Who can/will help me with highvoltage SMPS design for tube preamp

[wrenchone]

Much easier to just use L's and C's...

 

[NickKUK]

Much easier to just use L's and C's...

Which is what most d class use..

 

[Koifarm]

See post 1.

 

[Marek]

Hi,

Has anyone used SMPS successfully as anode PS in tube amplifier?
I'm thinking about using modular SMPS 2,5kV PS for GMI-30 amp. Any checked solutions? air purification, microvawe oven SMPS?

 

[Koifarm]

I have cascaded 3 times 260V smps to get 840V for my FU13 amp.

 

[Marek]

What is the ripple level o this SMPSs? any audible buzz?
Do you use additinal LC filtering?
FU13 in autobias or fixed bias?

 

[jackinnj]

Ron of u-tracer fame is suggesting using a microwave oven trafo for a HV supply.

 

[wrenchone]

I have taken to using DC-DC converters running from switching adapters for a lot of my vacuum-stage projects. That takes the nasty AC interface and locates it outside the box where it belongs. I've used this on an SE amp project using 6L6GC with 6AH6 front end, a 13DR7-based SE headphone amp, and I'll be using a DC-DC in an amp with a folded cascode front end using the 6LR8 with the big pentodes in P-P and an autobias circuit of my own devising. I'll also be using one to generate the negative supply for a mini-aleph clone from a 19V laptop adapter.

 

[Koifarm]

What is the ripple level o this SMPSs? any audible buzz?
Do you use additinal LC filtering?
FU13 in autobias or fixed bias?

About 50mV in the 30kHz region. No humm. No extra LC filter only small C.

And fixed bias.

 

[egellings]

First the choice for an expensive buffer because of the choice for tubes. Then executing it cheapest way. That makes the tubes more a gimmick isn't it?

The choice for DIYing an SMPS will be expensive again so against that philosophy. A lot of work and no certification at all. If SMPS is the choice then ready made is the way to go as all certification/safety/EMI work has been done by the manufacturer. You will need equipment for measuring if the device is not an EMI transmitter for instance. A noble idea on itself but hardly practical/executable in various aspects but hats off if you persevere.

It's easy to avoid the 60/120Hz (or 50/100Hz) hum in a preamp. With such low power consumption DC for the heaters & B+ is easy to get with little complexity using linear regulators. Switch-mode power will certainly work in a preamp, since the switching noise will be well above audibility. I just see it as overkill. In a preamp, power supply efficiency in not an issue in such a low power setting like that. You go with the complexity of switch-mode in high power settings, where efficiency can become paramount, and it's easily worth the added complexity.

 

[Koifarm]

Price of HV SMPS is much cheaper(30 euro) then linear supply(75 euro) for same preamp.
And it is just plug and play. And it sounds super.

 

[ratbagp]

Could you supply the model number for the 300-volt supply.

ray

 

[Koifarm]

https://www.diyaudio.com/community/...-etc-mu-follower-or-srpp.388295/#post-7072634

 

[platon.rado]

I use this one https://www.aliexpress.com/item/100...order_list.order_list_main.103.43031802rPhF3X
No hum!!

 

[ratbagp]

thankyou,

ray

 

[Marek]

What about higher voltage SMPS? eg 2,5kV?
Seems to be problem. I found only Matsusada RC250-2 (up to 2kV and 100mA) or RC250-3 (up to 3V but only 83mA...). Anyway price is not acceptable (1980€).
What about magnetron SMPS? It probalby needs heavy filtering because AFAIK it has no DC but pulsed output.