Bright_Star
Active Member
I realize the original discussion happened in 2017, but in finding it now and reading thru the comments, I thought it was very informative and was wondering how things turned out for Jameswie (and if you still have your Infinity Renaissance 90's, as I do- my #1 favorite speakers!, which I saw listed in your collection of equipment back then).
I have some similar concerns when it comes to passive Bi-amping and just wanted to clarify a few things if some knowledgeable folks could share their thoughts:
1) It seems that using two amps, one to drive the highs/mids, and the other for the woofers, would result in each amp having to do less "work", compared to using only one of the amps to drive the speakers on their own. But my question is, what is the difference in actual Impedance seen by each amp when used in both configurations? In other words, if I bi-amp, what impedance change does the amp "see", compared to the impedance when the amp was driving the speakers by itself? To further clarify, we all should know that Impedance is an ac characteristic, not DC, it involves caps and inductors in the crossover circuitry, not just resistors, thus the load is reactive, not just pure resistance, and caps & inductors behave very differently in ac vs DC. Each brand/model speaker has its Impedance curve showing its response over the audible 20-20K hz frequency range, and despite the usual 8, 6, or 4 ohm ratings, we must realize these are just AVERAGE values, when in fact, the value is always changing with frequency, and the main concern is when it dips low, under 4 ohms toward 2 ohms, whereby some speakers have a reputation for being "amp killers"- re: Infinity Kappa 9.
A similar thought to impedance being an average value, is the 120 US voltage in our homes- if we take a meter and insert probes into a powered wall outlet and measure 120V give or take- that is just an AVERAGE value, being that the meter cant read a sinusoidal waveform that is changing 60 times per second which actually has a peak value of about 170 volts.
Anyhow, back to the question, we can start by using one amp to drive a pair of speakers and the amp will see a certain impedance. Now, if we try to make things "easier" on that amp, but allowing it to share duties with a 2nd amp, so that each amp has less drivers to drive, so to speak, then what is the new impedance that the amp sees if it only has to drive the highs/mids, or only the woofers, vs when it had to drive All of them by itself?
My point is, bi-amping might seem to lessen the "load" on each amp, but that would only be the case if the impedance for each amp went up, as higher impedance= less current draw= less heat= less stress on the amp. So, does the impedance change, I am trying to get a clear answer on that, or hoping that my brain could do a deeper dive to visualize the concept as I am pouring a cup of coffee now and maybe it will stimulate the brain cells, Lol...
2) Question on the Sansui pre out main switch:
Using the AU-717 as an example: It normally functions as an integrated, but can be used as a preamp or power amp if the switch is moved to its
separated position. But in the old discussion, it seemed like the switch still be kept in the connected position so that its volume knob control would not be disabled if used to bi-amp with another amp, so that both amps have volume knobs that can be adjusted to balance each other. Is that correct?
3) The reason I ask:
I have a pair of vintage Infinity RSIIA speakers- large floorstanders with an array of EMIT tweeters/ mids and dual 10" woofers. They seem to have a
reputation for thriving on power, which is why I thought passive Bi-amping would be a good option. Actually, I dont have a choice to use a single amp being that when I acquired them several years ago, the jumpers were missing to attach the speaker terminals together. The terminals are odd- they
accept only speaker cables with banana jack connectors, which dont even go in all the way and are prone to easily falling out.
I have a Sony TA-E77ESD preamp with two line outs (I stupidly sold a Sansui CA-2000 I used to have), which can feed my Sansui B-2101 power amp (200Watts) and my G-901 receiver (160W) with the same pre out main in swicth as the 717, that I switched to separated power amp mode.
The G-901 is the closest match in wattage to the B-2101, but when I switched the G-901 to separated, I believe its volume knob becomes inactive, so I cant use it to balance the left/right volume knobs on the B-2101. Thus, the overall volume in the configuration comes from the Sony preamp, and I can adjust the left/right volume knobs on the B-2101 as well, but not on the G-901.
Now, tying it all back to the 2017 discussion: Is there a way I can use the G-901 as a power amp but still use its volume control, as if it was in connected position functioning as a receiver? I ask because it seemed like it could be done with the AU-717 that has the same switch. But in the '17 discussion, I only saw the 717 and X-901, I did not see any mention of an external preamp with two outputs being connected to them.
Thus, does that mean an AU-717 and X901 can be biamped without needing an external preamp, by just keeping the 717 in its connected position and then running cables to the 901's CD input (instead of using Source Direct?) so that 717 and X901 both has its own volume knob controls active? If this is true, then I dont really need the external Sony preamp, if I can just use the G-901.
I guess what my brain is fuzzy on it is that I keep thinking for an AU-717 to be used as a power amp, it has to be 'separated', when in fact, it can be kept in 'connected', and you just run cables from the pre out jacks.... And then all the sources- be it a cd player, tuner, etc can be connected to the various inputs on the AU-717 just as it does when running as an integrated.
Conclusion: So, I could use my G-901 and B-2101 as power amps to drive Infinity RSIIA speakers if I keep the G-901 in connected position and run cables form its pre out to the Aux input on the B-2101, so that volume knob still works on G-901?
It gets slightly more complicated as the Infinity come with whats called a "contour" or EQ box that is supposedly needed for improved bass response, and how it gets connected into the signal chain depends on if using one amp or bi-amping which the op manual attempts to explain.
I have some similar concerns when it comes to passive Bi-amping and just wanted to clarify a few things if some knowledgeable folks could share their thoughts:
1) It seems that using two amps, one to drive the highs/mids, and the other for the woofers, would result in each amp having to do less "work", compared to using only one of the amps to drive the speakers on their own. But my question is, what is the difference in actual Impedance seen by each amp when used in both configurations? In other words, if I bi-amp, what impedance change does the amp "see", compared to the impedance when the amp was driving the speakers by itself? To further clarify, we all should know that Impedance is an ac characteristic, not DC, it involves caps and inductors in the crossover circuitry, not just resistors, thus the load is reactive, not just pure resistance, and caps & inductors behave very differently in ac vs DC. Each brand/model speaker has its Impedance curve showing its response over the audible 20-20K hz frequency range, and despite the usual 8, 6, or 4 ohm ratings, we must realize these are just AVERAGE values, when in fact, the value is always changing with frequency, and the main concern is when it dips low, under 4 ohms toward 2 ohms, whereby some speakers have a reputation for being "amp killers"- re: Infinity Kappa 9.
A similar thought to impedance being an average value, is the 120 US voltage in our homes- if we take a meter and insert probes into a powered wall outlet and measure 120V give or take- that is just an AVERAGE value, being that the meter cant read a sinusoidal waveform that is changing 60 times per second which actually has a peak value of about 170 volts.
Anyhow, back to the question, we can start by using one amp to drive a pair of speakers and the amp will see a certain impedance. Now, if we try to make things "easier" on that amp, but allowing it to share duties with a 2nd amp, so that each amp has less drivers to drive, so to speak, then what is the new impedance that the amp sees if it only has to drive the highs/mids, or only the woofers, vs when it had to drive All of them by itself?
My point is, bi-amping might seem to lessen the "load" on each amp, but that would only be the case if the impedance for each amp went up, as higher impedance= less current draw= less heat= less stress on the amp. So, does the impedance change, I am trying to get a clear answer on that, or hoping that my brain could do a deeper dive to visualize the concept as I am pouring a cup of coffee now and maybe it will stimulate the brain cells, Lol...
2) Question on the Sansui pre out main switch:
Using the AU-717 as an example: It normally functions as an integrated, but can be used as a preamp or power amp if the switch is moved to its
separated position. But in the old discussion, it seemed like the switch still be kept in the connected position so that its volume knob control would not be disabled if used to bi-amp with another amp, so that both amps have volume knobs that can be adjusted to balance each other. Is that correct?
3) The reason I ask:
I have a pair of vintage Infinity RSIIA speakers- large floorstanders with an array of EMIT tweeters/ mids and dual 10" woofers. They seem to have a
reputation for thriving on power, which is why I thought passive Bi-amping would be a good option. Actually, I dont have a choice to use a single amp being that when I acquired them several years ago, the jumpers were missing to attach the speaker terminals together. The terminals are odd- they
accept only speaker cables with banana jack connectors, which dont even go in all the way and are prone to easily falling out.
I have a Sony TA-E77ESD preamp with two line outs (I stupidly sold a Sansui CA-2000 I used to have), which can feed my Sansui B-2101 power amp (200Watts) and my G-901 receiver (160W) with the same pre out main in swicth as the 717, that I switched to separated power amp mode.
The G-901 is the closest match in wattage to the B-2101, but when I switched the G-901 to separated, I believe its volume knob becomes inactive, so I cant use it to balance the left/right volume knobs on the B-2101. Thus, the overall volume in the configuration comes from the Sony preamp, and I can adjust the left/right volume knobs on the B-2101 as well, but not on the G-901.
Now, tying it all back to the 2017 discussion: Is there a way I can use the G-901 as a power amp but still use its volume control, as if it was in connected position functioning as a receiver? I ask because it seemed like it could be done with the AU-717 that has the same switch. But in the '17 discussion, I only saw the 717 and X-901, I did not see any mention of an external preamp with two outputs being connected to them.
Thus, does that mean an AU-717 and X901 can be biamped without needing an external preamp, by just keeping the 717 in its connected position and then running cables to the 901's CD input (instead of using Source Direct?) so that 717 and X901 both has its own volume knob controls active? If this is true, then I dont really need the external Sony preamp, if I can just use the G-901.
I guess what my brain is fuzzy on it is that I keep thinking for an AU-717 to be used as a power amp, it has to be 'separated', when in fact, it can be kept in 'connected', and you just run cables from the pre out jacks.... And then all the sources- be it a cd player, tuner, etc can be connected to the various inputs on the AU-717 just as it does when running as an integrated.
Conclusion: So, I could use my G-901 and B-2101 as power amps to drive Infinity RSIIA speakers if I keep the G-901 in connected position and run cables form its pre out to the Aux input on the B-2101, so that volume knob still works on G-901?
It gets slightly more complicated as the Infinity come with whats called a "contour" or EQ box that is supposedly needed for improved bass response, and how it gets connected into the signal chain depends on if using one amp or bi-amping which the op manual attempts to explain.
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