EMP modernization

Modernization of EMR

Hello everyone! So the time has come to tell and show everyone how I continue to modernize the keyboard electronic musical instrument – EMP. In the first publication on this topic, I mentioned my childhood dream and I think that dreams should come true not only among the employees of GAZPROM, but also among myself and my home-made guys. Modernization of EMP
I really hope so. Well, okay, I'm all about sad things, it's time to get involved in the topic. With great diligence and patience, I made and installed in the EMP case, all twelve basic note blocks, from “C” to “C”. In the process of installation and adjustment, I always have an idea. EMP modernization This time too, I intuitively felt that it would be very cool. EMP modernization
Remembering the sound of a 12-string guitar, and it is very different from the usual 6-string. And then I thought, why shouldn't I do something extravagant in sounding with my keyboard instrument. And as always, the man said – the man did, Modernization of EMP quickly developed and produced an addition to the main blocks.
Modernization of EMP
What is the purpose of this board? EMP modernization It, in addition to the main frequencies of the main block notes, creates its own, independent note frequencies for each octave, with a detuning frequency of 1%. For example, the “C” note in the main block has a tuning frequency of 3951.04 Hertz. And the additional board is configurable to 3951.04 * 0.99 = 3911.5 Hertz. By “mixing” these two frequencies together, we get a kind of surround sound with a change in out-of-sync phases  Modernization of EMP Now look at the schematic sketch.
 Modernization of EMP
In the process of checking the sound of the EMP, through an external amplifier, an unpleasant crack was heard in the speakers at the moment the keys were pressed. This is a bounce of keyboard contacts. It is especially noticeable for a sinusoidal signal. To remove this crackling, I used a common optocoupler – OEP-13 in the control circuit for supplying a sound signal. Soviet detail from the past. By the way, like that mica capacitor on the board of 1966, just from the days of my pioneer youth. EMP modernization In general, to remove the crackling due to bounce of contacts, I had to unsolder 10 more breadboards, like this.
 Modernization of EMP
With a selection of optocouplers, I also had to “tinker”. These parts have a very large scatter of parameters and the rejection rate was as much as 40%. I ordered them through CHIP and DIP for 11 rubles. But this is not a problem, the goal has been achieved and small financial expenses are nonsense. As I have already informed the readers that in the process of installing and adjusting the EMP circuits, new ideas are ripening for me on the topic being implemented. And so it happened again. I thought, why not use the sound of two consonant notes in the chord, for playing solo parts, pressing only one key. For example, click like this Modernization of EMP
 EMP modernization And it sounds like two keys are pressed. Like this
Modernization of EMP I had to play with each a suitable pair of notes. This, in my opinion, worked, but I had to buy another 60 optocouplers. And at this stage, this is what happened.
Modernization of EMP Now, for sure, each interested reader would like to listen to the sound of all that I have thought of here. I play my simple composed melody for you, but I'm not a keyboard player Modernization of EMP The question/topic is automatically published in the social. site network – follow the answers there too:


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