13.8 volt smps for a kt120 SE amp???

[mike567]

Found this link while surfing DIY UL SE Mono Block.

looks to have a smps for the high voltage

 

[gabdx]

the schematic shows that is for the Heaters.

THe B+ is 400V and +

 

[JonSnell Electronic]

Standard invertor supply from a car battery producing the required voltages to run a valve amplifier in a vehicle or on batteries.

 

[JZatopa]

I would love to hear how this amp sounds and see some specs on how it measures. I am not sure I buy that he is getting 30WRMS out of a single end KT120

 

[mike567]

Many people try to get around the expensive power transformers. Thought this may be of interest.

 

[gabdx]

Nagra used class D power supplies in their 300b pp.

Seems the be the same price to build quality class D. I don't like RF emitting electronics such as the CFL, hydro 'smart' meters and G2s.

 

[jazbo8]

The thread title is misleading, please ask the mod to change it.

 

[TonyTecson]

13.8v is by convention the terminal voltage of an unloaded, fully charged 12volt car battery....

if OP wants to change the tittle, i can do it....

 

[jazbo8]

The 13.8V refers to the input to the SMPS, not the actual filament voltage used by the KT120 - that's misleading...

 

[TonyTecson]

of course, but let us wait for the OP to tell us what he wants us to do...please be patient, we discussed this in the backroom and agreed a title change will help, OP has to ask though...

 

[mike567]

title can be changed. The 13.8 volt was used to bower the entire amp through a SMPS power supply.

 

[TonyTecson]

done....

 

[kstagger]

Telefunken claimed 24Ws @ 7.5% out of a EL156 in single-ended pentode. (If my German skills - which are close to zero - can be believed).
http://www.revoco.cz/data/datasheets/tubes/el156.pdf

I wonder how much power you could get out of a KT120 in UL + transformer loss

 

[PJL Electronics]

I'm getting 24w clean and 36w total power with a kt120, Edcor cxse25-4-2.5k, 4ohm load, and the platform in discussion here. I'm running safely under maximum ratings of the kt120. More to be had if you want to push it to max. The product itself has a surprising low end with any tube and any decent speaker but it is really excels with a kt120 and a high efficiency driver.

 

[stocktrader200]

A 200 watt inverter can be had for about $50.
voltage double the output to get 320v DC. ( smps transformer provides isolation)
mount in tube amp chassis and connect 12v heaters with appropriate resistor (14.4 v running) to 12v ignition.
Tube voltages can easily kill so be VERY careful

 

[PJL Electronics]

A 200 watt inverter can be had for about $50.
voltage double the output to get 320v DC. ( smps transformer provides isolation)
mount in tube amp chassis and connect 12v heaters with appropriate resistor (14.4 v running) to 12v ignition.
Tube voltages can easily kill so be VERY careful

Yes. Both work. Transformers also work well as a multiplier with inverters. Only real downfall to this approach is cost of caps. HF can be cleaned up for pennies compared to dollars and if the design is good it will make extremely clean power. It may be an overkill but I really like the idea of regulation in an automotive environment even if it’s just heaters.

 

[mike567]

I started this thread to see if I could bring out some interest in some alternative power supplies. It seems that I find something that I want to build I have output transformers but no suitable PT and vice versa. I am sure others have a similar problem.

It would be nice to find a relatively inexpensive adjustable or configurable smps for about the same price as a decent power transformer. 250 to 400 volts would be nice. line voltage source if possible or the 12 volt rail from an old computer supply.

 

[Sch3mat1c]

Question:

Is there a market for these things?

I could turn out a few prototypes for you to get a look at, but I don't want to go to the trouble if they aren't worth a damned thing.

In other words, if you'd eBay one from China for $50, that's pointless. I can't *buy* the parts for less than that. But if this is a $200 luxury kind of thing, I'd be interested.

Tim

 

[PJL Electronics]

It would be nice to find a relatively inexpensive adjustable or configurable smps for about the same price as a decent power transformer. 250 to 400 volts would be nice. line voltage source if possible or the 12 volt rail from an old computer supply.

Can you define “decent power transformer” in dollars?

 

[mike567]

I am a DIY'er so I come in at the cheap side of about $60 to $80 for a minimal power supply with sand rectifier and first capacitor. throw in another $15 for a choke which would not be necessary with smps.