Taylor Guitars K4 Equalizer

The new Taylor Guitars K4 Equalizer is the ultimate second stage of an acoustic guitar's direct output. "Taylor-made" to perfectly match the Taylor Expression System, the box raises the bar for the use of a direct output in live performance and recording.
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The new Taylor Guitars K4 Equalizer is the ultimate second stage of an acoustic guitar's direct output. "Taylor-made" to perfectly match the Taylor Expression System, the box raises the bar for the use of a direct output in live performance and recording. The K4 is a single-channel, three-band EQ with a parametric mid. It is specifically voiced for the acoustic guitar and a Rupert Neve-designed circuit that features transformer-coupled input and output and pure analog tone shaping.
Product PointsApplications: Studio, project studio, live performance

Key Features: Single-channel; three-band EQ with parametric mid; headphone controls; effects loop

Price: $898

Contact: Taylor Guitars at 619-258-1207, Web Site.

The beautifully-designed K4 ($898)perfectly blends the grandeur of a Taylor guitar with that of the most visually appealing studio equipment. The 8.5 inches wide x 3 3/8 inches high x 7.5 inches deep shiny aluminum box has blue front and rear panels and is topped with a beautiful piece of wood.

Except for the headphone jack, the rear panel houses all of the input and output connections as well as a few controls. The three-position ground lift switch allows the ground to be lifted at either the TRS output, the XLR output or not at all. The battery compartment allows the K4 to be powered via two C batteries (not recommended but a nice backup in the event of a misplaced power supply). The DC in jack allows the K4 to be powered from an external 5V, 800mA power supply (included). The 1/4-inch tuner out jack provides a pre EQ/mute output allowing the signal to reach a tuner when the box is muted. The K4's output is provided via a 1/4-inch TRS balanced jack (max output w/600 ohm load: +22 dBu) and a male XLR connector (max output w/600 ohm load: -18 dBu). An effects loop is provided via a pair of TRS jacks. The loop switch places the effects loop pre or post EQ. The loop input and output are low-impedance and balanced, so the box allows other equipment to be added into the signal path without sacrificing the Expression System's signal integrity. A dual input jack (accepts either XLR or 1/4-inch connectors) provides input to the K4. The TRS input is optimized for use with the Taylor Expression System (or any other high-gain source) and the XLR input is optimized for use with instruments with passive pickup systems.

The majority of the K4's controls are found on the front panel. The phase button reverses the phase of the input signal. The three-band EQ includes a low EQ control providing ±10 dB at around 100 Hz, with the lower knee at around 450 Hz, and a high EQ control providing ±10 dB at 10 kHz, with the lower knee at 1.6 kHz. The mid EQ is sweepable from 80 Hz Ð 8 kHz and provides ±10 dB gain. The mid EQ's shape control allows the Q of the mid-band to be varied. The high, mid and low gain controls all have a center detent position for easy return to zero. The EQ circuit also includes an 18 dB/octave high-pass filter set at 30 Hz that is always active. The loop button activates the loop circuit and the mute button mutes the signal to the primary outputs. The headphone and tuner outputs are not affected by the mute button. The power button activates the K4's power. An LED indicator glows green to indicate that the unit has power. When running off battery power, the LED acts as a low-battery indicator glowing red when approximately 30 minutes of power are remaining. The volume control adjusts the main output volume of the K4. The Headphone output jack provides headphone monitoring. A separate headphone control adjusts the output of the headphone jack.

In Use

Coupled with an Expression System equipped Taylor 514-CE guitar, I found the K4 to work brilliantly. The preset high and low frequencies work perfectly and the high and low bands feel like they are full featured parametric bands of EQ that were precisely set by none other than Rupert Neve himself. Even if I had a sweepable frequency and Q control on the high and low bands, I don't think I could do any better myself. In every instance (with the Expression System equipped guitar) I was able to attain the desired sound by solely using the high and low bands. In a live situation, I anticipate the mid band would be useful in helping to eliminate any problematic feedback.

I put the K4 to use with a wonderful sounding acoustic guitar equipped with an awful sounding peizo pickup and found the K4 to be a miracle worker. I was never able to get the instrument to the same level as the 514-CE that I checked with the Expression System, but I was able to take an apparently unusable sound and shape it into a perhaps not flattering but none-the-less completely usable sound.

Just to see how flexible the K4 really is, I ran a Shure SM57 into the XLR input and frankly, was quite surprised. Since it doesn't have phantom power, condenser microphones aren't an option but the box actually holds its own as a mic pre and EQ. I experimented using the 57 to record snare drum and had good results. The EQ worked well but in this instance I would have preferred having adjustable frequencies on the high and low EQ bands. I also used the K4, along with an E/V RE-20 to record a voice over and again had good results.


The K4 is the perfect sonic compliment for anyone who owns a Taylor Expression System equipped acoustic guitar. The box is feature packed meeting the needs of both the studio and live musician and it is reasonably priced.