spendorspain
New Head-Fier
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- Apr 10, 2005
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Hi all
I’m interested in the Meier passive crossfeed circuit. I’ve made the Linkwitz crossfeed but I’m not using it because it dulls too much the sound and reduces the available volume a lot, although I like the way it places the soundstage “farther” from my face. I have read that the Meier crossfeed reduces volume only a couple of dB and does not modify too much the LF/HF balance. Moreover, it is extremely simple to build in the “natural” version (the “enhanced bass” version is more complex), so perhaps this one is just what I need (fixed, not switchable). Searching about it in the web, I’ve got two little problems:
1) In the Meier webpage I’ve found two different values for the same “natural” crossfeed circuit (in both cases it is the low crossfeed setting).
In one schematic: R1=1kOhms; C1=470nF(0.47uF) and R2=2.2kOhms
(these are the values I’ve found in other sites too)
In other: R1=4.7kOhms; C1=100nF(0.1uF) and R2=10kOhms
I don’t understand why there are two sets of values for what, I suppose, is the same circuit with the same setting (low crossfeed level). Can someone explain this two versions? What are the correct R and C values?
2) According to Meier, “for optimal performance the natural crossfeed filter needs to "see" two (low output impedance) input buffers and two (high input impedance) output buffers. If the output impedances of the source are relatively high or if the input impedances of the load are relatively low, strong interactions will occur with the filter network and the filter characteristics will change considerably”. I’ve seen the crossfeed implemented just right after the RCA sockets and before the volume control, but in his headphone amplifier, Meier places it between the output stage of an op-amp and the input of other (both LM6171), so the crossfeed circuit is better isolated. I’m building a headphone amplifier with a volume control of the “shunt” type (not constant impedance) with a fixed resistor in series and an adjustable potentiometer to ground. I think the best place for crossfeed is the one painted in red in the picture below. Am I right?
Any opinions are welcome. Thanks in advance for your help.
Best regards
Jose
I’m interested in the Meier passive crossfeed circuit. I’ve made the Linkwitz crossfeed but I’m not using it because it dulls too much the sound and reduces the available volume a lot, although I like the way it places the soundstage “farther” from my face. I have read that the Meier crossfeed reduces volume only a couple of dB and does not modify too much the LF/HF balance. Moreover, it is extremely simple to build in the “natural” version (the “enhanced bass” version is more complex), so perhaps this one is just what I need (fixed, not switchable). Searching about it in the web, I’ve got two little problems:
1) In the Meier webpage I’ve found two different values for the same “natural” crossfeed circuit (in both cases it is the low crossfeed setting).
In one schematic: R1=1kOhms; C1=470nF(0.47uF) and R2=2.2kOhms
(these are the values I’ve found in other sites too)
In other: R1=4.7kOhms; C1=100nF(0.1uF) and R2=10kOhms
I don’t understand why there are two sets of values for what, I suppose, is the same circuit with the same setting (low crossfeed level). Can someone explain this two versions? What are the correct R and C values?
2) According to Meier, “for optimal performance the natural crossfeed filter needs to "see" two (low output impedance) input buffers and two (high input impedance) output buffers. If the output impedances of the source are relatively high or if the input impedances of the load are relatively low, strong interactions will occur with the filter network and the filter characteristics will change considerably”. I’ve seen the crossfeed implemented just right after the RCA sockets and before the volume control, but in his headphone amplifier, Meier places it between the output stage of an op-amp and the input of other (both LM6171), so the crossfeed circuit is better isolated. I’m building a headphone amplifier with a volume control of the “shunt” type (not constant impedance) with a fixed resistor in series and an adjustable potentiometer to ground. I think the best place for crossfeed is the one painted in red in the picture below. Am I right?
Any opinions are welcome. Thanks in advance for your help.
Best regards
Jose
