Hi everyone,
This may be old news to you all, but I have recently bought a Slm Phatty, put it in my rack and hoped to gig with it... I also bought a Minitaur which has been perfect from day one.
My SP though is causing me to loose sleep and more sadly to loose it from my live rack because I cannot wait a couple of hours (NO exaggeration unfortunately) for it to get into a stable tuning. Looking at some posts and taking advice it seems the best I get is 'that's what happens with analogue gear'. I am afraid its just not good enough for 21st century analogue gear and there is something either wrong with my unit or the design of SPs.
My old Memorymoog and Prodigys back in the day never had these issues. Sure they may need a tune up after 10 mins or so but then they were fine. My 21st century analogues including the Minitaur and Dave Smith Prophet 08 are both ready to go from cold so it should be possible for the SP to do the same.
I always loved Moog and probably always will for what the represent but this experience with the SP has really disappointed me.
Please tell me its a 'one off' and can be fixed as I have a tour coming up on which I'd love to use it. Otherwise I may have to trade to a LP if that's any better.
Thanks, Andy
SP tuning issues
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BrufordRules
- Posts: 103
- Joined: Sat Feb 26, 2011 3:03 pm
Re: SP tuning issues
Hi Andy, this is what Perry from Moog Technical Support posted on other thread.
The Slim is our most thermally sensitive product. With the compact size of the chassis and the proximity of the power supply to the oscillator circuits, it takes a long time for the Slim to achieve total thermal equilibrium. Our studies here at the factory show that it can take up to an hour or two for the Slim to reach a stable temperature. I strongly recommend that you wait about this amount of time to run all calibrations. Try to do it in the middle of the day when the temperature surrounding the Slim is at its most consistent. Also, if at all possible, try to leave the unit on for at least an hour before playing a show or recording.
The Autotune feature of the Slim will not adjust the Slim's oscillators to one another. Instead, it tries to bring the overall tuning of the Slim in tune with an A 440 Hz reference value that is stored within the firmware. This feature works best after the Slim is completely warmed up. I recommend the 'ON' feature in the Fine Tune menu for use during the warm-up period. All of this is normal behavior for the Slim Phatty.
The Slim is our most thermally sensitive product. With the compact size of the chassis and the proximity of the power supply to the oscillator circuits, it takes a long time for the Slim to achieve total thermal equilibrium. Our studies here at the factory show that it can take up to an hour or two for the Slim to reach a stable temperature. I strongly recommend that you wait about this amount of time to run all calibrations. Try to do it in the middle of the day when the temperature surrounding the Slim is at its most consistent. Also, if at all possible, try to leave the unit on for at least an hour before playing a show or recording.
The Autotune feature of the Slim will not adjust the Slim's oscillators to one another. Instead, it tries to bring the overall tuning of the Slim in tune with an A 440 Hz reference value that is stored within the firmware. This feature works best after the Slim is completely warmed up. I recommend the 'ON' feature in the Fine Tune menu for use during the warm-up period. All of this is normal behavior for the Slim Phatty.
Re: SP tuning issues
The Minitaur doesn't require a warm up time, because as a V/Hz synth, the oscillators don't have components that need to warm up. The SP is a V/octave synth, and requires a warm up time. Moog's explanation makes a lot of sense. 
Minitaur, CP-251, EHX #1 Echo, EHX Space Drums/Crash Pads, QSC GX-3, Pyramid stereo power amp, Miracle Pianos, Walking Stick ribbon controller, Synthutron.com, 1983 Hammond organ, dot com modular.
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BrufordRules
- Posts: 103
- Joined: Sat Feb 26, 2011 3:03 pm
Re: SP tuning issues
If you want to know a little more about V/Hz vs. V/Octave, I'd recommend you to read the answers from Curtis here.
I hope it helps.
I hope it helps.
Re: SP tuning issues
Earlier i was writing in response to Voltor07 comment saying "not true" but i stopped myself as i knew I wasn't 100% correct either. i had to think about it.
I'll start with a response to the first post, Dave Smith uses DCOs, not VCOs so they inherently have better tuning stability.
now the V/Oct Vs V/Hz thing. saying a synth needs to warmup because it's oscillators are V/Oct is not entirely true, but in practice it kinda is.
a bit of background first. a exponential response VCO is basically a linear response ICO with an V->I converter with an exponential response. now if you look at a transistor, it has a bunch of properties that make it useful, but in this application we are interested in the Base-Emitter voltage input to Collector-Emitter current output, or the Ever-Molls model. i'll spare the maths (google it), in short it gives a exponential current output from a linear voltage input, our V->I but with two included temperature variables. one variable is easily cancelled by using a pair of transistors, the other needs to be removed somehow to give a straight (pun intended) exponential response to the voltage input.
Moog has mostly always tried to remove this temperature variable by removing the variability, by heating. in the Phatty they use a MAT04 quad matched transistor array, but days of old they used something like the 3046 (or ua726 pair with inbuilt heater). 2 transistors are used for the V->I converter, 1 transistor is used as a temperature sensor and the last as a controllable heater. this inherently requires time from switch-on to "Warm Up" before the exponential V->I converter heats to a stable temperature.
The other way is to compensate for the temperature by using a temperature sensing element to adjust the input voltage to the V->I converter according to temperature. usually done with a PTC resistor with the same temperature co-efficient as the transistor itself. in theory, this shouldn't require time for the "temperature to stabilise". in practise there is always some latency between the sensing element temperature and the I->V converter temperature with a change in temperature (i.e.. turn-on). if implemented well, there will be no noticeable temperature or deltaT variable in the circuit. a V-Oct oscillator with no "warm-up" required.
I'll start with a response to the first post, Dave Smith uses DCOs, not VCOs so they inherently have better tuning stability.
now the V/Oct Vs V/Hz thing. saying a synth needs to warmup because it's oscillators are V/Oct is not entirely true, but in practice it kinda is.
a bit of background first. a exponential response VCO is basically a linear response ICO with an V->I converter with an exponential response. now if you look at a transistor, it has a bunch of properties that make it useful, but in this application we are interested in the Base-Emitter voltage input to Collector-Emitter current output, or the Ever-Molls model. i'll spare the maths (google it), in short it gives a exponential current output from a linear voltage input, our V->I but with two included temperature variables. one variable is easily cancelled by using a pair of transistors, the other needs to be removed somehow to give a straight (pun intended) exponential response to the voltage input.
Moog has mostly always tried to remove this temperature variable by removing the variability, by heating. in the Phatty they use a MAT04 quad matched transistor array, but days of old they used something like the 3046 (or ua726 pair with inbuilt heater). 2 transistors are used for the V->I converter, 1 transistor is used as a temperature sensor and the last as a controllable heater. this inherently requires time from switch-on to "Warm Up" before the exponential V->I converter heats to a stable temperature.
The other way is to compensate for the temperature by using a temperature sensing element to adjust the input voltage to the V->I converter according to temperature. usually done with a PTC resistor with the same temperature co-efficient as the transistor itself. in theory, this shouldn't require time for the "temperature to stabilise". in practise there is always some latency between the sensing element temperature and the I->V converter temperature with a change in temperature (i.e.. turn-on). if implemented well, there will be no noticeable temperature or deltaT variable in the circuit. a V-Oct oscillator with no "warm-up" required.
Re: SP tuning issues
Hi guys,
Thanks very much for the information, a fair bit of the techy stuff goes over my head but I get the general picture.
I still have the core problem which is that I need to gig with this synth and having to wait such a long time before I can use it means that it will have to go. Such a shame as its a great sounding synth.
I have learnt my lesson when it comes to using Moog products on stage and reluctantly it will be back to my MS2000 for lead lines; still a great sound but just not the same...
Andy
Thanks very much for the information, a fair bit of the techy stuff goes over my head but I get the general picture.
I still have the core problem which is that I need to gig with this synth and having to wait such a long time before I can use it means that it will have to go. Such a shame as its a great sounding synth.
I have learnt my lesson when it comes to using Moog products on stage and reluctantly it will be back to my MS2000 for lead lines; still a great sound but just not the same...
Andy