In that case changing the pot value cannot change the amount of bass.
If they don't use an output cap then they either use a DC servo or rely on the offset of the output opamps being sufficiently low. In either case there will probably be a capacitor somewhere in the unit which sets the actual LF rolloff.
If they don't use an output cap then they either use a DC servo or rely on the offset of the output opamps being sufficiently low. In either case there will probably be a capacitor somewhere in the unit which sets the actual LF rolloff.
Hello,
Just ran into this topic. My comment refers back to the transformer coupled passive volume control. I've built two of the ElectraPrint Audio PVA units. I installed a DACT 10k stereo pot and silver wire in each. They work great and are supposed to maintain the power bandwidth no matter what the volume setting. Regards, HeyBill
Just ran into this topic. My comment refers back to the transformer coupled passive volume control. I've built two of the ElectraPrint Audio PVA units. I installed a DACT 10k stereo pot and silver wire in each. They work great and are supposed to maintain the power bandwidth no matter what the volume setting. Regards, HeyBill
Will the introduction of a series shunt resistor possibly have any benefit in a passive preamp that uses a stepped attenuator [like this one]?
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DAC output impedance is high = 1.2K
DAC voltage output = 2.5Vpp
DAC has cap coupled outputs. Cap = 47uF
Length of the IC's between the DAC --> passive pre --> Amp will be 0.75 meters each
Amp input impedance = 22K
Amp line input sensitivity = 630mV
Amp has a low pass filter at 340kHz [series R 1K, || R = 22K and || cap = 470P]
If I use a 24K resistor with a 10K pot as a passive pre, will this be OK? If not, what values of the resistor and the pot would be recommended and why?
DAC voltage output = 2.5Vpp
DAC has cap coupled outputs. Cap = 47uF
Length of the IC's between the DAC --> passive pre --> Amp will be 0.75 meters each
Amp input impedance = 22K
Amp line input sensitivity = 630mV
Amp has a low pass filter at 340kHz [series R 1K, || R = 22K and || cap = 470P]
If I use a 24K resistor with a 10K pot as a passive pre, will this be OK? If not, what values of the resistor and the pot would be recommended and why?
This is what I get based on my calculations [and I might be wrong, so please correct me if I am wrong]
Depending on the pot position, the input impedance of this passive pre will range from a minimum of: 24K to a maximum of: 31K
Output impedance of the passive pre at pot all the way down will be: 0K
Output impedance of the passive pre at pot all the way up will be: 7.16K
At actual listening levels the R of the pot will be less, so, output impedance of passive preamp will be more like: 0.96K
This is around: 1/23rd the input impedance of the Load
Depending on the pot position, the input impedance of this passive pre will range from a minimum of: 24K to a maximum of: 31K
Output impedance of the passive pre at pot all the way down will be: 0K
Output impedance of the passive pre at pot all the way up will be: 7.16K
At actual listening levels the R of the pot will be less, so, output impedance of passive preamp will be more like: 0.96K
This is around: 1/23rd the input impedance of the Load
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