Well I opened up the amp and each XLR has an independent plug going to the main board. The connections where the plug connects are labeled, ground, positive, negative. i measured resistance to ground on pin 1 and got 39 ohms. To ground on pins 2 and 3 it jumps to a fluctuating 176k ohms, equal reading on 2 and three. I read an article on the internet that stated "balanced operation gives an increase in loudness of 6 db". There is a "balanced" switch on the back and the manual states that not having it in the balanced position results in a 6db LOSS of loudness. I am using the amp with the companion M6-PRE wich is definitely fully balanced with inputs and outputs. I think all this means I am safe thinking the amp is balanced. So if the 50k impedance is for RCA ? then I suppose I have to double it for Balanced XLR. I have tried on previous ocassions to email Musical Fidelity with no reply. Now that Project owns them I have no idea whom to contact.
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.