Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Powerful SMPS for tube ampifier
Powerful SMPS for tube ampifier
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th March 2019, 10:04 PM   #1
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
Default Powerful SMPS for tube ampifier

Hello, I designed a SMPS that creates 0 audiable noise in a tube ampifier. Originally this was a school project for a competition but things did not work out quite the way.

The powersupply steps up 10-30V input to whatever output voltage you desire up to the volate rating of the filter capacitor (1kV best estimate of the highest voltage). I have tested the powersupply on a resistive load and I managed to test at 450V 50W without any issues. The tube amplifier I tested the supply on is a well known 20W Mullard amplifier. The amp consists of a pair of EL34s a 12AX7 inverter and driver and a EF86 as the preamplifier. The onl change I did was to use a EF0 instead of the 86, and even it being a very microphonic tube does not create any issues whatsoever and it sound amazing. I designed the amplifier on a PCB and the powersupply too.

Right now the powersupply its been about the third prototipe, has a small issue so without a fan blowind lightly on the switching transformer an the heatsink of the IGBT, gets unbareably hot and the input filter cap too so I guess it acts as some sort of weird oscilator - I havent looked into it any deeper yet I was more interested to hear the amp.

What I would like to know, if there is anyone even lightly interested to see a switching powersupply for a tube amplifier. The current version creates the 410V for the amplifier from anywhere between 12 to 30V. It is also possible to use a different switching tranformer for rectified line votages- why would I use a swtiching powersupply istead of a regular simple transformer on the line voltage? Lets say the voltage if tightly regulated and stable-and this powersuppply is MUCH cheaper than the transformer itself.

Little about myself- Im a students I turned 17 last week and I was protiping this SMPS for about 6 months before i I got to a point of any real useable result. I made lots of amplifiers mostly transistor based or IC based AB amplifiers and Im also into analog technology. So basicaly a nerd

I apologise for the grammar im not a native speaking.

If anyone is interested in any measurements I can do them I do have a digital scope and other testgear to do almost any mesurements I can think of except EMI and interference measurements
  Reply With Quote
Old 28th March 2019, 02:23 AM   #2
kp93300 is offline kp93300  Malaysia
diyAudio Member
 
Join Date: Mar 2007
Hello CaterpillarSK,
I am interested in switching power supply for tube amp.
it is even better if it is stable and have adjustable voltage output .
Are you planning a kit for sale ?
  Reply With Quote
Old 28th March 2019, 03:08 AM   #3
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Powerful SMPS for tube ampifier
This works pretty well. Add a CRCRC with 450v 2.2uF film caps and 47k 5W resistors to clean it up.

Qianson High Voltage DC-DC Boost Converter 8V-32V to ±45V-390V Adjustable ZVS Capacitor Charging Power Supply Module Amazon.com: Qianson High Voltage DC-DC Boost Converter 8V-32V to +-45V-390V Adjustable ZVS Capacitor Charging Power Supply Module: Home Audio & Theater
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 28th March 2019, 08:53 AM   #4
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
I simply created a Fly back SMPS and I basically made the thing bombproof. Uses a transformer of a capacitor charger of the LT7351 BUT I don't use the chip itself to drive it tho. The operating voltage is about up to 1kV if you can get such a filtercap. I can pretty much just use a 10uF 450V cap right after a diode and done. But I noticed even tho I don't hear the hiss at all or see it with a scope on the output, turns out the preamp pentode grabs that 56KHz noise and amplifies it loading the phase inverter . This does not create any issues in the amplifier however I did use a RLC filter just to make sure. Series resistor 10Ohms 470uH and a 100uF 450V cap across the output and a ceramic SMD 630V 100nF capacitor. Makes it nearly dead silent. 1V P-P noise is visible on the scope at the 450V scale. Your plan to use a 47K resistor is only good for preamp stages . It delivers no power. While I provide high power at 400V.

Quote:
Originally Posted by kp93300 View Post
Hello CaterpillarSK,
I am interested in switching power supply for tube amp.
it is even better if it is stable and have adjustable voltage output .
Are you planning a kit for sale ?
No, at least not yet. The prototype version I don't even know which number has still some issues. And its also nowhere near safe to be operated for longer than 10 minutes. Not yet at least until I find out why because it seems to be just a matter of looking at it with a oscilloscope and it seems to be a simple fix
  Reply With Quote
Old 28th March 2019, 02:28 PM   #5
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
UPDATE: so by just about gently blowing on the switching transformer it keeps cool at 40C and I can play allday on the amp. For the ones unfamiliar the Mullard 20W is a 20W RMS amplifier. I have not done any actual measurements of what power goes in the amplifier itself, but I can tell you its a lot more than any chinese high voltage converter can do any day. Its really loud I did not expect it to be this powerfull
  Reply With Quote
Old 28th March 2019, 02:44 PM   #6
kodabmx is offline kodabmx  Canada
Spreading triode love.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
Powerful SMPS for tube ampifier
Quote:
Originally Posted by xrk971 View Post
This works pretty well. Add a CRCRC with 450v 2.2uF film caps and 47k 5W resistors to clean it up.

Qianson High Voltage DC-DC Boost Converter 8V-32V to ±45V-390V Adjustable ZVS Capacitor Charging Power Supply Module Amazon.com: Qianson High Voltage DC-DC Boost Converter 8V-32V to +-45V-390V Adjustable ZVS Capacitor Charging Power Supply Module: Home Audio & Theater
The one you listed is good for a preamp and available cheaper on eBay.

This one is a much better choice for a power amplifier. I've used one for 320V@500mA and it ran cool.
500W 12VDC transfer 18VAC & 0-220v-380v inverter module | eBay

I powered it from an ATX supply.

I would be interested in an SMPS like the OP has made except at the following specs.

90-265VAC input, 300-350VDC 1A output with a 12VDC output for heaters (at least 10A, and capable of starting into cold heaters). Any ideas?

Last edited by kodabmx; 28th March 2019 at 02:48 PM.
  Reply With Quote
Old 28th March 2019, 03:21 PM   #7
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
Quote:
Originally Posted by kodabmx View Post
I would be interested in an SMPS like the OP has made except at the following specs.

90-265VAC input, 300-350VDC 1A output with a 12VDC output for heaters (at least 10A, and capable of starting into cold heaters). Any ideas?
That is one hell of a constructive reply thank you!

The following can be solved- I can power the SMPS with 100-400VDC its all the matter of the switching transformer. for a 10-30V input I use the Coilcraft GA3459 transformer. For a 100-400V SMPS I would need the Coilcraft HA4060 and simply use the rest of the circuit as is, EXCEPT I did not have yet thought into galvanically isolating the HV side YET, with time everything can be solved and the 12V 10A source can be used as a auxilary powersuppply from ebay - those metal shielded supplies- one thing to keep in mind is that those power supplies some of them are audiably noisy on in the way of transferring noise into the amplifier itself but the switching transformer itself inside that powersupply is actually the loud part of the supply. But I tould technically do both on a single board its just nothing I thought yet of because im using a ATX supply to heat the tubes (2X EL34 in paralel and the 12AX7 and the EF80 have the same heater current so I paralled them to each EL-34).

If you would like to see such a powersuppply I could design one, but it takes time to even grab an idea and holdon to it, and also funding. I almost ran out of money building my tube amplifier with my powersupply for a competiotion that did not even work out the way I would like to (they did not even let me to compete- they said the online registration was incorrect thus not taking my work into consideration. But I bet that one old man saw me at the cross country competiton where I won 5th place (agan because of how poeple know eachother) and he probably did that on purpose because the school that went compeeting and it was the shool he was from totally failed to even gain a place.) So I gotta recover from this realitely big spending by doing all sorts of repairs and manufacturing and fixing other devices. I even do computers so wont take terribly long.

ONe detail I did not use a common chip to drive the reansistor I made the entire controller out of 4 op amps because the TL494 has simply a too tight of a voltage regulation and creates all weird noises of raising the PWM and stuff like that. But for a line powered supply it would porbably work best as of simplicity and practicallity. I also dont have the option to make custom trasnformers so Im limited to what I can dig out from real expesive and powerfull schematics that one guy gets me of extreme spec testear that is for sourcing massive currents and the use this kind of stuff. But its easy to find some components as I said the GA3456 transformer was found to be the cheapest and best option from the LT3751 datsheet and it is a high voltage regulator/ capacitor charger. Also the HA4060 is from the same datasheet- Id did try to use that chip but the chip was useless cause I couldnt really find a good footprint for Eagle and it also died during the soldering (I did not have a proper hot air station back then)
  Reply With Quote
Old 28th March 2019, 05:20 PM   #8
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
One small detail- the HA4060 transformer from coilcraft would be safe to use up until 1,5KV (the specs say its islation rating if 3KV). Also the datasheet specifies 500V out max but the isolation rating should be enough to get up to 1kV making it usefull in prettymuch anything from preamplifiers-alltho quite overkill, Powerfull amplifier up to id like to say 100W. The switching frequency is double the GA3459- 100kHz which gives more power crammed into it and nearly no noise that the tubes could amplify. Prettymuch clean DC with quite the practical and light powersupply. So basically halfing the total weight of the amplifier by not needin a power transformer.

The transformer is also shielded completely instead of only flux shielding the coils-I do recommend to use a coaxial cable within the tube amplifier because hissing noises is unacceptable and with a coax cable basically not possible to pick up any noise
  Reply With Quote
Old 29th March 2019, 09:47 PM   #9
CaterpilarSK is offline CaterpilarSK  Slovakia
diyAudio Member
 
Join Date: Jan 2018
Location: Slovakia, Nové Zámky
Since some poeple at EEVBlog also wanted to see the outcome of a mains powered HVPSU, I basically went into it and bought the different switching transformer. I hope that this wont be the last project im making work because I simply dont really feel okay working with mains voltages but hey, its about time to overcome some fears and lets to stuff. So expect some updates in the future about the PSU.
  Reply With Quote
Old 30th March 2019, 01:59 AM   #10
trobbins is offline trobbins  Australia
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
I would recommend a whole lot of caution if going down a mans ac input path.

That is a whole new world of safety and regulations for you, and even more if you want to progress that way in any commercial sense, or don't have any experience in that field.

I can recommend you grow your experience with confirming your thermal outcome, right down to junction temp level, and appreciate how to compare the source impedance of your hvdc supply to a much larger electrolytic cap.
  Reply With Quote

Reply


Powerful SMPS for tube ampifierHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Powersuply Le Bong? HDaudio Tubes / Valves 11 14th February 2007 11:10 PM
Powersuply mystery argo Solid State 6 10th May 2004 01:46 PM
2 trannies on one powersuply Per Solid State 15 10th October 2002 06:42 AM


New To Site? Need Help?

All times are GMT. The time now is 10:50 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki