Funk Tonstudiotechnik in Germany have a series of SMPS with quite impressive data, for example http://www.funk-tonstudiotechnik.de/SMPS-14T-Info-2-spaltig.pdf.
You may also have a look at Crayon Audio CFA-1 using standard SMPS from Traco, 6moons audio reviews: Crayon Audio CFA-1.
No association with them.
Wilfried
You may also have a look at Crayon Audio CFA-1 using standard SMPS from Traco, 6moons audio reviews: Crayon Audio CFA-1.
No association with them.
Wilfried
Tim,
I am using a resonant half-bridge topology. Hence the 50% duty cycle. (In fact, 50% minus dead time, which is around 300ns). I'll play with the feedback loop. Had a quick look at the L6599 application notes, there is also ripple: 75mV pk-pk on 24V O/P and 185mV pk-pk on 200V O/P. There is room for improvements.
Cheers,
Serge
I am using a resonant half-bridge topology. Hence the 50% duty cycle. (In fact, 50% minus dead time, which is around 300ns). I'll play with the feedback loop. Had a quick look at the L6599 application notes, there is also ripple: 75mV pk-pk on 24V O/P and 185mV pk-pk on 200V O/P. There is room for improvements.
Cheers,
Serge
Wilfried,
Thanks for the reply. I intend to use a modified Traco SMPS to power up the heaters of my next amp. They are small and quite reliable (hopefully). I quickly measured the Traco O/P and I liked what I saw. Very little ripple. A few additional caps and maybe a small choke and the voltage will be nice and flat. I also intend to shield the tubes from theses SMPSs with max. 10mm of aluminium. Some may see SMPSs in vacuum tube amp as heresy, but what the heck! If that improves the amp, makes it smaller, lighter...
CHeers,
Serge
Thanks for the reply. I intend to use a modified Traco SMPS to power up the heaters of my next amp. They are small and quite reliable (hopefully). I quickly measured the Traco O/P and I liked what I saw. Very little ripple. A few additional caps and maybe a small choke and the voltage will be nice and flat. I also intend to shield the tubes from theses SMPSs with max. 10mm of aluminium. Some may see SMPSs in vacuum tube amp as heresy, but what the heck! If that improves the amp, makes it smaller, lighter...
CHeers,
Serge
Yes Tim is correct, needs more loop gain at the line freq. Using Turns ratio + duty cycle + error amp gains come to play here. Increase error amp gain and Re-run stability analysis using a Bode plot/
Thanks Infinia,
BUT the L6599 has a fixed 50% duty cycle. However, the frequency can be altered by the feedback loop. If the frequency decreases, the O/P voltage increases, and vice-versa. The soft start is implemented by starting at four times the resonant frequency.
http://www.st.com/stonline/products/literature/ds/12337/l6599.pdf
Cheers,
Serge
BUT the L6599 has a fixed 50% duty cycle. However, the frequency can be altered by the feedback loop. If the frequency decreases, the O/P voltage increases, and vice-versa. The soft start is implemented by starting at four times the resonant frequency.
http://www.st.com/stonline/products/literature/ds/12337/l6599.pdf
Cheers,
Serge
Hi Serge
The forward loop gain is pretty much fixed by your design and will vary mostly by the spec'd input Line voltage range. So the bottom line is that the error amp gain needs to increase by 20 LOG [Vr (old)/Vr (*new)] with * = target ripple. Raise it too much and suffer unstable operation.
The forward loop gain is pretty much fixed by your design and will vary mostly by the spec'd input Line voltage range. So the bottom line is that the error amp gain needs to increase by 20 LOG [Vr (old)/Vr (*new)] with * = target ripple. Raise it too much and suffer unstable operation.
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Here is a paper that discusses forward gain for resonant converters so in your case XFmer is near 1:1 so the gains can be much higher lightly loaded ie LC Q's. Maybe a concern for stability and effectively causing a designer to over compansate using low error amps gain.
http://www.cpes.vt.edu/_media/annual_reports/2002/Report/VolumeIIPartII/1DPS/4.pdf
http://www.cpes.vt.edu/_media/annual_reports/2002/Report/VolumeIIPartII/1DPS/4.pdf
Great info about smps for tubes (nixie)
Best online info about SMPS for tubes (IMHO) is here:
NEONIXIE-L : Nixie Tube Collectors and Designers
http://groups.yahoo.com/group/NEONIXIE-L/files/Power Supply Designs/
Best online info about SMPS for tubes (IMHO) is here:
NEONIXIE-L : Nixie Tube Collectors and Designers
http://groups.yahoo.com/group/NEONIXIE-L/files/Power Supply Designs/
Just my take on SMPS'
It really boils down to a philisophical(?) question. Yes SMPS' can be made quiet and give good performance.
For me however it is the antithesis of tube gear at its very core. Moments ago I turned down the volume on my system & was nervous of the heat generated by my all SS gear....the Direct TV box, hot to the touch......all my gear creating watts & watts of thermal energy.
I myself have had two computer SMPS' go bye bye...& one X-Box unit.
The current generations of SMPS' are cheaply made by the hundreds of thousands....The PC boards small..the components fully crammed tight.........fans try to cool things down..
Yesterday here it was pushing the nineties F and lo & behold my computer decided its SMPS was too warm so it cycled the fan to its highest speed.....the dang thing howling trying to keep that PS cool!
It just seems to me the tube tenent is to be simple...straightforward, minimalistic.
If we have so much complexity in the support systems for tube circuits...where will it all end?
Will we have microprocessors deciding how our tubes will be run?
We could soon have an on-board computer ramp up our B+.........have selectable ramp curves.....How about voltage monitoring thruout the amp?
How about real-time filament voltage monitoring with out-of-spec auto shutdown?" Your right side 6550 has voltage errors outside its ideal parameters" Can you imagine your future amp talking to you like this?
A lot of designs already have 555 timers set-up for warm up with SS rectification.
I just think sand has no place anywhere near our glowing globes of gas.
Its a creeping thing.........Sand nibbling around the edges, trying to get inside the chassis.....followed by his evil friend..the microprocessor.
Just my two cents.
________________________________________________________Rick......
It really boils down to a philisophical(?) question. Yes SMPS' can be made quiet and give good performance.
For me however it is the antithesis of tube gear at its very core. Moments ago I turned down the volume on my system & was nervous of the heat generated by my all SS gear....the Direct TV box, hot to the touch......all my gear creating watts & watts of thermal energy.
I myself have had two computer SMPS' go bye bye...& one X-Box unit.
The current generations of SMPS' are cheaply made by the hundreds of thousands....The PC boards small..the components fully crammed tight.........fans try to cool things down..
Yesterday here it was pushing the nineties F and lo & behold my computer decided its SMPS was too warm so it cycled the fan to its highest speed.....the dang thing howling trying to keep that PS cool!
It just seems to me the tube tenent is to be simple...straightforward, minimalistic.
If we have so much complexity in the support systems for tube circuits...where will it all end?
Will we have microprocessors deciding how our tubes will be run?
We could soon have an on-board computer ramp up our B+.........have selectable ramp curves.....How about voltage monitoring thruout the amp?
How about real-time filament voltage monitoring with out-of-spec auto shutdown?" Your right side 6550 has voltage errors outside its ideal parameters" Can you imagine your future amp talking to you like this?
A lot of designs already have 555 timers set-up for warm up with SS rectification.
I just think sand has no place anywhere near our glowing globes of gas.
Its a creeping thing.........Sand nibbling around the edges, trying to get inside the chassis.....followed by his evil friend..the microprocessor.
Just my two cents.
________________________________________________________Rick......
Indeed, how dare modern technology threaten to make your amp safer, more efficient or more linear?
I gotta say, I have no idea what you're talking about... We don't listen to an idea, we listen to our system. Whatever makes that better is OK in my book. If SMPS can be used and improve upon an amplifier I say bring it on!!
Isaac
Well, I can understand the sentiments going either way on SMPS in audio. These are complicated devices, many economic compromises can be made, or conversely no expense spared to make the ultimate quiet unit. (satellites with solar panel converters, cell phone tower and communications power sources ...) Even the professional designers of these units are groups of specialists, expert in various facets of the design. Large voluminus texts are the norm for learning the technology.
Linear Tech has made some special chips for quiet designs that may be suitable for DIY, but one still needs adequate test equipment to verify any design and packaging/ shielding. Not to mention FCC licensing requirements. I recently came across some very nice SMPS on Ebay for automatic test equipment that measure just 5 mV noise (100 KHZ) with 160 V output. While testing them, I kept getting large intermittant bursts of HF noise on the scope. I eventually tracked that down to my cordless mouse on the PC. Sheesh!
Don
Linear Tech has made some special chips for quiet designs that may be suitable for DIY, but one still needs adequate test equipment to verify any design and packaging/ shielding. Not to mention FCC licensing requirements. I recently came across some very nice SMPS on Ebay for automatic test equipment that measure just 5 mV noise (100 KHZ) with 160 V output. While testing them, I kept getting large intermittant bursts of HF noise on the scope. I eventually tracked that down to my cordless mouse on the PC. Sheesh!
Don
Greetings,
I indeed intend to use a micro-controller (Arduino) to monitor voltages, for the start-up sequence, to measure bias...etc...etc... I already have picked a name for my amp: Heresy. I am pretty sure that I died burned at the stake in past lives. Once more is of no consequences to me.
Serge
I indeed intend to use a micro-controller (Arduino) to monitor voltages, for the start-up sequence, to measure bias...etc...etc... I already have picked a name for my amp: Heresy. I am pretty sure that I died burned at the stake in past lives. Once more is of no consequences to me.
Serge
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