT  Scotland
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To get 14.28Vac instead of 12Vac output from the F5 you need to change the four 100r to 123r. You could try 130r or 120r and see if you hear any difference.
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Old 23rd September 2013, 01:45 PM   #14
AndrewT is offline AndrewT  Scotland
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The overall gain through the INPUT Filter and the amplifier will be a bit lower than the amp's basic gain.
The attenuation of the RF Input Filter will depend on the Rin (series) used in the RF filter.

That would account for lower reported overall gain values and would also account for different reported values.

The basic gain of the amp is 6times.
A 1k series resistor feeding into 100k for Rin, reduces the overall gain to 15.48dB, cf. basic gain = 15.56dB
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Last edited by AndrewT; 23rd September 2013 at 01:51 PM.
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Old 24th September 2013, 09:37 PM   #15
Hikari1 is offline Hikari1  United States
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My f5 w/91db 8ohm speakers, Cd player and passive pre had enough volume w/200ohm feedback resistors. Not enough volume for use w/my vinyl setup though.

Switched to a Jfet BOZ and 100 ohm feedback resistors. It was the right choice I think.

Even though the F5/200ohm resistor/passive setup had enough gain and volume it seemed to lack punch and dynamics. All was cured when I went to the 100ohm feedback resistors and a preamp. You gain weight and dynamics and lose a little mid-range purity and detail. But it's worth it.
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Old 24th September 2013, 10:38 PM   #16
tinitus is offline tinitus  Europe
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a little preamp gain will probably make it sound 'harder'
you might hear that as being more dynamic
right or not, some multiway speaker may need that little exstra to sound 'more alive'

but in that case, maybe tone controls or some form of EQ would be even better
sometimes we know very little, and sometimes we know too much
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