Need help on Switch Mode Power Supply.
I have a general schematic but but its noisy. I know you can make them very quiet for tubes but i'm not sure how. I know it is going to have to do with frequency filtering.
Does anyone have any experience with SMPs and powering Tube preamps/amps?
Here is a schematic for a SMP running a preamp example. Ideally I would like to get this SMP to output 200v and have it quieter....I just am not sure how we get there.
I have a general schematic but but its noisy. I know you can make them very quiet for tubes but i'm not sure how. I know it is going to have to do with frequency filtering.
Does anyone have any experience with SMPs and powering Tube preamps/amps?
Here is a schematic for a SMP running a preamp example. Ideally I would like to get this SMP to output 200v and have it quieter....I just am not sure how we get there.
An externally hosted image should be here but it was not working when we last tested it.
Well, we can’t help you with your voltage goal because we don’t know what this design is capable of. If you want to attenuate the noise you should put some filtering between the supply and your audio section. Since the current is low try putting a series resistor to the right of S1 followed by a cap to ground. If you can do two or more such filters in series.
The post above is correct though, you’ll have fewer headaches with a linear supply.
The post above is correct though, you’ll have fewer headaches with a linear supply.
Im not familiar with the term. What is a Linear/ passive power supply?
If its with Transformers I get that. My latest build with transformers is using two 120 to 12v 1A transformers ran back to back with a Voltage doubler which gives me 340 volts DC at the plate. But Transformers take up a lot of space so I am trying to think of a different way to power a tube that doesnt require so much space.
You'll still need a power transformer no matter what, for isolation from the AC line.
The physical size of the transformer will be about the same regardless of the supply circuit.
A direct, transformerless connection is never acceptable for consumer products.
You can buy single transformers intended for tube circuits, for AC line to HV and filaments.
Classic Transformers - Hammond Mfg.
Last edited:
No sh!t LOL
But with a SMP or something of the like I can use a 12V external wallwart type power supply instead of internal.
Honestly I could save space by getting a power transformer with the proper power specs too.
But its just a preamp not a full on amp so im not looking to spend $70.00 on a power transformer just to save space.
As it is I got two smaller transformers that I can run back to back that will do the trick. Im just thinking of more creative ways to get to 200v
I’ve used wall wart supplies with a high voltage SMPS. In truth, it didn’t work very well but that was a high gain situation. I actually have some SMPS “chips” to try again. Look at Recom’s R12-150B:
R12-150B RECOM Power | Mouser
Good luck
R12-150B RECOM Power | Mouser
Good luck
I have never even heard of those. I imagine it will work but might need a bit of filtering. The only thing with this is they seem to be pretty expensive.
Every power supply needs “a bit of filtering”. Admittedly, they are pricey - and I plan to put two in series.
With an SMPS I would still be using a Transformer. An example would be I could use a Boss 9v 2000ma which would run through an SMPS circuit in the pedal then step up to 165-200v on the plate a separate circuit would take the 9v before the SMPS and step it down to 6.3 for the heater.
Also I’m talking about making a semi high voltage tube overdrive pedal not a full on amp.
I think pedals tend to use something like those RECOM DC/DC converters when they need high voltage for tubes. or even when they need 24V which some solid state circuits require. This may explain why real tube preamp pedals tend to be expensive, and maybe a bargain at that!
The interesting thing is you can make SMPS for fairly cheap and if you know what your doing you can make them very efficient and quiet.
A guy I know on Facebook builds pedal sized preamps for a living and uses 9v to 450V step up DC to DC converters in his designs and they are nearly silent. Of course he is a real pain LOL He absolutely will not give one spec of his smps design out nor will he help you troubleshoot one you have made.
I have just become interested in them really as a challenge because they are pretty tough to get quiet. As soon as I get some parts in I plan on taking this challenge on. From what i've seen they can usually be made fairly quiet with a LC on the power output consisting of an inductor 220uH coupled with 470uF cap, possibly an RC filter with 33-300ohm resistor and 47-220uF cap depending on different variables of your design. Or if you really like math a Snubber Network will do the trick without a second inductor.