www.eo-guitars.com A new dimension in guitars is unfolding.....


1. How does it work? - please see the "video" page..


2.How is it playing a thin guitar?

Experience so far is that people adapt to the instrument easier than you would think and players move from the Eo folding guitar to a full size seemingly without much trouble. After all, there has existed a wide and eclectic range of guitar - type instruments for many years - electric solid body, electric semi acoustic, folk narrow neck, ukelele, mandolin etc - and people move from one to another in gigs seamlessly. The Eo is very light and handles easily.

The detachable side pieces are raked back at ~7 degrees to help represent a deeper volume and allow bracing of the body between leg and right arm. The guitar is approx. 75 mm deep overall - string plane to the rim of "lower bout" side piece.. This is a side view:

In terms of the ergonomics for playing classical guitar, it would seem that the key positioning points of leg, body and right arm and then the fine positioning points of left and right hands all adapt fairly readily. The human sensory boundaries are adaptable!

Some players have reported using a cushion to bulk out the instrument but in the main, most players simply use the instrument instinctively without further accessories. The integrated knee prop on the wooden wing shapes helps to raise the instrument into a normal elevation and of course a foot stool can be also used, although carrying this around on travels may be seen as a bit of a disadvantage.

Of course with no body certain styles of guitar sounds will be a bit hard - percussive, tambour etc.

In the end it is always best to try an instrument before you buy, and make sure it is for you.

3. Do the strings get damaged?

The nylon strings do not appear to suffer from the fold - up which results in bending around the string keeper at 20mm diameter. The local pressure on the string is less than say at the nut or saddle or fret for that matter. Pure nylon (top three) and the overwound (lower three) strings are very durable.
It is feasible that some necking occurs when the string is pulled around the keeper which could in theory affect the harmonic operation because of mass/length changes in that local zone; but none is detectable in normal use. The main failure points of strings remains - as in a normal guitar - at the nut or saddle or in the playing zone.


4. Can metal strings be used?

I do not offer this as a standard product yet but in principle, lightweight, low tension metal strings can be used - contact me using the email link if you are interested in this option perhaps for your own build. The action height, fretting and neck relief set up require a specific set up using metal truss rods to achieve the norms for steel playability and the nut and saddle require positive fixing in place. (The neck width in the standard classical is 52 mm).
Because of the characteristics of metal strings, no string keeper is required to maintain tension when folded, which is a simplification and the strings can simply be left loose - a simple strap to keep the strings tidy is desirable.

If you are interested in this - please follow up through the email address.


5. Can a flamenco set up be achieved?

Yes a Flamenco set up - to achieve a reduced 3mm maximum action height (XII fret, E2 string) - is possible, although this is not a standard off shelf model. The neck dressing must be done carefully to get a buzz free progression along the frets. In a flamenco set up, more string rattle is accepted.

Specify if you want a flamenco set up before an order is placed.


6. What maintenance is needed on the joint?

After time, the joint may need a little lubrication using a solid grease or even candle wax. Oil can be used - but sparingly.

* Do not use too much oil as this can leach into the wood and cause staining.

A cotton bud dipped in the grease or oil and wiped over the curved segments of the joint is a way to apply a bit of lubrication.

Ultimately if the joint becomes damaged or otherwise can't be fixed with it assembled then the central block can be dismantled** by de-stringing the whole guitar and then removing the 5mm hex socket bolt with an allen key / wrench. This then allows inspection, cleaning/ lubing and replacement of parts if required.

** Not for those uncomfortable with tools!. Damage can be done to self and guitar in the process.


7. How do I adjust the tension in the tie- piece?

The "Protex" over centre lever clamp can be adjusted by screwing in, and out, its hook. Each full turn of the hook will change the length by about 0.7mm. Adjust the hook by rotating by half turn steps and checking the tension in the tie piece - the latch should close using finger force only and should not be overtightened.
Placing a 2-3mm diameter screw driver shaft into the hook is one way to get the clamp to rotate.

*Take care not to scratch the guitar body parts with tools- you may want to protect the body with cardboard.
*Take care not to pinch fingers when doing this work.


8. How do I adjust the action height?

See also - above. In a conventional set up the normal twelfth fret action is 3.5 - 3.8 mm for the bottom string (E2) and 3.1 - 3.4 for the top (E4) string; for a flamenco set up the figures are 2.8 - 3.2 and 2.4 - 2.8 mm.
Action height is mostly expressed as the distance between the bottom E (E2) string and the top of the XIIth fret and the top E (E4) string and the top of the XIIth fret. Of course all the other fret / string distances are important, but are assumed to become a dependent set of dimensions, once the E2 and E4 strings are set, assuming a straight saddle.
In the Eo guitar, the action height is influenced by the alignment of the joint as well as the usual guitar alignment elements of the neck, frets, saddle and nut height.

If the action height appears to have increased from the normal value range above, check first that the faces of the joint are being pulled up for face - face contact, by the lever clamp. The joint has to be tightly pulled together by the clamp so its faces are touching.

This can be checked by looking side on to the joint with a bright light the other side to view any gap; another way is to place the guitar strings down with the nut end on Left knee and the saddle on the right knee; push down gently and see if the joint visibly closes.

See above item too - the lever clamp can be adjusted to reduce its closed length and hence the pulling together of the joint; put the string keeper on the neck, undo the lever clamp and rotate the hook / tang - half a turn should achieve the necessary shortening and pull up any slack in the joint.

*Take care not to pinch fingers when doing this work. Not for those uncomfortable with tools!. Damage can be done to self and guitar in the process*DO NOT OVER TIGHTEN THE TIE - CABLE BY OVER SHORTENING THE LEVER CLAMP HOOK.
*Take care not to scratch the guitar body parts with tools- you may want to protect the body with cardboard.

Once satisfied that the joint is face-face tightened, if the action height requires adjustment then this is done in the conventional way by trimming the saddle height. Roughly speaking the action height change at the XII fret is half the change in height at the saddle.. To do this:

Slacken tension on all strings to the point where the bone saddle can be vertically lifted out of the woodwork slot. Some times the saddle will require a little working to free it, and careful gripping with small pliers and levering from one end will be needed.

* be careful not to chip the edges / fracture the bone saddle.
* be careful not to damage the guitar wood work - protect it with taped on cardboard from sharp tools like screwdrivers.
* Try to pull the saddle vertically and not do draw it along the bottom of the slot to get it free; the piezo pick up is set into the bottom of the slot and relies on a really close contact with the underside of the saddle - if you draw the saddle along the top of the piezo, it is possible to distort the piezo top surface - this will result in poor string pick up.


9. What does the electronics do?

In versions of Eo guitars with the built in electronics and volume control, this provides dual purpose amplification so that you can listen on headphones, or play Eo through a power amplifier (PA).
Eo uses a coventional piezo bi-morph array pick up in the saddle which connects to a two stage amplifier, stage one is an FET high impedance buffer and stage 2 is a driver / amplifier chip. The input impedance to the buffer is very high to preserve the low frequencies and has a large dynamic range, as the piezo can produce high voltage swings. The output impedance is a compromise 100 ohms to drive headphones and a line- in PA.

The saddle is carefully set so that it has uniform contact with the piezo to preserve a balance sound level across the strings. If the saddle is removed, take care to keep that uniformity of contact.

Some versions of Eo guitars are fitted with a push button switch and LED - to switch on the electronics.
Some have no push button and are switched on in the conventional way by plugging in a mono jack plug.
Some Eo instruments have a 3.5 mm socket and provide a 3.5 - quarter inch jack adaptor (for line connection to a PA).
Some Eo instruments have a quarter inch socket and provide a quarter inch- 3.5mm jack adaptor (for connection to headphones).

An early decision was to keep to a simple, lightweight travel friendly electronics package and keep to a minimum of connectors. Here is a picture of the electronics area / battery with the cover removed:

The electronics are conformally coated with laquer to help tolerate condensation / moisture.

A 9 volt alkaline PP3 or MN1604 battery is used being the simplest way to provide a drive voltage which tolerates the quite high piezo swing. A rechargeable 9 v can be used, but the supply voltage is generally lower and may distort the sound.
With a good quality MN1604 battery more than 50 hours of life can be expected.

* preferably use manganese - alkaline batteries for longest life, or carbon for lowest cost (not recommended).
* do not play headphones at high level which can damage hearing
* do not use Lithium - Ion batteries.
* make sure the battery is connected correctly.
* do not pull excessively on the battery wires when changing the battery.


10. Where is the Eo Guitar made?

The final assembly and suppliers of all the special custom components are in Hertfordshire, UK. Off-shelf commodity components are used elsewhere on the instrument.


11. Can the joint be used on a standard acoustic-bodied classical ?

Yes it can, with a revised clamping arrangement - although this is not an instrument I can currently supply as a standard. Make contact through the email address for this option.

Here is an example set into a spruce top classical:


12. I want to build my own folding guitar - is the joint available as a component?

Yes, contact us using the email address. I can supply the joint, 2d drawings to other makers. The skills and resources to achieve this are the usual luthiery and also suitable precision routing and deep drilling equipment.

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