Help & Troubleshooting

Applies to the Trinity Systems, Bass Master Pro, Bass Master Rockabilly, PowerMix Pure XT

If there is a malfunction, the first step is to isolate exactly which part is causing the malfunction. There are several possibilities:

• transducer

• the stereo jack

• the stereo cable between instrument and preamp

• the output cable from preamp to amp

• loose wiring or insufficient installation of pickups

• the preamp

Switch out all connection cables (stereo cable and output cable) to test if one of the cables is faulty.

With the PowerMix Pure XT, please check if the strap knob on the endpin jack is screwed in all the way. If in doubt, simply remove it for the testing.

If the stereo cable tests fine, test the pickup systems individually without going through the preamp:

1. Insert a working mono cable into the stereo jack on the instrument and connect it to an amp.

2. If the stereo jack produces an intermittent signal when you wiggle the plug, it is probably worn out and needs to be replaced.

3. You should hear one pickup at a time in passive mode. See the label on your preamp to determine which pickup on the ring terminal and which pickup is on the tip terminal.

4. Start with the pickup on the tip terminal by pushing the mono cable all the way into the jack. Test if the signal is clear or if it has a problem. Of course it will be quieter, as compared to connecting it via the preamp.

5. When the plug is partially pulled out of the stereo jack by about 1/4 inch, the pickup connected to the ring terminal (see box label) will be heard. It needs some trial and error to find the exact spot in the jack.

Unfortunately, a mic cannot be tested without the power supply of the preamp.

With upright bass systems especially, it also could be a mechanical problem like a loose pickup or a pickup cable that is not properly taped down or secured.

If all this checks fine, the problem comes down to the preamp. The preamps are very reliable and usually do not develop malfunctions. However, the battery clip can wear out over time and may need to be replaced.

We've experienced this phenomenon a few times and it seems to happen mostly with the Pure 12-String but a few incidents were reported with the Pure Mini as well. It has to do with two things: Extremely high impedance of the input you plug in (like LR Baggs Para Di or Fishman Platinum preamp or and very high impedance acoustic amp) and a special protection circuit used in some amps.

First off, the pickup does not shut down momentarily, but the amp you are using has a safety protection circuit, which shuts the power amp down momentarily in order to protect the speakers. Some Fender acoustic amps and powered studio monitors feature this protection circuit.

What happens is this: A “burst” of low frequencies is produced when you push down or bump on the bridge with your wrist. This “burst” would actually cause very dramatic speaker movement and the protection circuit kicks in.

If you use Baggs Para DI preamp, for example, this may happen. It exaggerates the bass frequencies due to its extremely high impedance input. The Pure Pickup has strong bass to begin with and does not need any further boost. The remedy here is to use our Pure Preamp and turn down the bass on the amp to the degree needed for good sound, but not more. You will also find that if you plug the guitar directly into a 1/4" line input of a mixing console, the “cut out” phenomenon will not happen. This is because the line input of the board is low impedance.

The superglue we supply does not bond super tight. This makes it possible to remove the pickups without damaging the wood, but you may damage a pickup during removal. You have to carefully test the pickups after removal and cleaning (explained later). You can purchase single replacement transducers from us if needed.

Removal can be tricky and is not recommended for non-professionals because we do not want you to accidentally hurt yourself. We recommend using a scraper blade (razor blade with a handle on one side) to separate the pickup from the bridge plate from the endpin side (the back of the pickup). Make sure to get the blade flat between wood and metal side of the pickup. This is the difficult part. The pickup usually pops off once the blade is about 1/8 - 1/4" or so under the pickup. The glue residue on the bridge plate can be removed with fine sandpaper or you can carefully scrape it off with the scraper blade.

Please be aware that K&K takes no responsibility for damage to your instrument or personal injury during the pickup removal process. We strongly recommend that this procedure only be performed by professional luthiers or guitar techs.

If done correctly there should be no damage to the bridgeplate or guitar top. But again - some skill is needed to do this. Any good luthier should be able to remove the pickups.

Be careful not to bend the pickups during removal. Visually inspect the pickups for bend marks or other irregularities. If they look damaged, they may still work but we recommend replacing bent or nicked pickups. Use the scraper blade to scratch off any remaining glue residue from the golden side of the transducers. Some fine scratches in the metal will not hurt the performance.

To test the pickups, plug the pickups into an amp. If you have a Trinity System you can still plug a mono cable into the endpin jack and you will get the pickups only. Hold one pickup at a time about 3/4" (2cm) from the pickup head on the cable and tap the pickup with your finger. Do this tapping in both directions, so that you tap the black side and the golden side. You can do this quite hard. The tapping sound has to be amplified and all pickups should produce about the same volume. There should not be any missing taps. There should not be any loud "crackles." If the pickups test out fine, you can reinstall them.

Make sure that all glue residue is cleaned off the wood of the bridge plate or guitar top. Smooth the wood surface until it is perfectly straight and clean. You can use any store-bought superglue to glue the pickups into your guitar. We recommend a superglue GEL, because it gives you a little more time to re-position the pickups before it dries.

It is quite difficult (but not impossible) to use the Pure pickup in loud band situations--especially on small stages. It is designed more for the acoustic musician and the best possible natural tone. A soundhole cover is the first remedy here and helps a lot. Bands like Tom Petty Band use the pickup successfully, but they play on huge stages. Our PowerMix Pure System would actually be the best choice for high volume situations.

In addition to this there is most likely an impedance match issue going on as well. Acoustic amps and most competitors' preamps are designed to work best with undersaddle pickups or other very high ohmic piezo pickups. They feature extremely high input impedance (5-10 meg), which boosts the bass response. Most competitors' pickups need this high input impedance to boost the bass response of their pickups, because most of them sound tinny in passive mode.

The Pure has a healthy bass response to begin with. It is overkill to boost it with extremely high input impedance. The Pure pickup sounds best with lower input impedance like 500 k to 1 meg, even just in a line input of a mixing board. One should try it on a PA and plug the Pure straight into the line input of the mixer, just to see that the excessive bass response is gone right away.

The best option to compensate for this is to get a Pure Preamp.

It may also be necessary to turn down the bass control on the amp. We use an Ultrasound acoustic amp (10 meg input) and we have to turn down the bass on the amp basically all the way. But it sounds great this way. If you are reluctant to turn down the bass because you think that the EQ must be at a centered position otherwise something would be wrong, it's important to remember that EQ exists to be used.

A defective transducer is not likely. We thoroughly test each of the transducers several times during production. It is a lot more likely that it is an installation issue.

There are many factors that can go wrong during an installation, but the one factor which seems to be the dominant one is that not enough glue was used. This may result in the pickup only being partially bonded to the bridge plate. This can be due to insufficient coverage that causes empty spots with no glue, or due to the glue drying prematurely and only partially or insufficiently bonding the pickup to the instrument. One indicator of good glue coverage is to see “oozed out glue” around the entire edge of the transducer.

To fix this problem, you'll have to carefully remove the system and re-install. See: Can I remove superglued Pure pickups and can I re-install them?

If the problem is with the high E string, the issue is a little more complicated. First of all, this is not caused by a weak high string transducer. This phenomenon seems to happen only on guitars with tight X bracing. The brace closest to the high strings seems to inhibit the vibration on the high E string area of the bridgeplate. This seems to affect bridgeplate pickups in general. LR Baggs reports the same problem with their I-Beam.

Acoustically, these guitars sound fine and balanced, the phenomenon affects only the bridgeplate. It may be corrected by adding a fourth transducer beyond the X brace on the high string side. This one would be glued to the soundboard. Soldering is necessary here.

It may also help to relocate the e-b string transducer towards the high string side X brace as far as possible. These remedies may not correct the problem 100 percent.

The “surefire” way to correct this problem is to add an undersaddle pickup by upgrading to a PowerMix Pure System. You would not need to blend in a lot of undersaddle pickup to amplify the E string. Unwanted undersaddle characteristics like quack or harsh tone are not an issue in the final, overall tone of the system.