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Lee Jackson Preamp tone

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9/2/1999 4:37 PM
Giacomo	Lee Jackson Preamp tone I have a Perfect Connection GP-1000 preamp. Its tone is bright and cold. I can't understand if it's a "feature" or there is some problem (I hook it to a SFDR or Pro Jr. input). I noticed that adding a high value resistor (>1M) in series with the signal wire the tone goes much less bright. Maybe an impedance matching issue? Thanks in advance Giacomo

9/2/1999 6:15 PM

I have no experience with that preamp, so I can't comment on its inherent tone. However, I do know that most rack preamps are designed to be plugged into a power amp (or into a chain of effects, then into a power amp), not into the input of a guitar amplifier. Power amps generally have a flat frequency response. Guitar amplifiers typically have a very un-flat frequency response, even if all the tone controls are set to "5" (or any other number). Guitar amps usually give a substantial treble boost and a often also create midrange dip around 250 to 500Hz.

Your tone may be sounding to cold and bright because the guitar signal is going through not one, but two EQ sections: one in the preamp itself, and another in the amp its plugged into.

When using a rack preamp with a combo or head amp, its better to plug the preamp into the effects return/line-in jack of the amp (if there is one; probably not the case with your SFDR and Pro Jr., unless someone added a LINE-IN jack) so that you bypass the amp's preamp section.

9/3/1999 1:06 AM
MKB	I had one of these a few years ago. It was strange in that it would oscillate and squeal with certain manufacture 12AX7 tubes. Mine was somewhat warm sounding, but the thing is so simple that it may have been the tubes. You might try different 12AX7's and see if that helps.

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