Normally for differentially baIanced amps the impedance doubles for a balanced input. The Musical Fidelity manual only gives the 50 kohm spec. Reading the manual leads me to think they tout balanced connections, but I see no remarks to lead me to think the unit is differentially balanced.I was not aware that AC impedance can be reliably measured with a DVM. Therefore you probably should presume the 50 kohm spec for your connections. You might wish to contact Vandersteen to see if they approve using the balanced crossover it the unit is not truly balanced, and also contact Music Fidelity to confirm the M6 series topology.
Confusion on amplifier impedance
Hello to all. My question is, is the imput impedance of an amp the same in RCA and Balaced mode. In setting up the M5-HP crossovers ( Balanced) for my Vandersteen 5a speakers I have to use the input impedance of my amp. Now what I dont understand is the amplifier, a Musical Fidelity M6PRX, is rated at 50K of input impedance but when I decided to check with a voltmeter it was way off the 100Hz target of the crossover. Requirement is play 1KHz tone at 1VAC and measure, then play a 100Hz tone and measure. The resuts should be .707 VAC of the first reading or as close as you can get.
In order to get a proper reading I had to set the M5-HP for 200KHz. My results were then 1KHz at .990 VAC and 100KHz .722 VAC. I previously had a set of RCA crossovers on a set of Vandersteen 5 with the same amp and had no sonic problems however I never did the check I did now. I just set it at 50K impedance and that was that. Can the difference between RCA and Balanced be so great ? Not sure how this works. Thanks in advance for any help.
In order to get a proper reading I had to set the M5-HP for 200KHz. My results were then 1KHz at .990 VAC and 100KHz .722 VAC. I previously had a set of RCA crossovers on a set of Vandersteen 5 with the same amp and had no sonic problems however I never did the check I did now. I just set it at 50K impedance and that was that. Can the difference between RCA and Balanced be so great ? Not sure how this works. Thanks in advance for any help.