bozak

Hi All, I thought I might share with you my midibox project. Its a work in progress, I hope it wont always be though. I wanted a decent cross fader for scratching, with a digital vinyl system. I chose the infinium www.infiniumtechnologies.com 45 mm fader as it is cheaper than a lot of other third party scratch faders. I've hooked it up to the core module via the AIN. As it only gives out 3.3v, It doesnt give full range, but I'm only interested in cutting signals in and out, so am not worried about that. So, its either left, centre or right, no fading. The cut in distance is adjustable via a pot. It works great, with no discernable lag. so if anyone wants a scratch fader for their midibox, this is a great option. I'll post some photos or a video if anyone would like to see it in action. cheers bozak

Hi done84, I am in the process of building exactly the same thing you are planning to. I use timecoded vinyl & wanted a midi scratch solution. I have hooked up the infinium crossfader to the midibox core & it works fantastically. The beauty of the infinium is it costs a quarter the price of other specialist third party scratch crossfaders and is non contact so should last forever. (hopefully) The infinium fader is powered 3.3 volts and gives out 0v to 3.3v in analogue mode. This is not enough to get the full range needed for MIOS (0v to 5v) unless the signal is amplified. To amplify the signal you will need a rail to rail op amp which I havn't tried & I'm not sure will even give you the full range. I havn't tried. Or a regular opamp with a higher supply voltage to overcome the voltage loss of the op amp itself. This means you cannot power the fader & associated circuit from the 5v the Midibox core gives you. I have not amplified the faders signal to as I have overcome this problem by programming the core to meet my needs. My fader basically jumps from 0 midi value to 63 then to 127 depending on the fader's position. I have programmed a pot to adjust the cut in point, This may not be suitable for everyone as there is no fading, just instant cut in. But is perfect for me and my scratching. You will still need to buffer the signal from the fader with an op amp. this is very simple. If you need any help I'm more than happy to share my limited knowledge. cheers bozak

Hi, I've been looking for a similar knob for a crossfader. These are 25p, far cheaper than anything you will find in a dj shop. Pennies rather than pounds. http://uk.farnell.com/1440017/mechanical-office-workplace/product.us0?sku=multicomp-cp-l175 cheers

Hi, thanks for the replies. stryd_one: you mentioned in another thread that you should use the SPI mode of these faders, as the voltage of the faders output in analogue mode is only 3.3 volts. I thought it would be easier using digital than adding extra electronics to adjust the voltage. fluke: can I use the digital inputs and outputs from the DIN & DOUT modules to connect to a slave? cheers

Hi, First I'd like to say that this is a great website and Thorsten (and everyone else), thanks for sharing your knowledge & designs. I have read lots & learned a little, but need help to know if what I am planning is possible. I hope I am posting in the relavent section of the forum. I am planning to build a DJ type midi mixer using MIDIbox, mostly for scratching & mixing using a digital vinyl system. For a description of what the hell a digital vinyl system is have a look here. http://www.mixxx.org/wiki/doku.php/vinyl_control The software I use is xwax http://www.xwax.co.uk/ The problem with these systems is (for my setup) is the audio is routed out to a mixer, if i want to record my mix I have to route the audio back into the computer. This could be much more flexible if this mixing can be done in software with a midi mixer. I posted before about which faders would be a good choice for heavy duty scratching and have decided to use Infinium optical faders. I want to use three of these, one for a cross fader, and two for channel faders to control volume changes in software on the computer. I also want to use standard pots, buttons, maybe LEDs for controlling other functions such as EQ & effects. So MIDIbox64 seems a good choice. I have basic electronic skills but cannot design circuits, but have reasonable computer knowledge including programming in perl (and BBC basic). Digital electronics makes more sense to me as it works the same as a computer (obviously). I digress. I have a few questions on how to implement the Infinium faders into my design. They can interface using SPI, which the PIC18F452 can do out of the box, but only has one slave select pin. Am I correct so far? So, I plan to daisy chain three (maybe more later on) faders like so. The data sheet for the PIC18F452 tells me I should use these pins for SPI RC4 and RC5 for SPI data in & data out. RC3 for the clock. RA5 for slave select. But it seems the MIDIbox Core Module uses the RC3 & RA5 pins for other things, so how do I hook up the faders via SPI ? Am I being stupid here? Next questions: Now, assuming i have managed to connect everything as above I need to get coding. The data sheet for the fader tells me the fader sends two bytes to the SPI master. the first is the position of the fader, the second is reserved for for error checking. I assume I can ignore the second byte. So, when daisy chained I send 6 dummy bytes to receive six bytes in return, three of which are discarded, the other three values are processed & sent out as midi data. Is this the right way to do it? I'm also assuming i need to code this in ASM or can I do this in C ? here is a link to the data sheet of the Infinium fader. http://www.infiniumtechnologies.com/downloads/20060804_14/download sorry for the long post. Thanks Rob

Hi sasha, Did you find yourself a decent fader to use? I to am into scratching & want to find something equivilent to a cross fader found on a pro scratch mixer but doesnt cost £90 (pro x fade). I plan to build a mixer/controller & dont want to have to replace the fader once a month. :( cheers bozak Please reply in the crosspost and not in this >1 year old thread. Infinium optical faders

Hi Screaming_Rabbit, I haven't had the chance to use an Infinium fader unfortunately. The main reason I am thinking of using one is for taper wear. On any mixer I have ever used, it is the taper that has worn out, resulting in the sound bleeding through. Sometimes only lasting a matter of a week or two before this happens. I could just use a cheap alps fader like this http://uk.farnell.com/jsp/Passive+Components/Resistors,+Thermistors+&+Potentiometers/ALPS/RS4511110K/displayProduct.jsp?sku=1191727 but am worries in wont last long. can you or anyone shed some light on alps faders lastablility? or maybe recommend a decent fader for scratching? cheers bozak

Hi, I've just discovered midibox & am planning to build a controller for DJing. The infinium faders sound great. I would rather use one of these than a standard fader for wear & tear reasons. I do a lot of scratching & dont want to replace the fader every few months. I was wondering if anyone has integrated one into their controller yet. Any info on how to do so would be much appreciated. cheers bozak