toneburst

Quick question: testing the simple i2s Synth project in trunk/apps/tutorials/024_i2s_synth with my newly-soldered DAC board. Is velocity supposed to be mapped to OSC frequency? I seem to get a different frequency with the same note at different velocities (plus massive amounts of aliasing distortion, too), but if I press each key realllly softly (giving a velocity of 1, I guess), it sounds as expected- ie a clear basic sawtooth wave, tracking the keyboard. Is this expected? Can't see anything in the code comments to suggest this is how it's supposed to work. If not, could it be a hardware error somewhere on my DAC board? a|x

Thanks very much TK, that's excellent! Sorry about your upgrade hassles. a|x

Hi Thorsten. Hope you had a good weekend. Did you have a chance to do a quick diagram for this? Cheers, a|x

Perfect for diagram-drawing then ;) Thanks Thorsten. a|x

My TDA1543 chips arrived the other day, so was wondering if you'd had a chance to draw up that circuit-diagram/layout for the I2C board, TK. No huge hurry- I have plenty of other things to keep me occupied at the moment. Just thought I'd mention it. Cheers, a|x

Thanks TK, that's great! I'm still waiting for the components now, anyway, so there's no massive hurry. Cheers, a|x

Hi, just bought a couple of TDA1543 DAC chip from eBay. Can anyone give me any tips on utilising these chips to give stereo audio output from a LPC17-based Core board? I notice TK has used one for his MIDIBox Speech Synth project, and there is mention of I2S audio output in some of the MIOS32 tutorial applications, but I haven't been able to find any newbie-friendly documentation on getting them to work. I'm sure the circuitry required is probably very simple, but I'd love to see a circuit diagram or matrix/vero board layout for a basic I2S audio output board. Cheers, a|x

Thanks ilmenator. I did a search for forum 'standard control surface', and it didn't come back with anything... Odd. Anyway, cheers! a|x

Also, do you have diagrams for the control-surface above :) I'm sure I've seen discussion of a 'standard control-surface' here, but I can't seem to find it now... a|x

Hi Thorsten, do you happen to have a circuit-diagram or vero/matrixboard layout diagram for the I2S board? Just bought a couple of TDA1543s on eBay. Interested to know if your I2S board uses this DAC chip. a|x

Thanks for the info Wilba. I've installed the jumper, and my LCD is now nice and bright. Cheers, a|x

It's a shame (though as you say, predictable) they're not proving as popular. The OPL chip certainly doesn't have the analogue warmth of the SID, but you can get some amazing sounds out of it. Any plans for other Sammich projects, Wilba? How about a a SammichSEQ, or maybe even a SammichSJ (SpaeakJet)? a|x

Thanks TK. Are higher-res or vector versions of the files available? a|x

Can anyone point me in the direction of the MIDIBOX.org logo graphic (as used on the uCapps.de front page)? I'm planning to use it on a front-panel for my LPC17-based MIDIboxSpeakJet project. a|x

I see. Guess it's not going to happen, then. Thanks for getting back to me, anyway, TK. a|x

Thanks m00dawg. It does look nice in the photo. Up close, it's not so great though. It's a bit uneven, and the paint isn't thick enough to smooth over the bumps at the bottom of the engraving, so it looks quite messy, unfortunately. I used acrylic paint, rather than an oil-based gloss enamel, as recommended, which in retrospect maybe wasn't the best choice. Having said that, I'm generally pleased with it overall. The sound is good, too, once you get over how terrible the presets are, and start creating your own sounds. The patching randomising functions are both inspiring and addictive, I've been finding! Incidentally, I had no problem at all finding a power-supply that worked. I've tried two different cheapo 9v DC wall-warts, and both have worked fine. I'll probable settle on the £7 one I got from Farnell, as I bought a matching set of 4, to power this box, and my 3x Shruthi-1 synths. a|x

That formant patch is cool! I don't know if this is the correct place for feature-requests for the next MB_FM application version, but.. How about an extra Velocity parameter for each operator? This would allow for more dynamic velocity-response, and the Velocity assignment at the Instrument level could be used for something else. a|x

All done! a|x

Hi Imp, I'll try randomising the Operators only. I'm finding randomising everything more often than not ends up producing LFO madness. I sometimes regret getting rid of my EVS-1. I think now, I'd probably have a bit more of an idea about how to get usable sounds out of it that I did when I had it. The biggest downside is that you can't edit the sounds at all from the front-panel. This isn't surprising, given the complexity of the architecture, and the fact it only has a 2-character LED display, but it means to get the best out of it, you need an editor of some kind. As far as I know, the only modern patch editor/librarian that supports it is MIDIQuest, which has an atrocious GUI, and is laughably over-priced. Evolution themselves did produce Atari and Windows editors, but since they stopped production of the EVS-1 in 1990, I don't know if the PC one still works in more recent Windows versions. In terms of synthesis features, it's actually quite impressive, on paper. It offers all kinds of different synthesis algorithms, including FM, AM, subtractive (but don't expect virtual-analogue), and some more obscure ones like VOSIM and Formant synthesis. The envelopes are nearer to the Yamaha FM synth ones than standard ADSRs, too, which makes them quite flexible, and you can modulate lots of parameters with LFOs, velocity and assignable CCs, too. It's also got a selection of single-cycle waveforms, a bit like the Korg DW-6/8000, plus quite a comprehensive set of drum and percussion sounds, in a typical 80s drum-machine short lo-res PCM style. I'd say go for it, if you can pick one up cheap enough, and you're sure you will be able to run an editor for it, but don't expect hi-fi sound out of it. I think they were trying to make it a jack-of-all-trades, but on a budget, so inevitably it ended up being a master of none. I don't know what internal resolution it uses, but I suspect it 12-bit at most, and the DACs probably weren't of the best quality, even for the late 80s. I used to like it for latelybass-style basses, weird FM-like bell tones, synth choir, cold string-type sounds and random overmodulated LFO weirdness. Occasionally I'd even use some of the percussion sounds. It's also quite cool to make a fat brassy synth sound, then stack it up across all 8 parts, with detuning and panning, to make one monster sound. Here's an example I found of a track using the EVS-1 as the only sound-source: There's also this thread from this forum, in fact that contains a link to the Windows editor (might be dead, haven't checked). Also, this site http://www.deepsonic.ch/deep/htm/evs-1.php has some EVS-1-only example MP3s a|x

Something I've noticed: none of the presets that come with the MB_FM application seems to respond to MIDI velocity. Am I right in thinking that velocity can only be mapped to a single parameter, on a per-INS (instrument) basis? I guess this means that you can have velocity set the overall volume of a note (by mapping to carrier amplitude), or change the timbre of a note (by mapping it to amplitude of one of the carrier operators), but not both. Or is there a way of doing both things at the same time? The drumkits also don't seem to respond to velocity, and I can't seem to find any parameters for making them do so. Am I missing some global parameter to enable velocity-sensitivity, or do the drum sounds just not have the capacity to respond to velocity data? a|x

Wow, several hours later... Press Random All, press a key, repeat... Reminds me a lot of the kind of sounds I used to get out of my EVS-1 synth, poking around with the parameters in the Atari ST editor. The EVS-1 was theoretically much more flexible than the OPL3 chip, but in practice, the kind of sounds I used to come up with were remarkably similar to the ones I've been getting out of the SammichFM in the last couple of days. I'm struck also by how rarely the randomisation produces anything with a playable note. I guess the trick is for these, to find something similar to what you're looking for, then tweak it, rather that attempting to build a usable sound from scratch. a|x

Hi Flemming, it's not very dim- just not as bright as I'd been expecting. I did adjust both trimpots for brightness and clarity of the characters. a|x

Ah, thanks guys. I'll give that a go. I have a Waldorf Pulse, so I know how many happy hours can be spent randomising synth parameters ;) a|x

Sorry Imp, I can't find the random patch function in the MIDIboxFM manual. How do you do it? a|x

Apologies if this has been covered before, but I recently bought a SammichFM kit from Wilba, with the (really nice) neg. green LCD display. I decided to try to put together the base PCB without the jumper to supply a larger voltage to the LCD backlight. The display looks OK, but is quite dim. Should I add this jumper at JR4A? I'm reluctant to try it without confirmation that it won't fry the display. Cheers, a|x