User`s manual

The Phase Switch allows you to invert or reverse the phase of the output signal. In the normal posi-

tion, output signals are in phase with the input signal on all jacks. When engaged, both the XLR and

¼” outputs have their signals changed to 180 degrees out of phase. This function comes in handy to

prevent a hollow sound, due to phase cancellations, when using multiple microphones on a single

source or when using a combination of direct and microphone pickups on the same source. In a Live

Sound application you may be able to get more gain before feedback by reversing the phase of the

vocal microphone.

The Output Control adjusts overall level just after the tube and metering and before the output ampli-

fiers. This allows you to scale the output to the system you are driving. Typically you would set this

about mid way for going into a line level input. When directly plugging into an instrument amp or the

microphone inputs on another piece of equipment you may find that a 9 o’clock position gives you

plenty of output.

The LED metering circuitry covers a wide 30dB range and has a fast attack to help indicate any

clipping. It is located in the signal chain just after the tube. The Output control comes after the meter

so that you can use the meter to set the overall input gain for best dynamic range then trim the output

signal level to the system you are driving. The red “Clip” LED comes on just before clipping and

should light on extreme musical peaks only. The yellow “0dB” LED is set to 15dB below the “Clip”

LED. If the “0dB” LED is on half the time then you have about 15dB of headroom on the average.

The green “-7” and “-15” LEDs indicate how far below the nominal “0dB” LED your signal is. They

have a long release time. These LEDs should be on much of the time during performance and if not it

indicates that your signal or input gain is too low for best results.

The FET limiter has its output level set to be at the “0dB” LED point so if the limiter is engaged and

the “0dB” LED is on then you are in limiting. This helps in setting output level for your system. To do

this you would start with the limiter off, apply a signal and increase the gain until the red “Clip” LED

comes on occasionally, then engage the limiter. At this point the signal at the tubes output will be in

limiting most of the time. You can then adjust the Output control so you are just below clipping at your

A/D, computer, recorder, or amplifiers input. Now you can back off on the Gain control. At this point,

as long as the Output control is at the current position, you can use the “0dB” LED to indicate that you

are at full signal level for your equipment that follows.

Note: All front panel push switches are lit when in the active position to aid in setup and operation.

A brief note from customer service:

Once in a while a customer will call and say: I think my ART preamp is "noisy". What's wrong?

If you experience unwanted "noise" in your system when you use a stand-alone preamp, please

consider what your signal is and where you're sending it. Some people send the signal from their

preamp to a mic input (they figure, "well, I'm using a mic!") on the board or recorder. This is in fact

incorrect and could be the problem. ART preamps are actually intended to output a nice fat LINE

LEVEL signal. If you send that line level signal to a recorder or mixer's Mic input, that circuit will

usually add more gain to the signal. Gain on top of gain will indeed result in noise. Please treat the

output signal as line level and you'll be pleasantly surprised at your new clean and warm sound.

The same rule applies for guitar and bass players that use ART preamps as their front end. Send the

signal from your preamp to a low gain input on your amp, or even a "loop return" jack which allows

you to bypass the amp's solid state preamp altogether.