Hi all,
A while back I built the Twisted pair My_Ref by Mauro Pensa(?) and it is still performing beautifully. I found the gain high so I was lazy and just put a resistor in the signal path (shunt to ground) to reduce the level. It worked and sounded great.
However now I went to use it in a bi-amp setup where it is high passed via simple cap(6db/oct) and of course the shunt resistor is causing an issue.
Since I still need the high pass and the level attenuation I was going to change the shunt resistor to a voltage divider circuit (l-pad) and see if that worked.
Since I don’t know the input impedance of the amp I figured a simple 10k in series and 5k to shunt should give me a basic 6db loss and NOT affect the frequency but I wanted to check here first before I opened the amp and fired up the soldering iron.
Thank you in advance,
Dumb@$$, uh I mean Troy
A while back I built the Twisted pair My_Ref by Mauro Pensa(?) and it is still performing beautifully. I found the gain high so I was lazy and just put a resistor in the signal path (shunt to ground) to reduce the level. It worked and sounded great.
However now I went to use it in a bi-amp setup where it is high passed via simple cap(6db/oct) and of course the shunt resistor is causing an issue.
Since I still need the high pass and the level attenuation I was going to change the shunt resistor to a voltage divider circuit (l-pad) and see if that worked.
Since I don’t know the input impedance of the amp I figured a simple 10k in series and 5k to shunt should give me a basic 6db loss and NOT affect the frequency but I wanted to check here first before I opened the amp and fired up the soldering iron.
Thank you in advance,
Dumb@$$, uh I mean Troy
The amp's input impedance will alter the passive filter's response,
so you do need to take that into account. Looks like 100k, with an
input coupling capacitor of 1uF. You should be able to adjust the
value of that capacitor downward to make your filter.
http://www.claudionegro.com/download/articoli/axpress 04-2011 Solid State Duo part1.pdf
The 10k/5k resistors will give about 10dB loss, but that's with no output loading.
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The Rev_C should have the same input so thank you!
Cap on the output of the servo controller, resistor to ground and 1uf cap on the amp makes for an 18 db high pass! That surely explains what it's doing...
I will most like short the cap in the amp and use a linear pot to figure out the best attenuation level for the top end amp.
The low frequency amp has a moderately adjustable level control.
Pic just because..
Troy
Cap on the output of the servo controller, resistor to ground and 1uf cap on the amp makes for an 18 db high pass! That surely explains what it's doing...
I will most like short the cap in the amp and use a linear pot to figure out the best attenuation level for the top end amp.
The low frequency amp has a moderately adjustable level control.
Pic just because..
Troy
Sorry to drag this out again but in the link you posted above what happens if i decrease R13? Wouldn't that lower the input sensitivity?
TIA,
Troy
Decreasing R13 would lower the input impedance, but not the sensitivity (gain).
Also it would raise upward the low frequency pole with C13, since f = 1/(2Pi x R x C)
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