Brendan Power Signature
Brendan Power

TWIN-DIATONIC HARPS - A World of New Possibilities!

This is just an introduction to these exciting new harps. Individual pages with dedicated videos for each type, as well as ordering options, will be up around 20th September.

The idea of combining two 10-hole harps behind a single mouthpiece is not new - but it's not easy to get good reed response, and has never been done convincingly before. That's all changed! After intensive R&D over the past couple of years, I've come up with a quick-change assembly that really works. I'm now releasing my ground-breaking Twin-Diatonic harps in a range of exciting options - check out the two videos to see and hear them all in action.

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The OctaHarp, TremoloHarp, and OctaHarp Selectable give 10-hole players access to rich double-reed sounds in the size and hole spacing they're used to, for the first time! The OctaHarp and TremoloHarp have two harps stacked behind a single mouthpiece unit, and enable you to swap in different keys quickly with a few turns on the retaining screws. The patent pending OctaHarp Selectable is two harps inline an octave apart, which can be moved laterally against each other. They can be played together for a full octave sound, or just the front harp can be selected with a simple thumb movement- allowing typical single-reed playing with bends. A quick thumb movement puts them back into octave mode again.
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TWIN-DIATONIC HARPS Part 1 - Octaharp, TremoloHarp, & OctaHarp Selectable:

TWIN-DIATONIC HARPS Part 2 - MiniChrom, DoubleHarp Selectable, X-Reed UniBender:


My patent pending MiniChrom and DoubleHarp Selectable use the same format to achieve two new and exciting possibilities. A moveable slider mouthpiece switches your breath to each of the harps in turn. If they are tuned a semitonbe apart (eg. C and Db harps), you have the MiniChrom: a real chromatic blues harp, with all the bending and soul you're used to PLUS the chromatic notes built in! This makes playing jazz and other advanced forms of music much easier on the 10-hole harp: just move the slider and you have all those notes that were only attainable with overblows in the past. And possibly, with expert overblow setup and no valves, it could be possible to have the slider notes PLUS overblows on two harps at your disposal - the jury is out on that. But in half-valved setup it works great -as you can hear on the Part 2 video. But it doesn't stop there: the same front unit with slider could be used to house two harps in widely different keys, or even different tunings! Just move the slide and suddenly you're playing a completely different harp, without taking your lips off the instrument. This has a lot of cool possibilities... If this is your main use, you could remove the spring so the slider stays in place at either of the two positions.
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The X-Reed UniBender uses a patent-pending front valve strip to isolate two attached harps according to your breath. Blow, and the air only goes to the top harp; draw, and only the bottom harp sounds. This gives several interesting new harmonica options, with the advantage of no valves on the reedplates (eg. other types of octave and tremolo harps). But the one I show in the video is an all-bending x-reed type. 20 of its reeds make the main notes, and the other 20 are x-reeds which allow them ALL to bend - as much as you want!

An obvious choice is to make 8 of the bends the same as on stock harps (which only has 8 bendable notes), and the rest to go down a semitone. This gives a fully chromatic harp with bends alone, plus lots of cool 'bend enharmonics': notes you can get two ways, bending or non-bending. Another way is to tune the x-reed so the bends go down to the next note of the home scale, whatever that is. It's very expressive - I demonstrate a Solo tuned version in the video.

My Twin-Diatonic harps will play valveless as long as you have close reed gapping and expert embossing, but most definitely benefit from either half or full valving. Most harp players are leery of valves, associating installing/using them with hassle and problems - but it doesn't have to be that way! After much testing, I've developed my own line of Stealth Valves for all brands and sizes of diatonic harmonica. Laminated valves with a soft under-surface for low noise, they lie flat and work reliably - you won't even know they're there! I've come up with an easy way to install them as well, something anyone can do. Video and options here.
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Most commercial and custom 10-hole combs don't have adequate room for fitting valves. To ensure my Stealth Valves fit without hassle, I've developed a range of Diatonic PowerCombs with special valve pockets on the underside of the comb, to take the bases of the valves. My PowerCombs have several other great features too, and can be bought for normal single-harp use. Video and options coming shortly.

Using my combs and valves with the TwinDiatonics will ensure they work to their best. Good reed gapping and slot embossing will always help too, though valving makes these aspects less important than they are on un-valved harps.

This is just an introduction to these exciting new harps. Individual pages with dedicated videos for each type, as well as ordering options, will be up around 20th September.


I've created two types of small 10-hole octave harmonica: the OctaHarp and the OctaHarp Selectable. Both of them combine two diatonic harps an octave apart to make one compact instrument with the big double-reed octave sound. It's a very satisfying tonality that suits many kinds of music - Cajun and Irish would be two that spring to mind, but octave playing can suit any style you can think of! My OctaHarp stacks two 10-hole harps one above the other behind a single mouthpiece, one harp in the standard range and the other in the same key one octave lower, allowing you to play both simultaneously. At this stage three manufacturers make low-range harps, Hohner, Suzuki and Seydel, and I've designed a version of the OctaHarp to fit each brand.
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Because there are double the number of reeds in the airstream at all times, to avoid excessive air loss and get the best sound, full valving is pretty much essential for the OctaHarp. Without valves the instrument will work but sound quite airy; with valves it will sound crisp and loud. In order to facilitate adding valves to various brands and sizes of diatonic harps, I've created my valve friendly PowerCombs and easy-fit Stealth-Valves . These have special 'valve pockets' at the rear of each chamber, so the valve bases don't get snagged between the comb and reedplates.

While you can just buy the front unit to assemble your own OctaHarp using stock combs, trying to fit single valves to combs not designed for them can be tricky and frustrating. Adding my specially-designed PowerCombs and Stealth-Valves to your order will simplify and speed up the process of making an OctaHarp that sounds great straight away. They are available at half-price when ordered for the TwinDiatonic harps. Watch the videos to see how the valving is done, and all the parts fit together:


All TwinDiatonics are made to order. That allows you to choose from a big range of keys, colours, brands, tunings and other special features. Once we get your order we make the bespoke parts in our workshop and order the harmonicas you've chosen. We then either post to you (DIY option below) or to the Recommended Customser you've selected. Here's how the two options work:

  1. An easy and guaranteed option is to choose to get your TwinDiatonic assembled and customised by a specially chosen Recommended Customiser. I've teamed up with three world-class diatonic harmonica techs to do the work for you, each with a high reputation for the fine quality of their work and excellence of their customer service. They offer a range of customisation options for all my TwinDiatonic harmonicas, and will make sure your OctaHarp sounds super responsive and beautifully in tune as soon as you put it to your lips. Each one specialises in a particular harmonica brand; check out the resumes and special services of my TwinDiatonic Recommended Customisers here. If you choose one of my Recommended Customiser to make your OctaHarp, PowerCombs and Stealth-Valves must be selected (as that’s what the guys are expecting to receive to do their work easily). Choose the service option you want from the Recommended Customiser according to their description on the RC page, and all the rest will be taken care of for you! After your Recommended Customiser receives my parts and the two harmonicas for your order, he'll work his magic and post the finished OctaHarp out to you with tracked international shipping (included in the price). For your extra security and peace of mind, the finished instrument will be covered by the warranty his good reputation is built on. I'll be working closely with my Recommended Customisers to maintain high standards and introduce occasional refinements according to their suggestions. Shipping time to you will be longer as the RC needs to receive the parts from us, make the assembled OctaHarp and ship to you.

  2. DIY: The second option is that you order the parts you want and fit everything together yourself. If you are experienced with working on harmonicas, this is the cheapest and fastest option. The one essential part you require is the Front Unit, but we recommend you also purchase PowerCombs and Stealth-Valves (at half-price on this page!). They are specially designed to suit the TwinDiatonic harps; some stock combs might not fit perfectly, and they will definitely cause more hassle to install valves. You can also order the correct brand-new harps for your OctaHarp here, or you can supply your own. If ordered from us, the harps will be sent unopened in their boxes along with our bespoke parts for you to fit together to make your OctaHarp. (In the case of Hohner and Suzuki they will be complete harmonicas; with Seydel you will receive all essential parts necessary for your OctaHarp minus combs and valves; you'll need to include PowerCombs and Stealth-Valves to complete the order.)

    With the DIY option, our responsibility is only with the parts we make, not with the harmonicas or your fitting skills - they are entirely your responsibility
    . Another way to go is to buy my parts (plus the new harps if you wish) and send them to a harp tech of your choice to do the fitting/assembly of your OctaHarp. In that case the deal is totally between you and the person you choose. Here is a list of people who might be available to do the work: Other Harp Techs.

OctaHarp Buying Options

OPTION 1 - Expert Build

read about the customisers and their service levels here
HARMONICA MAKE (£90-£110):




CUSTOMISER (£100 - £299):

OPTION 2 - Parts Only (DIY)




HARMONICA MAKE (£90-£110):


All Orders Sent with International Tracked Postage INCLUDED in the price.


Coming soon...


Coming soon...

The MiniChrom and SelectaHarp

Coming soon...

X-Reed UniBender

Coming soon...

TWIN-DIATONIC HARPS - Recommended Customisers

I own harmonicas customised by Boris, Joel and Sergey and can personally vouch for the high quality of their work. In addition to superb tech skills they are all good straightforward guys with reputations for great customer service. They stand by their work, and you have the security of their standard warrenties for your TwinDiatonic (see their websites for details).

Boris Plotnikov Russia customiser  Seydel

Boris Plotnikov

Boris is a professional harmonica player, teacher and customizer from Moscow, Russia affiliated with Seydel. Boris regularly performs as bandleader and as sideman with famous Russian bands. In 2013 Boris got two prizes in World Harmonica Festival-2013 and earlier that year he also won at the international jazz-contest "Master-jam fest" in Odessa (Ukraine). As soon as Boris start to play he start to tweak harmonicas and now he is an amazing harmonica customizer - he works using a microscope to make his harmonicas much more airtight, allowing to play all overblows and overdraws fluently and without any squealing, and to make them to play with a more prominent articulation.

Customisation/Assembly Prices

Stage one: GBP £135

Basic custom. Light embossing, arking/gapping, correcting tuning by octaves, polishing draw reedplates, adding valves if necessary. Two weeks to produce after I get parts.

Stage two: GBP £215

Medium custom. Tighter embossing, arking/gapping, correcting tuning by octaves, polishing draw reedplates, adding valves if necessary.  Two weeks to produce after I get parts.

Stage three: GBP £285

Full custom. Full microscope embossing arking/gapping, correcting tuning by octaves, polishing draw reedplates, adding valves if necessary, overblow stabilisation if necessary. Month to produce after I get parts.

All TwinDiatonics sent with tracked international shipping (included in the overall price).

Joel Andersson Sweden customiser  Hohner

Joel Andersson

Joel is a Hohner Affiliated Customizer and has the attention of the world's premier harmonica players, inventors, and innovators. He has built a reputation as a quality customizer from his clients around the world. By their testimony, J.A. Custom Harmonicas, based on Hohner reed and cover plates, increase a player's authority over the instrument, regardless of playing style or experience. All customization is completed by Joel, and his workshop features both hand and electric tools, including CNC milling machines, CNC lasers, and lathes.  Joel spends most of his time building and developing custom harmonicas and accessories, but he is regarded as one of the finest Irish music harmonicists in the world. In 2014 he came in third place at the biggest Irish music competition in the world, Fleadh Cheoil na hEiréann.

Customisation/Assembly Prices

Level 1: Basic GBP £160

Precision gapping- Reed curvature set up using unique techniques - Flat comb and draw reed plate (lapped on a lapping disk in 2 different stages) - Well tuned

Level 2: Advanced GBP £205

Expert embossing - Ultimate reed curvature - Flat comb and draw reed plate (lapped on a lapping disk in 4 different stages) - Great tuned

Level 3: Master GBP £299

Expert embossing - Re-profiled reeds for a smooth and dynamic playability throughout the whole harmonica - Ultimate reed curvature - Flat comb and draw reed plate (lapped on a lapping disk in 6 different stages) - Tuned to perfection

All TwinDiatonics sent with tracked international shipping (included in the overall price).

Sergey Zernosek Latvia customiser  Easttop/Suzuki

Sergej Zernosek I only offer only one level of customization: THE HIGHEST LEVEL. This includes all the following services using my own methods and techniques: reed arcing, embossing, gapping, fine tuning, four ways to increase the fatigue strength of reeds, waxing, comb grinding, and other works. This is my standard process which is already proven, with many satisfied customers around the world; since 2011 over 500 handmade harmonica posted to more than 27 countries. My harmonicas are louder than others, and require less effort to play. For your safety the harmonica is disinfected.

The Easttop version comes with the lowest cost of the harmonicas but has excellent playability and durability, because of the good basic quality of their parts. It allows me to do high-level custom harmonicas at a low price. The Suzuki version has a higher basic cost of the parts, but comes with the Suzuki reputation for quality manufacture and great reed life. I take quality very seriously. My custom Easttop and Suzuki TwinDiatonic models may be returned unconditionally within 2 weeks of receipt if you are not satisfied. All reeds are warranted against failure for five years. Reed plates have engraving date customization.

WARNING: My custom harmonicas are works of precision. Unqualified adjustments or attempted modifications may destroy the tuning or the entire instrument.

Customisation/Assembly Price

GBP £100

The full cost of the work (the maximum amount of customization).

All TwinDiatonics sent with tracked international shipping (included in the overall price).

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