Guitar Pre-Amp Multi Effects Unit

(5 customer reviews)


Legacy (Discontinued) Product

Ironstone Custom Logo

Guitar Pre-Amp Summary:

“What an amazing gadget. works perfectly, like a guitar supercharger.”
Suitable for use with Ironstone or other pickup system, this guitar pre-amp / multi overdrive effects PCB is designed for on-board guitar installation. Powered by a standard PP3 9V battery (not supplied) giving between 1000-2000 hours of use, this easy to install pre-amp mounts through a 9mm (approx) diameter body or scratchplate hole.
Easy to install with just some basic soldering skill, these little wonders will protect and enhance your guitar’s tone no matter what pickups you use as well as giving you a range of distortion / drive tones at the turn of a knob. For example, on a Stratocaster style guitar, simply replace one of the tone pots with this rotary switch (using your existing knob) and reconfigure the remaining tone control as a ‘master’ tone – circuit diagram included with each item. The photos include a typical pre-amp installation for a Stratocaster style guitar, using different coloured wires to give an easy reference and with the unit in place of the Neck tone pot (the remaining tone pot is configured to control the Neck and Middle).
Each pre-amp unit is supplied with;
One multi-effects PCB and integrated rotary switch
Full installation diagrams for Stratocaster & LP style guitars and annotated photos
A battery connection clip and harness (Note; PP3 9 volt battery not supplied)
A switched Stereo jack socket to allow the unit to be powered only when a (normal) guitar jack / lead is inserted
All in simple, cost saving protective packaging.
Please note: The price above is the UK total price including standard Royal Mail postage. Non UK customers will be advised of an additional small postal charge during the checkout process (see Shop page for current charges). Please also note that since the UK left the EU Customs Union on January 1st 2021, all items posted to the EU will be subject to EU customs checks. As of July 1st 2021, EU VAT rule changes will mean that EU customers may also be subject to VAT payments.

Out of stock


Guitar Pre-Amp FX Unit

Guitar Pre-Amp Sound Clips:

Note; It is suggested when switching from passive to active modes on the guitar pre-amp FX unit, (first to second switch position), to first turn down the guitar volume. This will eliminate any small switch over noise.
So first up, many thanks for a great (extended) video from Jeremy Broun (JB Custom Guitar). A fine woodworker, builder of acoustic instruments, and a keen supporter of mixing acoustic and electronic ‘technology’.

The following sound clips give a sense of the tonal changes stepping through the switch positions. The recordings were made via GarageBand on the ‘Clean Combo’ setting, with tone controls at Bright. No effects are used other than the pre-amp unit. The recording process naturally tends to equalise out some of the gain changes described on the settings above.
Each clip has 4 ‘quarters’ (of 12 bars), moving from Bridge to Middle to neck and back to Bridge Pickups.

And thanks to Robin Thompson for the following YouTube clip, stepping through the pre-amp settings against some well known guitar pieces.


Product dimensions;
PCB size; 30x23mm
Threaded shaft length 10mm
Shaft diameter 9mm
Minimum body cavity depth required 25mm

Guitar Pre-Amp Installation:Ironstone Pre-amp Wiring Diagram Ironstone Pre-amp Wiring Diagram



Maybe you like the idea of active electronics in a Strat’ but don’t fancy the idea of burying a battery under the scratchplate?
Well check out this neat solution from Ironstone customer Gus Hunnybun. Using 2 springs for the trem., a PP3 battery fits perfectly in a normal Strat’ trem. cavity. A bit of velcro or double sided tape to hold it in place, and  some foam for a tight fit under the back plate, this is easy battery change personified! It just needs the battery clip leads to be extended through the normal access hole, or a larger aperture cut as the photo. Worth investing in a robust pair of steel springs rather than the weaker alloy jobs that are often stock, to ensure the whole set-up process keeps integrity.
Strat Battery Housing

Using the Pre-Amp

No matter how great your pickups and guitar are, the effects of electrical loading due to the guitar cable, stomp boxes and amplifiers can be devastating on tone, particularly loss of treble ‘brightness’ (see the ironstone guide to Impedance Matching ). The most effective way of minimising these losses is to use a buffer guitar pre-amp at the point the signal leaves your guitar. Using surface mount technology, that is exactly what the Clean Boost setting is designed for. The difference the Clean Boost setting will make in preserving your guitar’s tone is enough to justify the cost of this device on its own! But there’s more! On top of the bypass and sparkling Clean Boost tones, you also have access to 3 increasing levels of drive / distortion. These range from ‘just breaking up’ blues (i.e single notes are relatively clean, chords and double stops just break) to a full bore Heavy Metal distortion setting with masses of bottom end grunt as well, by way of a solid 70’s classic rock distortion effect. And just like in a good multi-stage amplifier, your guitars volume control effectively becomes the ‘gain’ knob, allowing you even more control of when and how strongly the drive / distortion effects kick in. it really is like having a set of stomp boxes in your guitar!The units built in rotary switch gives 5 modes;

True-bypass; can be used even without a battery connected (or in case of a flat battery) to revert to the normal guitar tone
Clean Boost; A slight gain increase (equivalent to approx 1.5 digits on a Strat volume knob) giving crystal clear tones
Vintage ‘Blues’ style overdrive (equivalent to approx 2 digits on a Strat volume knob)
Classic Rock distortion
Heavy Metal distortion

While the gain steps between each setting are fixed, a small user adjustable pot on the device allows tailoring of the gain of position 2 (relative to the true bypass setting). This is initially factory set, allowing the unit to be used ‘out of the box’, but users can alter the position 2 Clean Boost to be at the same level as the bypass, or with a level of initial boost.

It is suggested when switching from passive to active modes (first to second switch position), to first turn down the guitar volume. This will eliminate any small switch over noise.

5 reviews for Guitar Pre-Amp Multi Effects Unit

  1. Colin Williams (verified owner)

    Absolutly rollickinly brilliant preamp that I have fitted to an Epi Les Paul.
    The overdrives are rich and full and not at all raspy. Really decent pre-amp its really useful. And its really small and quite easy to fit. Thank you Tony, All we need now is one that does delay and chorus!!!

    • Anthony Partridge

      I think that’s called a stomp box Colin!

  2. Tony Partridge

    “A+++ very quick delivery, great bit of kit, very helpful and good communication”
    “What an amazing gadget. works perfectly, like a guitar supercharger.”
    “Great service with offer of customer support, will use this ebayer again”
    “arrived perfectly packaged and looks good! can’t wait to try it!”
    “Quick shipping, item as described. Great.”

  3. ChrisAdmin (verified owner)

    “This is my second purchase of this amazing piece of kit. My first was fitted to a Parker Dragonfly which I modified (a quad rail humbucker fitted at the bridge)… it has taken a very good guitar and transformed it into an awesome instrument. At first I was a little concerned and anxious about drilling an extra hole into such a pristine top but it was definitely worth the stress! The result is stunning.
    I have also installed a similar Artec pre-amp into one of my Strats but, although the Artec is good, your product is streaks ahead… and because it has positive clicks between the overdrive variations… it is much more user-friendly from a player’s point of view. So, as both a luthier and a player, I will be recommending your kit to my future clients and upgrading some of my existing stock with the Ironstone pre-amp.”

  4. ChrisAdmin (verified owner)

    “Just installed the guitar pre amp into a Tokai Les Paul, along with a Gibson and a Seymour Duncan pickup, I have to say the result is just amazing.”

  5. ChrisAdmin (verified owner)

    “I got the pre amp working and it sounds fantastic, really makes the guitar sing you can hear the notes clearer and there seems to be more sustain as the signal is stronger. The various tones are great as well giving a nice gritty blues tone, what a brilliant device. Thanks once again for all of your help with fantastic service, that makes all the difference.”

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