Future-Retro 777

[djfunkshowkid]

Being an obsessive fan over the FR777 for many years now, I decided that if I cannot buy it...I'll design it. I've been told that internally, it is a very complex synth...but can be done. So far....I have created the 2 OSC's, with the FREQ - WAVEFORM - and LEVEL (volume) knobs. However, I still need to learn how to create the switch between playing via Keyboard....and the internal sequencer to complete the OSC section (for now).

Next on the list is the NOISE and FILTER sections....however would like to know what is "RES MAX" , "ACCENT" , and the difference between 3 and 7 pole.

Also, if anyone can post a link of an example of a OSC blend where they modulate eachother, would be great.

Here is an image of the 777 so ya'll can see what im talking about. Thanks!

http://www.schneidersbuero.de/images/full/fr_777.jpg

[djfunkshowkid]

Hey guys....I downloaded the "Dream Sequencer" and modified it a bit to fit my needs a bit more because im still learning all this stuff (great job to its creator btw).

However....I'd like to modify it even more, by either changing the OCTIVE knob (below the triggers) to a NOTE knob.....

OR completely change the whole sequencer to be more like the real thing, where there is a PUSH BUTTON that changes the pattern mode...in which one could scroll through the 16 steps....and the triggers now become NOTE SELECT.

However....I have no idea how to do either of those options. So, if anyone has idea's on how to acheve this...it would be greatly appreciated...and any EXAMPLES would be fantastic!!! Then I could break down what the creator did...and do it myself.

BTW....I updated the signal flow chart...and the OSM

IF ANYONE KNOWS WHAT A DIODE LADDER FILTER IS, OR HAVE AN EXAMPLE...PLEASE LET ME KNOW!!!

777 signal flow

frroute.jpg (33.03 KiB) Viewed 4148 times

FR777 v1.osm

FR777 OSM

(162.09 KiB) Downloaded 295 times

[trogluddite]

Hi there, welcome the forum.
I think I can maybe answer some of your questions - but I'm more of an FX person than synths, so I'm sure others will be able to elaborate.

A diode ladder filter is a particular way to build a real analogue filter on a circuit board - It was created for the early Moog synths because the usual options (using transistors) were under patent at the time. Bob Moog himself was said to have not liked it very much at the time - he considered it a bodge to avoid legal problems rather than quality engineering. But the general opinion among three generations of synth fanatics is that it is one of the best sounding filters ever - especially for bass, where you need warmth and depth.
A search for 'filters' on the forum will find some very good examples, including some modelled on the Moog - but, as ever, trust your ears when it comes to deciding which one suits your sounds best.

3pole and 7pole is a similar thing - the more 'poles' a filter has, the sharper the division between the sound you want, and the sound that's filtered out. Technically, each pole makes the volume of frequencies outside the filter go down by 6dB per octave - so you commonly see 12dB/octave filters (2pole) or 24db (4pole). A 3 pole filter (18dB/oct) is what the classic TB303 used, and is quite unusual and gives it a distinctive sound. 7 pole is very unusual indeed - a very steep filter - I'll have to check out what it sounds like when I get back on my big machine.

The accent feature is also best known from the TB303. When programming a sequence, you can assign accent to any steps you like using the button. The idea is that when the sequence plays, the accented steps will have more emphasis - to add some dynamics to the groove. The accent knobs on the filter, envelope and amplifier let you program how the note is emphasised - by making that note louder, giving it a longer release, or raising the filter cutoff (or any combination of them).

Rez max, I've never seen on a synth before, but if it's what I think it is, it's a great idea.
With most filters turning up the resonance really high makes the filter so peaky that it turns into an oscillator. Sometimes, that's cool - you can even use the filter deliberately as an oscillator in some patches. But on a bass line, it sounds bad - because you hear only the frequency that the filter is screaming at, and none of the actual note.
I'm guessing that Rez Max, limits (or extends) the range of the resonance controls so that you can keep this under control.

[djfunkshowkid]

I found a T-Ladder Filter...

viewtopic.php?f=4&t=6571&st=0&sk=t&sd=a&hilit=Ladder

Maybe its because of my ignorance....but wmakes a Diode Ladder different from the others...is it a matter of adjusting the parameters?? Or is T-ladder basically the same thing as a Diode ladder, its just a matter of real circuitry....

Im now learning how to go about adjusting notes. I thought I had it figured out...but it seems to adjust frequency instead. :-(

Thank you for your response....VERY informational and helpful!

[trogluddite]

It's important to remember that the only way to build a ladder filter is to use real electronic components on a circuit board - using software, you can only make an emulation that approximates the 'correct' sound. Electronics engineers do use software emulation (e.g. SPICE) that actually models the way that each individual component in a circuit interacts with all the others - but that uses huge amounts of CPU power and is impractical for making plugins.

Pretty much every filter you see has cutoff and resonance controls - but these are just the starting point for the maths that actually affects the sound. There are dozens of different ways to do the processing, and each of them have many hidden variables inside that affect the final sound. Like most things, there isn't any such thing as a practical 'perfect' filter, a real filter design will have uneven bits in its frequency response, different phase changes, different damping to its resonance etc etc. Each designer chooses to make different compromises, so practical filters all have slightly different sounds.

OK, OK, so I haven't told ypu how to build one yet! I'll own up; I wouldn't dare to even try! That's because, as I've hinted, it's actually pretty hard to do from scratch - the maths alone is university level stuff. Luckily, there are some people who do know what they're doing who have been generous enough to share their skills. All the filters I've ever used have been taken from examples I've seen on the forum - check out 'Dozius filter pack' for a start, that contains a big collection of filters that you can switch between to compare the sounds. From there, you can start poking around inside them, and get the beginnings of understanding how they work.

Whether any of the current examples truly emulate a ladder filter, I don't know. In reality it doesn't matter very much - your ears will tell you when you are hearing the sound that you want. All too often, the blurb telling you that a plugin is 'modelled on a vintage Korgolandamahamoog mkV from 1963' is just marketing bulls**t, so searching out a ladder filter emulation may well just lead you to a generic 18dB/oct filter that doesn't really sound much like a 303 anyway.

BTW. My crappy memory mixed up the Bob Moog story - the transistor filter (the T-ladder that you found) was Moog's design (though still not perfect enought for him) - the diode ladder was Roland's attempt at a copy - for the TB303 of course!

[djfunkshowkid]

Well....that wasnt very inspiring...lol.

Yeah, like I posted before, I downloaded the T-Ladder filter...and I could notice the difference in the sound....however, I have an issue. I have NEVER had "hands-on" experiences with a FR-777....so I dont know exactly what sound it is that im going for because most of the examples that I've heard im sure had some major cross modulation going on. Right now im only at the point of where I have the two osc's...and that t-ladder.

I've basically been looking at other examples that have been made....and looking for certain parts....then will add them into my device. Like if I find an example where OSC A is mixed into OSC B...then I'll find that snippet of the example...and place it into mine. Not exactly perfect....but it will at least give me a canvas to modify as I learn more later down the road.

As you can see with the image: http://www.schneidersbuero.de/images/full/fr_777.jpg that the filter section is not only the "ladder filter"..but has many parts such as: GAIN - SLOPE (3 or 7 Pole) - CUTOFF - RES - RES MAX - ACCENT - HIGH PASS.....so I just need to learn WHAT and HOW these different "tweaks" effect the outcome of the sound. I've downloaded the manual to help me understand even more.

WHY THE HELL AM I BUILDING A VIRTUAL MODEL OF THIS SYNTH IF I BARELY KNOW ANYTHING ABOUT IT??

Well, That question is rather simple. I've been into electronic music for 20 years now...and im facinated about how one can take a raw electrical current....and make it sound so beautiful. For 15 of those 20 years....I've had my sights set on the FR-777...because THAT sound just does something to me. It holds my interest more than any other device out there....even the FR-XS (big brother of the 777).

So if anyone reading this comes across anything that is on the 777, or that you think I may find interesting....I URGE you to PLEASE let me know....and post a response.

Thanks so much for all of the information so far!

[trogluddite]

Sorry, wasn't meaning to put you off!

Actually, it sounds like you have just the right approach. Getting some rough and ready modules together to make a 'skeleton' is exactly how most projects start - and will give you a good grounding in using SM. I was really just hinting not to try and understand everything all at once, or your head will go pop!

After that you can take each of your building blocks one at a time, and begin to trim and tweak to get closer to the sound you're after - you can be assured of getting plenty of help with that on the forum.
There's also no shame in making use of the modules you find here (as long as you remember to say thankyou!) - those of us fluent in code and assembly still use and adapt ready made chunks of code, and even the designers of real hardware synths will borrow bits of circuit from data sheets and textbooks (just as Roland were inspired by Moog with their ladder filter, and the FR777 is inspired in turn by Roland's TB303).
One of the joys of not quite understanding all the theory is that by experimenting wildly you may stumble across something that is even better than the idea that you started with.

One hint for your filter. You can add poles to a filter simply by chaining one filter after another and then feeding them with the same frequency and resonance values. So the FR777 7pole filter is most likely the regular 3pole ladder filter feeding into a 4pole filter that gets turned on/off by the switch.
As a guide to the sound of the 3pole ladder filter, check out one of the many TB303 clones available - the 303 seems to be the main influence for the 777, but only has a very simple single oscillator, so you will be able to tune in to the sound of the filter more easily.

[djfunkshowkid]

No, you didnt put me off...I was kidding...lol.

I certainly appreciate your advice on chaining the filters to switch from 3 to 7 pole! I tried that, and will add the .osm to see if what I did was correct. Its not 7 pole....but may be 6...lol, as I don't know how to create the filters from scratch yet. I just chained the T-Ladder filter found at viewtopic.php?f=4&t=6571&st=0&sk=t&sd=a&hilit=Ladder to another one....I can hear the difference, and if its chained correctly....I see why the 777 has a RES MAX.

Downloaded the filter pack....pretty cool filters in there, but when I hook up the filters, I dont hear a filter change....unless im hooking it up wrong. I assume you just hook knobs up...lol.

[trogluddite]

Looking good so far - the chained filter sounds great - even in '7 pole' mode it still has a lovely richness about it.
Not sure about the filter pack problem without seeing what you're doing (could be we even have different versions) - but all the individual filter modules have Freq and Res scaled the same way, so they should act as 'drop-in' substitutes for the regular filters. The only compilcation is the way that selectors have been used - if you want to keep the ability to select different filters then the inputs to the selectors need to see integer inputs (0,1,2,3 etc), so you need to watch the scaling if you're to use a knob.
You might also like to have a look at this thread Trance Gate. The trance gate itself may not really be what you need, but the discussion of how to keep sequencers running accurately to tempo etc. may be useful - using a 'green' sequencer connected internally by MIDI can be fraught with problems in SM due to timing innacuracies. You may find further down the line that converting the synth to be purely mono can help with sequencer 'tightness' - but I'd get your sound honed to perfection first, the conversion is pretty simple.

[djfunkshowkid]

Quick question....If I wanted something where: I have a WAVE B knob, and a AMOUNT A knob....where as

WAVE B - Adjusts the shape of OSCILLATOR B to modulate OSCILLATOR A's frequency....from Saw to Square....

AMOUNT A - Adjusts the amount of affect OSCILLATOR B has on the pitch of OSCILLATOR A.....Where LEFT would be NO MODULATION, and RIGHT would be FULL MODULATION...

What exactly is it that im looking for? Ring Modulator? Im rather stumped by this...Any example of clarification would be fantastic....thanks!

[trogluddite]

The easiest way to change the oscillator waveform would be to use a crossfader to mix the waveforms from two oscillators together in whatever proportion you need. It's quite a handy little building block to have...

Crossfade.png (22.63 KiB) Viewed 3815 times

...with the knob fully counter-clockwise (zero) you hear only source 1, with it fully clockwise (one) you hear only source two - and a mix of the two when it's in between.

Modulating one oscillator with another can actually be done in several ways, but in a synth it's usually the frequency of the target oscillator that you would modulate (though modulating the phase or volume can be interesting too) - that's Frequency Modulation (FM), a technique that all the 80's Yamaha DX synths used for their sounds. It's very nice for making 'metallic' and 'gritty' kinds of sounds.
Firstly you need to scale the oscillator B output - just multiply it with the value from your 'Amount' knob.
Then you feed that into ocillator B's frequency input - this is where it gets a little more complicated...

There are 3 different scales for frequency used in SM.
1) Frequency Hz - Hz is what most engineers etc are used to using for frequency, but in SM it's probably the least useful - most of the oscillator and filter primitives prefer the 0-1 version.
2) Frequency 0-1 - this is what most of SMs oscillators and filters use, in this scale 1 represents half of the sampling frequency - so if you're running at 44.1kHz sample rate, the top frequency is 22050Hz. Like using Hz, it is a logarithmic scale though, so combining several values together for modulation etc. can involve some tricky maths.
3) Pitch - this is just an integer number that represents the note number from a MIDI keyboard. It's very useful because it is nice and linear - adding 1 always changes pitch by a semitone, adding 12 always goes up an octave.

So, the first thing I'd do is to alter your schematic so that the wavetable oscillators use Pitch rather than Freq (Hz), that will make adding knobs for tuning, octave etc. far simpler. Just change the oscillator freq inputs to come from the MIDI2Poly pitch output, and swap the 'Hz to 0-1' for a 'Pitch to Freq' in each oscillator.

Now you have a choice - you can take your scaled oscillator B output and either just add it to the Pitch value - or add one to the scaled Osc B output (to make it always positive) and multiply it by the Freq (0-1) value. The second way is probably more technically correct - and it will avoid the frequency value ever going below zero (which sounds nasty).
The two methods will sound slightly different, and you'll need to tweak the range of the Amount knob in either case to get a nice response.
I've shown it here with stock saw oscillators, but using the Wavetable osc's is the same principle...

FM.png (27.88 KiB) Viewed 3815 times

[djfunkshowkid]

Wow, for as detailed that explaination was....im completely confused. I sortof see what you're saying...but when I tried it....I must have done it wrong, because it doesnt sound very pretty...lol. I'll keep trying though (trial and error is my friend...lol). I uploaded the Schematic if ya wanna view how its done (its a bit complicated)...and see what or if I did anything wrong.

I finally got the sub-oscillators to work...although it may not be the most effecient way of doing it, I happy with the outcome.

I added a NOISE generator...which adds some white noise to the sound. I also added an ENV DECAY, ENV AMOUNT, ACCENT and RES MAX knobs....which they arn't hooked up, because I have NO IDEA how to link the RES MAX to the RESONANCE levels....or even what the ENV D and ENV A is supposed to even modify.

Im decently happy with how far this has come so far. Even thogh I know its resembling NOTHING like the real 777...Maybe I should call it the "FSK-666" (FunkShowKid-666)...lol.

Here is my schematic so far....if ya'll find anything wrong with it, please let me know.

[trogluddite]

Wow, for as detailed that explaination was....im completely confused

That's one of my extra special talents! Can't have you upstarts coming along and making better synths than mine!
But seriously, looks like I did throw you a bit of a red herring with the oscillator mix thing - looking closer at the schematic, the wave oscillators you're using already do the smooth mixing between waveforms.

One thing that looks as if it needs a good going over is the sequencer. The little knobs for setting the pitch are very inconsistent - some are giving note numbers, while others are giving octaves, with some of the values being set by the little sliders that don't appear on the screen (from what I remember of the original, these would normally appear on top of the little keyboard graphic that is also hidden)
The sequencer has lots of little modules that are basically all the same, so the Synchronise feature may be handy here. Once you have one module that works well - CTRL-C to copy it, then SHIFT+CTRL+V to 'Paste Synchronise' (a little 'Recycle' icon appears on the modules) - from now on you can edit any one of the Sync'ed modules, and all the other ones will change to follow the edited one. You can have as many groups of sync'ed modules as you like, and parameters which appear on the Properties panel can still be edited independently, so you can still give them all unique preset names etc.

(WARNING: I'm about to digress onto the philosophy of plugin design!)
I think this is one of those cases where deviating from the original hardware design would actually add something good to the synth. Looking at the 777 front panel, it is one of those 80's style 'digital' interfaces where programming the sequencer was a real pain - you'd have to use a button to select the step to edit, then press the UP/DOWN buttons a load of times to select a note for that step; then repeat for each step until you got RSI!
The original design of the SM sequencer you are using, with its octave knobs and nice keyboard'y display would actually be far quicker to use, and easier to see what's going on. It is also possible with SMs GUI features to have things like that in little hide-away windows if you want user-friendliness AND the nice clean appearance of the original front panel.

The user interface of real hardware synths is limited by the technology available (and the cost of components), seems a shame to saddle plugins with the same restrictions when there's no need to - as long as the sound is just as good.
That's just a personal opinion, of course - I have to confess to being somewhat underwhelmed with space on my sequencer display taken up with fake wooden end-cheeks, illegible 'psychedelic' fonts etc.

[djfunkshowkid]

Well, after talking to my friend Dennis, from skylab2000 ( www.skylab2000.com ) he gave me a few suggestions. Stating that it is a VSTi, and NOT an actual hardware synth....I have the freedom to add whatever element I want, and not have to worry about space, or it blowing up on me...lol. He suggested that I have a display above each step, telling the OCTIVE and NOTE that it is set on, with buttons below it.... an UP - DOWN button for OCTIVE...and an UP - DOWN for NOTE. Now, I borrowed the LOGIC 2 NOTE componet from "X-Series" synth located in the projects section of the forum...and it now displays the NOTE of the trigger. However, He suggested that it reads as "C# - C#1 - C#2 - C#3" for example....where it displays the NOTE....and OCTIVE.

That is the tricky part. I have no idea how to go about modifying this....so im going to try to see what the maker of DREAM SEQUENCE did, to make the pattern sequencing to work....then add the OCT and NOTE select buttons and display, as suggested. Maybe this will give me the chance to add what I wanted (bank and pattern save and load). Add a lil more eye candy as well...lol.

I decided to un-link the FM's for now, because with a certain setting....it seems to hit such a high frequency, that it cuts all sound...and sort of..."Shorts out", and sound isnt re-enabled unless you exit out of the VSTi, and load it again.

Soooo, thats where im at for now. I better get to it...lol. Any suggestions, examples, or help would be greatly appreciated on how to add these buttons (not a dropdown menu). I did have the idea on how to setup the buttons....where as the NOTE buttons will adjust the MIDI note by +1 or -1....and the OCT buttons will skip +12 or -12. I assume having 1 componet like this, will take less CPU than seperate componets.

Blah blah blah, im rambling....

[trogluddite]

I assume having 1 componet like this, will take less CPU than seperate componets.

When you are doing the 'Green' bits of a schematic you don't have to worry about this so much.
They have a special system of working where they only use CPU when you are actually changing a setting from the knobs or MIDI etc., or you use a 'Tick25' or 'Tick100' to create regular changes on purpose.

You'll have seen already the 'Green' trigger type of connection which sends pulses to modules telling them to do something. In fact, ALL the different kinds of green connection send triggers whenever their values change, and the triggers then 'flow' through the schematic to update all the connected bits. Without any triggers, the Green bits of a schematic use pretty much no CPU at all. Also, they can also only be triggered about 100 times a second, unlike the 44000 or more times a second of the stream/poly parts. So for keeping CPU low, you only really need to worry about the stream/poly bits of your design (and drawing moving things on screen, that can be greedy too).
I won't bore you with the 'weirdy' exceptions to the rules, you can always ask on the forum if something is behaving strangely.

The stream/poly bits also have a special trick - if a stream/poly module has no outputs connected (maybe because you used a Selector to 'Bypass' them), they will also get turned off to save CPU. Just remember that it must be the outputs that you disconnect, not the inputs, if you want to see the CPU savings.

One last point on CPU load. The meter at the bottom of the SM window is a bit odd (i.e. misleading!)- it only shows CPU for stream/poly (not Green) - also, SM always uses only one core of a multi-core processor, and the CPU meter only reads the load on that one core. So if you see 40% CPU on the meter, but you are using a Dual Core machine, you really have a 20% CPU load (or only 10% on a Quad Core). If you are worried about CPU load, it's always best to check using the Windows Task Manager (or do a 'How-many-can-I-run-at-once' test in a VST host).

Blah blah blah, im rambling....

You are learning well from a zen master of the art of the rambling post!