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#1
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NEED ADVICE on preamp output capacitor
I have a solid state phono preamp which has a 50 micro farad electrolytic
capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg |
#2
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NEED ADVICE on preamp output capacitor
TUBELOVER wrote:
I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen |
#3
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NEED ADVICE on preamp output capacitor
TUBELOVER wrote:
I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen |
#4
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NEED ADVICE on preamp output capacitor
TUBELOVER wrote:
I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen |
#5
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NEED ADVICE on preamp output capacitor
Stig Erik Tangen wrote in
: TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen What is the formula for this? r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#6
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NEED ADVICE on preamp output capacitor
Stig Erik Tangen wrote in
: TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen What is the formula for this? r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#7
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NEED ADVICE on preamp output capacitor
Stig Erik Tangen wrote in
: TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Stig Erik Tangen What is the formula for this? r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#8
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NEED ADVICE on preamp output capacitor
On Fri, 26 Dec 2003 20:58:44 +0100, Stig Erik Tangen
wrote: 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Unfortunately this gives about 2 kOhm load to an induced current of 60 Hz. So there is some chance for hum. What about checking the voltage across the current capacitor and if it is some tens of millivolt the capacitor is not needed at all - unless the power amp is fully DC coupled? Norbert |
#9
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NEED ADVICE on preamp output capacitor
On Fri, 26 Dec 2003 20:58:44 +0100, Stig Erik Tangen
wrote: 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Unfortunately this gives about 2 kOhm load to an induced current of 60 Hz. So there is some chance for hum. What about checking the voltage across the current capacitor and if it is some tens of millivolt the capacitor is not needed at all - unless the power amp is fully DC coupled? Norbert |
#10
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NEED ADVICE on preamp output capacitor
On Fri, 26 Dec 2003 20:58:44 +0100, Stig Erik Tangen
wrote: 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. Unfortunately this gives about 2 kOhm load to an induced current of 60 Hz. So there is some chance for hum. What about checking the voltage across the current capacitor and if it is some tens of millivolt the capacitor is not needed at all - unless the power amp is fully DC coupled? Norbert |
#11
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NEED ADVICE on preamp output capacitor
i received info that a 2 uf cap gives -3 db at 10 hz . i will use a 4.7 uF
cap.thanks to all. rg |
#12
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NEED ADVICE on preamp output capacitor
i received info that a 2 uf cap gives -3 db at 10 hz . i will use a 4.7 uF
cap.thanks to all. rg |
#13
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NEED ADVICE on preamp output capacitor
i received info that a 2 uf cap gives -3 db at 10 hz . i will use a 4.7 uF
cap.thanks to all. rg |
#14
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NEED ADVICE on preamp output capacitor
"Rich Andrews" wrote in message
.44 Stig Erik Tangen wrote in : TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. F(-1 dB) of 20 Hz is a common standard. This requires a 1.6 uF cap for a standard 10K line level load. I'd recommend more like 2 uF. If this is for driving power amps, there are power amps with input impedance that is more like 5K, so now a 3-5 uF cap seems to be in order. If you have really good subwoofer, 10 uF might make sense. What is the formula for this? F(-3 dB) = 1/(2*pi*R*C) R in ohms, C in Farads For high pass: F(-1 dB) = 2* F(-3) F(-0.1 dB) = 6.666* F(-3) |
#15
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NEED ADVICE on preamp output capacitor
"Rich Andrews" wrote in message
.44 Stig Erik Tangen wrote in : TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. F(-1 dB) of 20 Hz is a common standard. This requires a 1.6 uF cap for a standard 10K line level load. I'd recommend more like 2 uF. If this is for driving power amps, there are power amps with input impedance that is more like 5K, so now a 3-5 uF cap seems to be in order. If you have really good subwoofer, 10 uF might make sense. What is the formula for this? F(-3 dB) = 1/(2*pi*R*C) R in ohms, C in Farads For high pass: F(-1 dB) = 2* F(-3) F(-0.1 dB) = 6.666* F(-3) |
#16
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NEED ADVICE on preamp output capacitor
"Rich Andrews" wrote in message
.44 Stig Erik Tangen wrote in : TUBELOVER wrote: I have a solid state phono preamp which has a 50 micro farad electrolytic capacitor in series with the preamp signal at the very output of the preamp. i wish to replace this cap with a film cap. what is the minimum value cap i can use and still have a response that is not rolled off due to too low a value? the phono preamp will feed a line amp with a minimum of 10000 ohms input resistance. rg 1 uF into 10kOhms load equals approx 16 Hz -3 dB. 1 uF or more should work. F(-1 dB) of 20 Hz is a common standard. This requires a 1.6 uF cap for a standard 10K line level load. I'd recommend more like 2 uF. If this is for driving power amps, there are power amps with input impedance that is more like 5K, so now a 3-5 uF cap seems to be in order. If you have really good subwoofer, 10 uF might make sense. What is the formula for this? F(-3 dB) = 1/(2*pi*R*C) R in ohms, C in Farads For high pass: F(-1 dB) = 2* F(-3) F(-0.1 dB) = 6.666* F(-3) |
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