Handy Preamp Shopping Tips
If you are using a tube preamp with a solid-state amplifier, the ONLY compatibility issue you need to think about is the preamp’s output impedance. The input impedance of the amplifier needs to be 10 times or higher than the output impedance of the preamp.
ProLogue Premium is 2800 ohms: Amplifier Input Impedance needs to be 28k ohms or higher
DiaLogue Premium is 256 ohms: Amplifier Input Impedance needs to be 2560 ohms or higher
Very few power amps have an input impedance below 28k ohms, so PrimaLuna’s can be used with confidence in 99% of the systems out there. Consult the owner’s manual for your amplifier.
When you are using a preamp, you are usually lowering the gain (volume) of your CD player or phono stage by 6dB or even more. For reasons that baffle us, some manufacturers sell preamps with 23, 26, and even 30 dB of gain that you will never use. This practice is nothing short of insane. Not only do you have to deal with the thermal noise and microphony, it causes problems like premature tube failures; with zero upside benefits. PrimaLuna preamps have always had between 10-12dB and are as quiet as solid state.
We use 12AU7 gain tubes because of flexibility. There are more types of 12AU7 tubes being made today than any other tube, and in the world of vintage new old stock (NOS) tubes, there is such a huge supply and variety you can have all the fun you want. And dirt cheap. Amperex, Cifte, Mullard, Brimar. Tons of choices. If you buy a preamp that uses 6H30 tubes, it’s a one-trick pony (besides the fact that 6H30’s sound thin). There’s only one factory that makes them so there’s no fun to be had and you can’t “season your system to taste”. You better like what you get, because you are stuck. And, what happens if 6H30 tubes go out of production?
Quality parts and designs simply weigh more. Compare weights when comparing preamps. Then, type the model you are researching into Google and look at “images” until you find an interior photo. What we say is true, but YOU need to see it for yourself. The PrimaLuna ProLogue Premium weighs 37.5 lbs., and the DiaLogue Premium, 52.9 lbs.
And remember this: Magazine critics review many brands. They buy PrimaLuna.