Amplifier Input Impedance Question

[saerwin]

Hi Keith
I need help confirming the correct input impedance value for the balanced inputs of my XPA-1's. I am going to be setting up a pair of Vandersteen Wood Quatros I just bought used.
These speakers have integrated powered subwoofers and require the use of an included in-line high pass filter which is placed between the preamp and amp. The filter has internal dip switches which are set to match the amp's input impedance so the 11 band equalizer in the subwoofer section of the speaker is calibrated and the mid bass driver is protected from overload from the amp.
Both my XPA1 manual and the Emotiva product page list this value as 18 kOhms. This is a much lower value than those listed for all the other Emotiva amps on their product pages and I found another review site which listed the the value for the XPA1 as 47 kOhms.
Could you please confirm the correct value for me to use? The speaker's manual states setting this incorrectly could damage the speakers and I want to get it right.
Thanks

[Cory Cooper]

The XPA-1 manual states the following for input impedance:

Unbalanced: 20kohms (RCA connection)
Balanced: 18kohms (XLR connection)

The list on the top of the M5-HP shows a value for 20kohms (20K) - switches 6 and 8 on. That would be an exact match for an unbalanced RCA connection. You would have to go 20K or 15K (probably 20K) using the balanced XLR inputs.



20K on the M5-HP is the same as 20kohms in the XPA-1 manual.

Hopefully Keith will confirm the XPA-1 spec for you. Not trying to step on your toes Keith!

C

[saerwin]

Thanks! That's what I thought but I wanted to be sure.

[Cory Cooper]

No problem. I would still hold off for Keith's confirmation, just in case.

C

[KeithL]

On the unbalanced inputs (from the picture that's what you will be using), the input impedance of the XPA-1 is 20k ohms.