What happened to the old website? ?

In April 2015, I let my ownership of the domain name expire, changed the domain for H-Pi Instruments to and made a completely new website for the business. You may notice that hpi is a subdomain of the parent domain At you will find links to all my online endeavors. As the name suggests, this is my way of collecting the various strands of my work together in one place, to organize them under a common parent domain. This is an easier and more flexible way for me to work.


What is this transaction fee added at checkout all about?

Since its opening in 2007, H-Pi Instruments has accepted payments primarily through PayPal. PayPal charges fees for every transaction. They also charge fees for currency exchange. They charge additional so-called "cross-border" fees for international transactions. As a one-person business operating in Germany as "Einzelunternehmen" (similar to "Sole Proprietor" in the US) I pass these fees on to you. These fees fluctuate slightly from time to time, and I update them to try to maintain a fair rate for everyone. The fees are not the same for everyone. The final amount depends on your location, whether your country is a member of the EU, and whether your country uses the Euro or not. The fee will be listed on on the PayPal invoice as a tax, but it is not a tax. The reason for this is that PayPal provides no way to charge their transfer fee to the buyer, and there is no other way to add a fee to a PayPal transaction, other than to call it a "tax". So I repeat, it is not a tax, but rather a fee, which pays for the money PayPal takes away from the amount you are sending. The fee may seem like a lot, but in all cases it is much lower than VAT.

Can I pay you by Bank Transfer?

Yes, but only for large orders. For small orders, PayPal's fees are high but bearable considering the added value provided (see below). For large orders, PayPal's fees become unreasonably large, and bank transfers make more sense. But before requesting to pay by bank transfer, please be sure that you understand the following.

For many reasons, including speed, accuracy, security, liability, and ease of use, the Point-Of-Sale system used for this website expects payments to arrive only in the form of PayPal notifications. When a notice of payment is received from PayPal, an automatic process is set into motion, including transaction creation, software license creation, stock updating and customer email deployment. This means that when you pay, you get the results of your purchase almost immediately, and all the necessary information is correctly created and put in its proper place, without having to handle the transaction manually.

H-Pi Instruments is a one-person business. Considering the above information, it must be understood that asking to pay by bank transfer instead of using PayPal is the same as asking me to personally do a lot of extra work for you. For example, a pro-forma invoice must be made, address and telephone contact verified, transfer made and verified, required licences created and stored in the database, license emails written and sent, stock and transaction data in the database — all manually. Therefore, I add a handling fee to any payment which is made by bank transfer.

From 2007 to 2016, H-Pi Instruments operated out of the US. Since October 2016, business is done from Germany. Sending a bank transfer within Germany is usually free, but not always. Sending within the EU may be free, but often it is not. Paying in any currency other than Euros requires currency conversion fees. It is the responsibility of the sender (you) to pay all fees associated with the transfer, and to make certain that the correct amount arrives in Euros.

At some point in the future I may update the user account and checkout system to simplify the process of paying by bank transfer, but for now it must all be done manually. If you understand all of this and accept the terms, then the process of paying by bank transfer can be started by sending an email containing the following information:

  1. Name
  2. Address
  3. Telephone
  4. List of items to be purchased
  5. Bank Name from which the payment will be sent


I can't register my software and it doesn't work anymore. Can you help?

Sorry for the inconvenience. Please first read What happened to the old website? above. When the website domain changed, I also developed a completely new software registration system to improve security and to automate the process of issuing licenses. (Previously I had issued all software licenses manually which is extremely tedious.) The old software tries to connect to the old website which now doesn't exist; this is why you can't authorize or deauthorize your old software. Everyone who owns an old manually issued software license needs to open an account at the new website and update that old license. I sent out an email to everyone on the H-Pi Instruments customer list explaining everything back in April 2015, but apparently a lot (maybe most) of those emails went straight to the spam box.

Here is all you need to do:

  1. Create an account. Just follow the instructions. Here is some info about what an accounts is and why it is a good thing.
  2. Go to account > my licenses. There you will see how to update your license(s).

I bought your software at the Mac App Store. Can you change it over to a license I can see in my account here?

Sorry, but no. When you buy a license through the Mac App Store, everything is handled by Apple and I have no record of your purchase. For your licenses to appear in your account here, you need to buy the license here.

After I buy a software license, how many times can I install it?

At least twice. Some licenses allow 3 or more installs.

I want to use the software on both a Mac and a Windows PC. Do I have to buy two licenses?

No, not if you buy the license from this website. If you bought a license from the Mac App Store, then you would have to buy a separate license here for Windows.

Tonal Plexus

For more information, see the Tonal Plexus webpage.

When will you start making the Tonal Plexus again?

I don't know. Please be patient.

I know you stopped making them, but could you make one for me please?

No, I'm sorry but you'll have to wait.

How much does the Tonal Plexus cost?

Formerly I sold the keyboards for between $600 and $3000 USD. I do not know how much the keyboards will cost in the future.

Does the Tonal Plexus have the same span as a piano?

Previously I made the keyboards with between 2 and 6 octaves.


Can I use TBX2 to retune all my synths at once?

TBX2 is expected to be connected to one input controller and one output synth (possibly the same device with LOCAL CONTROL OFF). It is not intended to connect to more than one output destination. We may update the firmware to support limited multi-destination operation, but this is not supported in the initial release.

Can TBX2 retune my [insert name of your synthesizer here]?

A list of compatible synthesizers used to be maintained for TBX1, but in many cases it caused confusion for users. For TBX2, please first check the compatibility page before buying.


Where do I install .sf2 soundfont files?

On Mac OSX, the directory is: ~Library/Audio/Sounds/Banks

On Windows, there appears to be no standard directory, so you may put them wherever you like.

DAW / VST / AU / RTAS / Softsynth

Can I use your software to retune synths in my DAW?

Yes, but unless you have a plug-in synth in the DAW which already supports microtuning or MPE*, in most cases it is not exactly easy to do this, and there is really no way to make it easier.

*MPE is a new part of the MIDI specification which standardises the algorithm used by H-Pi products for over a decade.

If the synth in your DAW can load a standard tuning file like .scl or .tun, then all you have to do is export the tuning file from CSE and load it into the synth.

If the synth in your DAW supports MPE, then the synth should be easily retuned by any H-Pi product. You can skip the next two paragraphs and start reading below at the number 1.

You might expect there to be a microtonal plug-in which would allow you to retune all your non-natively-microtonal synths, the way TBX1 or TBX2 can retune so many hardware synths. The problem with that idea is that it expects plug-in softsynths to behave like hardware synths, which in almost all cases they do not.

If a non-microtonal softsynth supports pitch bend with the pitch bend range set to +/- 1 semitone, then it CAN be microtuned using either CSE or microsynth; however, the number of microtuned voices possible with the softsynth corresponds to the number of MIDI channels it supports. Most softsynths support only 1 MIDI channel, which means one instance of the synth will give you a MONOphonic microtuned result. Be careful with an input channel setting of ALL or OMNI for a softsynth, because this does NOT necessarily mean it is responding to 16 channels individually, but rather it can mean that it is simply ignoring the channel information, which will NOT result in correct tuning.

Some softsynths, like Apple's DLSMusicDevice or the Cubase default synthesizer, are General MIDI (GM) compatible, which means they do properly support 16 MIDI channels. These GM synths will give you up to 15 voices microtonal POLYphonic output. The reason this number is 15 and not 16 is that GM synths reserve channel 10 for percussion. An input setting of ALL or OMNI is correct for any GM synth. If the synth is not GM, receiving only on 1 channel to give only MONOphonic microtonal output, it is still possible to acheive polyphony, by setting up multiple instances of the sofsynth and routing MIDI input channels accordingly. The following three-step plan should help you get things working.

1. To use H-Pi software with a DAW, first you have to understand how to route MIDI IN and OUT of each software, because none of H-Pi Instruments software is a plug-in; they are (so far) all stand-alone applications. On Mac, H-Pi software provides virtual MIDI input and output ports for this purpose, but it is recommended to use Apple's IAC Bus ports instead, which are created using Apple's Audio-MIDI Setup utility, because these are more reliable. On Windows, you must install a third-party driver for virtual MIDI ports, such as LoopBe1 or MIDIYoke. These are free.

2. You must understand how to work with MIDI output channels according to the capabilities of your destination synth(s). Each MIDI port supplies 16 channels. Each of these channels will carry data to produce 1 microtuned note. If your receiving synth is GM, then you can route all channels to it for up to 15-voice POLYphonic output. If the synth responds only on 1 channel, it will be MONOphonic.

3. You must have a clear understanding of the MIDI signal path from beginning to end, and make sure you do not create an infinite loop, also known as a MIDI Feedback Loop, which happens when your input source and your output destination are the same. Data goes out, then comes back in, and repeats ad infinitum so that your software will immediately crash. A correct MIDI path is as follows:


You must make certain that the output from (A) reaches the input of (B), and the output of (B) reaches the input of (C) handling the incoming MIDI channels properly at (C). You must also make sure that the output of (A) does NOT go directly to the input of (C). This can be a problem if (C) is set to listen on all incoming MIDI ports and channels. In every case, (B) will be the H-Pi software. (A) and (C) vary depending on how you are using your DAW and what you are trying to do. For example, you may want to record MIDI live from your keyboard controller into your DAW. In this case, (A) is your keyboard, and (C) is your softsynth(s). To make that work, uniquely connect your keyboard's MIDI output to the MIDI input of the H-Pi app, and then send output from the app to your DAW's MIDI input, with your softsynth's channels matching the channels you have selected in the H-Pi app.

Problems getting this to work normally fall into these categories:

  1. Port Errors: MIDI ports are incorrectly connected between (A) (B) and (C)
  2. Channel Errors: MIDI channels are incorrectly sent to (A) managed at (B), or routed at (C)
  3. Tuning Table Errors: you have not prepared the tuning properly at (B)
  4. Synth Errors: the destination synth(s) at (C) do not support pitch bend, or the bend range is not +/- 1 semitone
  5. App Conflicts: sometimes running audio apps simultaneously results in strange behavior or crashing, and the only solution is to not run certain applications simultaneously.

These kinds of difficulties are generally non-issues when working with MIDI hardware, because MIDI hardware tends to adhere better to MIDI standards, inputs and outputs are physical so routing is easier to see and manage, and crashing is not an issue. So some of the problems in the above model can be minimised by using hardware instead of software. For example, using a hardware keyboard for (A) and a TBX2 for (B), you may still use your DAW for (C) and possibly your workflow will be easier to manage.