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You have just become the proud owner of a Dobro and you're wondering whether you should try to amplify it or not; you would like to alter your acoustic guitar to play slide; you still haven't found a good way of using your old lap-steel...
Well here are a few tips to help you follow in the steps of Ben Harper.
How to adapt your guitar (acoustic or electric) to play slide
Whether you're determined on playing your instrument lying on your lap like Ben Harper or standing like Duane Allman, the first thing you need to do is raise your strings in order to avoid the inevitable buzz that the slide will create when the strings are pressed against the instruments neck with the metal slide. All Dobros have their strings set higher than the usual, especially the wood model that is used to play Bluegrass, flat on the lap, with strings set unusually high. The frets are only used here as guide-lines. Thanks to the extra space between the neck and the strings, nothing can interfere with the sustain you get with a steel bar. Therefore you need to find something to raise the bridge, or simply replace it with something more suitable. For electro-acoustic models, beware of the piezzo! The layman will often be wary to play bottleneck on a metal Dobro. Needless to say that if you want to play slide on this new instrument, it's going to be really hard to play bends "a la Hendrix" otherwise, also because the second alteration will be to mount thicker strings (at least some), which is partially compensated by the fact that open tunings will reduce the tension strain. As an indication, you'll often find a 0.13 for a high pitch on an electric and 0.15 on a Dobro. On their electric guitars Derek Trucks use DR Pure Blues strings in a 0.11-0.46 gauge. That might sound heavy, but by comparison, the slide guitarist Sonny Landreth uses 0.13-0.56s! Of course you'll need a high density steel bar or bottleneck to maintain the sustain. These are pretty easy to come accross. The third alteration will be to increase the string separation on the nut, or better yet, change the nut for a metal one, specially made to be fitted on top of the original wood one if you want to play the instrument on your lap. The fourth alteration will be to be careful with the trussrod adjustment because of the extra tension caused by the hightening procedure along with the thickness of the strings. Last but not least, the fifth alteration will be to adjust the mics on an electric model for the high pitches that could otherwise result in a contact between the bass mic and the strings.How to amplify a Dobro
Amplification is necessary, unless you never intend to play outside your living room. Most manufacturers have ready-made instruments with these features already available in their range of electro-acoustic instruments. However, if you need to adjust your own instrument, you will experience exactly the same difficulties with the Dobro as you would with the adjustments on a regular acoustic guitar.Here are 6 options:
- Magnetic mics, such as those on an electric guitar, but set accross the sound hole, the De Armond, Lawrence, Duncan, Dobro or Sunrise type. The kind of mic Django used. The guitar doesn't need to be altered.
- Piezzo under the bridge: following the electro-acoustic principal of the Takamine, but available in separate versions by brands such as L.R. Baggs or Fishman.
- Contact piezzo on the sound board, based on the same technique as above, however the capsule transmitters are stuck to the sound board or on any other vibrating part of the instrument. Easy - Simple. It's the McIntyre, FRAP, Barcus Berry, FWF system. The piezzos need to be carefully mounted and small alterations to the body need to be made.
- Miniature mics (like pin-mics) mounted with tweezers on the edge or inside of the sound hole (Audio-Technica, L.R. Baggs, Fishman, Highlander, FWF).
- A hybrid solution: this is an alternative that most musicians use, by mixing two kinds of mics, generally one piezzo and one mini-mic. L.R. Baggs, Fishman, Highlander offer a kit with a pre-amp-mix equalizer. Both are connected with a stereo jack.
- A perch-mic facing the guitar "jus' like in the ol' days", alright in a studio, but very "daring" in a live situation, because of all the feedback plus all the other sounds you're picking up through the mic from the stage. However many musicians choose this option whenever possible. A plain Shure SM57 will do the job if it's set up properly, and will obviously avoid balance and equalization problems that result from the other options above.
