tube pre-amp for active monitors

canibefrank OP

Most active speakers have ridiculously low input impedance and many/most tube preamps will not drive them properly, solid state preamps should have no trouble.

QUOTE: " Airpulse Model 1: The input impedance is quite low, so do check that the source is happy with such a loading. Valve pre-amp use is presently contraindicated by that low 2.5kohm value for the RCA input sockets"

Cheers George

@georgehifi
I am using the XLR balanced inputs on the Air Pulse monitors

I wonder if there is a simple stereo tube buffer I can fit between DAC and monitors? 

George makes a good point about impedance compatibility.

The description of your A200 speakers at the AirPulse site **seems** to imply that the balanced analog inputs are received by a Texas Instruments PCM1804 A/D converter chip. The datasheet for that chip indicates that it has an input impedance of "10K single-ended," which may mean that it has a balanced input impedance of 20K. However the website description of the speaker doesn’t explicitly say that there isn’t a buffer chip or other circuitry "ahead" of that chip.

Also, the PCM1802 chip that is described as receiving the unbalanced analog inputs is specified in its datasheet as having an input impedance of 20K.

I wonder if there is a simple stereo tube buffer I can fit between DAC and monitors?

Before anyone can make a suitable recommendation, if in fact one can be made at all, you should contact AirPulse and ask them to clearly state what the input impedances of the balanced and unbalanced analog inputs are.

Regards,
-- Al

@almarg  
The balanced inputs bypass the built-in dac and tone stack