Interesting model D / Voyager comparision

[LivePsy]

The 2 previous posts by BrianK and MG are great insights into the complexity of a musical instrument and how production runs vary. I personally find it hard to believe that some mini's didn't have matched transistor pairs in the filter ladder, surely that would be a tiny cost saving to a labour intensive and expensive manufacturing process of back then. Are they matched in the Voyager? I assume so because array IC's are quite common. You also have to consider that transisters were pretty hit and miss back then, most likely yesterdays matched transisters are as similar as any 2 picked out of a bin today.

But we're in danger of being like the 303 fanboys of which I am one. For years the experts on 303's claimed it was the 18db filter which made it sound great, when in fact it is a rip off of a 24db moog ladder filter but using 2 pins of transistors as a diode ladder - just different enough not to break Moog's patent. In the same way there's no consensus on what makes a mini sound unique even when a modern version of it is produced decades later. I mean come on, the Voyager *IS* a modern day mini. Didn't anyone notice that ?

So we have tantalising ideas that its the waveforms, the filter and the VCA which are different. And considering that's the entire signal chain, we've got everything covered. I'm quite sure that the mini would have sounded like the Voyager if technology made it possible back then. Many great sounds would not exist if circuits were perfect. Odd that sometimes we want to emulate something that a designer tries to eliminate.

The only thing I don't understand is why the Phatty got filter distortion but the Voyager doesn't.

Cheers,
B

[sunny pedaal]

the voyager has noise generator .

also i found that the form of the envelopsignal has great influence on the sound. mostly envelop and vca influences aren't considers as important parts in the soundformation so nice to read something 'bout it now.
i think the mini sound overall better in basicsound then the voyager, which is important in substractive synthesis. i tried several model-d's , have 3 myself and find that statement thru for all of them.
having said that if i go for a gigg , or to a lonely island the voyager would be the more interesting instrument to take.

i wonder what brian's impression is on the difference between the modified voyager and the original one. i always loved his presetssound so , would really appreciate some light from him on that subject too.

[Captain Beardy]

..' KIN - ellllll ! !!!!,..lol

Just got hold of a Model d to keep my Voyager SE company, and
whilst that comparison test is superb, my head's hurting already !!!!

( Well, I'm a drummer,. 'nuff said * note to myself * must look on eBay for an oscilloscope ).

[bosonob]

MC,

I'm really confused about your ramp waveform comparisons. You state that the voyager uses rising ramp. This is not the case. Both the voyager and the Model D use falling ramp as the "sawtooth" waveform. They should and do at least from my tests look the same given same frequency. The mini does have rising ramp as 3rd osc. selection. From my understanding a rising or falling ramp without glitches should produce the exact same harmonics. Any differences in sound should be minimal.

It would be very interesting to see a schematic of the voyager. I have seen the Moog T-shirt and cap with a partial schematic drawn for the oscillator. I truly feel that Moog used some interesting choices in the circuit design that radically differ from the mini-Moog architecture. I have spent many hours looking at the analog board and tracing some of the circuit areas. Indeed the VCA use a OTA design and I feel there may be bandwidth and slew-rate issues for that implementation.I would love to hear the voyager post filter but no VCA. I would mod mine to take the post filter signal and route it to a handmade discrete differential VCA ala Model D, but without a schematic that might be difficult. I would love to be able to open the voyager OTA designed VCA to "DC to daylight".

I will ask a bold question; Did they purposefully limit the bandwidth of the voyager output to hide digital noise produced by the memory and processing CPU? Think about it. I have radio receivers that hear my mini and other computer equipment at short distances. A full bandwidth amplifier that close in proximity to its CPU might pick up chugging and noise sounds at ultrasonic and MHz frequencies from the CPU and due to mixing products, down convert to audible noise heard when the VCA is open. I have not fully explored this idea and am not sure if that could happen. When my voyager first is turned on I hear all sorts of whooping etc. The voyager OS also uses the same analog board as regular voyager so it would probably sound the same.

I have also been adventurous and carefully changed some of the trimpot setting to fatten and "dirty" the sound a bit to where it sounds much more like a model D. My experiments resulted in increasing the output to the mixer causing distortion and clipping at high mixer settings and IMHO that the factory tuning is a little too exact. I have spent a lot of time tweaking the tuning on mine to give a "beating" effect that is not exactly the same across the keyboard for any of the oscillators tuned to "zero". I compared mine to a factory EB. The factory EB "beating" was nearly the same for each oscillator for every footing across the keyboard. It sounded a little too polished.

Truly the minimoog sound is a collection of effects. Its the oscillators, the tuning, the mixer,the filter, and maybe more importantly the VCA.

Those are my research, musings and my opinions,

Stefan

[MC]

I stand by my assessment that the Voyager is rising ramp, confirmed by my oscilloscope



Yes there is a sonic difference between the falling and rising ramps. My ears can hear it. Subtle but it's there.

I did some work for Moog and have seen schematics of the Voyager. Did they purposely limit the bandwidth of the Voyager? Not that I could find on the schemo. Play a patch with extreme ring mod and you'll hear really high end. I'm also an EE and the standard practice to reduce digital artifact noise is by maintaining separate ground paths (digital ground, analog ground) and good bypass cap design at the IC power pins, not by restricting bandwidth. My Moog Source and Memorymoog has digital control and they put out a high end that will cut your head off.

The Voyager has range/scale trimpots like the model D. When they leave the factory they are calibrated tight. Over time the trimpots shift and I have had to re-calibrate mine on occasion. If the SCALE is off on any oscillator then of course they won't track together ("beating") across the keyboard.

The model D sound is indeed the sum of the components. Few people realize the impact the VCA has on the sound.

[LivePsy]

Rising and falling ramps... What happens when a rising ramp goes through an inverting stage? Does it still sound like a rising ramp or does it now sound like a falling ramp? It must sound the same if the inverting stage is not coloring the sound. The properties of speakers, air waves and room acoustics may affect how you perceive the sound, but its mathematically impossible that the electronic wave is different.

[bosonob]

My apologies to MC and everyone,

My O-scope and PC O-scope both show the voyager sawtooth as inverted (i.e ramp down) to what is real (ramp up). I currently do not understand why my instrumentation inverts the signal. However listening to oscillator 1 being modulated by oscillator 3 in low mode indeed you hear the ramp increase osc 1 and reset. I'm really flumoxed as to why I can see it only inverted.

Amos @ Moog also stated the core of each oscillator is a down ramp but the waveshaper re-shapes it as ramp up.

Funny, as both the manual and the front panel describe it as a down ramp.

Both ramps should contain the same harmonic content just different as a modulation source.


Sorry for the mistake and misinformation,

Stefan

[BrianK]

i wonder what brian's impression is on the difference between the modified voyager and the original one. i always loved his presets sound so , would really appreciate some light from him on that subject too.

From what I can hear the slew rate mod has a nice bright edge but I don't hear it as more musical. (Personal subjective taste). I remember a friend having his old ARP 2600 modded for faster slew rate. It WAS much brighter but I no longer loved the sound.

In listening to the examples given, I find the unmodded one more musical, the modded one more clear. So it depends on what you're doing. I rarely do fully bright sounds - in fact, as most of my work is mixing together audio, I find I like darker sounds. I prefer the later Minimoog D's from the middle 70s to the earliest (bright and hard) and late (soft and thick) ones. They have a nice mix of punch and tone that I like.

While I loved the design of the old Minimoog originally, I find it's very limited in today's world. The Voyager is a huge improvement in SO many ways. Dozens if not hundreds of really, really significant things. People nowadays always demand "perfection" if it exists (that now includes including original distortions etc), yet they have no understanding of what it took to make something like this. The Voyager was not intended to clone a Minimoog D, just start from there as a basis. Like with hotrod cars, mod to your heart's content to make it do what you want (that's what we did on old Minimoogs!), but I won't call Chevrolet and ask them for different stick shift knobs - they're manufacturers.

[BrianK]

i always loved his presetssound so , would really appreciate some light from him on that subject too.

Thanks, sorry for the late reply. I recall Bob sending out the only working Voyager they had built, and the digital electronics were not yet done, so there was really no way to "Save" the sounds inside. If you've ever seen the old Minimoog "Patch Sheets" they used to sell, it shows plain diagrams of the front panel, and you draw on the paper to show where all the knobs were set.

I had one weekend to make 120 programs. Not easy to make good ones, so I told them I would only be able to do 60 (I think) leaving the rest blank so people WOULD program their own (read the stories on the old Prophet V where people never changed a single preset). Some sounds were easy (Popcorn) and others took some time, using recordings and trying to closely match the sounds. After each sound was done, I recorded a few notes of audio of that patch and made a diagram on paper. When the Voyager prototype went back to the factory, they finally loaded the digital software and re-built my sounds using the patch sheets and comparing to the audio, then saved them as the presets. Those were the original set loaded in the Signature Series, the 600 signed ones.

Later on, I made more sounds so we'd have a full bank.

[peter ripa]

theres no sonic difference between ramp up and ramp down. there may be differences due to different methods used to generate one or the other but really whatever method you use to generate one you could just invert and get the other.
theres no differences between pw 10+90 compared to 90+10 right?
the scope shows rising ramp from the voyagers audio out but from my memory when ramp is used as modulation it is falling

[latigid on]

What about the phase relationship with other oscillators having different tuning and beat frequencies, different waveforms, FM or sync? What if the slew rate is non-linear or asymmetric between the two?

[David Bulog]

who is Rudi???
Rudi Linhard (slewrate mod) modified Voyage

[diddi_jo]

Thanks for that. Now back to enjoying that Voyager...

[flowdesigner]

I will ask a bold question; Did they purposefully limit the bandwidth of the voyager output to hide digital noise produced by the memory and processing CPU? Think about it.

nope, off course they did not.
Highend analog mastering gear like crane song HEDD and Distressor also have a cpu.

[Don Solaris]

until you open the filter all the way.

By that - did you mean setting the Cutoff knob to the max and Filter Env amount to 0?

Cheers!