Oscillator sync

System 55 • System 35 • Model 15
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Rarecomponentadsr
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Oscillator sync

Post by Rarecomponentadsr » Fri Jan 01, 2016 8:10 am

Does anyone have any tips or special tweaks for syncing oscillators ?

I'm using 921b's and basically slaving via sawtooth and adjusting octave and frequency on the controller...but is that it ? Is there any further adjustments apart from using different waveform and can syncing be taken any further ?

M00G
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Re: Oscillator sync

Post by M00G » Sat Jan 02, 2016 1:43 am

I’ve only just received my Model 15, so I’m still a newbie with the Moog modules.
But I’ve noticed that if you send a slow sine wave to modulate the synchronising waveform, then the synced oscillators will move in and out of sync. They don’t do this smoothly but try and ‘hang-on’ to the synchronising frequency until they finally let go. They then move back into sync as the frequency returns. A little goes a long way here, so I run the incoming modulating sine through a 995 attenuator first. It makes for some unusual rhythmic synced/non-synced moogness. 8)

Also, don’t forget that the 921b oscillators will not just sync to the octaves, but also the whole number overtones or sub-tones.
This means that we can sync a fifth above or below as well (and maybe even others).

This is from the early Model 15 manual:
When the frequency of the synchronized output signal is to be a whole number multiple (perfect overtone) of the synchronizing input signal, the synchronizing waveform should be a sawtooth. When the frequency of the synchronized output signal is to be a whole number submultiple (perfect sub-harmonic) of the input synchronising signal, the input synchronizing waveform should be a sine.

I don’t know why this is so - mine seem to sync on either waveform.

Happy syncing….
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Last edited by M00G on Sat Jan 02, 2016 10:56 pm, edited 1 time in total.

EricK
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Re: Oscillator sync

Post by EricK » Sat Jan 02, 2016 3:41 pm

Someone noticed that the sync on the Moog 921B isn't what it is on a dotcom or a Mos-lab 921b.

You can get that classic sync sound but "it requires the use of one of the 921b's fed into the mixer and the output of that inserted into the 921 which then becomes the noise source. The Sync on the 921b's is for the purpose of keeping the oscillators in perfect PLL Lock-step tuning across 4 octaves."
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Rarecomponentadsr
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Re: Oscillator sync

Post by Rarecomponentadsr » Sat Jan 02, 2016 6:48 pm

Thank you for these excellent tips . I'm getting pretty good effects particularly on the lower registers with some sync patches ...on other patches it's hard to detect the sync effect but I do have a KOTk 921 and the weak/strong sync is pretty effective. The sweet spots can take some time finding,

I wonder if the sync output can be used in the filters in any different way to normal wave inputs ?
I'm really looking for actual musical scale tones rather than efx sounds or sequencer use. I was thinking about modifying the controller in some way or other...just a thought .

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noddyspuncture
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Re: Oscillator sync

Post by noddyspuncture » Sat Jan 02, 2016 10:08 pm

M00G wrote:Also, don’t forget that the 901b oscillators will not just sync to the octaves, but also the whole number overtones or sub-tones
Don't you mean the 921b....?

Cheers,
Tom

M00G
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Re: Oscillator sync

Post by M00G » Sat Jan 02, 2016 10:53 pm

Oops :oops: Corrected - thanks.
I just can't seem to get 901s out of my mind...

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noddyspuncture
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Re: Oscillator sync

Post by noddyspuncture » Sun Jan 03, 2016 8:54 am

M00G wrote:Oops :oops: Corrected - thanks.
I just can't seem to get 901s out of my mind...

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Well, that's understandable - they do sound a lot nicer... :D

M00G
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Re: Oscillator sync

Post by M00G » Sun Jan 03, 2016 6:19 pm

noddyspuncture wrote:
M00G wrote:Oops :oops: Corrected - thanks.
I just can't seem to get 901s out of my mind...

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Well, that's understandable - they do sound a lot nicer... :D
And it's all your fault NP :evil: - Since watching your 901 comparison vid I think I'm on the slippery slope... :wink: :lol:
(great vid btw - one of the best clone 901 vs Moog 901 comparisons around).

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noddyspuncture
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Re: Oscillator sync

Post by noddyspuncture » Mon Jan 04, 2016 10:41 am

M00G wrote:
noddyspuncture wrote:
M00G wrote:Oops :oops: Corrected - thanks.
I just can't seem to get 901s out of my mind...

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Well, that's understandable - they do sound a lot nicer... :D
And it's all your fault NP :evil: - Since watching your 901 comparison vid I think I'm on the slippery slope... :wink: :lol:
(great vid btw - one of the best clone 901 vs Moog 901 comparisons around).

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Hey thanks... :D
By the way when you say "clone comparisons" are you meaning home brew units like mine or are you also including those from the well known, established 'cloners'...?

Cheers,
Tom

M00G
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Re: Oscillator sync

Post by M00G » Mon Jan 04, 2016 8:19 pm

I guess I'm referring to both types - both clones and hb like yours.
What really impresses me with yours is that it's a true A/B comparison - and boy they are sooo close I doubt if anyone could pick it in a blind test.
The cloners also produce great 901s, but without the A/B live comparison it's very hard to know just how close they are (but they all sound great!)

Question: did you notice any difference in sound within your own builds? With the tolerances in discrete/vintage components I would expect some subtle deviations. I'm sure Bob's original builds had the same deviations from module to module.
But maybe it's just us Moog geeks pondering the Universe... :lol:

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noddyspuncture
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Re: Oscillator sync

Post by noddyspuncture » Tue Jan 05, 2016 10:01 pm

M00G wrote:I guess I'm referring to both types - both clones and hb like yours.
What really impresses me with yours is that it's a true A/B comparison - and boy they are sooo close I doubt if anyone could pick it in a blind test.
The cloners also produce great 901s, but without the A/B live comparison it's very hard to know just how close they are (but they all sound great!)

Question: did you notice any difference in sound within your own builds? With the tolerances in discrete/vintage components I would expect some subtle deviations. I'm sure Bob's original builds had the same deviations from module to module.
But maybe it's just us Moog geeks pondering the Universe... :lol:

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Do you know of any other home-brew 901 demos...? I'd like to see them if you have any links...!

When you say "within my own builds" - I only actually built one 901b and then later a 901a. So I can only compare them to my original R.A.Moog ones. I have four original 901b's and two original 901a's. The R.A. 901b's all sound very similar, as you would expect - but you know the saying no two Minimoogs sound alike... even Hammond organs have subtle differences... well I think module to module each have their own "personality". It could be a calibration anomaly... but it's definitely there...!

The comparison video of mine was shot by a friend on his mobile phone... so the picture quality is great... but it has the 'room sound'. I am thinking maybe I should do another one - recording the sound direct onto my Zoom - but my only video camera is an old Hi-8 one and it leaves a bit to be desired picture quality wise. I suppose it's the sound that's the most important thing here. Also, I could then include my 901a controller which wasn't ready when that comparison video was shot... :D

The 901a worked first time as well. I was really surprised, haha!

The reason they sound good I suppose is because I didn't change anything - except for performing a few minor 'upgrades' which I also performed on all of my R.A a's & b's when I got them and serviced them originally.

Basically they are calibration modifications. I brought all the adjusters to the rear slot - visible because I changed the old 22 way connector to the newer 'D type' - which are much more reliable. The adjusters that I then brought to the rear are "multi-turn" and I also changed a couple of resistors 'feeding' the (901a) calibration presets, to board mounted presets so I can set the multi-turns to the centre position - then roughly calibrate the module with what would been fixed value resistors before - and then work from there. That way there is no danger of end-stopping. Also the modules never need pulling out to calibrate - I can do that just from looking into the back of the case.

When I made these modules I actually cloned the circuit boards using copper board and etchant and I sourced all the original components... such as the germanium diodes, the CA3019 diode arrays and even the CL-1 diodes..! I don't think any of the clone manufacturers do that - they all have quite marked differences form the original Moog design..!?

Anyway I have a story for you now...

Recently I was asked to take the Modular out to a seminar type thing to display it - which I did. It was a mid-week event so I needed help getting it into my van before hand. That was at the weekend when friends were free... so the Modular stayed in my van in the garage for a few days. It was raining heavily during that time so there was a lot of moisture. When I took the Moog to the seminar during the afternoon and set it up - it was really bad. I had actually never seen it like that. One of the original R.A. controllers was playing up big style... as was my own home-brew 901a In exactly the same way..! The other R.A. 901a was not at all bad. I had to wait until they put the heating and air-con on and it all settled and acclimatised after a while - and then it was perfect. I have gigged this thing a lot and it has never been like that when setting up, which would be a nightmare. But it was a good exercise seeing it that way, as now i know what to do and expect. So I have got myself a couple of small hairdryers to point into it which I shall carry to future gigs so I can dry it out quickly... :)

Cheers,
Tom

M00G
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Re: Oscillator sync

Post by M00G » Wed Jan 06, 2016 9:22 pm

Tom - since we've kinda hijacked this thread I've started a new one just about 901s... :wink:

Keith
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