Customer classes

By default every registered customer is assigned to the customer class 'default buyer'; i.e. he/she is treated as a 'private person' or 'end-customer.'
For this customer class the VAT (Value Added Tax) is always applied following German trade law.
Buyers outside EU should take care of 'customs fee' and probable taxes that apply due to 'customs regulation' in their target country as we are in no way responsible for this.

Businessmen in the European Union (EU) can buy without VAT provided that they have supplied their 'Tax excemption number' in the customer profile and accept the 'Reverse-Charge-Method'' for paying tax themselves in their own country. The 'Tax-Usage-Type' is to be set to 'EU Reverse-Charge-Method' for businesses in EU countries.

Businessmen outside the European Union (non-EU) always buy without VAT. It is in your own responsibility to handle tax certainties that are in accordance with tax laws in your target country. 
For all other cases where you cannot get a Tax-Excemption-Number, we need a copy of your 'trade license'  to be send to This email address is being protected from spambots. You need JavaScript enabled to view it. as a proof, that you are running a legal business and you are not a private person.

Note: Businesses in non-EU countries are subject to 'customs handling' of the target country. We are in no way responsible for dealing with your customs authorities.  Provided by us are just the documents that are needed for 'customs handling' for your country. All customs fees & taxes go on you.

We provide special discounts and priviledges for registered Resellers & Partners.

For details and conditions and how to apply for partnership see 'Resellers & Partners' in the menue.

The Helmholtz-Resonator Thing ...

So is a guitar, a violin even a drum or any other musical instrument that fullfills the marks:

• hollow body
• opening to the outside

... regardless of the shape of the instrument and the shape of the so-called 'soundhole'.

The background and basics

The effect of 'Helmholtz resonance' was revealed by Hermann von Helmholtz in the late 1850s.

A indispensable mark of such a Helmholtz resonator is its 'Helmholtz resonator frequency'. This is the frequency where one gets an tremendous over-shot in sound strength at the opening (e.g. a 'soundhole')  compared to the emited strength of sound of the body, if the body is stimulated by a mechanical frequency. (See Wikipedia for "Helmholtz Resonance" and/or "Helmholtz Resonator")

An excellent article about Helmholtz resonance [↑] can be found at the University of New South-Wales (UNSW) in Sydney/Australia and the 'Basics' section [↑] provides essential knowledge about the physics of musical instruments and the human voice as well.

Bringing this into practice ...

Below are two pictures from a 3D-spectrum analyser.

These pictures  show the impact of the Helmholtz-Resonator-Frequency to an instrument if the soundhole is not covered and if the soundhole is covered: i.e. the opening is closed and therefore the Helmholtz-Resonator is 'turned off. Mounted into the instrument was an AnyMic/i from the normal production.

The chosen instrument was a Western-/Steel-string guitar that has a typical Helmholtz-Resonator-Frequency of 55 Hertz. This is half of the frequency of the the base-frequency that is for a steel-string guitar the open A string (A5; 110 Hz). The bad impacts of an uncovered soundhole can be seen clearly ...

UN-covered soundhole Tremendous over-shot @ H.R frequency Drastic cutdown of over-tones fast degrading sustain	Covered soundhole Clear 'spike' from the string pluck Clear built-out of over-tones better sustain

Using an internal microphone in the instrument demands, that the soundhole is covered by a 'soundhole cover'.
Only this turns the Helmholtz-Resonator 'off'' with all the bad impact. Some call that a 'feedback killer' - which is wrong, because Helmholtz-Resonance has nothing to do with 'feedback'.

Specific instruments have typical H.R. frequencies.
I can speak here only for instruments, for which I have investigated it or have tested it with instrument that I have at hand.

The following table shows results from my invstigations and measures:

Payment methods

We provide the following payment methods for you:

• Bank transfer
• PayPal

Bank transfer ... will always work for you - but in international payment it can turn out very expensive and time intensive. Banks charge tremendous fees for international transactions and transactions can take 2...3 weeks to succeed.

PayPal ... You should consider paying with PayPal which is a real good alternative, since it is fast (seconds!), save and easy. By signing-up at PayPal with your regular email address, your email address is the key to access your PayPal account from every WEB browser you can get hands on - even on your smart-phone. When logged-in to your PayPal account you may charge your bank account or any credit card that you have checked-in to your PayPal account.