Hi everyone!

I'm new to this forum and have a question I hope someone can help me with. I have a keyboard with line out jacks (output level 1.5 vrms, 600 ohms) and a power amp with balanced inputs (10 Kohms/+4dBu). Do I need to use an instrument preamp, mixer, or something else between the keyboard and power amp to match impedances? If so, does anyone have any suggestions as to what would be the best to use?

Many thanks for any help.

pg

Welcome to the forum!
It shouldn't hurt to try going directly into the power amp. Turn the input levels down on the amp, then gradually bring them up while the keyboard is playing.
Most everybody uses some sort of mixer, however, when using a power amp. There are many good, inexpensive choices available. Alesis and Behringer both make small mixers for $100. or less. They would give you more control and more options.
DonM

Impedance matching is usually done to obtain good power-transfer efficiency. That's particularly important when it comes to power amp output and speakers. However, in the case of line-level signals, there are other things to consider. In your case, it's good to have the output (keyboard) at a relatively low impedance and the input (amp) high. This will help ensure good voltage-transfer and likely result in a decent signal-to-noise ratio. The +4dBu input sensitivity of your amp translates to 1.23Vrms, meaning that a 1.5Vrms level from the keyboard should easily be able to drive the amp to full output.

While a mixer or other devices could be useful for several reasons, they shouldn't be needed to make the connection from keyboard to amp. If you get a proper cable, that should be adequate. You can always get the additional equipment later if you find the need. Of course, as DonM suggested, keep the volume control(s) down until you determine a reasonable level.

--Barry

Hi DonM and Barry!

Thanks for replying to my post.

I connected my keyboard directly to the power amp as you suggested, but did not get any amplification.

I read the power amp manual closer and they recommended a mixer before the power amp. I went down to Guitar Center and bought a Mackie DFX 6 mixer. A little overkill for what I need, but I wanted something good, quiet, and reasonably priced. Connected it to the keyboard and power amp and everything is working great. That mixer is really nice although it will probably take me quite a while to figure out how to use everything it has on it.

Thanks again, guys, for the suggestions.

pg