GHOST Acousti-Phonic FAQ

How does the ghost Acousti-Phonic sound?

The Acousti-Phonic preamp sounds remarkably like a studio-quality acoustic guitar. It's downright spooky to hear an acoustic guitar, yet see the sound being produced on a solid body electric guitar. Your eyes won't believe your ears!

Does the Acousti-Phonic "color" my mag sound as it passes through?

The Acousti-Phonic is renowned for having exceptionally good sound quality. Musicians are often surprised to learn that the mag signal passed through a unity-gain preamp, as they swear it sounds like its going "straight out". If you need to bypass the Acousti-Phonic for your setup, you will lose the blending feature of the Acousti-Phonic. This can be implemented as a permanent modification, or with an "emergency" bypass switch, so you can play your mags until you have a chance to replace you battery.

How does the Acousti-Phonic change my electric sound when I mix the two signals together?

It's the difference between playing in a garage, and playing in a cathedral. The Acousti-Phonic adds a depth to your magnetic sound without altering your tone. People phone Graph Tech and say, "I installed the Acousti-Phonic, and after I got off stage, a guy came up to me and said, 'I know you've got something amazing in that guitar, but I can't figure out what it is!'" A lot of players use the Acousti-Phonic to enhance their electric sound, not just to make an electric guitar sound like an acoustic guitar.

How big is the Acousti-Phonic?

The PC board measures 1-5/8" x 1-1/8". With the connectors on, it's about 3/8" high. Piggybacked with the Hexpander, they are 1/2" high.

Can I add a tone control to the ghost system?

You can add a tone control to the piezo circuit as shown in the user's guide. You can't add a master tone pot just before the output jack. The Acousti-Phonic doesn't tolerate having anything between the board and the output jack, because it interferes with the sensor that detects whether the patch cord inserted is stereo or mono.

How do I wire a stacked pot to the ghost system?

There seems to be confusion about stacked pots. A lot of people think they work like the ones on car stereos, where you push in and adjust one pot (bass) and pull out and adjust another pot (treble). These aren't available for guitars.

Stacked pots are two pots, one on top of the other, with a pair of concentric knobs, each controlling one of the pots. This enables you to add another pot to your guitar without drilling another hole in the guitar top. Stacked pots are available from most guitar parts retailers with both pots the same value, or two different values. The Acousti-Phonic can use either a 250K or a 500k pot. You can put the mag and acoustic volume together on your stacked pot so you can turn them together or mag volume and tone together and acoustic volume as a separate pot.

Consider also our Acoustic Volume Pot with Mid/Dark Switch, PE-0206-00, as it's designed to avoid drilling a new hole for another pot when you add the ghost system. When you replace your tone control with the Mid/Dark pot, the pot becomes the volume control for the acoustic, and the Mid/Dark switch (toggled by pushing in on the acoustic volume knob) gives you two tone positions, instead of a tone knob. You'll have bright (Mid-boost), or dark.

Wouldn't it be better to control the mag/acoustic mix with a Blend Pot?

Blend pots for guitars are like cross faders, where both pots are full-up when the dial is centered, and each one fades as you turn to each side, leaving the other at full volume. A wider variety of sounds are available when you can control both the acoustic and the mag volume separately, as you can control how hard you're driving your amp and effects.

Can I put my mag volume and tone on a blend pot?

This works for two volumes, but not for a volume and a tone. You would have to turn the volume all the way up to roll off your treble. Try a stacked pot instead, which has two independent pots with concentric knobs.

Can I keep the output jack that came with my guitar, instead of using the one that came with the Acousti-Phonic?

There are a lot of functions wrapped up in the Stereo Switched Jack, so you have to have a good understanding of the Acousti-Phonic to make changes in this area. The main function of the jack is to turn off the battery when no cable is installed. Note that the switch in the Stereo Switched jack works backwards -- open is on, and closed is off. Many other wiring options are possible, and you can use dual jacks or SwitchCraft deep jacks, but you have to make sure all functions are addressed correctly or the Acousti-Phonic won't work properly. Check out the wiring diagrams in the Knowledge Base on this Web site.

The Acousti-Phonic is described as "18V compatible". Does that mean I need to put two 9v batteries inside my guitar?

The Acousti-Phonic needs a minimum of 7v to operate properly, and works fine on anything from 9 to 18 volts. This is a useful feature when you are installing it on an instrument that already has an 18v active pickup system, and you want to avoid having two separate battery systems

Can I install the Acousti-Phonic without a battery if I'm installing the Hexpander too?

Yes, but you will have no acoustic or mag output unless the Hexpander is plugged into a MIDI converter. This is only a practical option if you are always using the guitar with a MIDI converter, such as in studio or some stage setups. For adding MIDI to a guitar that's used for a wide variety of applications, an on-board battery is essential.

Can I use the Mid\Dark switch also to blend?

Yes, the Piezo pot with Mid/Dark Switch is an acoustic pot to blend piezo sound with your magnetic sound, and the push/pull switch toggles two equalization options, a “mid-boost” and a “bassy dark" setting. It provides two tone options on the acoustic sound, to make up for converting your tone control to the acoustic volume.

Are the switches available in a different finish?

We only stock our switches in chrome finish, but the switch is a regular on/off/on SPDT mini toggle, available at most guitar parts retailers. You can special-order the QuickSwitch harness-only by phone (for half the price), but you may find it easier to order the whole switch assembly and just move the wires over to your gold switch one at a time.

If I plug a mono cable into the stereo jack does the guitar still function normally as it would prior to installing the Acousti-Phonic preamp?

Yes. If you turn the acoustic volume down to zero, or set the QuickSwitch to Mag, your guitar will play like a regular electric guitar. The only difference is that you need the battery to be good even to run on mag only, as this signal does pass through the Acousti-Phonic for blending purposes.

How long does the battery last? Can I just play my magnetic pickups if the Acousti-Phonic battery dies?

If your battery dies, you get no sound, not even your magnetic pickups. When using an alkaline battery, 500 hours of battery life can be expected (350 hours more than any other acoustic system). This means you will have to change your battery twice a year. Unplug your guitar when it's not in use to prevent unnecessary power consumption.

Can I wire the Acousti-Phonic with two output jacks instead of one stereo jack?

Yes, but you have to decide how you're going to use it, and what's most important to you, because there are at least three ways of wiring dual jacks, and each has advantages and disadvantages. Check out the wiring diagrams page for more information.

Can I install the ghost Acousti-Phonic on a guitar that is string-thru-body?

There is a quirk when installing the Acousti-Phonic in a guitar with this style of string loading and a Tune-O-Matic style bridge because the strings load through metal ferrules embedded in the wood of the body. The ghost saddles are non-conductive, so they isolate the strings from the string ground attached to the bridge. In most guitars with a Tune-O-Matic style bridge, you simply run a ground wire to the tail piece. Your strings will have to be grounded another way. Grounding the six individual ferrules is a possibility, but takes some creativity to do it invisibly. I have done it by pulling out the ferrules and running a fine wire along the sides of the ferrule holes. It may be possible to accomplish this by painting the ferrule holes with conductive shielding paint (as is used in guitar control cavities) and trailing this paint through a hole drilled back to the main cavity.

Will the Acousti-Phonic work with more than six strings?

The ghost Acousti-Phonic offers 7 string compatibility right out of the box for acoustic sound. If you would like to use more than seven, you would need to purchase an additional summing board (PE-5017-00) and dual connector cable (PE-5021-00). This will get you another seven strings. There is no limit to how many pickups you can connect.

What if I am installing the ghost system into an instrument that does not have any magnetic pickups?

If you have an instrument with a metal bridge plate, it would be good practice to ground that plate rather than leave it floating. Because the bridge is a big chunk of metal near the pickups and their wires, which are high-impedance and thus prone to pickup. If the bridge is floating it will tend to help to couple the ambient 60Hz field to the pickups and wires. On the other hand, if it is grounded it will tend to act as a screen, shielding the pickups and their wires from the ambient 60Hz field.